MDCB LATEST 2026 CORE EXAM MANUAL QUESTIONS
AND ANSWERS MARKED A+
✔✔According to AAPM TG report #142, when performing periodic linac quality
assurance procedures, which of the following is the acceptable tolerance for electron
flatness - ✔✔3%
Flatness-3%
✔✔an individual receives a dose of 0.1 cGy from a gamma source and 0.05cGy from
neutrons. The dose equivalent from both radiation sources is? -
✔✔0.1x1+0.05x20=1.1cGy =11 mSv
✔✔For quality assurance of brachytherapy tx planning computers, the dose rates
should agree with published data tables to which of the following degrees? - ✔✔+/-2
✔✔The expected accuracy of tx planning systems that perfrom brachytherapy dose
calc's should be within - ✔✔+/-5%
✔✔The number of nuclei decaying per second is expresssed in terms of their? -
✔✔activity
✔✔Prior to tx h&n pts with IMRT, a 3 field techn was used. Choose the best option to
keep the cord dose under cord tolerance when total rx dose would normally go higher
than 50Gy - ✔✔reduce lateral fields post and add an electron beam fields
✔✔The adv fo an electron beam over kilovoltage x-ray beam for tx of superficial tumors
is - ✔✔decrease dose to bone
✔✔The five year survival rate for a pancreatic tumor tx with primary radiation is? - ✔✔0-
5%
✔✔If the exposure rate constant is 0.87 rcm^2hr^-1mCi^-1 and the average pt
transmission factor is 0.20, the exposure rate at 12.5cm for a pt who has been injected
with 20 mCi of Tc99m is - ✔✔Activity x dose rate/d^2
0.87x.20x20/12.5^2= 0.0223R/hr-22.3mR/hr
✔✔What is the term that defines radiation intensity at points equidistant around the
source, normalized to the radiation intensity at a reference distance on the radius
bisecting the source? - ✔✔anisotrophy function
✔✔In malignant tumor of the nasopharynx that spreads directly to the middle cranial
fosaa, what is the usual route of invasion? - ✔✔Foramen rotundum
, ✔✔The measured and computer generated isodose curves should agree within: -
✔✔+/-2%, 2mm
✔✔What is the deviatation for the "maximum dose (in % of dose prescribed) @ 2cm
from PTV in any direction, d2cm (%)? - ✔✔max dose :28.2/48 total dose =.5875 which
is <58.0 so major
✔✔Optic tract - ✔✔
✔✔basilar artery - ✔✔in front of brainstem
✔✔prescription for dose and monitor unit calculations using Monte Carlo based
treatment planning systems should be based on dose to: - ✔✔target volumes
✔✔According to the AAPM # 76 the use of respiratory management techniques is
appropriated for the pt's radiation treatment when: - ✔✔The respiratory motion of the
tumor is the same from day to day
✔✔The most common interation for megavoltage photon beams in water-like tissues
(Z=75), is the: - ✔✔compton effect
✔✔The ratio of the dose rate of a given field size to the dose rate of the reference field
size is: - ✔✔relative output factor
✔✔During which stage of mitosis do the chromosomes align across the equator of the
spindle fibers - ✔✔Prophase, spindle fibers
✔✔Which types of DVH shows the volume receiving a dose within a specific dose
range? - ✔✔Differental
✔✔Any error in the placement of adjacent fields during radiotherapy tx is most likely to:
- ✔✔Be more serious with beams of smaller penumbra
-Gamma knife has tight penumbra
✔✔A radiation oncology department has a selection of 6, 10, and 18 MV photon beams.
