This is the collimator rotation required for the brain fields in a craniospinal treatment if the jaw setting of the upper spine field is 7.5
What is 4.3 degrees?
100
The number of MUs required to treat a patient given the following: Single AP beam, Rx = 400cGy, Sc = 1.03, Sp=1.05, TMR = 0.93, Inverse square = 1.03, treated on CAX with no beam modifiers.
What is 386?
100
This is when a photon interacts with an electron, resulting in an ejected electron and a lower energy photon.
What is Compton scattering?
100
Given a temperature of 26 degrees Celsius and a pressure of 986 millibar, this is necessary correction factor.
What is 1.04?
200
This is the necessary couch rotation for a craniospinal treatment if the brain laterals are being treated with symmetrical 20x20 fields.
What is 5.7 degrees?
200
A breast boost is going to be treated with a 9MeV electron field without using a cutout at an SSD of 105cm. The output factor for the cone is 0.984. 200cGy is being prescribed to the 90% isodose line. This is the required number of monitor units.
What is 226 MU?
200
This is the maximum depth of penetration for a 10 MeV electron.
What is 5cm?
200
If a field is 10x10 on the surface at 95cm SSD, this is the field size on the surface at 140cm SSD.
What is 14.7cm?
300
This is the skin gap in millimeters when matching a 15x15 field to a 12x12 field at a depth of 4cm.
What is 5.4mm?
300
A patient is to be treated with a single large photon field. 200 monitor units were calculated using an SSD of 90 to a depth of 10cm. The field is not large enough so the treatment distance is changed to 110cm. This is the new required number of monitor units.
What is 288?
300
These are x-rays emitted when an electron falls to a lower energy state within an atom.
What are characteristic x-rays?
300
When treating with a wedged pair using gantry angles of 55 and 145, this is the wedge angle we would expect to use.
What is 45 degrees?
400
This is the required gantry offset from zero when divergence matching two 22x22 fields.
What is 6.3 degrees?
400
A patient is to be treated on a linac using a wedged field. The patient is set up so that the prescription point is at 100cm SAD. The output is calibrated to be 1cGy/MU at dmax at 100 SAD. The output factor for the field being used is 1.04 and the TMR is 0.8. The wedge transmission factor 0.86. This is the required number of monitor units required to deliver 1Gy for this field.
What is 140?
400
This is the linear attenuation coefficient for a photon beam with a HVL of 6.3cm.
What is 0.11?
400
If the HVL is 3.2cm, this is the thickness of the TVL for that same beam.
What is 10.6cm?
500
Treating with a 7x7 field and a 13x13 field with a skin gap of 8mm, this is the match depth in centimeters.
What is 8cm?
500
This is the number of monitor units required per field for the following: A whole brain patient is being treated with two isocentric 17x23 lateral fields. The thickness is 16cm. The total Rx is 300cGy. TMR at 8cm depth = 0.867, at 14.4cm depth = 0.708. Sc(17x17) = 0.97, Sc(20x20) = 1.01, Sp(20x20) = 1.02, Sp(23x23) = 0.95. The machine was calibrated using an SSD technique.
What is 163?
500
This is the angle the photon was scattered in a Compton interaction when the maximum possible energy was transferred to the electron.
What is 180 degrees or directly backwards?
500
This is the approximate percent depth dose for a 6X beam at a depth of 10cm.