Newest Tx Planning Qs

Question 1

A representation of the dose in an irradiated volume, as a function of spatial position along a single line is known as a/an:
A. isodose curve
B. percent depth dose line
C. dose profile
D. dose volume histogram

Answer 1

A. isodose curve
B. percent depth dose line
C. dose profile
D. dose volume histogram

Question 2

Dose rates in air express the dose measured:
A. at 10 cm depth in a phantom
B. without a phantom, with a buildup cap at a certain distance
C. with a phantom, without a buildup cap at a certain distance
D. without a build up cap or phantom with a 10 x 10 cm field size

Answer 2

B. without a phantom, with a buildup cap at a certain distance

Question 3

In order to make custom Cerrobend blocks, the following information is needed:
1. target-to-film distance
2. beam energy
3. patient thickness

Answer 3

All

Question 4

Which of the following radioisotopes is sometimes administered into the peritoneal cavity in the treatment of gynecological malignancies?
A. Cesium-137
B. Iridium-192
C. Iodine-131
D. Phosphorus-32

Answer 4

D. Phosphorus-32

Question 5

When comparing an isodose profile from a linear accelerator with one from an orthovoltage machine, the linear accelerator isodose will have the following characteristics:
1. greater penetration
2. greater side scatter
3. higher % DD at depth
4. flatter isodose lines

Answer 5

1 3 4

Question 6

The field size of an X-ray or gamma ray beam is defined as the area enclosed within the boundary of the __________% depth dose line.

Answer 6

50

Question 7

Wedge angle refers to:
A. the angle of the actual wedge filter
B. the angle at which an isodose curve at a specific depth is tilted as a result of the wedge being inserted in the beam
C. the angle at which an isodose curve at a specified depth is tilted with respect to the central axis of the beam

Answer 7

B. the angle at which an isodose curve at a specific depth is tilted as a result of the wedge being inserted in the beam

Question 8

While treating lateral fields in the treatment of the craniospinal axis, to avoid having the caudal margin of the lateral fields diverge into the posterior spine field, the couch should be rotated:
A. way from the collimator
B. toward the collimator
C. until the table is at 5 degrees
D. until the table is at 10 degrees

Answer 8

B. toward the collimator

Question 9

When a missing tissue compensator is used, it should be placed:
A. directly on the skin surface
B. at some distance from the skin surface
C. on the end of an electron cone
D. on top of a bolus material at isocenter

Answer 9

B. at some distance from the skin surface

Rationale:
To preserve the skin-sparing effect, tissue compensators should be placed at least 15 cm from the patient’s skin surface.

Question 10

The shape of the isodose curves depends largely upon:
1. field size
2. depth dose
3. flattening filters
4. SSD

Answer 10

1 3
Rationale:
The shape of the isodose curve depends on the field size, filters and accessories such as blocks, wedges, cones and multi-leaf collimators.