ASRT mock exam math questions and
answers
Calculate the gap needed for the following treatment. Field 1 is 10 cm in length, and Field 2 is
20 cm in length. Both fields are treated at 100 cm at a depth of 6 cm with a 6 MV beam. -
ANSWERS-0.9
A 360 degree rotation has an MU/degree setting of 0.72 MU/degree. How many monitor units
will be delivered? - ANSWERS-Use direct proportion. 0.72 MU:x as 1 degree:360. 0.72 (360) =
259.
The patient's prescription is for a total dose of 66 Gy. Daily fraction sizes will be 2 Gy for the first
5 fractions decreasing to 1.5 Gy for the remaining fractions. How many total fractions will this
patient receive? - ANSWERS-The first 5 fractions will deliver 10 Gy leaving 56 Gy to complete the
prescription. At 1.5 Gy per fraction for the remaining fractions, 37 more fractions are needed to
for a total dose of 66 Gy.
How many monitor units are needed for this AP treatment field? A dose of 200 cGy is prescribed
to a depth of 6 cm with a 6 MV beam. The field size of a 14 cm equivalent square is used. There
are no wedges and minimal multileaf collimator (MLC). The percent depth dose is 0.78 and the
output factor is 1.0 cGy/MU. - ANSWERS-256
Monitor units can be calculated by TD/%dd x output x TF x WF. Because wedges and cerrobend
blocks are not used, MU = 200/0.76 x 1 = 256.
Dr. Smith writes her radiation treatment prescription to have 180cGy/fx at the patient midplane
with a right and left lateral field. The patient's separation at the central axis (CAX) measures 34
cm. At what depth would the motor units (MU) be calculated to? - ANSWERS-17
What is the given dose for the following treatment? Patient treated at 100 target to skin
distance (TSD) with 6MV beam to a PA spine field. The patient's separation is 15 cm. The tumor
answers
Calculate the gap needed for the following treatment. Field 1 is 10 cm in length, and Field 2 is
20 cm in length. Both fields are treated at 100 cm at a depth of 6 cm with a 6 MV beam. -
ANSWERS-0.9
A 360 degree rotation has an MU/degree setting of 0.72 MU/degree. How many monitor units
will be delivered? - ANSWERS-Use direct proportion. 0.72 MU:x as 1 degree:360. 0.72 (360) =
259.
The patient's prescription is for a total dose of 66 Gy. Daily fraction sizes will be 2 Gy for the first
5 fractions decreasing to 1.5 Gy for the remaining fractions. How many total fractions will this
patient receive? - ANSWERS-The first 5 fractions will deliver 10 Gy leaving 56 Gy to complete the
prescription. At 1.5 Gy per fraction for the remaining fractions, 37 more fractions are needed to
for a total dose of 66 Gy.
How many monitor units are needed for this AP treatment field? A dose of 200 cGy is prescribed
to a depth of 6 cm with a 6 MV beam. The field size of a 14 cm equivalent square is used. There
are no wedges and minimal multileaf collimator (MLC). The percent depth dose is 0.78 and the
output factor is 1.0 cGy/MU. - ANSWERS-256
Monitor units can be calculated by TD/%dd x output x TF x WF. Because wedges and cerrobend
blocks are not used, MU = 200/0.76 x 1 = 256.
Dr. Smith writes her radiation treatment prescription to have 180cGy/fx at the patient midplane
with a right and left lateral field. The patient's separation at the central axis (CAX) measures 34
cm. At what depth would the motor units (MU) be calculated to? - ANSWERS-17
What is the given dose for the following treatment? Patient treated at 100 target to skin
distance (TSD) with 6MV beam to a PA spine field. The patient's separation is 15 cm. The tumor
