MEDICAL DOSIMETRY EXAMS LATEST STUDY
GUIDE QUESTIONS AND ANSWERS SURE A+
✔✔Shoulder on survival curve - ✔✔Indicates reduced efficiency of cell killing at low
doses
✔✔Total body irradiation - ✔✔Most important dose-limiting tissue is the lung
✔✔Linear attenuation coefficient - ✔✔0.51 cm-1 for a 6 MV beam
✔✔Morbidity in lung cancer treatment - ✔✔Includes pericarditis
✔✔Inadvertent 18 MV treatment - ✔✔Delivers 225 cGy to 5 cm depth
✔✔Total CNS technique - ✔✔Requires non-divergent beam junctions
✔✔Mechanical isocenter location - ✔✔Determined by rotating the gantry around a
pointer
✔✔Waveguide component - ✔✔Directs electron beam to the output window
, ✔✔Off-axis ratio - ✔✔Represents the dose ratio at off-axis point to central axis at the
same depth
✔✔Density of fat - ✔✔Approximately 0.95 g/cc
✔✔Activity of Cesium-137 source - ✔✔After 6.5 years, will be 21.5 mCi
✔✔Stochastic effect of radiation - ✔✔Example is decreased sperm count
✔✔Enface electron beam dose - ✔✔Increased due to an increase in the electron
fluence
✔✔Ionization chamber readings - ✔✔Monitor unit setting is 217 MU for 6 cm x 10 cm
cut-out
✔✔Secular equilibrium - ✔✔Occurs when parent and daughter isotopes have a
constant ratio of activity
✔✔Inhomogeneity corrections in treatment plans - ✔✔TPS converts CT numbers to
Hounsfield units
✔✔Avoiding cord overdose - ✔✔Achieved by angling lateral fields off the cord
✔✔Annual equivalent dose limit for hands - ✔✔According to NCRP guidelines #116, is
50 mSv (5.0 rem)
✔✔Photoelectric interactions - ✔✔Entire energy of incident photon is absorbed by
resulting electron
✔✔Film badges in personnel monitoring - ✔✔Contain filters to reduce dose from low-
energy radiations
✔✔Prognostic factor in breast cancer - ✔✔Status of the axillary nodes
✔✔Axillary Nodes - ✔✔Lymph nodes that indicate cancer spread in breast cancer.
✔✔Quadrant of Origin - ✔✔Specific area within the breast where cancer originates.
✔✔SSD - ✔✔Source-to-Surface Distance used in radiotherapy.
✔✔Electron Beam Output Factors - ✔✔Corrected using energy coefficient or equivalent
thickness.
✔✔Electron Arc Therapy - ✔✔Effective for treating tumors like pituitary or brain.
GUIDE QUESTIONS AND ANSWERS SURE A+
✔✔Shoulder on survival curve - ✔✔Indicates reduced efficiency of cell killing at low
doses
✔✔Total body irradiation - ✔✔Most important dose-limiting tissue is the lung
✔✔Linear attenuation coefficient - ✔✔0.51 cm-1 for a 6 MV beam
✔✔Morbidity in lung cancer treatment - ✔✔Includes pericarditis
✔✔Inadvertent 18 MV treatment - ✔✔Delivers 225 cGy to 5 cm depth
✔✔Total CNS technique - ✔✔Requires non-divergent beam junctions
✔✔Mechanical isocenter location - ✔✔Determined by rotating the gantry around a
pointer
✔✔Waveguide component - ✔✔Directs electron beam to the output window
, ✔✔Off-axis ratio - ✔✔Represents the dose ratio at off-axis point to central axis at the
same depth
✔✔Density of fat - ✔✔Approximately 0.95 g/cc
✔✔Activity of Cesium-137 source - ✔✔After 6.5 years, will be 21.5 mCi
✔✔Stochastic effect of radiation - ✔✔Example is decreased sperm count
✔✔Enface electron beam dose - ✔✔Increased due to an increase in the electron
fluence
✔✔Ionization chamber readings - ✔✔Monitor unit setting is 217 MU for 6 cm x 10 cm
cut-out
✔✔Secular equilibrium - ✔✔Occurs when parent and daughter isotopes have a
constant ratio of activity
✔✔Inhomogeneity corrections in treatment plans - ✔✔TPS converts CT numbers to
Hounsfield units
✔✔Avoiding cord overdose - ✔✔Achieved by angling lateral fields off the cord
✔✔Annual equivalent dose limit for hands - ✔✔According to NCRP guidelines #116, is
50 mSv (5.0 rem)
✔✔Photoelectric interactions - ✔✔Entire energy of incident photon is absorbed by
resulting electron
✔✔Film badges in personnel monitoring - ✔✔Contain filters to reduce dose from low-
energy radiations
✔✔Prognostic factor in breast cancer - ✔✔Status of the axillary nodes
✔✔Axillary Nodes - ✔✔Lymph nodes that indicate cancer spread in breast cancer.
✔✔Quadrant of Origin - ✔✔Specific area within the breast where cancer originates.
✔✔SSD - ✔✔Source-to-Surface Distance used in radiotherapy.
✔✔Electron Beam Output Factors - ✔✔Corrected using energy coefficient or equivalent
thickness.
✔✔Electron Arc Therapy - ✔✔Effective for treating tumors like pituitary or brain.
