MDCB LATEST 2026 EXAM QUESTIONS AND ANSWERS
MARKED A+
✔✔Order for e head of machine - ✔✔ec12dcc
electron, prim coll, 1st SF, 2nd SF, dose chamber, sec coll., cone
NO TARGET and NO FF
✔✔e first scatting foil - ✔✔spreads e- pencil beam out
✔✔e second scatter foil - ✔✔flattening
✔✔MLC transmission - ✔✔Intraleaf 1-2%
Interleaf 3-4%
✔✔G-M Counter - ✔✔used to find leaks
used to locate lost sources
measures beta and gamma
muy sensitivo
✔✔Unit for dose equivalent - ✔✔Rem
✔✔SI for dose equivalent - ✔✔Sievert
✔✔1REM - ✔✔1cSv
✔✔1 Sv - ✔✔100 rem
✔✔Dose equivalent (rem) formula - ✔✔Absorbed dose (rad) x QF
✔✔QF 1 - ✔✔X-ray gamma electrons betas
✔✔QF 2 - ✔✔Thermal neutrons
✔✔QF 10-20 - ✔✔Fast neutrons
✔✔QF 10 - ✔✔Protons
✔✔QF 20 - ✔✔Alphas
✔✔X-rays produced by - ✔✔Characteristic and bremstrahlung
✔✔X-rays by Linacs - ✔✔Bremstrahlung
✔✔Average photon energy - ✔✔1/3-1/2 Emax
, ✔✔Characteristic energies are - ✔✔Discrete based on shell
✔✔Gamma rays produced from - ✔✔Radioactive decay
✔✔Photoelectric energies - ✔✔Less than 50 keV
✔✔Photoelectric proportional to - ✔✔Z^3
The higher the z the more likely
✔✔Photoelectric interaction proportional - ✔✔1/E^3
Higher energy less likely to interact
✔✔Compton scattering energies - ✔✔50 keV -25 MeV
✔✔Target for Compton - ✔✔Free or way outer electron
✔✔Compton interaction - ✔✔Independent of Z
✔✔Compton to E - ✔✔Proportional to E
Higher the energy more likely
✔✔Photons scattered at 90 degrees - ✔✔0.511 MeV
✔✔Photons scattered at 180 degrees - ✔✔0.255 MeV
✔✔Rayleigh scattering - ✔✔Photons that do not transfer a notable amount of E and do
not change direction
✔✔Pair production threshold - ✔✔1.022MeV
2x energy of rest mass of e
✔✔Pair production energies - ✔✔Greater than 25 MeV
✔✔Pair production proportional to - ✔✔Z^2
✔✔Pair production site - ✔✔Nucleus
✔✔In PP Nucleus releases - ✔✔Positron and electron
✔✔Proton and E form - ✔✔Annihilation radiation photons 180degrees with 0.511
✔✔HVL - ✔✔0.693/linear attenuation coefficient
MARKED A+
✔✔Order for e head of machine - ✔✔ec12dcc
electron, prim coll, 1st SF, 2nd SF, dose chamber, sec coll., cone
NO TARGET and NO FF
✔✔e first scatting foil - ✔✔spreads e- pencil beam out
✔✔e second scatter foil - ✔✔flattening
✔✔MLC transmission - ✔✔Intraleaf 1-2%
Interleaf 3-4%
✔✔G-M Counter - ✔✔used to find leaks
used to locate lost sources
measures beta and gamma
muy sensitivo
✔✔Unit for dose equivalent - ✔✔Rem
✔✔SI for dose equivalent - ✔✔Sievert
✔✔1REM - ✔✔1cSv
✔✔1 Sv - ✔✔100 rem
✔✔Dose equivalent (rem) formula - ✔✔Absorbed dose (rad) x QF
✔✔QF 1 - ✔✔X-ray gamma electrons betas
✔✔QF 2 - ✔✔Thermal neutrons
✔✔QF 10-20 - ✔✔Fast neutrons
✔✔QF 10 - ✔✔Protons
✔✔QF 20 - ✔✔Alphas
✔✔X-rays produced by - ✔✔Characteristic and bremstrahlung
✔✔X-rays by Linacs - ✔✔Bremstrahlung
✔✔Average photon energy - ✔✔1/3-1/2 Emax
, ✔✔Characteristic energies are - ✔✔Discrete based on shell
✔✔Gamma rays produced from - ✔✔Radioactive decay
✔✔Photoelectric energies - ✔✔Less than 50 keV
✔✔Photoelectric proportional to - ✔✔Z^3
The higher the z the more likely
✔✔Photoelectric interaction proportional - ✔✔1/E^3
Higher energy less likely to interact
✔✔Compton scattering energies - ✔✔50 keV -25 MeV
✔✔Target for Compton - ✔✔Free or way outer electron
✔✔Compton interaction - ✔✔Independent of Z
✔✔Compton to E - ✔✔Proportional to E
Higher the energy more likely
✔✔Photons scattered at 90 degrees - ✔✔0.511 MeV
✔✔Photons scattered at 180 degrees - ✔✔0.255 MeV
✔✔Rayleigh scattering - ✔✔Photons that do not transfer a notable amount of E and do
not change direction
✔✔Pair production threshold - ✔✔1.022MeV
2x energy of rest mass of e
✔✔Pair production energies - ✔✔Greater than 25 MeV
✔✔Pair production proportional to - ✔✔Z^2
✔✔Pair production site - ✔✔Nucleus
✔✔In PP Nucleus releases - ✔✔Positron and electron
✔✔Proton and E form - ✔✔Annihilation radiation photons 180degrees with 0.511
✔✔HVL - ✔✔0.693/linear attenuation coefficient
