MDCB: MOCK EXAM 2 QUESTIONS AND
ANSWERS 100% ACCURATE
A patient receiving treatment to the head and neck region has experienced a skin
reaction and mucositis at a total dose much lower than anticipated. The radiation
oncologist requests an evaluation of the treatment. Which of the following steps should
be taken?
A. recalculate the treatment plan
B. ensure that the depth dose, build-up region, wedge parameters, and other pertinent
information for the treatment unit are correct
C. review the treatment setup with the therapist
D. recalculate the monitor unit settings
E. all are correct - ANSWER-E
For megavoltage dosimetry, TLD can provide accuracy of:
A. plus/minus 20%
B. plus/minus 10%
C. plus/minus 3%
D. plus/minus 1% - ANSWER-C
With megavoltage film dosimetry, isodose curves can be measured to within:
A. plus/minus 10%
B. plus/minus 7%
C. plus/minus 3%
D. plus/minus 1% - ANSWER-C
In megavoltage therapy, typical use(s) of diodes is for:
A. patient dosimetry
,B. beam scanning
C. quality assurance
D. all of the answers are correct - ANSWER-D
Which of the following is best suited for calibration of a megavoltage beam:
A. diode detector
B. thermoluminescence dosimetry
C. film
D. ionization chamber - ANSWER-D
The f-factor:
A. is the roentgen to cGy conversion factor
B. is greatest for high Z materials and low energy photons
C. is 0.873 in air
D. all of the answers are correct
E. none of the answers are correct - ANSWER-D
Clinical application of MLC include which of the following?
A. shaping of electron fields as a replacement for cerrobend blocks
B. dynamic field shaping as a function of patient respiration
C. field shaping without penumbra
D. modulating beam intensity - ANSWER-D
In the image below, the label "a" is referencing what structure?
A. left atrium
B. right atrium
C. left ventricle
,D. right ventricle - ANSWER-C
For an Ir-192 implant, it is found that the sources were 0.5 mg-Ra equivalent instead of
0.5 mCi. The exposure rate constant for Ir-192 is 4.69 R-cm/mCi-hr. What impact does
this change have on the dose rate in the patient?
A. increase
B. decrease
C. remain the same - ANSWER-A
Treatment planning for pediatric cancer patients assumes increased importance
because:
A. many pediatric patients are treated with curative intent
B. children often receive chemotherapy which can interact with the complications of the
radiation treatment
C. growth disturbances due to radiation treatment are expected so exposed tissues
must be kept to a minimum volume
D. growth disturbances occur as a long term complication at relatively low doses (far
below those required for control of many tumors)
E. all are correct - ANSWER-E
The 104% isodose lines at the four corners of the target shown are due to the:
A. inhomogeneity of the femur
B. scatter from the femur
C. horns of the beams
D. weights of the lateral beams
E. use of a wrong algorithm - ANSWER-C
Exposure is:
A. the amount of energy in Joules/kg transferred from a photon beam to a material
B. only defined for photons and charged particles below 3 MeV
, C. the charge liberated by photons in a given mass of air
D. the absorbed dose multiplied by the quality factor
E. None of the answers - ANSWER-C
The quantity that an ionization chamber actually measures is:
A. roentgen
B. gray
C. charge
D. kerma
E. voltage - ANSWER-C
Geiger counters:
A. are sensitive enough to detect individual photons or particles
B. are less sensitive than ionization chambers
C. are used to calibrate linac output
D. operate on the principle of scintillation - ANSWER-A
Which of the following is an advantage of using an MRI for treatment planning?
A. there is no patient anatomy distortion on the images
B. it is reliable for locating tumors within tissue
C. it always displays an accurate external patient contour
D. the brightness of the image is directly related to tissue density - ANSWER-B
Based on clinical experiences with TBI before bone marrow transplantation and
hemibody irradiation, the most important dose-limiting tissue is the:
A. lens of the eye
B. spinal cord
C. lung
ANSWERS 100% ACCURATE
A patient receiving treatment to the head and neck region has experienced a skin
reaction and mucositis at a total dose much lower than anticipated. The radiation
oncologist requests an evaluation of the treatment. Which of the following steps should
be taken?