For a 7 beam prostate intensity modulated radiation therapy (IMRT) plan, would be
appropriated to select: - ✔✔A 6mv photon beam b/c it would deliver no neutron dose
and the lowest doses to the tissue outside the planning target volume
or
2014 MDCB 10 MV photon beam bc it would deliver a lower neutron dose than an 18
mv photon beam and clinically be accepatable dose to rectum and bladder
AND ANSWERS MARKED A+
✔✔According to AAPM TG report #142, when performing periodic linac quality
assurance procedures, which of the following is the acceptable tolerance for electron
flatness - ✔✔3%
Flatness-3%
✔✔an individual receives a dose of 0.1 cGy from a gamma source and 0.05cGy from
neutrons. The dose equivalent from both radiation sources is? -
✔✔0.1x1+0.05x20=1.1cGy =11 mSv
✔✔For quality assurance of brachytherapy tx planning computers, the dose rates
should agree with published data tables to which of the following degrees? - ✔✔+/-2
✔✔The expected accuracy of tx planning systems that perfrom brachytherapy dose
calc's should be within - ✔✔+/-5%
✔✔The number of nuclei decaying per second is expresssed in terms of their? -
✔✔activity
✔✔Prior to tx h&n pts with IMRT, a 3 field techn was used. Choose the best option to
keep the cord dose under cord tolerance when total rx dose would normally go higher
than 50Gy - ✔✔reduce lateral fields post and add an electron beam fields
✔✔The adv fo an electron beam over kilovoltage x-ray beam for tx of superficial tumors
is - ✔✔decrease dose to bone
✔✔The five year survival rate for a pancreatic tumor tx with primary radiation is? - ✔✔0-
5%
✔✔If the exposure rate constant is 0.87 rcm^2hr^-1mCi^-1 and the average pt
transmission factor is 0.20, the exposure rate at 12.5cm for a pt who has been injected
with 20 mCi of Tc99m is - ✔✔Activity x dose rate/d^2
0.87x.20x20/12.5^2= 0.0223R/hr-22.3mR/hr
✔✔What is the term that defines radiation intensity at points equidistant around the
source, normalized to the radiation intensity at a reference distance on the radius
bisecting the source? - ✔✔anisotrophy function
✔✔In malignant tumor of the nasopharynx that spreads directly to the middle cranial
fosaa, what is the usual route of invasion? - ✔✔Foramen rotundum
, ✔✔The measured and computer generated isodose curves should agree within: -
✔✔+/-2%, 2mm
✔✔What is the deviatation for the "maximum dose (in % of dose prescribed) @ 2cm
from PTV in any direction, d2cm (%)? - ✔✔max dose :28.2/48 total dose =.5875 which
is <58.0 so major
✔✔Optic tract - ✔✔
✔✔basilar artery - ✔✔in front of brainstem
✔✔prescription for dose and monitor unit calculations using Monte Carlo based
treatment planning systems should be based on dose to: - ✔✔target volumes
✔✔According to the AAPM # 76 the use of respiratory management techniques is
appropriated for the pt's radiation treatment when: - ✔✔The respiratory motion of the
tumor is the same from day to day
✔✔The most common interation for megavoltage photon beams in water-like tissues
(Z=75), is the: - ✔✔compton effect
✔✔The ratio of the dose rate of a given field size to the dose rate of the reference field
size is: - ✔✔relative output factor
✔✔During which stage of mitosis do the chromosomes align across the equator of the
spindle fibers - ✔✔Prophase, spindle fibers
✔✔Which types of DVH shows the volume receiving a dose within a specific dose
range? - ✔✔Differental
✔✔Any error in the placement of adjacent fields during radiotherapy tx is most likely to:
- ✔✔Be more serious with beams of smaller penumbra
-Gamma knife has tight penumbra
✔✔A radiation oncology department has a selection of 6, 10, and 18 MV photon beams.
For a 7 beam prostate intensity modulated radiation therapy (IMRT) plan, would be
appropriated to select: - ✔✔A 6mv photon beam b/c it would deliver no neutron dose
and the lowest doses to the tissue outside the planning target volume
or
2014 MDCB 10 MV photon beam bc it would deliver a lower neutron dose than an 18
mv photon beam and clinically be accepatable dose to rectum and bladder
