MDCB UPDATED STUDY GUIDE QUESTIONS AND
ANSWERS MARKED A+
✔✔Describe grazing hit Compton effect - ✔✔photon goes forward electron at 90° w/T=0
✔✔Describe direct hit Compton - ✔✔Max energy electron, which travels fwd photon @
180°
✔✔Max energy Compton photon scattered @ 180° - ✔✔me/2 = 0.255 MeV
✔✔Max energy Compton photon scattered @ 90° - ✔✔me =0.511 MeV
✔✔max Energy compton photon scattered @ 0° - ✔✔energy initial photon
✔✔total KE available for e+e- pair for pair production - ✔✔hf - 2*me = hf - 1.02 MeV
✔✔"Annihilation radiation, energy each annihilation photon" - ✔✔0.511 MeV
✔✔Describe the photons created in annihilation radiation - ✔✔Two 0.511 MeV particles
scattered in opposite directions
✔✔threshhold kVp for xray tube for Compton effect - ✔✔90 kVp
✔✔define stopping power - ✔✔rate of kinetic energy loss per unit path length
✔✔Number of elements = - ✔✔103
✔✔Radioactive threshold in Z = - ✔✔82
✔✔Name the 3 naturally occuring radioactive series - ✔✔"uranium, actinium, thorium"
✔✔define: equilibrium isotopes - ✔✔ratio of daughter to parent activity constant
✔✔KE alpha particles - ✔✔5 - 10 MeV
✔✔Describe K capture - ✔✔"Electron capture of electron in orbit closest to nucleus,
competes with positron decay"
✔✔Define fission - ✔✔Bombarding high atomic elements with neutrons resulting in
nuclear disintegration
✔✔Describe fusion - ✔✔low mass nuclei combined to produce one nucleus
,✔✔"formula exposure rate, C =" - ✔✔gamma X activity / ISF
✔✔define apparent activity - ✔✔in terms of encapsulated 0.5 mm Pb radium at 1-m
✔✔Gamma factor radium - ✔✔8.25 Rcm2/mCi-hr WATCH UNITS
✔✔converting mCi to mg-Ra equiv - ✔✔strength = gamma/gamma-Ra x app activity
mCi
✔✔radial dose important for which low energy sources? - ✔✔I-125 P-103
✔✔Which brachy system implants more dose at periphery? - ✔✔PP
✔✔When do you need more radium in Quimby sys than in PP? - ✔✔When dose RX at
min
✔✔Which system uses long lines sources for implants? - ✔✔Paris
✔✔Which implant system calcs RX from basal dose? - ✔✔Paris
✔✔What 3 things needed for implants according ICRU? - ✔✔dim target ref kerma ref
pts
✔✔Decay I and Pd - ✔✔e- capture
✔✔Which nuclides anisotrophy factors? - ✔✔I 125 Pd 103
✔✔Energy radium and radon - ✔✔800 keV
✔✔rad protection stds for nuclear reactors set by this US body - ✔✔NRC
✔✔stds for naturally occuring radionuclides set by this body - ✔✔state
✔✔recomm adhered to by states set by this body - ✔✔NCRP
✔✔Factor that converts dose to bio effect - ✔✔Q
✔✔Negligible risk factor - ✔✔0.01 mSv
✔✔occup dose lens - ✔✔150 mSv
✔✔formula for exposure from brachy sources for rad safety and barrier Thickness -
✔✔X [R] = gamma x activity x time x B / ISF
, ✔✔Formula to calc - ✔✔TVLs
✔✔Formula to calc thickness of wall from TVL - ✔✔- TVL log (B)
✔✔"If B = 10^-5, how many TVLs?" - ✔✔5
✔✔5 TVLs of concrete for 6X - ✔✔168 cm
✔✔Year R adopted ICRU as unit - ✔✔1928
✔✔Year Cobalt 60 - ✔✔1951
✔✔Si unit X - ✔✔C/kg
✔✔Clinical unit X - ✔✔r
✔✔Energy limit free air ionization measurements - ✔✔3 MeV
✔✔Density of mass in air in thimble chamber increases with... - ✔✔decreasing T
increasing P
✔✔TG report concerning measurements absorbed dose - ✔✔51
✔✔In tx breast, dose at chest-lung interface" - ✔✔80% E = depth x 3
✔✔Ripple in - ✔✔1) ~0%
✔✔1) constant - ✔✔2) 5-10%
✔✔2) three phase 6 pulse - ✔✔3) 4%
✔✔3) three phase 12 pulse - ✔✔Tungsten k edge
✔✔70 KeV - ✔✔increase of mAs of 100% is equal to what increase of kVp
✔✔15% - ✔✔Fluoroscopy x ray tube currents
✔✔1-6 mA - ✔✔Radiography/CT xray tube currents
✔✔~100s mA - ✔✔Focal spot in CR
✔✔Small 0.6 mm Large 1.2 mm - ✔✔Typical anode angle