A. recalculate the treatment plan
B. ensure that the depth dose, build-up region, wedge parameters, and other pertinent
information for the treatment unit are correct
C. review the treatment setup with the therapist
D. recalculate the monitor unit settings
E. all are correct - ANSWER-E
For megavoltage dosimetry, TLD can provide accuracy of:
A. plus/minus 20%
B. plus/minus 10%
C. plus/minus 3%
D. plus/minus 1% - ANSWER-C
With megavoltage film dosimetry, isodose curves can be measured to within:
A. plus/minus 10%
B. plus/minus 7%
C. plus/minus 3%
D. plus/minus 1% - ANSWER-C
In megavoltage therapy, typical use(s) of diodes is for:
A. patient dosimetry
,B. beam scanning
C. quality assurance
D. all of the answers are correct - ANSWER-D
Which of the following is best suited for calibration of a megavoltage beam:
A. diode detector
B. thermoluminescence dosimetry
C. film
D. ionization chamber - ANSWER-D
The f-factor:
A. is the roentgen to cGy conversion factor
B. is greatest for high Z materials and low energy photons
C. is 0.873 in air
D. all of the answers are correct
E. none of the answers are correct - ANSWER-D
Clinical application of MLC include which of the following?
A. shaping of electron fields as a replacement for cerrobend blocks
B. dynamic field shaping as a function of patient respiration
C. field shaping without penumbra
D. modulating beam intensity - ANSWER-D
In the image below, the label "a" is referencing what structure?
A. left atrium
B. right atrium
C. left ventricle
,D. right ventricle - ANSWER-C
For an Ir-192 implant, it is found that the sources were 0.5 mg-Ra equivalent instead of
0.5 mCi. The exposure rate constant for Ir-192 is 4.69 R-cm/mCi-hr. What impact does
this change have on the dose rate in the patient?
A. increase
B. decrease
C. remain the same - ANSWER-A
Treatment planning for pediatric cancer patients assumes increased importance
because:
A. many pediatric patients are treated with curative intent
B. children often receive chemotherapy which can interact with the complications of the
radiation treatment
C. growth disturbances due to radiation treatment are expected so exposed tissues
must be kept to a minimum volume
D. growth disturbances occur as a long term complication at relatively low doses (far
below those required for control of many tumors)
E. all are correct - ANSWER-E
The 104% isodose lines at the four corners of the target shown are due to the:
A. inhomogeneity of the femur
B. scatter from the femur
C. horns of the beams
D. weights of the lateral beams
E. use of a wrong algorithm - ANSWER-C
Exposure is:
A. the amount of energy in Joules/kg transferred from a photon beam to a material
B. only defined for photons and charged particles below 3 MeV
, C. the charge liberated by photons in a given mass of air
D. the absorbed dose multiplied by the quality factor
E. None of the answers - ANSWER-C
The quantity that an ionization chamber actually measures is:
A. roentgen
B. gray
C. charge
D. kerma
E. voltage - ANSWER-C
Geiger counters:
A. are sensitive enough to detect individual photons or particles
B. are less sensitive than ionization chambers
C. are used to calibrate linac output
D. operate on the principle of scintillation - ANSWER-A
Which of the following is an advantage of using an MRI for treatment planning?
A. there is no patient anatomy distortion on the images
B. it is reliable for locating tumors within tissue
C. it always displays an accurate external patient contour
D. the brightness of the image is directly related to tissue density - ANSWER-B
Based on clinical experiences with TBI before bone marrow transplantation and
hemibody irradiation, the most important dose-limiting tissue is the:
A. lens of the eye
B. spinal cord
C. lung
