ASRT mock exam math questions
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 dose is 300 cGy prescribed at a depth of 5 cm from the posterior. The
percentage depth dose curve (PDD) at 5 cm is 87% and PDD at 10 cm is 57.7%. -
answer345 cGy
Given dose is solved by taking the tumor dose divided by PDD of point prescribed,
therefore 300 cGy / .87 = 345 cGy.
Using the equivalent square formula, what is the equivalent square for a 15 x 18 field? -
answer16.4
A palliative patient's plan is calcualted to deliver 8 Gy in 1 fx to the supine patient with
100 cm SSD spine PA only field. The patient is in severe pain at the time of treatment,
and the physician orders a mattress be used. The distance to the spine is now 103 cm
SSD. What is the dose to the target when the 103 cm SSD is used? - answer7.5
use inverse square correction factor (100/103)2 x 8 = 7.5 Gy.
What dose will be given to dmax if a dose of 180 cGy is prescribed to the gross tumor
volume (GTV) and the percentage depth dose curve (PDD) dose is 64.3%. - answer280
Given dose = tumor dose / PDD. Given dose is also known as the dmax dose or
electron equilibrium dose. This is where you will see the maximum dose or 100% of the
radiation delivered.
Calculate MU for the following extended distance treatment. Treat an AP/PA lung
mantle at 105 target to skin distance (TSD) with 6 MV beam. The field size at 105 TSD
is 15 x 15 cm on the skin. Treatment is prescribed to midline with a daily dose of 200
cGy. The separation of the patient is 20 cm. Calibration factor is .971 cGy/MU,
Sc=1.023, Sp=1.01, PDD=69.4%. Be sure to include all needed factors. - answer158
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. - answer0.9
A 360 degree rotation has an MU/degree setting of 0.72 MU/degree. How many monitor
units will be delivered? - answerUse direct proportion. 0.72 MU:x as 1 degree:360. 0.72
(360) = 259.
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 dose is 300 cGy prescribed at a depth of 5 cm from the posterior. The
percentage depth dose curve (PDD) at 5 cm is 87% and PDD at 10 cm is 57.7%. -
answer345 cGy
Given dose is solved by taking the tumor dose divided by PDD of point prescribed,
therefore 300 cGy / .87 = 345 cGy.
Using the equivalent square formula, what is the equivalent square for a 15 x 18 field? -
answer16.4
A palliative patient's plan is calcualted to deliver 8 Gy in 1 fx to the supine patient with
100 cm SSD spine PA only field. The patient is in severe pain at the time of treatment,
and the physician orders a mattress be used. The distance to the spine is now 103 cm
SSD. What is the dose to the target when the 103 cm SSD is used? - answer7.5
use inverse square correction factor (100/103)2 x 8 = 7.5 Gy.
What dose will be given to dmax if a dose of 180 cGy is prescribed to the gross tumor
volume (GTV) and the percentage depth dose curve (PDD) dose is 64.3%. - answer280
Given dose = tumor dose / PDD. Given dose is also known as the dmax dose or
electron equilibrium dose. This is where you will see the maximum dose or 100% of the
radiation delivered.
Calculate MU for the following extended distance treatment. Treat an AP/PA lung
mantle at 105 target to skin distance (TSD) with 6 MV beam. The field size at 105 TSD
is 15 x 15 cm on the skin. Treatment is prescribed to midline with a daily dose of 200
cGy. The separation of the patient is 20 cm. Calibration factor is .971 cGy/MU,
Sc=1.023, Sp=1.01, PDD=69.4%. Be sure to include all needed factors. - answer158
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. - answer0.9
A 360 degree rotation has an MU/degree setting of 0.72 MU/degree. How many monitor
units will be delivered? - answerUse direct proportion. 0.72 MU:x as 1 degree:360. 0.72
(360) = 259.
