Passion of the Christ Essay

Becoming A Better Person For most of us, there has been a particular piece of art that has taken great effect on our lives in a positive way. Whether it being a painting, song, or even a movie, these positive influences change us as people, and we don’t even realize it until we actually think about it. The most influential piece of art that has affected me was the movie, The Passion of the Christ, directed by Mel Gibson. This movie is based on the New Testament in the bible; the film primarily covers the final twelve hours of Jesus Christ’s life. The Passion of the Christ has had a profound influence on my life by reminding me of the importance of being a better person. This movie has helped me to become more forgiving of others who betray me, to always be accepting towards the people who surround me, to grow stronger in my faith, and to trust in God’s plan for me. Throughout our lives we all come across a betrayal by someone we care about, and this movie has taught me to be more forgiving towards people who have deceived me. In the beginning of the film Jesus tells his disciples, â€Å"An eye for an eye a tooth for a tooth.’ But now I tell you: do not take revenge on someone who wrongs you. If anyone slaps you on the right cheek, let them slap your left cheek too. Love your enemies and pray for those who persecute you.† In this scene Jesus teaches his disciples that the urge of revenge is sinful; he tells them to pray for the people who mistreat them. This scene taught me how important it is to never fight fire, with fire. Holding a grudge against someone who has wronged you takes a toll on your life not his or hers. One of the most influential scenes in the movie is when Jesus is nailed on the cross to die and instead of cursing the people who wounded him, he tells his father, â€Å"Forgive them, father. They know not what they do.† This line really taught me to be a more forgiving person because if Jesus was able to forgive murderers, adulterers, and the people who nailed him to a cross, then what makes me think I cannot forgive people as well. I learned that hating others only brings poison to my own heart; it doesn’t hurt the people that have betrayed me in any way. Forgiveness is the act of overcoming the feeling of resentment towards someone who has treated you in a wrong way, and this scene reminds me that although others will hurt me, loathing them will only bring darkness upon myself. Not only have I become more forgiving of others, but I have learned to love the people who surround me. It is natural for humans to judge others on the way they look, or what they believe, and The Passion of the Christ taught me to love and accept everyone for their differences. We live in a diverse population with different styles, beliefs, and cultures, and this film has taught me that we are children of God, and we should love each other the way Jesus loves us. There is a scene where Jesus says, â€Å"You are my friends, and there is no greater love than a man to lay down his life for his friends,† My interpretation of this quote was Jesus telling his disciples that he will stand up for them even when no one else will, and this helps to show me how important it is to stand up for what is right. Countless people are mistreated because they are different and this scene reminds me that we are all created equally and should be treated with respect regardless of our disparity. A nother line in this film that has taught me to always love the people who surround me is when Jesus says, â€Å"My commandment to you after I am gone is this: Love one another as I have loved you.† When Jesus knew that he was going to be killed he told his believers that they should continue to love each other just as he has loved them. This scene has taught me the significance of valuing everyone you come to meet, not only because Jesus said it was right, but also because the small act of kindness you share to a stranger may be the only kindness they receive. The catholic religion has always been a great aspect in my life, but ever since watching this movie my faith has developed in multiple ways. The Passion of the Christ took all of my beliefs and expanded them, making them much stronger. The bible stories I have read multiple times were no longer pictures of my imagination, but were all shown to me so authentically. When the cynics told Jesus to prove that he is the Son of God he replied, â€Å"Because you have so little faith. I tell you the truth, if you have faith as small as a mustard seed, you can say to this mountain, ‘Move from here to there’ and it will move. Nothing will be impossible for you.† This excerpt has greatly affected my life because the Catholic and Christian religion is based on having faith in God. Watching the resurrection scene in the film helped solidify everything that I stand for and believe in. When the  non-believers doubted Jesus’ true identity, it reminded me of myself when so mething I had prayed for didn’t turn out as I had wished. This scene showed me that we don’t need physical proof that Jesus is the Son of God because the whole catholic faith is based off of Jesus’ resurrection from the dead. Mel Gibson did a great job making everything so realistic and this guided me towards becoming a stronger Catholic. Having faith in God gives me purpose in life; it creates an understanding, comfort and love with an idea that I have someone to look up to. Amongst my growing faith after watching this film, I also learned to trust that God has a plan for each and every one of us. I grasped onto the thought that wherever I am in the world, and whatever I am going through, it is exactly where I need to be at that moment. When the doubtful man pleaded to Jesus that none of his prayers were being answered Jesus answered, â€Å"Trust in the Lord with all your heart, and do not lean on your own understanding. In all your ways acknowledge him, and he will make straight your paths.† This line from the movie reminds me how important it is to believe that if something is meant to be, it will be. After I truly comprehended the meaning of this quote, it helped me see all the choices I have ahead of me that can alter the direction of my future. I realized that because of this plan I wouldn’t be given any obstacle that I couldn’t handle, and this has made me significantly more patient towards problems that come my way. During the film Jesus also states, â€Å"The heart of a man plans his way, but the Lord establishes his steps,† this reminds me that the choices I choose to make with my own freewill will not affect my final destination in life. This line in The Passion of the Christ has taught me that God will provide all of the resources necessary to help me reach my endpoint; he supplies me with the grace to accept the trials and tribulations to endure any circumstances. Throughout my life I have been given many things to be thankful for, but I have also been given multiple difficulties along the way. The Passion of the Christ helps to remind of the different ways that I can be a better person towards the world. Although this movie is based on Catholic and Christian beliefs, it has the potential to change anyone’s viewpoint on life. If people watched The Passion of the Christ they can learn to become more  patient, forgiving, and accepting towards others. This movie has the ability to change everyone’s outlook on life in a positive way, even if your beliefs differ from the Christian or Catholic faith. The Passion of the Christ Synopsis The Passion of the Christ is an American drama film made in 2004. It was directed by Mel Gibson, and is starring Jim Caviezel as Jesus Christ. This film portrays Jesus Christ’s life according to the New Testament in the Bible; also known as the gospel’s by Mathew, Mark, Luke, and John. The movie primarily covers the final 12 hours of Jesus Christ’s life, flashbacks of Jesus as a child with his mother Virgin Mary, and also briefly displays his resurrection. Works Cited The Passion of the Christ. Dir. Mel Gibson. Perf. Jim Caviezel and Monica Bellucci. Icon Productions, 2004. Film.

Personal, Organizational and Cultural Values Essay

Personal, organizational and cultural values are common approach to understand conflict or success in today global business environment. With the increasingly globalized economy and climate of multicultural workforce, organizations is continuously implementing and establishing desired core values to remain competitive. This paper will discuss how one can reconcile personal, organizational and cultural values in global settings. Personal values develop when the individual start to interact within family, school or religious organization. The followings are considered the core personal values in my life personally: goals oriented, respect, caring and trustworthy. Personal values will always be the foundation for each individual path of life. They are personal belief and philosophy for one to live by. Personal values shape our choices, impact the decision about our ability and how to treat ourselves and others. Experiences and interactions with external units influence the values people deem important to them. Personal values become a personal direction for people on how to live their lives. Ghosh (2008) explains â€Å"The individual’s cognitive moral development stage determines how an individual thinks about ethical dilemmas, his or her process of deciding what is right and wrong in a situation. †(Ghosh, 2008). Organizational values are established rules and polices that each organization believes to be acceptable and logic, professional and practical. Organizational values also provide a basis for employee decision making in the workplace. In my professional career, I have always set my goals to develop the following core organizational values: loyalty, reliability, hard work and commitment. Fenton (2007) explains: â€Å"when organizations articulate their values, they take what are thought to be shared, stable, and deeply held beliefs and communicate them as standards to guide decisions and actions, often with the intent of increasing productivity, improving efficiencies, and acting socially responsible. † (Fenton, 2007). Findings in a Deloitte and Touche Ethics and Workplace survey also reveal the critically important influence that management and supervisors have in promoting ethical workplace behavior by all workers. (Verschoor, 2007). The above mentioned survey explains: â€Å"Management and leadership have a huge responsibility in setting examples for their organizations and living the values they preach if they want to sustain a culture of ethics. † (Verschoor, 2007) Similar to personal values, cultural values are deep-rooted since childhood. Cultural values are developed in social heritage, traditions and reflect psychological, religious or spiritual, and moral experiences. Cultural Values are closely related to personal values since they are developed from the individual tradition, heritage and origin. Cultural values differ in several levels: ethnicity, religion, organization. Different cultures interpret moral and values differently therefore, affect individual interactions in many level. The influence of cultural values has a significant impact on how people and organizations operate and make their decisions. Cultural values affect actions in both personal and organizational level Verschoor, C. (2007) survey also found that more than 91% of working adults are more likely to behave ethically at work when they have a good balance between their job and their personal life. It was said that quality of an employee’s personal life strongly influences job satisfaction and related productivity, the 2007 Deloitte and Touche Ethics and Workplace survey shows that work-life balance also promotes ethical behavior in the (Verschoor, 2007) Values are energizing, motivating and inspiring. When people care passionate about something they will urge themselves with achievement Instilling and maintaining a values-oriented approach to ethics in the workplace, together with giving greater attention to related work-life balance issues, should remain at the top of the agenda of organizations. Employee fulfillment is essential to customer satisfaction, good quality, high productivity, low turnover, and other factors that lead to superior corporate financial performance (Verschoor, 2007) Employees make decisions in the workplace often reflecting value judgment and having ethical connotations. Corporate values are often used interchangeably with the concept of corporate culture. The usual paradigm is that corporations with strong positive cultures have institutionalized a set of corporate values. These values help employees identify with the organization and develop a commitment to its goals (Ghosh, 2008). In conclusion, personal and cultural values have become core elements in today global economy. Organizations calculate and implement these core values with the intent to improve efficiency and productivity, and establish organizational values and standards to communicate to all employees. Personal and cultural values have a major effect in people lives and interactions, and clearly work performance. To be able to find a balance between organizational values and personal, cultural values is the solution to career fulfillment and life satisfaction.