ANSWERS MARKED A+
✔✔Describe grazing hit Compton effect - ✔✔photon goes forward electron at 90° w/T=0
✔✔Describe direct hit Compton - ✔✔Max energy electron, which travels fwd photon @
180°
✔✔Max energy Compton photon scattered @ 180° - ✔✔me/2 = 0.255 MeV
✔✔Max energy Compton photon scattered @ 90° - ✔✔me =0.511 MeV
✔✔max Energy compton photon scattered @ 0° - ✔✔energy initial photon
✔✔total KE available for e+e- pair for pair production - ✔✔hf - 2*me = hf - 1.02 MeV
✔✔"Annihilation radiation, energy each annihilation photon" - ✔✔0.511 MeV
✔✔Describe the photons created in annihilation radiation - ✔✔Two 0.511 MeV particles
scattered in opposite directions
✔✔threshhold kVp for xray tube for Compton effect - ✔✔90 kVp
✔✔define stopping power - ✔✔rate of kinetic energy loss per unit path length
✔✔Number of elements = - ✔✔103
✔✔Radioactive threshold in Z = - ✔✔82
✔✔Name the 3 naturally occuring radioactive series - ✔✔"uranium, actinium, thorium"
✔✔define: equilibrium isotopes - ✔✔ratio of daughter to parent activity constant
✔✔KE alpha particles - ✔✔5 - 10 MeV
✔✔Describe K capture - ✔✔"Electron capture of electron in orbit closest to nucleus,
competes with positron decay"
✔✔Define fission - ✔✔Bombarding high atomic elements with neutrons resulting in
nuclear disintegration
✔✔Describe fusion - ✔✔low mass nuclei combined to produce one nucleus
,✔✔"formula exposure rate, C =" - ✔✔gamma X activity / ISF
✔✔define apparent activity - ✔✔in terms of encapsulated 0.5 mm Pb radium at 1-m
✔✔Gamma factor radium - ✔✔8.25 Rcm2/mCi-hr WATCH UNITS
✔✔converting mCi to mg-Ra equiv - ✔✔strength = gamma/gamma-Ra x app activity
mCi
✔✔radial dose important for which low energy sources? - ✔✔I-125 P-103
✔✔Which brachy system implants more dose at periphery? - ✔✔PP
✔✔When do you need more radium in Quimby sys than in PP? - ✔✔When dose RX at
min
✔✔Which system uses long lines sources for implants? - ✔✔Paris
✔✔Which implant system calcs RX from basal dose? - ✔✔Paris
✔✔What 3 things needed for implants according ICRU? - ✔✔dim target ref kerma ref
pts
✔✔Decay I and Pd - ✔✔e- capture
✔✔Which nuclides anisotrophy factors? - ✔✔I 125 Pd 103
✔✔Energy radium and radon - ✔✔800 keV
✔✔rad protection stds for nuclear reactors set by this US body - ✔✔NRC
✔✔stds for naturally occuring radionuclides set by this body - ✔✔state
✔✔recomm adhered to by states set by this body - ✔✔NCRP
✔✔Factor that converts dose to bio effect - ✔✔Q
✔✔Negligible risk factor - ✔✔0.01 mSv
✔✔occup dose lens - ✔✔150 mSv
✔✔formula for exposure from brachy sources for rad safety and barrier Thickness -
✔✔X [R] = gamma x activity x time x B / ISF
, ✔✔Formula to calc - ✔✔TVLs
✔✔Formula to calc thickness of wall from TVL - ✔✔- TVL log (B)
✔✔"If B = 10^-5, how many TVLs?" - ✔✔5
✔✔5 TVLs of concrete for 6X - ✔✔168 cm
✔✔Year R adopted ICRU as unit - ✔✔1928
✔✔Year Cobalt 60 - ✔✔1951
✔✔Si unit X - ✔✔C/kg
✔✔Clinical unit X - ✔✔r
✔✔Energy limit free air ionization measurements - ✔✔3 MeV
✔✔Density of mass in air in thimble chamber increases with... - ✔✔decreasing T
increasing P
✔✔TG report concerning measurements absorbed dose - ✔✔51
✔✔In tx breast, dose at chest-lung interface" - ✔✔80% E = depth x 3
✔✔Ripple in - ✔✔1) ~0%
✔✔1) constant - ✔✔2) 5-10%
✔✔2) three phase 6 pulse - ✔✔3) 4%
✔✔3) three phase 12 pulse - ✔✔Tungsten k edge
✔✔70 KeV - ✔✔increase of mAs of 100% is equal to what increase of kVp
✔✔15% - ✔✔Fluoroscopy x ray tube currents
✔✔1-6 mA - ✔✔Radiography/CT xray tube currents
✔✔~100s mA - ✔✔Focal spot in CR
✔✔Small 0.6 mm Large 1.2 mm - ✔✔Typical anode angle
