ANSWER KEY Exam 1

B is the coloradon a high let or low let particle

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Unformatted text preview: 7. (10 points) Briefly explain: A. What does LET stand for? B. How is LET related to the reason for why a piece of paper can stop an alpha particle, but several inches of lead shielding are needed to stop a gamma- ray? LET – Linear Energy Transfer Alpha particles (high LET) deposit their energy quickly, in a short distance, as soon as they interact with matter, therefore they do not carry their energy very far. Gamma rays (low LET; high energy photons) deposit their energy sparsely, over a long distance, therefore they must travel through a longer distance, through more matter (lead shield) to give up their whole energy. 8. (10 points) A new form of particulate radiation was recently discovered, the Coloradon. Exposure of human cells in culture to 1 Gy of Coloradon particles resulted in 25% cell killing. In contrast, it takes a 10 Gy dose of 250 KeV X- rays to produce the same outcome. A. What is the Relative Biological Effectiveness (RBE) of Coloradon particles? B. Is the Coloradon a high LET or low LET particle? RBE is of Coloradon particles = Dose X- ray 250 Kev / Dose Coloradon...
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