Business Process Inside Companies Essay Example | Topics and Well Written Essays - 1250 words

Business Process Inside Companies - Essay Example The department conducts regular updating of the website with the resent information for the business to cope with the changing environment. The department also has the responsibility of managing the suppliers and vendors in the organization. This is through ensuring that the materials received are in a cost effective manner for the business to make the target profit. There are numerous activities, which are involved in order to ensure that the suppliers and vendors are managed effectively. One of these activities includes the sending and receiving of invoices to customers and from the suppliers respectively. When the materials are received from the vendors, and the suppliers, the department communicates to the department of finance and accounting in order to make payment. The department has also the responsibility of sending the invoices to those customers who have been billed for getting the services from the organization. All these transactions in the organizations have a lot of do cumentation, and the organization has the responsibility of keeping records of transactions in the business. Human resource department In this department, there is the management of the employee in the organization. ... The department also concentrates on the employee benefit systems while keeping the relevant documents of the payment details. The department files the tax on the salaries of employees for the federals purposes of tax payment. There is also the employee evaluation of their performance. The department also keeps records of their performance. The department actively engages in the reviews the performance of employees, for the identification of the best performing employee in the organization, in order for their efforts to be recognized, and awarded through the department there is an arrangement of training and development programs for employees. Accounting and Finance This department deals with the cash flows of the organization. This is in terms of the dealing with the cash payment and receiving of cash, for the monitoring of the cash flow of the organization. There is the coordination with the administration for the receiving of the invoices from suppliers in order to make payments to suppliers and vendors. This department processes the checks for making the payment of invoices. The checks are given to the administration for the payment. In the department, there is also coordination with the HR department for the updating of information about the employee payroll. This updates are made with the motive of making the alteration that are required for the compensation of employees for the services provided to the organization. The department processes the checks meant to make the payment of the employees’ salaries. Mail center The department receives the messages in the organization from the other departments. After receiving the messages, the department in turn does the processing on the message ,in order to identify the

Impact of Racism in the School Environment Research Paper

Impact of Racism in the School Environment - Research Paper Example Academically, a student that suffers from bullying will have low self-esteem and lack the push he or she requires to perform well in school. They may be shy in presenting themselves in the school and have no morale to continue with learning. It is common to see students that suffer from bullying want transfers to other schools. It means that the victim hates the school and would not concentrate on any activity. Their grades in the class drop as they slow or even stop studying in the fear of attack. As a part of the parents protecting their children, they opt to take them to other schools. If the school does not find a solution to bullying, the parent must protect the child (Burgis, 2012). As a measure to curb the harsh results of racism, schools have launch zero tolerance to racism policies. It ensures that students get the appropriate education as expected and do not suffer from any negative forces. The victims of racism are in three groups; students, teachers, and the schools itsel f. While we appreciate cultural diversity, racists take these differences and use them to intimidate others. It is not only students that suffer from racism. A teacher whose culture does not conform to that of the environment of operation may face racism and suffer its effects. The schools' atmosphere is equally affected when bullying and racism are in progress.   Students that face racism may be afraid to go to school. When they remember the embarrassing moments, they resist any attempts to have them go back to the same place.  Ã‚  

Airline Regulation Essay Example | Topics and Well Written Essays - 750 words

Airline Regulation - Essay Example Also, back then, ticket prices did not depend on the time of purchase (Whitaker 7). If a flight was missed for any reason, the ticket is still valid for the next available flight and on any alternate airline flying the same route; all this without any additional cost for the passenger. Reservations too were much simpler – all it took was a phone call. There was enough room to stretch one’s legs and the food was much better that what is being dished up these days (The Economist 67). However, it is through conscious consumer choice - where cheaper prices were preferred to luxurious traveling experience – that the changes came about. Hence, this line of argument for re-regulation is weak and not sound. Much had been said about the reduced prices during the de-regulated period. However, there are some definite costs, though not very conspicuous. The recent plane crash accidents are a good example. The December 1994 crash of American Eagle ATR 72 and the ValuJet McDonnell Douglas DC-10 crash had significantly added to the public unrest. Analysts now generally agree that â€Å"low-cost† is synonymous to â€Å"high-risk†. The airlines industry had promoted the concept of â€Å"low-cost† travel quite successfully, but there is a lot of illusion attached to it. The advertisements don’t reveal the complete reality – minimum seat-pitch, cheap meals, inconvenient scheduling, etc. There is also evidence that security had been compromised on more than a few occasions in the name of cost-saving. In this circumstance, regulative restrictions on the marketing practices of the industry are quite appropriate. The regulations would screen for deceptive or unreali stic claims. It will lead to more factual advertisements that serve the public need for accurate and reliable information. It will also empower the consumer in demanding more stringent security standards, especially in light of the events of September the 11th. (Whitaker 7) An

JULIAN OF NORWICH & MICHAEL HARNER Assignment Example | Topics and Well Written Essays - 500 words

JULIAN OF NORWICH & MICHAEL HARNER - Assignment Example So while Julian talks about Christ being â€Å"the foundation, he is the substance, he is the teacher, he is the end†, Harner talks about the matter of fact aspects of the tsentsak and non-drug forms of shamanism in ordinary, factual language (Harner 57-68; Julian of Norwich 43). Both sources narrate forms of spiritual quests, and a common element in both is a sense that both are honest and sincere in their quests and in the way they tried to make sense of their experiences and visions. This is important because both are narrating extremely subjective experiences whose validity cannot be experienced or confirmed by an external party, but only felt as genuine and believable from an intuitive point of view. The integrity of the narrators can make or break the narratives. One gets a sense of the integrity of Harner’s narratives especially with regard to the subjective experience of ayahuasca, confirmed by a blind shaman for instance. For Julian, her reputation and the internal consistency of her message attest to the sincerity and the genuineness of her narratives and religious insights (Harner; Julian of Norwich). Julian contextualizes her sufferings in the context of Christ’s own suffering and death, couched in language tied to compassion and love. She learns from a desire to suffer the bodily pains and sufferings of Christ also of the internal reality of the compassion that exists in men as a spark too of the divine in men, of the Christ in men. Her key insights are with regard to the love of God shown through the Christ’s own passion, so that she and all who love God and desire to follow the will of God may experience that love as well (Julian of Norwich). The sacred drink ingested by Harner is ayahuasca. When he ingested this he had visions of another dimension, including that of a creature that is reptile-like, who reveals to him an inner reality tied to the nature of man’s past, of the way man had evolved

Low Production and High Unemployment Essay Example | Topics and Well Written Essays - 1000 words

Low Production and High Unemployment - Essay Example A change in either the demand or the supply will cause a similar shift of the other. However, for an economy to experience sustained economic growth and equilibrium, it must step up its factors of production such as labour, capital, and land. Several economic indicators depict the state of an economy and the stage (Frenkel, Razin 29). The Growth Domestic Product (GDP) is a total market value of goods, and services produced and consumed, investments, minus government spending plus the exports minus the imports. A GDP of a country depicts what is happening now in an economy. Rises in the GDP depicting a rise in the economy while a drop in the GDP depicting a recession. In this scenario, country A has a RGDP, which means that its GDP has fallen. Its economy has shrunk, by the amount of the GDP drop. A Second indicator of an economy is the rate of unemployment that describes an economy after it happens. An increase in the rate of unemployment depicts a lagging economy. A country is said to be in a long run economic equilibrium when no firm in the industry wants to leave or enter the market. In this state, no existing firms make losses and those entering the market make losses. Every firm produces at the efficient cost of production and the maximum profit they can make is zero. This means that price is equivalent to average cost of production (Osborne Web). ... In country A, high levels of unemployment depict a recession. Country A is not in an equilibrium state, meaning that it has to undertake some fiscal and monetary policies to take it to this level. A fiscal policy is a tool used by the branches of government via either spending or taxes to attain a desired change. It is an act done with a conscious mind and geared towards effectiveness and efficiency. For country A that is in a recessionary period, imposing taxes will make the situation worse. Therefore, first, country A will have to increase government spending in the areas it deems fit. This king of fiscal policy is called expansionary that increases the government spending and decreases the taxes. This will increase the government budget deficit to increase and lead the country to a long-run equilibrium. According to Keynes, a government can achieve a real GDP every year through market mechanisms where it influences prices and wages, which they assume to be flexible. They believed that in a recessional economy one should not wait for the prices to go down but instead an expansionary fiscal policy can be used. The government should ensure that its spending is higher than the current tax receipts. This way the level of unemployment will fall as the unemployed persons get to work in the government projects increasing their purchasing power. Secondly, the government can engage in purchasing of bonds to release more fund to the corporate and to individuals. As people gain purchasing power, they will invest in various categories of businesses or even purchase goods increasing demand. Price levels will go up, employment levels going up and eventually raise the RGDP. Thirdly, to achieve a long run

Session Planning Essay Example | Topics and Well Written Essays - 500 words

Session Planning - Essay Example However, these requirements are different for Bass players. They will play directly from our solid-state pre amps and direct boxes for direct recording. Please be advised to use strings in your guitar and don’t forget to tune them a several times before the session for the correct pitch. For keyboardists, please note to bring your own keyboards and its stand. You are required to bring your own power cables, pedals and manuals. Although, we have different MIDI gear and other devices available at the studio but we would advise you to use your own for better sound quality. Similarly, Drummers need to bring their own drums to the studio on the day of session. Before final recordings make sure the heads are newly installed along with pedals that do not squeak at all. Drums should be finely tuned before the session. For vocalist, please rehearse again and again to know the notes and lyrics by heart. Make sure you know all the highs and lows of the notes required in your song. Musicians required will be: One drummer, one keyboardist, two bass guitarists, one on electric guitars, a vocalist with three background supporting vocalists and other musicians if required any by the band. The setting of the musicians is set apart so their mics will not interfere with each other. We have made sure that there should be enough distance between vocalist and the drummer and between the guitarists and the keyboardists. There are 9 tracks to be played in the session. 5 out of 9 tracks will be recorded on acoustic guitars whereas; the remaining 4 songs will be pop/country. They would be the unplugged low versions. Each day each song will be given approximately 5-6 minutes during the entire session including the rehearsals. The people apart from the musicians will consist of our technical team, studio engineer, sound engineer and the management. Please avoid bringing any

