Radioactive Iodine-125 and Palladium-103 Decay by X-Ray Emission and Are

question 95

Multiple Choice

Radioactive iodine-125 and palladium-103 decay by X-ray emission and are used in brachytherapy to treat cancer. Consider two patients, one being treated with I-125 and the other with Pd-103. Both receive a total dose of 145 Gy delivered over 10 months. What can be concluded from the data in the table about these treatments?
Note: 1 keV = 1.602 * 10^-16 J. $$\begin{array} { | c | c | c | c | c | } \hline \text { Isotope } & \begin{array} { c } \text { X-ray Energy } \\\text { keV }\end{array} & \begin{array} { c } \mathbf { t } _ { 1 / 2 } \\\text { days }\end{array} & \begin{array} { c } \text { Initial Dose } \\\text { mGy/h }\end{array} & \begin{array} { c } \text { Initial Activity } \\\mathbf { m C i }\end{array} \\\hline \mathrm { L } - 125 & 27 & 60 & 80 & 0.42 \\\hline \mathrm { Pd } - 103 & 21 & 17 & 200 & 1.30 \\\hline\end{array}$$
I. The level of radiation is more uniform over the 10 months using I-125.
II. Initially the level of radiation is higher using Pd-103.
III. The density of sites damaged by radiation is higher initially using Pd-103.

• A) All are correct.
• B) None are correct.
• C) I and III only
• D) I and II only
• E) II and III only

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