Deck 14: Aspects of Brachytherapy

Question 1

17)The term radium substitute in brachytherapy indicates which of the following?

A) An isotope whose dosimetry is based on original radium work
B) An isotope whose dosimetry is more accurate than that of radium
C) Any source implemented when radium is unavailable
D) A source that has a greater average energy than radium

Answer 1

A
The term radium substitute is used to indicate any isotope used for brachytherapy whose dosimetry is based on the original radium experience and calculations.

Question 2

18)What is the average energy of iridium 192?

A) 170 keV
B) 730 keV
C) 450 keV
D) 380 keV

Answer 2

D
This radioisotope undergoes beta decay and has an average energy of 370 keV.

Question 3

3)Of the following, which radionuclide is used for permanent prostate implants?

A) Gold 198
B) Cobalt 60
C) Cesium 137
D) Iridium 192

Answer 3

A
Some isotopes, such as radon 222 and gold 198, have very short half-lives and are implanted permanently rather than temporarily.This type of therapy is used frequently in the case of prostate cancer.The prostate can benefit from interstitial implants with permanent gold seeds because other isotopes would require surgical procedures for both insertion and removal of sources.

Question 4

1)What is the half-life of gold 198?

A) 27 days
B) 27 years
C) 2.7 days
D) 3.8 days

Question 5

8)Decay constant is expressed as which of the following?

A) The time it takes for activity to decay to half its original value
B) Total number of atoms that decay per unit time
C) Average lifetime for the decay of radioactive atoms
D) Total number of atoms that decay

Question 6

6)For brachytherapy to the cervix, where is point A located in relation to the cervical os?

A) 2 cm superior and 2 cm lateral
B) 1 cm superior and 2 cm lateral
C) 2 cm inferior and 2 cm lateral
D) 2 cm superior and 1 cm lateral

Question 7

11)Of the following, which brachytherapy application would be used to treat the breast?

A) Intracavitary
B) Interstitial
C) Topical
D) Permanent implant

Question 8

16)Which of the following is true regarding the Quimby system?

A) It is used more often than the Paterson-Parker system.
B) It is adapted into system called the Manchester system.
C) There is a uniform distribution of activity within the implant.
D) The result is a uniform dose distribution.

Question 9

20)The radioisotope used to treat uveal melanoma of the eye is _________________.

A) iridium 192
B) cesium 137
C) gold 198
D) iodine 125

Question 10

2)Which of the following is an advantage of high-dose rate (HDR)over low-dose rate (LDR)?

A) HDR is noninvasive.
B) HDR dosimetry is simpler.
C) Treatment time is decreased from 72 hours to 24 hours.
D) HDR can be given on an outpatient basis.

Question 11

15)What is an advantage of remote afterloading?

A) Less invasive for the patient
B) Limits exposure to the patient and personnel
C) Decreased treatment time
D) Allows the patient to have a semiprivate room

Question 12

19)Which of the following is true regarding cobalt 60?

A) It is a common radionuclide used in brachytherapy.
B) It has a half-life of 5.27 years.
C) Its energy is 3.25 MeV.
D) It was not effective as an external beam source.

Question 13

12)The half-life of radium is __________________.

A) 1.6 years
B) 162 days
C) 1,622 years
D) 16 years

Question 14

10)The purpose of intravascular brachytherapy is to _______________________.

A) eliminate arterial plaque
B) treat cancers of the heart
C) prevent heart disease
D) inhibit restenosis in coronary arteries

Question 15

4)Areas commonly treated with external applicators include which of the following?
I)Hard palate
II)Skin
III)Orbital cavity

A) I and II
B) I and III
C) II and III
D) I, II, and III

Question 16

5)What is the purpose of dummy sources used for temporary implants?

A) Localize the tumor in surgery
B) Enable visualization of source placement
C) Give physics residents experience with loading sources
D) Determine dose to the bladder and rectum

Question 17

13)Which of the following is one disadvantage of radium?

A) Has a long half-life
B) Decays by alpha emission
C) It is not as effective as other radioisotopes
D) Decays to form a radon, a dangerous gas

Question 18

7)The Paterson-Parker (Manchester)system uses a set of guidelines to do which of the following?
I)Provide a dose of +10% within the implanted area
II)Assume the use of linear sources to be implanted
III)Use a uniform distribution of radioactive material to produce a uniform dose distribution

A) I and II
B) I and III
C) II and III
D) I, II, and III

Question 19

9)Tandem and ovoids are used to treat which of the following?

A) Prostate
B) Bladder
C) Cervix
D) Esophagus

Question 20

14)Which of the following has the shortest half-life?

A) Gold 198
B) Iodine 125
C) Cesium 137
D) Cobalt 60

Question 21

22)Which of the following brachytherapy sources is used to treat breast cancer?

A) Gold 198
B) Iodine 125
C) Iridium 192
D) Radium 226

Question 22

21)Regarding question 20, why is brachytherapy the treatment of choice?

A) It has a high energy.
B) It is more effective than stereotactic and proton therapy procedures.
C) Vision is spared due to a lack of radiation-induced changes.
D) It is less expensive for the patient.

Question 23

28)Which of the following is the radionuclide with the largest average photon energy?

A) Cobalt 60
B) Cesium 137
C) Iridium 192
D) Radium 226

Question 24

27)The radionuclide with radon as its daughter product is __________________.

A) cobalt 60
B) cesium 137
C) iridium 192
D) radium 226

Question 25

25)The Paris system is based on which of the following?

A) Radioactive sources must be rectilinear.
B) Source centers must be in a different plane.
C) Linear activity must be nonuniform along each source.
D) Sources can be spaced at any distance.

Question 26

26)An autoradiograph is taken to ________________________.

A) determine the energy of the source
B) check source placement in the patient
C) verify uniformity of source
D) determine source strength

Question 27

24)The shape of the isodose distribution for a tandem and ovoid treatment is ____________.

A) apple shaped
B) triangular
C) mushroom shaped
D) pear shaped

Question 28

29)The average or mean life of iridium 192 is __________ days.

A) 51
B) 74
C) 107
D) 148

Question 29

30)As half-life increases, the overall activity ______________________.

A) increases
B) decreases
C) remains unchanged

Question 30

23)Permanent implants involve which of the following?
I)Sources packaged as tiny seeds
II)Sources with long half-lives
III)Sources implanted with needles in surgery
IV)Tumors that cannot be reached surgically

A) I and II
B) I and III
C) II and III
D) I, II, and III