Ethnic study Essay Example | Topics and Well Written Essays - 1250 words

Ethnic study - Essay Example This is because man is a giver and female is a receiver in a sexual encounter .However, homosexuality has been succumbed to many prejudices and arguments, but still it continued to persist as an ever forbidden pleasure for male population. Men have always dominated sexual rights, and women were restricted and tabooed from experiencing sexual activities like men do. Men have been given more opportunity to explore their sexual desires whereas women have been condemned from following her whims and fancies about sex. It was considered natural for men to practice any means to satisfy his sexual needs as it was his utmost biological or physiological need. However the author, Mathew Guttman considered that such outward sexual fantasies of men have led to the practice of homosexuality among them which led to AIDS and other sexually transmitted diseases. â€Å"The notions of â€Å"men natural sexual desires† were blamed for a host of health problems like AIDS on Oaxaca†(Guttmann ,3). It is a common perception that all men carry same sexual desires and wants and all want to have sexual encounter with women in order to reach pleasure and satisfaction. But the fact is different, as various men indulge in different sexual acts with different gender to accomplish their sexual fetishes. They predominantly are sexual beings, and their needs are more connected to the body than mind, and, want their urges to be met invariable of the sexual object of desire. According to the author, men are not heterosexual always as most people think, many keeps a secret sexuality of themselves which they tend to explore in hides -out or darkness. Birth Control Issue Birth control is practiced among Mexican families for the main objective of restricting the birth of children and to give men more chances of indulging in sexual pleasures. Since generations, women have been given contraceptive methods to stop themselves from getting pregnant. In Mexico, men are more concerned about the reproductive health and sexuality and birth control measures are taken keeping in mind these two said factors. â€Å"It is just too obvious that much of the decision making – about what birth control methods , about what antiretroviral treatment for people with HIV and AIDS, are available – take place in boardrooms of pharmaceutical companies of Basel, Switzerland and New Jersey†(Gutmann,14).This shows that the men and women have little control on the birth control decision making and they depend on foreigners and medical specialist for this purpose. The main issue regarding gaining information on sterilization among Oaxaca men is tedious. Most of them men are deceitful when it comes to explaining the real reason behind their choice of sterilization. However, most men resort to sterilization for not taxing women’s health too much as they are the one who always get succumbed to contraceptive methods and techniques in earlier tiems. The men even want to ha ve more sexual experience with women and if they are sterilized they can engage in sex with female partners more frequently and carelessly. The medicalization of men sexuality, is another major concern of Mexican nation. The author here means that, sexual activities and phenomena of men in Mexico should be a subject of concern among the health care reforms and medical centers. They should study why men are infected with HIV and should stop the widespread of disease across the

The Birth of American Imperialism Essay Example for Free

The Birth of American Imperialism Essay The United States of America was founded on July 4, 1776 and has fought three wars before the Spanish-American War. The United States has fought numerous times for different reasons. The States fought Britain for their independence in 1776, and then in 1812 they fought Britain because American ships were being taken prisoner by the British for no apparent reason. America stood up against the British and let them know that was going to push America around. America also fought against itself trying to preserve the nation and keep The United States as one and from not separating. The United States of America unified again in 1865 becoming one with unified ideas. In 1898 the United States fought a new enemy for new reasons, but these reasons were not justified and not appropriate to declare war on Spain. In the 1890’s the United States attitude turned much aggressive and expansionistic than it had ever been. There was in fact a lust for forming colonies. What triggered the war was the blowing up of the Maine Battleship. The blame was put on Spain’s shoulders believing the Spanish had a hand in the destruction of the Maine. Years after the end of the war investigators have concluded that the Maine blew up due to the boiler room overheating and blowing up. The Spanish-American War is the most unnecessary war of all-time and could have easy been avoided if America did not declare wars on other nations solely on belief without any evidence. The defeat of the Spanish forces marked the end of their rule in the Americas and also marked the rise of the United States as a global military power. The Spanish-American War affected the United States in a number of other ways. It helped speed the construction of the Panama Canal and also resulted in the U. S. s acquisition of foreign territories. This war marks the being of American Imperialism, and the beginning of American intervention in other countries. Before the war and before the explosion of the USS Maine there was a lot of tension between America and Spain at the time. The United States and Spain all most started a war when Spain captured an American ship in 1873. The captain and the crew were executed on charges of having rebel leaders aboard (Gay 9). There were many reports of U.  S citizens in Cuba being imprisoned or murdered. Spanish officials even confiscated U. S property (Gay 9). Also, Americans living in Cuba were captured and sent without trial to this prison known as Morro Castle (Gay 23). Also, Cuba was rebelling against Spanish rule and wanted its own independence. Constant fighting between Spain and the natives became deadly. Cuba was an important colony for the Spanish. The islands export sugar, tobacco, and other raw materials were traded by the Spanish to generate great amounts of wealth (Bachrach 15). In January 25, the USS Maine arrives in Havana, Cuba. The Maine is there to protect Americans in Cuba against the riot occurring in Havana (Bowan 103). February 15, the USS Maine while docked in the Havana harbor is rocketed by two explosions. The ship begins to sink killing 266 U. S sailors (Bowan 104). The United States places the blame upon Spain for the destruction of the Maine and in April the United States and Spain break off diplomatic relations. The U. S president orders a naval blockade of Cuba’s ports (Bowan 104). McKinley stressed that the United States had tried to remain neutral, but too many Americans were treated inhumanly in Cuba by the Spanish (Gay 28). In 1823, the Monroe Doctrine stated that further efforts by European governments to colonize land or interfere with states in the Americas would not be accepted by the U. S. , but Spains colony in Cuba was exempted. In 1890, Captain Alfred Thayer Mahan wrote The Influence of Sea Power upon History, which credits the rise of Britain to world power to the Royal Navy. Mahan’s ideas on projecting strength through a strong navy had a powerful worldwide influence. Historians debate how much Americans were interested in obtaining an empire, while noting that the European powers had in recent decades dramatically expanded their empires, especially in Africa and Asia. The United States had great interest in the England motto, which was make the world England. The United States wanted to colonize, take over new territories, and expand. Unfortunately, America’s ambitions were inopportune for the current state of the world, because most of the world was colonized and had governments. America probably pinned the blame of the Maine blowing up on Spain to grab new territory and some other spoils of war. On April 23 President McKinley called for a hundred twenty five thousand volunteers, more than a million men answered the call (Golay 41). The U. S Navy’s Asiatic Squadron, is headed by Commodore George Dewy. He is based in Hong Kong, China. His job is to combat the Spanish in the Pacific (Bowman 104). Amazingly the U. S had so little information about the Philippines that Dewey had to buy charts of Manila Bay from Hong Kong (Golay 22). In the early hour of May 1, 1898, Dewy spots the Spanish fleet 5 miles south of Manila. The U. S fleet sails towards the Spanish fleet (Bowman 107). Dewey’s ships have destroyed the majority of the Spanish fleet and captured the remaining Spanish fleet. The Spanish lose more than 400 men. Only 6 Americans die or are wounded. When word reaches America of Dewey’s victory he becomes a national hero (Bowman 107). Dewy stays in Manila harbor with his fleet to keep the German Navy from the weak situation in the Philippines. The U. S does not want Germany to take territory or resources from the Philippines (Bowman 107). Following Deweys victory, Manila Bay was filled with the warships of the United Kingdom, Germany, France, and Japan; all of which outgunned Deweys force. The German fleet of eight ships were in Philippine waters to protect German interests acted provocatively cutting in front of American ships, refusing to salute the United States flag, taking soundings of the harbor, and landing supplies for the besieged Spanish. The Germans, with interests of their own, were eager to take advantage of whatever opportunities the conflict in the islands might afford. The Americans called the bluff of the Germans, threatening conflict if the aggressive activities continued, and the Germans backed down. At the time, the Germans expected the confrontation in the Philippines to end in an American defeat, with the revolutionaries capturing Manila and leaving the Philippines ripe for German picking. Most of the Spanish fleet is anchored in Santiago. The commander of the Spanish fleet is Pascual Cervera. He does not want to challenge the U. S, because he knows that he is out gunned (Bowan 109). On 1 July, a combined force of about 15,000 American troops in regular infantry and cavalry regiments, including all four of the armys Colored regiments, and volunteer regiments, among them Roosevelt and his Rough Riders, the 71st New York and 1st North Carolina, and rebel Cuban forces attacked 1,270 entrenched Spaniards in dangerous Civil War-style frontal assaults at the Battle of El Caney and Battle of San Juan Hill outside of Santiago. More than 200 U. S. oldiers were killed and close to 1,200 wounded in the fighting. Supporting fire by Gatling guns was critical to the success of the assault. Cervera decided to escape Santiago two days later. The Spanish forces at Guantanamo were so isolated by Marines and Cuban forces that they did not know that Santiago was under siege and their forces in the northern part of the province could not break through Cuban lines. This was not true of the Escario relief column from Manzanillo, which fought its way past determined Cuban resistance but arrived too late to participate in the siege. After the battles of San Juan Hill and El Caney, the American advance ground to a halt. Spanish troops successfully defended Fort Canosa, allowing them to stabilize their line and bar the entry to Santiago (Bowan 109). The Americans and Cubans forcibly began a bloody, strangling siege of the city. During the nights, Cuban troops dug successive series of trenches toward the Spanish positions. Once completed, these parapets were occupied by U. S. soldiers and a new set of excavations went forward. American troops, while suffering daily losses from Spanish fire, suffered far more casualties from heat exhaustion and mosquito-borne disease. At the western approaches to the city, Cuban general Calixto Garcia began to encroach on the city, causing much panic and fear of reprisals among the Spanish forces. The success at the two forts on July 1, 1898 combined to give the Americans command over the ridges surrounding Santiago. By July 3, the American forces had demolished Admiral Pascual’s Spanish fleet there. On July 17, the Spanish surrendered the city (Nelson 111). There was likelihood that the Spanish could carry the War onto the Atlantic seaboard cities of the U. S (Golay 31). The Spanish Admiral Cervera could not have raided the U. S coastal cities because they had no charts of the Atlantic Seas (Golay 33). The Spanish fleet attacks the seven American ships. After four hours of gunfire the Spanish ships are all sunk. The Spanish have 474 dead while the Americans only suffer 1 fatality (Bowan 109). On 7 August, the American invasion force started to leave Cuba. The problem was fiebre amarilla, yellow fever, which had quickly spread amongst the American occupation force, crippling it. A group of concerned officers of the American army chose Theodore Roosevelt to draft a request to Washington that it withdraw the Army, a request that paralleled a similar one from General Shafter, who described his force as an â€Å"army of convalescents† (Bowan 111). By the time of his letter, 75% of the force in Cuba was unfit for service. The evacuation was not total. The U. S. Army kept the black Ninth Infantry Regiment in Cuba to support the occupation. The logic was that their race and the fact that many black volunteers came from southern states would protect them; this logic led to these soldiers being nicknamed â€Å"Immunes†. Still, by the time the Ninth left, 73 of its 984 soldiers had contracted the disease. The Treaty of Paris was signed December 10, 1898, settled the conflict that had resulted in the Spanish-American War( Nelson 111). As a result of the Spanish-American war, which lasted for only four months from April 25 to August 12, 1898, the treaty gave Cuba independence. Andrew Carnegie the richest man in America wrote a personal check for twenty million dollars to buy Philippine independence (Marrin 150). The U. S would pay 20 million dollars for the Philippines. The Philippines would become a common wealth in November 1935 (Nelson 112). U. S. also acquired Puerto Rico and Guam. By gaining these territories it helped America gain some more resources. Also the result of the war leaves thousands dead on each side of the playing field and many more wounded. These deaths could have been avoided if only the United States did not jump to conclusions and did not use the Maine incident to enter a war in order in gain new territory. In the end, U. S. goals were overwhelmingly achieved. They succeeded in securing Cuban independence, removing Spanish forces from the Americas, establishing themselves as a world and military power, and also accomplished much more, with minimal losses. Other positive outcomes from the war include a positive change in the army, a surge in the economy, and as well as a strong international political influence. Senator Thurston of Nebraska said before the war: War with Spain would increase the business and earnings of every American railroad, it would increase the output of every American factory, and it would stimulate every branch of industry and domestic commerce. All of these predictions, indeed, turned out to be results of the Spanish-American War. The United States, both as a nation and as a people, prospered tremendously from this war. The United States birth as an imperialistic power occurred during the Spanish-American War.

