| 1. |
Regarding targets and filters in mammography: a. The Rh–Mo target–filter combination is used for thicker breast tissue b. Using a Rh filter with a Mo target increases the mean and peak photon energy of the spectrum compared with Mo–Mo c. Rh produces a characteristic radiation slightly lower than Mo d. The combination of W–Rh has the best contrast e. In the Mo–Mo combination, the dose is higher than in other combinations |
|
Answer» a. False. The combination of Rh-Mo is not used, because the effect of the filter would be to attenuate the Rh characteristic radiation with energy that is just greater than the K-edge of Mo. b. False. Use of a Mo–Rh combination increases the mean energy of the spectrum, because it will transmit Bremsstrahlung photons in the energy range just below 23.2 keV, thus increasing the beam penetration, but peak photon energy is determined by the tube potential and the target material does not affect this. c. False. The characteristic radiation of Rh is 23.2 keV and Mo is 20 keV. d. False. Contrast in different target–filter combinations decreases as follows: Mo–Mo > Mo–Rh > Rh–Rh > W–Rh. e. True. The dose in different target–filter combinations decreases as follows: Mo–Mo > Mo–Rh > Rh–Rh > W–Rh. |
|