1) Highest neutron flux in a therapy treatment room is produced by _____.
A. a Cobalt-60 source
B. a 10-MeV electron beam
C. a 10-MV photon beam
D. a 20-MV photon beam
E. a 20-MeV electron beam
2) In the treatment of Hodgkin s disease with a mantle field on a linac, patients may experience a skin reaction in the neck region. This could be due to which of the following?
A. Smaller thickness of tissue at neck than on the central beam axis.
B. Oblique incidence at sides of neck reduces skin sparing.
C. Use of a blocking tray and large field size tend to increase skin dose
D. All of the above
3) Parallel-opposed 18 MV photon beams (dmax = 3.5 cm) are used to treat an area which includes nodes at a minimum depth of 2.0 cm, If the nodes are to receive at least 90% of the midplane dose:
A. 3.5 cm bolus is needed.
B. More than 3.5 cm bolus is needed.
C. Between 2 and 3.5 cm bolus is needed
D. Bolus is not needed.
E. Less than 2cm
4) Which of the following could be used as a tissue compensator?
A. Shaped bolus.
B. A wedge.
C. Shaped CerrobendTM
D. Dynamic MLC.
E. All of the above
5) The formula used to calculate the gap on the skin between adjacent fields, matched at depth, relies on the fact that:
A. Both beams are treated with photons of the same energy.
B.The projection of the edge of the light field follows the 50% decrement line of the radiation field.
C. The angle of divergence of adjacent beams is the same
D.Both fields arc treated simultaneously.
E. The depth at the junction is less than 10 cm.