Development of CT Scans for Cancer Studies

Development of CT Scans for Cancer Studies According to the statistics presented by the World Health Organization (WHO), with around 7.4 million deaths (around 13% of the total death) in 2004, cancer is the leading cause of death throughout the world (WHO, 2009). These levels are expected to rise further in future, with an estimated 12 million death in 2030 (WHO, 2009). There are more than 100 different types of cancer (Crosta, n.d.), among them the Lung cancer, stomach cancer, colorectal cancer, liver cancer and the breast cancer are the most common types. Tobacco is the most important risk factor for cancer, with nearly 1.3 million deaths per year just due to lung cancer alone (WHO, 2009). Cancer At the primary level, human body consists of large number building blocks, called the cells. Under normal circumstances, new cells are formed by the body depending on the body requirement, in order to replace the dead cells. But sometimes, under abnormal conditions, there is an exponential (uncontrolled) increase in the formation and growth of new cells. The accumulation of these extra cells forms mass or lumps of tissues, called the tumor (National Cancer Institute, 2010). Most of the cancers, in general form tumors, but there are certain exceptions, like leukemia, that do not form tumors (in leukemia or blood cancer, the cancer cells hinder the normal blood functions due to abnormal cell disintegration in the blood stream (Crosta, n.d.)). The tumors can be of two types; benign tumor and malignant tumor. The benign tumors do not propagate to other sections of the body and have restrained growth (Crosta, n.d.), whereas the malignant tumor cells have the ability to invade into the sur rounding tissues. Also the malignant tumor cells can escape from their initial location and spread to other sections of the body through blood or lymph. Only the malignant tumors are cancerous in nature. Therefore, the cancer has three distinctive properties that distinguish malignant tumors from benign tumors: Uncontrolled growth Invasive nature Metastasis (ability to spread to other sections of the body) These disorders in cells are the result of the interaction between the genetic factors and external agents (which are called carcinogens) (WHO, 2009). The carcinogens can be categorized as (WHO, 2009): Biological carcinogens, like certain bacteria, viruses or parasites. Physical carcinogens, which includes the high energy radiations (ionizing radiations). Chemical carcinogens, these include substances like tobacco smoke, arsenic (water contaminant), aflatoxin (food contaminant), asbestos etc. Another factor essential in the development of cancer is the age. According to the studies conducted by the Cancer Research UK, the risk increase predominantly with increasing age, with nearly 74% of the cases of cancer diagnosed in people aged 60 and above (Cancer Research UK, 2009). Cancer Treatment Principle In case of normal cells there is specific pattern of growth, division and death (orderly destruction of cells is called apoptosis) (Crosta, n.d.). It is known that the cancer is the result of the uncontrolled growth of cells which do not die (Crosta, n.d.), that is, the apoptosis process fails in the cancer cells. The cancer cells thus do not die and rather continue to grow, resulting in the formation of tumors. As the problem in the cancer cells lies in the DNA, therefore a possible treatment of cancer is the destruction of the DNA in cancer cells, leading to a self initiated destruction of the cells. There are various methods used for the treatment of cancer depending upon the type of cancer. The most common types of treatment are (Fayed, 2009): Surgery Chemotherapy Radiation therapy or Radiotherapy Biologic or Targeted Therapy Radiotherapy Radiotherapy, also referred to as radiation therapy, is one of the most common types of treatments used for cancer. It is the utilization of higher energy radiations like x-rays, gamma rays in order to kill cancer cells, treatment of thyroid disorder and even some blood disorders, in a particular section (effected part) of the body (Nordqvist, 2009). The high energy ionizing radiations can be produced using a number of radioactive substrates like Cobalt (60Co), Radium (228Ra), Iodine (131I), Radon (221Rn), Cesium (137Cs), Phosphorus (32P), Gold (198Au), Iridium (192Ir), and Yttrium (90Y) (Howington, 2006). The cancer cells have the ability to multiply faster than other body cells. The high energy ionizing radiations are more destructive towards the faster growing cells, and thus they damage the cancer cell more than the other body cells (Mason, 2008). These high energy radiations like gamma rays and x-rays; especially damage the DNA inside these cancer cells (or tumor cells) thereby annihilating the ability of the cells to reproduce or grow. Apart from treatment of cancer, radiation therapy is also used to shrink a tumor before being surgically removed (Mason, 2008). Depending upon the method of irradiation, the process of radiation therapy is categorized into two forms (Mason, 2008): External Radiotherapy In this method (more common), the infected part of the body (tumor) is irradiated by high energy x-rays from outside the body. Internal Radiotherapy For this method, a radioactive substance are injected (or taken orally) into the body (close to the tumor) in the form of fluids. These substances, taken up by the cancer cells, radiate the tumor through internal beam radiation (or interstitial radiation) (Mason, 2008). Radiotherapy Planning A careful planning is essentially required for radiation therapy, as over exposure can be critically dangerous to healthy tissues in the body. The ionizing radiations have side effects, therefore once the full dose of radiations is decided; the patient is given these radiations in the form of small doses in a series of therapy sessions (Cancer Research UK, 2009). Each small dose of radiation is called a fraction. The gap between sessions provides the recovery time for the body, which may depend on the type of cancer and patients health condition. The area of the body that is radiated during the treatment is called the radiotherapy field and the section inside the body that experiences the maximum exposure dose is called the target volume (Cancer Research UK, 2009). The doctors decide the marginal area around the tumor that should be radiated to encapsulate any movement of the cancer cells. In order to accurately determine the position of tumor (or target volume), body scans are done. Computed Tomography (CT) scans are done as a planning procedure, this provides vital information regarding the location of the tumor as well as the kind of treatment required by the patient (Cancer Research UK, 2009). The radiotherapy treatment planning process can be divided into 6 major steps . Computer Tomography (CT) Scan The invention of Computer Tomography (CT) scanned is credited to Sir Godfrey Hounsfield in early 1970s, for which he along with Allen Cormack, was awarded the Nobel Prize in 1979 (Smith, n.d.). A CT scanner, also known as the Computed Axial Tomography (CAT) scanner uses X-rays to produce cross sectional images (or slices) of the body like a slice in a loaf of bread (FDA, 2010). The word tomography suggests the process of generating a two-dimensional image of a slice or section through a 3-dimensional object (a tomogram) (Nordqvist, 2009). These cross-sectional slides render an accurate picture of the size and location of the tumor along with the position of major organs in the body (Cancer Research UK, 2009). This would be essentially useful during the radiotherapy process, where these can be used to lower the dose of radiations on the organs. It is known that in case of radiation therapy treatment, the doses are given in fractions over a certain period of time (to prevent major side effects), which may vary from few weeks to months. Thus, before each fraction of radiation dose, computed tomography (CT) scan of the patients is done to determine the exact location of the tumor or cancer cells. So in case the full dose has been divided into 30 fractions, then the patient has to undergo 30 CT scans, each before a fractional therapy. The machine used for the radiation therapy planning is known as the simulator (Cancer Research UK, 2009). The simulator identifies the position of the tumor and marks the position of radiation on the body with the help of light rays. The radiographer uses ink markers on the body before the actual radiotherapy is begun. These linear ink marks are used by the radiographer for positioning the machine for radiotherapy (Cancer Research UK, 2009). Simulators take the pictures (CT scans) in the form of X-rays, which locates the accurate tumor position for the radiographer to carry out the treatment. During a CT scan, it is essential that the person remains completely still so that the measurements are accurate. In order to insure the correct position supports like neck rest, chest board or arm pole are used (Cancer Research UK, 2009). In case of children it is ensured by giving proper sedatives. Sometimes, under critical condition, extra measures are taken in order to prevent essential organs from being radiated during the therapy. These measures include injecting fluids or dyes which mark the position of vital human organs in the CT scan (Cancer Research UK, 2009). These markers may be given orally, through injections or rectally depending upon the requirement. Using this vital information from the CT scans, a treatment plan for radiation therapy is prepared. This plan indicates the position and direction of the radiations during the therapy, so as to minimize the exposure of healthy cells and organs. The scans generated by a CT scanner are in the form of 2 dimensional (2-D) slides, but by the used of digital geometry processing they can be used to generate a 3 dimensional (3-D) images of the body (Nordqvist, 2009). This can be achieved by integrating all the slides (along the same axis) together using a computer system. The CT scan can be understood as a technically advanced format of X-rays machines. The x-rays images are produced by the projection of a broad beam of x-rays on a film after passing through the body (Medindia, 2010). It provides a 2-dimentional projection of the body, where much of the information is lost. In case of CT scan, a thin beam of x-rays is absorbed by the detector after passing though the patients body (Medindia, 2010). Like the x-ray process, the CT scanning is a painless process for the patients but has been known to be accompanied with some side effects. These side effects may vary from the patient to patient depending upon the amount of radiation dose and health of the patient. The detailed discussion on the health effects of CT scanning has been discussed in the later sections of the project. Theory In order to understand the working of a computed tomography (CT) scanner it is essential to understand the properties of ionizing radiations (X-rays) used in the scanning process. The electromagnetic radiations are the arrangement of electric-field and magnetic-field vectors perpendicular to each other and also perpendicular to the propagation direction of the wave (Resnick et al., 2009). These Electromagnetic radiations have penetrating powers, which are directly dependent on the energy (or frequency) of these radiations. So that radiations with higher frequency have higher penetration powers. Therefore, on the basic the energy, the electromagnetic radiations are categorized as Non-ionizing radiations and Ionizing radiations. Non-Ionizing radiations refer to the electromagnetic radiations which have energy lower than that required for an atomic ionization (MIT, 2001). The non-ionizing radiations include radio waves, micro waves, visible light etc. These radiations have lower penetration powers. Alternatively the Ionizing radiations are the high frequency radiations which have enough energy to knockout an electron from an atom and thus causing ionization (MIT, 2001). The Gamma rays and X-rays are the common type of ionizing radiations. Even the alpha particles and beta particles emitted in a nuclear reaction are ionizing radiations (MIT, 2001). Due to the higher energy they have higher penetration power than the non-ionizing radiations. Principle of CT Scanning The most important section of a Computed Tomography (CT) scanning is the interaction of the ionizing X-ray radiations with the living tissues in the body. When the ionizing radiations (X-rays) interact with the living tissues in the body, they break up atoms and