Radiation Therapy Chapter 8 Questions
and Answers| Latest Update
1. Which of the following is the measurement of the angle between central rays of two
intersecting treatment beams?
a. Wedge angle
b. Hinge angle
c. Isodose angle
d. Central axis angle B
The orientation of multiple fields to one another during treatment may produce
inhomogeneous dose distributions over the target volume. The wedge is designed to change
the angle of the isodose curve relative to the beam axis at a specified depth within the patient.
The hinge angle (measure of the angle between central rays of two intersecting treatment
beams) decreases and doses delivered to overlapping areas vary significantly, thus creating
areas of high- and low-dose regions in the desired target volume.
p. 170
2. Wedge systems used include which of the following?
I. Global
II. Universal
III. Virtual
a. I and II
b. I and III
c. II and III
d. I, II, and III C
Standard wedge systems use externally mounted wedges that must be positioned on a tray
above the patient. Treatment units using internal wedging methods allow for customizing the
wedge angle for each treatment plan. One system uses a 60-degree universal wedge. Other
, systems use a virtual wedge system in which a dynamic, or moving, jaw starts at one side of the
field and opens to a full field over the course of dose delivery.
p. 170
3. Which of the following is used in shaping the field of an electron beam treatment?
a. MLC
b. Bolus
c. Aluminum
d. Cerrobend cutout D
Electron shielding differs considerably from photon beam treatment. Attenuated much more
efficiently, full shielding for electron beams requires lead thicknesses of only several millimeters
(general rule: energy in millimeters of lead). Field-defining apertures or "cutouts" can be
designed to fit directly inside the electron cone. After completion of a template of the defined
treatment area, a model for creation of a Cerrobend cutout is made.
p. 174
4. Where would the radiation therapist find the information regarding the status of the
treatment unit?
a. Console
b. Interlock system of the unit
c. Patient record
d. Cameras in the room A
The console provides information to the radiation therapist regarding the status of the
treatment unit. The use of beam modifiers may require verification of placement to release a
safety interlock for treatment.
p. 171
and Answers| Latest Update
1. Which of the following is the measurement of the angle between central rays of two
intersecting treatment beams?
a. Wedge angle
b. Hinge angle
c. Isodose angle
d. Central axis angle B
The orientation of multiple fields to one another during treatment may produce
inhomogeneous dose distributions over the target volume. The wedge is designed to change
the angle of the isodose curve relative to the beam axis at a specified depth within the patient.
The hinge angle (measure of the angle between central rays of two intersecting treatment
beams) decreases and doses delivered to overlapping areas vary significantly, thus creating
areas of high- and low-dose regions in the desired target volume.
p. 170
2. Wedge systems used include which of the following?
I. Global
II. Universal
III. Virtual
a. I and II
b. I and III
c. II and III
d. I, II, and III C
Standard wedge systems use externally mounted wedges that must be positioned on a tray
above the patient. Treatment units using internal wedging methods allow for customizing the
wedge angle for each treatment plan. One system uses a 60-degree universal wedge. Other
, systems use a virtual wedge system in which a dynamic, or moving, jaw starts at one side of the
field and opens to a full field over the course of dose delivery.
p. 170
3. Which of the following is used in shaping the field of an electron beam treatment?
a. MLC
b. Bolus
c. Aluminum
d. Cerrobend cutout D
Electron shielding differs considerably from photon beam treatment. Attenuated much more
efficiently, full shielding for electron beams requires lead thicknesses of only several millimeters
(general rule: energy in millimeters of lead). Field-defining apertures or "cutouts" can be
designed to fit directly inside the electron cone. After completion of a template of the defined
treatment area, a model for creation of a Cerrobend cutout is made.
p. 174
4. Where would the radiation therapist find the information regarding the status of the
treatment unit?
a. Console
b. Interlock system of the unit
c. Patient record
d. Cameras in the room A
The console provides information to the radiation therapist regarding the status of the
treatment unit. The use of beam modifiers may require verification of placement to release a
safety interlock for treatment.
p. 171
