Homework 11

Question 1

which radioactive source is used in most HDR afterloaidng units?

a. palladium-103
b. cesium-137
c. iodine-125
d. iridium-192

Answer 1

d. iridium-192

Question 2

cesium-137 sources are most often used for

a. intracavitary brachytherapy
b. interstitial brachytherapy
c. intraluminal brachytherapy
d. surface molds

Answer 2

a. intracavitary brachytherapy

Question 3

which of the following seeds is only used in temporary implants?

a. palladium-103
b. iodine-125
c. iridium-192

Answer 3

c. iridium-192

Question 4

palladium-103 and iodine-125 are both popular radioactive seeds for permanent implants for which type of cancer?
a. prostate
b. cervix 
c. sarcoma of the extremity
d all of the above

Answer 4

a. prostate

Question 5

why is the sievert integral used for brachytherapy line sources?
a. the exposure rate at distances close to a line source of radiaiton does not follow the inverse square law
b, it accounts for the absorption through the source containment
c. it corrects for the difference in dose in the radial direction
d. all of the above

Answer 5

a. the exposure rate at distances close to a line source of radiaiton does not follow the inverse square law

Question 6

the average anisotrophy factor is used in interstitial seed implants becuase

a. the seeds are randomly oriented
b. the sievert integral does not apply to seed implants
c. each seed shields radiaiton from adjuacent seeds
d. none of the above

Answer 6

a. the seeds are randomly oriented

Question 7

the activity of an unshielded radioactive source that would deliver the same exposure rate at a meter as compared with a shielded radioactie source is called the

a. monial source activity
b. reference source activity
c. specific activity
d. apprent activity

Answer 7

d. apprent activity

Question 8

which of the following radionuclides is used for treating bone metastases?

a. samarium-153, quadramet
b. strontium-89, metastron
c. radium-233, xofigo
d. all of the above

Answer 8

d. all of the above

Question 9

which of the following is an advantage of cesium-137 over radium-226

a. longer half life
b. requires less shielding
c. higher average enrgy
d. all of the above

Answer 9

b. requires less shielding

Question 10

what is the effective half life of iodine-131 if the biological half life is 80 days

a. 7.3 days
b. 1.4 days
c. 0.14 days
d. 5.6 days

Answer 10

a. 7.3 days