molecules from the living tissues and disrupt chemical reactions within the body (Zamanian Hardiman, 2005). The intensity of absorption of the x-ray radiations by the body varies depending upon the tissue coming in interaction. Different body tissues have different absorption power, where some are permeable to x-rays others are impermeable (Medindia, 2010). It is due to this difference in the absorption ability of different sections of the body, which results in the generation of a graded pattern in the scans. High density tissues like the bones appear white in the scan while the soft tissues (like brain and kidneys) appear dark. The cavities (like the lungs) are seen as black sections in the scan (Medindia, 2010). Therefore, this gradation in the pattern can be used as method to distinguish different body organs depending upon their absorption capacity. This forms the basic principle behind the working of an X-ray scanning. Radon (1917) was the first to develop the principles of computed tomography (CT) mathematically (Bushberg et al., 2002). According to Radon, with the help of infinite number of projections through an object, it could be possible to produce an image of an unknown object. In case of film imaging (as in conventional X-rays), a two-dimensional (2-D) projection of the body is generated on the film. Due to this, details in the dimension of the body along the direction parallel to the x-ray beam are lost. In order to overcome this drawback (only up to a certain level) projections can be taken along two directions; posteroanterior (PA) projection and lateral projection (Bushberg et al., 2002) (as shown in Figure 4). Increasing the number of scans improves the amount of information but in critical and complex cases where much more details are required. For these critical cases, CT scan is done. The CT scan provides the tomographical image, which is the picture of patients body in the sections or slabs. The thickness of these uniform slabs may vary from 1 millimeter to 10 millimeter (Bushberg et al., 2002), according to the program, depending upon the requirement. Each CT image consists of an array of large number of pixels forming a two dimensional (2-D) image, which corresponds to the same number of three dimensional thin rectangular slabs called the voxel. The voxels are the volume element whereas the pixels are the picture element (Bushberg et al., 2002). Every ray from the X-ray source passes (transmits) through the patient before the transmission measurement is done by the detector. Intensity of the un-attenuated x-ray radiation emitted by the source is Io whereas the intensity of the attenuated radiation after transmitting through the patient is given as It. The intensities Io and It are related by the equation (Bushberg et al., 2002):   Ã‚  Ã‚  Ã‚  Ã‚  It=Ioe-ÃŽ ¼t   Ã‚  Where;   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚ µ is the total linear attenuation coefficient of the tissue (Smith, n.d.).   Ã‚  Ã‚  Ã‚  Ã‚  t is the distance travelled by the radiation in the tissue i.e. the tissue thickness. The coefficient  µ is dependent on the atomic number and electron density of the tissues (Smith, n.d.). Higher the atomic number and electron density of the tissues, higher would be the attenuation coefficient (Smith, n.d.). This form the basic principle of CT scanning, that different tissues have different level of attenuation properties depending upon their atomic number and electron density. For every measurement, the overall attenuation coefficient is calculated using the above equation. During a complete 360o ­ scan, various transmission measurements for the intensity of X-ray photon are done. Using these intensity measurements specific attenuation values are allotted to every voxel (volume element). These attenuation numbers are directly proportional to the linear attenuation coefficient. The average of these attenuation values is called the CT number (Smith, n.d.). These values can be arranged on a linear scale, the units of which are called the Hounsfield units (HU). The scale for modern CT scanners varies from approximately -1,000 to 3,000 HU. The attenuation scale is based on binary system and therefore the exact values range from -1,024 to +3,071, with a total of 4,096 (or 212) attenuation numbers. Here, the lower represent the black section while the higher values represent the white section of the CT image. On this scale the attenuation value of water is zero HU and that of air is -1,000 HU (Smith, n.d.). Both of these values act as the reference points. Construction of a CT scanner CT scanner is a complex machine, but the basic structure is simple. A common CT scanner has been shown in Figure 2. Two most important parts of a CT scanner are the X-ray source and detector. The source and detector are placed in a circular structure, which has a shape similar to a doughnut. This doughnut shaped circular opening is called the gantry (RadiologyInfo, 2009), with an inner (opening) diameter varying from 60 cms to 70 cms. The X-ray source and detector are placed exactly (diagonally) opposite each other, so that the radiations emitted by the source pass through the body and the transmitted radiations are measured by the detector. The x-ray source and detector system in the gantry is motorized to rotate around the patient for measurements in different projection angles. The rational speed of the system is adjusted according to the detectors ability to measure and convert the x-ray beam into electronic signal. Cobalt (60Co) is generally used as the source of x-rays in the CT scanners. The detector used in CT scanner consists of an array of detectors in a slightly curved shape (like a banana). This curved shape is especially useful in fan-shaped beam projects. Two types of detectors are generally utilized in the CT scans; solid state or scintillation detector and Xenon gas detector (Reddinger, 1997). But the solid state detectors with scintillators like Cadmium Tungstate (CdWO4), yttrium, gadolinium ceramics etc are commonly used (Bushberg et al., 2002). The principle of the scintillation detector is that, when it is struck by a x-ray photon, it produces light. This light signal is then transformed to electrical signal with the help of photodiode. The Depending upon their structure, the detectors are categorized into two categories; single detector array and multiple detector array. Another essential part of a CT scanner is the motorized examination table. The table is controlled to move in and out of the gantry during the scanning process. As the position of the x-ray source and detector is fixed therefore the section being scanned is controlled by the movement of the examination table. For a better scan it is necessary that the patient remains completely still. To insure this table is equipped with neck rest, chest board and arm pole (Cancer Research UK, 2009). The detector measures the intensity of the radiation and converts them into electrical signals. These raw signals are analyzed and manipulated by the computer to convert them into images which can be understood by the radiologists and the technicians. Multiple computers are required in a CT scanner. The main computer that controls the operation of the entire system is called the host computer (Imaginis, n.d.). The computers and controls are located in a room adjoining the scanning room. This prevents the technicians and the radiographer from exposure to x-rays. Scanning Procedure in a CT scanner Initially the patient is positioned on the examination (or scanning) table in a flat upright posture (face towards the roof). In order to insure the correct and stationary position, straps and pillows may be used along the body. Once the patient is correctly positioned on the scanning table, the motorized table moves the patient into the circular opening of the CT scanner (FDA, 2010), which the x-ray radiations are projected on the patient from the scanning. For a particular position of the x-ray source and detector, the rays from the source pass through a region called the projection or view. There are two different types of projection geometries that are used in CT scanning; parallel beam geometry and fan beam geometry. In the parallel beam geometry, the rays projected on the patient are parallel to each other whereas in fan beam geometry, the rays diverge from the source in the shape of a fan (Bushberg et al., 2002) as shown in Figure 7. The fan beam projections are the most commonly in used x-ray projections in the CT scanners. The X-ray tube is attached with a collimator which controls the thickness of the fan beam. This thickness (of the fan beam projection) determines the width of the tissue slide in the scanning process. It is through the collimator that the slice thickness is varied between 1mm to 10mm (Smith, n.d.). The x-ray source and detector rotate around the patient (for imaging) in a circular motion such that they always remain exactly (diametrically) opposite to each other (as shown in Figure 7). During the rotation the source keeps emitting x-rays which are attenuated after passing through the patient. For a single projection (or slice), the x-ray source and detector make a complete 360o rotation around the patient. During the rotation the detector takes a large number of snapshots of the absorbed X-ray beam at different projection angles. A single image may involve approximately 800 rays and there can be up to 1,000 different projection angles (Bushberg et al., 2002). Therefore for a single projection (one slice), the detector does nearly 800,000 transmission measurements (Bushberg et al., 2002). The scanning of a single projection generally takes around 1 sec (for axial CT scanners) (FDA, 2010). Once all the transmission measurements (complete 360o) for a projection (or slice) are completed, the motorized table moves along the axis of the gantry so that the next slice of tissues forms the projection view. The process is continued till the complete required section of the body has been scanned. In the traditional CT scanners, the table moved on to the next projection (slice) only when the scanning of the previous was completed. Such conventional type of scanning is called the axial scanning. But in modern CT scanners, called the helical or spiral CT scanners, the rotation of the x-ray source and detector is accompanied with the uniform movement of the examination table, thus producing a helical projection. The helical CT scanning has been shown in Figure 9. These modern helical CT scanners are much faster than the traditional scanners due to continuous scanning process. They have been reported to take nearly half the time for scanning as compared to the traditional CT scanner s. In order to analyze and study the cardiac structure which is under constant motion, even helical CT is ineffective. For such applications a special CT scanner with an exposure time of 50ms and a maximum exposure rate of 17 images per second are used (Smith, n.d.). These scanners, called the cine CT, freeze the cardiac motion due to extremely low exposure time resulting in a sharp image (Smith, n.d.). These scanners use electron beam to generate x-rays, thus are also known as Electron Beam Computed Tomography (EBCT). In the CT scanning process large volume of data and operations are required to be processed, which is achieved with the help of multiple computers. The detector converts the intensity measurements of the attenuated x-rays in to electrical signals. The main computer, called the hub computer processes these signals and converts them into an image. These images can then be analyzed for radiotherapy planning. Result Computed Tomography (CT) has become an invaluable medical tool. It provides detailed 3-D images of various sections of the body like pelvis, soft tissues, lungs brain, blood vessels and bones (Nordqvist, 2009). Generally, CT scanning is the preferred method of diagnosing different types of cancers like liver, lungs and pancreatic cancers (Nordqvist, 2009). The tomographic images produced by the CT scan provide specific location and size of the tumor along with the details of affected tissues in the proximity of the tumor. This is especially advantageous in planning, guiding, and monitoring therapies like radiotherapy (FDA, 2010). CT scanning has various benefits over other traditional diagnostic techniques; some of the benefits are (RadiologyInfo, 2009): It is non-invasive, painless and extremely accurate. A major advantage is the ability to identify and distinguish bones, soft tissues and blood vessels in the same image. It also provides real time images which cannot be