RAD 400 Final Exam Questions and Answers (SCORED A+) If the number of fields increases what happens to beam uniformity? - ANSWERit increases
If beam energy increases what happens to the beam uniformity? - ANSWERit increases
If you increase patient thickness increases what happens to beam energy? - ANSWERit
decreases
if you increase SSD what happens to penumbra - ANSWERit increases
if sdd increases what happens to penumbra - ANSWERit decreases
if you increase source size what happens to penumbra - ANSWERit increases
if you increase field size what happens to MU - ANSWERit decreases
if you increase field size what happens to PDD - ANSWERit increases
if you increase field size what happens to TAR - ANSWERit increases
if you decrease beam energy what happens to PDD - ANSWERit decreases
if you increase beam energy what happens to MU - ANSWERit decreases
if you increase beam energy what happens to treatment time - ANSWERit decreases
if you increase beam energy what happens to the peripheral midpoint ratio - ANSWERit decreases
if you decrease beam energy what happens to the buildup/entrance dose - ANSWERit increases
if you decrease beam energy what happens to the hotspot value - ANSWERit increases
the hotspot
if you increase the prescription depth what happens to the PDD - ANSWERit decreases
if you increase prescription depth what happens to MU - ANSWERit increases
if you increase SSD what happens to PDD - ANSWERit increases if you decrease SSD what happens to TAR - ANSWERno effect
How does ICRU report 62 define a hotspot - ANSWER2cm^2
if you increase patient thickness what happens to skin dose - ANSWERit increases
If you increase the number of fields what happens to treatment time - ANSWERit increases
if you increase the number of fields what happens to the skin dose - ANSWERit decreases
What is the equation for hinge angle - ANSWERHA= 180-2WA
How does ICRU define report 62 for a hotspot - ANSWER2cm^2
what is true concerning the benefits of a dynamic wedge over a physical wedge? - ANSWER- less scatter on the patient w/a dynamic wedge - less chance of error w/respect to the wedge direction - physical wedges are less efficient due to their static size
-a wedge factor must be applied to the MU setting for both
What is true concerning penumbra? - ANSWER- the edge of the light field represents the 50% isodose line - a field size of 4x4 cm is more difficult to measure than a 20x20 - a cobalt machine has wider penumbra compared to a linac beam
What is true concerning flattening filters? - ANSWER- TomoTherapy doesn't utilize a flattening filter - a 10 FFF beam has a lower energy than a 10x beam w/a flattening filter - flattening filter free beams are very useful for high dose per fx
what is the Dmax for a 1.25 mv beam - ANSWER.5 cm
What is the Dmax for 4 mv beam - ANSWER1.0 cm
What is the Dmax of a 6 mv beam - ANSWER1.5 cm
What is the Dmax of a 10 mv beam - ANSWER2.5 cm
What is the Dmax for a 18 mv beam - ANSWER3 cm
what is the equation to find % hot or cold - ANSWERPOI dose / RX
If beam energy increases what happens to the beam uniformity? - ANSWERit increases
If you increase patient thickness increases what happens to beam energy? - ANSWERit
decreases
if you increase SSD what happens to penumbra - ANSWERit increases
if sdd increases what happens to penumbra - ANSWERit decreases
if you increase source size what happens to penumbra - ANSWERit increases
if you increase field size what happens to MU - ANSWERit decreases
if you increase field size what happens to PDD - ANSWERit increases
if you increase field size what happens to TAR - ANSWERit increases
if you decrease beam energy what happens to PDD - ANSWERit decreases
if you increase beam energy what happens to MU - ANSWERit decreases
if you increase beam energy what happens to treatment time - ANSWERit decreases
if you increase beam energy what happens to the peripheral midpoint ratio - ANSWERit decreases
if you decrease beam energy what happens to the buildup/entrance dose - ANSWERit increases
if you decrease beam energy what happens to the hotspot value - ANSWERit increases
the hotspot
if you increase the prescription depth what happens to the PDD - ANSWERit decreases
if you increase prescription depth what happens to MU - ANSWERit increases
if you increase SSD what happens to PDD - ANSWERit increases if you decrease SSD what happens to TAR - ANSWERno effect
How does ICRU report 62 define a hotspot - ANSWER2cm^2
if you increase patient thickness what happens to skin dose - ANSWERit increases
If you increase the number of fields what happens to treatment time - ANSWERit increases
if you increase the number of fields what happens to the skin dose - ANSWERit decreases
What is the equation for hinge angle - ANSWERHA= 180-2WA
How does ICRU define report 62 for a hotspot - ANSWER2cm^2
what is true concerning the benefits of a dynamic wedge over a physical wedge? - ANSWER- less scatter on the patient w/a dynamic wedge - less chance of error w/respect to the wedge direction - physical wedges are less efficient due to their static size
-a wedge factor must be applied to the MU setting for both
What is true concerning penumbra? - ANSWER- the edge of the light field represents the 50% isodose line - a field size of 4x4 cm is more difficult to measure than a 20x20 - a cobalt machine has wider penumbra compared to a linac beam
What is true concerning flattening filters? - ANSWER- TomoTherapy doesn't utilize a flattening filter - a 10 FFF beam has a lower energy than a 10x beam w/a flattening filter - flattening filter free beams are very useful for high dose per fx
what is the Dmax for a 1.25 mv beam - ANSWER.5 cm
What is the Dmax for 4 mv beam - ANSWER1.0 cm
What is the Dmax of a 6 mv beam - ANSWER1.5 cm
What is the Dmax of a 10 mv beam - ANSWER2.5 cm
What is the Dmax for a 18 mv beam - ANSWER3 cm
what is the equation to find % hot or cold - ANSWERPOI dose / RX