done in conventional X-rays. This technique is fast and simple; and is extensively used to locate internal injuries after accidents. It is less sensitive towards patient movement as compared to MRI. CT scanning can be used on patients with medical implants unlike the MRI. For an effective radiation therapy treatment, it is necessary that only the tumor is irradiated while minimum damage occurs to the surrounding health (normal) body tissues (Badcock, 1982). This is achieved with the help of CT imaging technique. In a study by Badcock (1982), 186 patients with various malignancies were studied and it was found that in nearly 39% of the treatment cases CT scanning was valuable in the assessment of the radiationdose calculation (Badcock, 1982). According to his study, CT scanner resulted in an alternation in target dose by more than 5%, (as compared to the traditional methods) in 27% of the patients (Badcock, 1982). The result has been shown in the table below. The mean alternation was 6.5% of the target dose and usually resulted in reduction of dose per fraction by factors upto 35% (Badcock, 1982). Even with these advantages, the adverse affect of the ionizing x-ray radiations cannot be neglected. Various experiments and researches have consolidated the fact that ionizing radiations like x-rays, gamma rays etc have adverse effect on living tissues. Zamanian Hardiman (2005) have explained that when high energy ionizing radiations interact with living tissues they strip-off atoms and molecules from them. This disrupts the chemical reaction within the body and failure in organ functioning (Zamanian Hardiman, 2005). The adverse effects of ionizing radiations were seen shortly after its discovery in 1890s, with a scientist involved in the study of radioactivity were reported with skin cancer in 1902. But is was not until 1944, that the role of radiations in causing leukemia in human was first documented, mainly in radiologists and physicists (Zamanian Hardiman, 2005). In recent years the use of x-rays has extensviely increased in medical field for diagonostic and treatment application. According to the U.S. Environmental Protection Agency, X-ray deveices are the largest source of man-made radiation exposure (US_EPA, 2007). According to NCRP Report No. 160 (2006), the average annual effective dose per individual in the US population, from all sources has increase from 1.7mSv in 1980s to 6.2mSv in 2006. This increase is mainly attributed to the striking growth of high dose medical imaging procedures that utilize x-rays and radionuclides (NCRP, 2008). Such man-made devices include X-ray machines, CT scans etc. CT scans, especially result in high dose x-ray exposure, with nealy 100 times the exposure dose as compared to standard x-ray equipments (Coach, 2008). Some of the major risks associated with CT scanning are: It is well documented that ionizing radiaitons like x-rays have the ability to cause cancer on exposure. Therefore, the CT dose in radiotherapy increase the probabilty of cancer in the future. Even though only 4% of the total x-ray examinations are CT scans, they account for more than 20% of the radiation dose to the population by medical x-rays (King Saud University, 2004). In general, the effective dose in a CT scan procedure ranges from 2 mSv to 10mSv, which is nearly equivalent to the amount of radiation that a person receive from the background exposures in three to five years (RadiologyInfo, 2009). A CT scan during preganacy make cause serious illness or even birth defects in the unborn baby (FDA, 2010). Children are more sensitive and vulnerable to x-ray exposures than the adults, therefore their CT scanning should be done only under extremely essential and necessary conditions. Women have higher risk of developing cancer in the lifetime, as compared to men under same levels of exposure (FDA, 2009). In some rare situation of high-dose prolonged radiation exposure, the x-rays can cause adverse effects like skin reddening (erythema), skin tissue injury, hair loss, cataracts etc (FDA, 2010). In a study, Sawyer et al (2009) estimated the effective dose resulting from a cone beam CT scanning for planning of radiation therapy using thermoluminescent dosemeters (TLDs) for organ dose and using International Commission on Radiological Protection (ICRP) 60 tissue weighing factor (Sawyer et al., 2009). The results obtained for effective dose from TLD measurements and ICRP 60 weighting factor, for breast, pelvis and head simulation have been shown in the table below. The scanning process results in the exposure of the normal tissues outside the treatment volume (Waddington McKenzie, 2004). It is thus important to analyze the effect that the irradiation caused by the CT scanning process has on the patients body. In a study, Waddington McKenzie (2004) analyzed the propability of developing cancer from the irradiations caused by the extended field portal imaging techniques, the results of which are given in the table below (Waddington McKenzie, 2004). In order to illustrate a real life situation, the calulations in the study were done for an average man with a height of 170 cms and weight of 70 kgs (Waddington McKenzie, 2004). Therefore, these values may change depending upon the height, weight and tumor size of the patient. Discussion Various studies have been done to statistically evaluate the effect of the ionizing radiations on the human health. These risks have severely amplified due to the rapid increase in the number of CT scans for diagnostic applications. CT scans form nearly 5% of all procedures used in diagnostic radiology in the developed countries (Wrixon et al., 2004). In U.S., nearly 70 million CT scans were done in 2007 as compared to just 3 million done in 1980 (Steenhuysen, 2009), this includes more than 4 million children in 2006 (Brenner Hall, 2007). Thus, according to the NCRP Report no. 160, the average radiation dose per person has increased from 3.6 mSv in early 1980s to 6.2 mSv in 2006 (NCRP, 2008). Steenhuysen (2009) has reported that the radiations from CT scans done in 2007 will cause 29,000 cancers and kill nearly 15,000 people in America (Steenhuysen, 2009). These stats explain the level of exposure caused by the CT scans. According to estimates by Amy Berrington de Gonzalez of the National Cancer Institute, Development of CT Scans for Cancer Studies Development of CT Scans for Cancer Studies According to the statistics presented by the World Health Organization (WHO), with around 7.4 million deaths (around 13% of the total death) in 2004, cancer is the leading cause of death throughout the world (WHO, 2009). These levels are expected to rise further in future, with an estimated 12 million death in 2030 (WHO, 2009). There are more than 100 different types of cancer (Crosta, n.d.), among them the Lung cancer, stomach cancer, colorectal cancer, liver cancer and the breast cancer are the most common types. Tobacco is the most important risk factor for cancer, with nearly 1.3 million deaths per year just due to lung cancer alone (WHO, 2009). Cancer At the primary level, human body consists of large number building blocks, called the cells. Under normal circumstances, new cells are formed by the body depending on the body requirement, in order to replace the dead cells. But sometimes, under abnormal conditions, there is an exponential (uncontrolled) increase in the formation and growth of new cells. The accumulation of these extra cells forms mass or lumps of tissues, called the tumor (National Cancer Institute, 2010). Most of the cancers, in general form tumors, but there are certain exceptions, like leukemia, that do not form tumors (in leukemia or blood cancer, the cancer cells hinder the normal blood functions due to abnormal cell disintegration in the blood stream (Crosta, n.d.)). The tumors can be of two types; benign tumor and malignant tumor. The benign tumors do not propagate to other sections of the body and have restrained growth (Crosta, n.d.), whereas the malignant tumor cells have the ability to invade into the sur rounding tissues. Also the malignant tumor cells can escape from their initial location and spread to other sections of the body through blood or lymph. Only the malignant tumors are cancerous in nature. Therefore, the cancer has three distinctive properties that distinguish malignant tumors from benign tumors: Uncontrolled growth Invasive nature Metastasis (ability to spread to other sections of the body) These disorders in cells are the result of the interaction between the genetic factors and external agents (which are called carcinogens) (WHO, 2009). The carcinogens can be categorized as (WHO, 2009): Biological carcinogens, like certain bacteria, viruses or parasites. Physical carcinogens, which includes the high energy radiations (ionizing radiations). Chemical carcinogens, these include substances like tobacco smoke, arsenic (water contaminant), aflatoxin (food contaminant), asbestos etc. Another factor essential in the development of cancer is the age. According to the studies conducted by the Cancer Research UK, the risk increase predominantly with increasing age, with nearly 74% of the cases of cancer diagnosed in people aged 60 and above (Cancer Research UK, 2009). Cancer Treatment Principle In case of normal cells there is specific pattern of growth, division and death (orderly destruction of cells is called apoptosis) (Crosta, n.d.). It is known that the cancer is the result of the uncontrolled growth of cells which do not die (Crosta, n.d.), that is, the apoptosis process fails in the cancer cells. The cancer cells thus do not die and rather continue to grow, resulting in the formation of tumors. As the problem in the cancer cells lies in the DNA, therefore a possible treatment of cancer is the destruction of the DNA in cancer cells, leading to a self initiated destruction of the cells. There are various methods used for the treatment of cancer depending upon the type of cancer. The most common types of treatment are (Fayed, 2009): Surgery Chemotherapy Radiation therapy or Radiotherapy Biologic or Targeted Therapy Radiotherapy Radiotherapy, also referred to as radiation therapy, is one of the most common types of treatments used for cancer. It is the utilization of higher energy radiations like x-rays, gamma rays in order to kill cancer cells, treatment of thyroid disorder and even some blood disorders, in a particular section (effected part) of the body (Nordqvist, 2009). The high energy ionizing radiations can be produced using a number of radioactive substrates like Cobalt (60Co), Radium (228Ra), Iodine (131I), Radon (221Rn), Cesium (137Cs), Phosphorus (32P), Gold (198Au), Iridium (192Ir), and Yttrium (90Y) (Howington, 2006). The cancer cells have the ability to multiply faster than other body cells. The high energy ionizing radiations are more destructive towards the faster growing cells, and thus they damage the cancer cell more than the other body cells (Mason, 2008). These high energy radiations like gamma rays and x-rays; especially damage the DNA inside these cancer cells (or tumor cells) thereby annihilating the ability of the cells to reproduce or grow. Apart from treatment of cancer, radiation therapy is also used to shrink a tumor before being surgically removed (Mason, 2008). Depending upon the method of irradiation, the process of radiation therapy is categorized into two forms (Mason, 2008): External Radiotherapy In this method (more common), the infected part of the body (tumor) is irradiated by high energy x-rays from outside the body. Internal Radiotherapy For this method, a radioactive substance are injected (or taken orally) into the body (close to the tumor) in the form of fluids. These substances, taken up by the cancer cells, radiate the tumor through internal beam radiation (or interstitial radiation) (Mason, 2008). Radiotherapy Planning A careful planning is essentially required for radiation therapy, as over exposure can be critically dangerous to healthy tissues in the body. The ionizing radiations have side effects, therefore once the full dose of radiations is decided; the patient is given these radiations in the form of small doses in a series of therapy sessions (Cancer Research UK, 2009). Each small dose of radiation is called a fraction. The gap between sessions provides the recovery time for the body, which may depend on the type of cancer and patients health condition. The area of the body that is radiated during the treatment is called the radiotherapy field and the section inside the body that experiences the maximum exposure dose is called the target volume (Cancer Research UK, 2009). The doctors decide the marginal area around the tumor that should be radiated to encapsulate any movement of the cancer cells. In order to accurately determine the position of tumor (or target volume), body scans are done. Computed Tomography (CT) scans are done as a planning procedure, this provides vital information regarding the location of the tumor as well as the kind of treatment required by the patient (Cancer Research UK, 2009). The radiotherapy treatment planning process can be divided into 6 major steps . Computer Tomography (CT) Scan The invention of Computer Tomography (CT) scanned is credited to Sir Godfrey Hounsfield in early 1970s, for which he along with Allen Cormack, was awarded the Nobel Prize in 1979 (Smith, n.d.). A CT scanner, also known as the Computed Axial Tomography (CAT) scanner uses X-rays to produce cross sectional images (or slices) of the body like a slice in a loaf of bread (FDA, 2010). The word tomography suggests the process of generating a two-dimensional image of a slice or section through a 3-dimensional object (a tomogram) (Nordqvist, 2009). These cross-sectional slides render an accurate picture of the size and location of the tumor along with the position of major organs in the body (Cancer Research UK, 2009). This would be essentially useful during the radiotherapy process, where these can be used to lower the dose of radiations on the organs. It is known that in case of radiation therapy treatment, the doses are given in fractions over a certain period of time (to prevent major side effects), which may vary from few weeks to months. Thus, before each fraction of radiation dose, computed tomography (CT) scan of the patients is done to determine the exact location of the tumor or cancer cells. So in case the full dose has been divided into 30 fractions, then the patient has to undergo 30 CT scans, each before a fractional therapy. The machine used for the radiation therapy planning is known as the simulator (Cancer Research UK, 2009). The simulator identifies the position of the tumor and marks the position of radiation on the body with the help of light rays. The radiographer uses ink markers on the body before the actual radiotherapy is begun. These linear ink marks are used by the radiographer for positioning the machine for radiotherapy (Cancer Research UK, 2009). Simulators take the pictures (CT scans) in the form of X-rays, which locates the accurate tumor position for the radiographer to carry out the treatment. During a CT scan, it is essential that the person remains completely still so that the measurements are accurate. In order to insure the correct position supports like neck rest, chest board or arm pole are used (Cancer Research UK, 2009). In case of children it is ensured by giving proper sedatives. Sometimes, under critical condition, extra measures are taken in order to prevent essential organs from being radiated during the therapy. These measures include injecting fluids or dyes which mark the position of vital human organs in the CT scan (Cancer Research UK, 2009). These markers may be given orally, through injections or rectally depending upon the requirement. Using this vital information from the CT scans, a treatment plan for radiation therapy is prepared. This plan indicates the position and direction of the radiations during the therapy, so as to minimize the exposure of healthy cells and organs. The scans generated by a CT scanner are in the form of 2 dimensional (2-D) slides, but by the used of digital geometry processing they can be used to generate a 3 dimensional (3-D) images of the body (Nordqvist, 2009). This can be achieved by integrating all the slides (along the same axis) together using a computer system. The CT scan can be understood as a technically advanced format of X-rays machines. The x-rays images are produced by the projection of a broad beam of x-rays on a film after passing through the body (Medindia, 2010). It provides a 2-dimentional projection of the body, where much of the information is lost. In case of CT scan, a thin beam of x-rays is absorbed by the detector after passing though the patients body (Medindia, 2010). Like the x-ray process, the CT scanning is a painless process for the patients but has been known to be accompanied with some side effects. These side effects may vary from the patient to patient depending upon the amount of radiation dose and health of the patient. The detailed discussion on the health effects of CT scanning has been discussed in the later sections of the project. Theory In order to understand the working of a computed tomography (CT) scanner it is essential to understand the properties of ionizing radiations (X-rays) used in the scanning process. The electromagnetic radiations are the arrangement of electric-field and magnetic-field vectors perpendicular to each other and also perpendicular to the propagation direction of the wave (Resnick et al., 2009). These Electromagnetic radiations have penetrating powers, which are directly dependent on the energy (or frequency) of these radiations. So that radiations with higher frequency have higher penetration powers. Therefore, on the basic the energy, the electromagnetic radiations are categorized as Non-ionizing radiations and Ionizing radiations. Non-Ionizing radiations refer to the electromagnetic radiations which have energy lower than that required for an atomic ionization (MIT, 2001). The non-ionizing radiations include radio waves, micro waves, visible light etc. These radiations have lower penetration powers. Alternatively the Ionizing radiations are the high frequency radiations which have enough energy to knockout an electron from an atom and thus causing ionization (MIT, 2001). The Gamma rays and X-rays are the common type of ionizing radiations. Even the alpha particles and beta particles emitted in a nuclear reaction are ionizing radiations (MIT, 2001). Due to the higher energy they have higher penetration power than the non-ionizing radiations. Principle of CT Scanning The most important section of a Computed Tomography (CT) scanning is the interaction of the ionizing X-ray radiations with the living tissues in the body. When the ionizing radiations (X-rays) interact with the living tissues in the body, they break up atoms and molecules from the living tissues and disrupt chemical reactions within the body (Zamanian Hardiman, 2005). The intensity of absorption of the x-ray radiations by the body varies depending upon the tissue coming in interaction. Different body tissues have different absorption power, where some are permeable to x-rays others are impermeable (Medindia, 2010). It is due to this difference in the absorption ability of different sections of the body, which results in the generation of a graded pattern in the scans. High density tissues like the bones appear white in the scan while the soft tissues (like brain and kidneys) appear dark. The cavities (like the lungs) are seen as black sections in the scan (Medindia, 2010). Therefore, this gradation in the pattern can be used as method to distinguish different body organs depending upon their absorption capacity. This forms the basic principle behind the working of an X-ray scanning. Radon (1917) was the first to develop the principles of computed tomography (CT) mathematically (Bushberg et al., 2002). According to Radon, with the help of infinite number of projections through an object, it could be possible to produce an image of an unknown object. In case of film imaging (as in conventional X-rays), a two-dimensional (2-D) projection of the body is generated on the film. Due to this, details in the dimension of the body along the direction parallel to the x-ray beam are lost. In order to overcome this drawback (only up to a certain level) projections can be taken along two directions; posteroanterior (PA) projection and lateral projection (Bushberg et al., 2002) (as shown in Figure 4). Increasing the number of scans improves the amount of information but in critical and complex cases where much more details are required. For these critical cases, CT scan is done. The CT scan provides the tomographical image, which is the picture of patients body in the sections or slabs. The thickness of these uniform slabs may vary from 1 millimeter to 10 millimeter (Bushberg et al., 2002), according to the program, depending upon the requirement. Each CT image consists of an array of large number of pixels forming a two dimensional (2-D) image, which corresponds to the same number of three dimensional thin rectangular slabs called the voxel. The voxels are the volume element whereas the pixels are the picture element (Bushberg et al., 2002). Every ray from the X-ray source passes (transmits) through the patient before the transmission measurement is done by the detector. Intensity of the un-attenuated x-ray radiation emitted by the source is Io whereas the intensity of the attenuated radiation after transmitting through the patient is given as It. The intensities Io and It are related by the equation (Bushberg et al., 2002):   Ã‚  Ã‚  Ã‚  Ã‚  It=Ioe-ÃŽ ¼t   Ã‚  Where;   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚ µ is the total linear attenuation coefficient of the tissue (Smith, n.d.).   Ã‚  Ã‚  Ã‚  Ã‚  t is the distance travelled by the radiation in the tissue i.e. the tissue thickness. The coefficient  µ is dependent on the atomic number and electron density of the tissues (Smith, n.d.). Higher the atomic number and electron density of the tissues, higher would be the attenuation coefficient (Smith, n.d.). This form the basic principle of CT scanning, that different tissues have different level of attenuation properties depending upon their atomic number and electron density. For every measurement, the overall attenuation coefficient is calculated using the above equation. During a complete 360o ­ scan, various transmission measurements for the intensity of X-ray photon are done. Using these intensity measurements specific attenuation values are allotted to every voxel (volume element). These attenuation numbers are directly proportional to the linear attenuation coefficient. The average of these attenuation values is called the CT number (Smith, n.d.). These values can be arranged on a linear scale, the units of which are called the Hounsfield units (HU). The scale for modern CT scanners varies from approximately -1,000 to 3,000 HU. The attenuation scale is based on binary system and therefore the exact values range from -1,024 to +3,071, with a total of 4,096 (or 212) attenuation numbers. Here, the lower represent the black section while the higher values represent the white section of the CT image. On this scale the attenuation value of water is zero HU and that of air is -1,000 HU (Smith, n.d.). Both of these values act as the reference points. Construction of a CT scanner CT scanner is a complex machine, but the basic structure is simple. A common CT scanner has been shown in Figure 2. Two most important parts of a CT scanner are the X-ray source and detector. The source and detector are placed in a circular structure, which has a shape similar to a doughnut. This doughnut shaped circular opening is called the gantry (RadiologyInfo, 2009), with an inner (opening) diameter varying from 60 cms to 70 cms. The X-ray source and detector are placed exactly (diagonally) opposite each other, so that the radiations emitted by the source pass through the body and the transmitted radiations are measured by the detector. The x-ray source and detector system in the gantry is motorized to rotate around the patient for measurements in different projection angles. The rational speed of the system is adjusted according to the detectors ability to measure and convert the x-ray beam into electronic signal. Cobalt (60Co) is generally used as the source of x-rays in the CT scanners. The detector used in CT scanner consists of an array of detectors in a slightly curved shape (like a banana). This curved shape is especially useful in fan-shaped beam projects. Two types of detectors are generally utilized in the CT scans; solid state or scintillation detector and Xenon gas detector (Reddinger, 1997). But the solid state detectors with scintillators like Cadmium Tungstate (CdWO4), yttrium, gadolinium ceramics etc are commonly used (Bushberg et al., 2002). The principle of the scintillation detector is that, when it is struck by a x-ray photon, it produces light. This light signal is then transformed to electrical signal with the help of photodiode. The Depending upon their structure, the detectors are categorized into two categories; single detector array and multiple detector array. Another essential part of a CT scanner is the motorized examination table. The table is controlled to move in and out of the gantry during the scanning process. As the position of the x-ray source and detector is fixed therefore the section being scanned is controlled by the movement of the examination table. For a better scan it is necessary that the patient remains completely still. To insure this table is equipped with neck rest, chest board and arm pole (Cancer Research UK, 2009). The detector measures the intensity of the radiation and converts them into electrical signals. These raw signals are analyzed and manipulated by the computer to convert them into images which can be understood by the radiologists and the technicians. Multiple computers are required in a CT scanner. The main computer that controls the operation of the entire system is called the host computer (Imaginis, n.d.). The computers and controls are located in a room adjoining the scanning room. This prevents the technicians and the radiographer from exposure to x-rays. Scanning Procedure in a CT scanner Initially the patient is positioned on the examination (or scanning) table in a flat upright posture (face towards the roof). In order to insure the correct and stationary position, straps and pillows may be used along the body. Once the patient is correctly positioned on the scanning table, the motorized table moves the patient into the circular opening of the CT scanner (FDA, 2010), which the x-ray radiations are projected on the patient from the scanning. For a particular position of the x-ray source and detector, the rays from the source pass through a region called the projection or view. There are two different types of projection geometries that are used in CT scanning; parallel beam geometry and fan beam geometry. In the parallel beam geometry, the rays projected on the patient are parallel to each other whereas in fan beam geometry, the rays diverge from the source in the shape of a fan (Bushberg et al., 2002) as shown in Figure 7. The fan beam projections are the most commonly in used x-ray projections in the CT scanners. The X-ray tube is attached with a collimator which controls the thickness of the fan beam. This thickness (of the fan beam projection) determines the width of the tissue slide in the scanning process. It is through the collimator that the slice thickness is varied between 1mm to 10mm (Smith, n.d.). The x-ray source and detector rotate around the patient (for imaging) in a circular motion such that they always remain exactly (diametrically) opposite to each other (as shown in Figure 7). During the rotation the source keeps emitting x-rays which are attenuated after passing through the patient. For a single projection (or slice), the x-ray source and detector make a complete 360o rotation around the patient. During the rotation the detector takes a large number of snapshots of the absorbed X-ray beam at different projection angles. A single image may involve approximately 800 rays and there can be up to 1,000 different projection angles (Bushberg et al., 2002). Therefore for a single projection (one slice), the detector does nearly 800,000 transmission measurements (Bushberg et al., 2002). The scanning of a single projection generally takes around 1 sec (for axial CT scanners) (FDA, 2010). Once all the transmission measurements (complete 360o) for a projection (or slice) are completed, the motorized table moves along the axis of the gantry so that the next slice of tissues forms the projection view. The process is continued till the complete required section of the body has been scanned. In the traditional CT scanners, the table moved on to the next projection (slice) only when the scanning of the previous was completed. Such conventional type of scanning is called the axial scanning. But in modern CT scanners, called the helical or spiral CT scanners, the rotation of the x-ray source and detector is accompanied with the uniform movement of the examination table, thus producing a helical projection. The helical CT scanning has been shown in Figure 9. These modern helical CT scanners are much faster than the traditional scanners due to continuous scanning process. They have been reported to take nearly half the time for scanning as compared to the traditional CT scanner s. In order to analyze and study the cardiac structure which is under constant motion, even helical CT is ineffective. For such applications a special CT scanner with an exposure time of 50ms and a maximum exposure rate of 17 images per second are used (Smith, n.d.). These scanners, called the cine CT, freeze the cardiac motion due to extremely low exposure time resulting in a sharp image (Smith, n.d.). These scanners use electron beam to generate x-rays, thus are also known as Electron Beam Computed Tomography (EBCT). In the CT scanning process large volume of data and operations are required to be processed, which is achieved with the help of multiple computers. The detector converts the intensity measurements of the attenuated x-rays in to electrical signals. The main computer, called the hub computer processes these signals and converts them into an image. These images can then be analyzed for radiotherapy planning. Result Computed Tomography (CT) has become an invaluable medical tool. It provides detailed 3-D images of various sections of the body like pelvis, soft tissues, lungs brain, blood vessels and bones (Nordqvist, 2009). Generally, CT scanning is the preferred method of diagnosing different types of cancers like liver, lungs and pancreatic cancers (Nordqvist, 2009). The tomographic images produced by the CT scan provide specific location and size of the tumor along with the details of affected tissues in the proximity of the tumor. This is especially advantageous in planning, guiding, and monitoring therapies like radiotherapy (FDA, 2010). CT scanning has various benefits over other traditional diagnostic techniques; some of the benefits are (RadiologyInfo, 2009): It is non-invasive, painless and extremely accurate. A major advantage is the ability to identify and distinguish bones, soft tissues and blood vessels in the same image. It also provides real time images which cannot be done in conventional X-rays. This technique is fast and simple; and is extensively used to locate internal injuries after accidents. It is less sensitive towards patient movement as compared to MRI. CT scanning can be used on patients with medical implants unlike the MRI. For an effective radiation therapy treatment, it is necessary that only the tumor is irradiated while minimum damage occurs to the surrounding health (normal) body tissues (Badcock, 1982). This is achieved with the help of CT imaging technique. In a study by Badcock (1982), 186 patients with various malignancies were studied and it was found that in nearly 39% of the treatment cases CT scanning was valuable in the assessment of the radiationdose calculation (Badcock, 1982). According to his study, CT scanner resulted in an alternation in target dose by more than 5%, (as compared to the traditional methods) in 27% of the patients (Badcock, 1982). The result has been shown in the table below. The mean alternation was 6.5% of the target dose and usually resulted in reduction of dose per fraction by factors upto 35% (Badcock, 1982). Even with these advantages, the adverse affect of the ionizing x-ray radiations cannot be neglected. Various experiments and researches have consolidated the fact that ionizing radiations like x-rays, gamma rays etc have adverse effect on living tissues. Zamanian Hardiman (2005) have explained that when high energy ionizing radiations interact with living tissues they strip-off atoms and molecules from them. This disrupts the chemical reaction within the body and failure in organ functioning (Zamanian Hardiman, 2005). The adverse effects of ionizing radiations were seen shortly after its discovery in 1890s, with a scientist involved in the study of radioactivity were reported with skin cancer in 1902. But is was not until 1944, that the role of radiations in causing leukemia in human was first documented, mainly in radiologists and physicists (Zamanian Hardiman, 2005). In recent years the use of x-rays has extensviely increased in medical field for diagonostic and treatment application. According to the U.S. Environmental Protection Agency, X-ray deveices are the largest source of man-made radiation exposure (US_EPA, 2007). According to NCRP Report No. 160 (2006), the average annual effective dose per individual in the US population, from all sources has increase from 1.7mSv in 1980s to 6.2mSv in 2006. This increase is mainly attributed to the striking growth of high dose medical imaging procedures that utilize x-rays and radionuclides (NCRP, 2008). Such man-made devices include X-ray machines, CT scans etc. CT scans, especially result in high dose x-ray exposure, with nealy 100 times the exposure dose as compared to standard x-ray equipments (Coach, 2008). Some of the major risks associated with CT scanning are: It is well documented that ionizing radiaitons like x-rays have the ability to cause cancer on exposure. Therefore, the CT dose in radiotherapy increase the probabilty of cancer in the future. Even though only 4% of the total x-ray examinations are CT scans, they account for more than 20% of the radiation dose to the population by medical x-rays (King Saud University, 2004). In general, the effective dose in a CT scan procedure ranges from 2 mSv to 10mSv, which is nearly equivalent to the amount of radiation that a person receive from the background exposures in three to five years (RadiologyInfo, 2009). A CT scan during preganacy make cause serious illness or even birth defects in the unborn baby (FDA, 2010). Children are more sensitive and vulnerable to x-ray exposures than the adults, therefore their CT scanning should be done only under extremely essential and necessary conditions. Women have higher risk of developing cancer in the lifetime, as compared to men under same levels of exposure (FDA, 2009). In some rare situation of high-dose prolonged radiation exposure, the x-rays can cause adverse effects like skin reddening (erythema), skin tissue injury, hair loss, cataracts etc (FDA, 2010). In a study, Sawyer et al (2009) estimated the effective dose resulting from a cone beam CT scanning for planning of radiation therapy using thermoluminescent dosemeters (TLDs) for organ dose and using International Commission on Radiological Protection (ICRP) 60 tissue weighing factor (Sawyer et al., 2009). The results obtained for effective dose from TLD measurements and ICRP 60 weighting factor, for breast, pelvis and head simulation have been shown in the table below. The scanning process results in the exposure of the normal tissues outside the treatment volume (Waddington McKenzie, 2004). It is thus important to analyze the effect that the irradiation caused by the CT scanning process has on the patients body. In a study, Waddington McKenzie (2004) analyzed the propability of developing cancer from the irradiations caused by the extended field portal imaging techniques, the results of which are given in the table below (Waddington McKenzie, 2004). In order to illustrate a real life situation, the calulations in the study were done for an average man with a height of 170 cms and weight of 70 kgs (Waddington McKenzie, 2004). Therefore, these values may change depending upon the height, weight and tumor size of the patient. Discussion Various studies have been done to statistically evaluate the effect of the ionizing radiations on the human health. These risks have severely amplified due to the rapid increase in the number of CT scans for diagnostic applications. CT scans form nearly 5% of all procedures used in diagnostic radiology in the developed countries (Wrixon et al., 2004). In U.S., nearly 70 million CT scans were done in 2007 as compared to just 3 million done in 1980 (Steenhuysen, 2009), this includes more than 4 million children in 2006 (Brenner Hall, 2007). Thus, according to the NCRP Report no. 160, the average radiation dose per person has increased from 3.6 mSv in early 1980s to 6.2 mSv in 2006 (NCRP, 2008). Steenhuysen (2009) has reported that the radiations from CT scans done in 2007 will cause 29,000 cancers and kill nearly 15,000 people in America (Steenhuysen, 2009). These stats explain the level of exposure caused by the CT scans. According to estimates by Amy Berrington de Gonzalez of the National Cancer Institute,