Raphex Exam Study Guide 2026 - Fully Solved and Verified

Raphex Exam Study Guide 2026 - Fully Solved and Verified as energy increases the, the tissue max ratio at dmax a. increases b. decreases c. remains the same - answer - c. remains the same TMR at dmax for any beam energy is 1 depth of max dose for a photon beam is approx equal to? a. where kerma & dose are equal b. approx range of secondary electrons c. point of electronic equilibrium d. all of the above - answer - d. all of the above patient is irradiated 7cm deep with a PDD of 0.65 & a dose rate of 100cGy/min at an 80 cm SSD. the field size is 10x10 on the skin what is the dose at dmax ? time to deliver 150 cGy is how many min? what is the field size at the 7cm depth? - answer - - 150 cGy/0.65 = 231 cGy - 150cGy/(100 cGy/min x 0.65) = 2.3 min -(10/80) = (x/87) = 10.9 field size if 4000 cGy was delivered to midplane using POP fields what energy and technique would allow doe lowest dose to the spinal cord? a. 8 mv SSD b. 8 MV isocentric c. 16 MV isocentric d. 16 mV SSD - answer - d. 16 mv SSD to get lowest dose to a point between midplane and surface the highest energy and largest SSD is needed to maximize the PDD PDD increases when SSD increases because - answer - inverse square effect is smaller at large distances what is true regarding geometric penumbra? - answer - -increases as source DIAMETER increases -depends on source to collimator distance -as SSD increases the geometric penumbra increases a patient with Hodgkins is treated with 10 MV, a 1cm Lucite board is added to scatter dose, which is true: a. as the distance from the patient skin to the spoiler increase the surface dose is less b. if the Lucite thickness goes from 1 cm to 1.5 cm the surface dose will decrease c. a beam spoiler is needed for all energies less than 10 MV d. all of the above - answer - a. as the distance from the patient skin to the spoiler increase the surface dose is less if a 3D field was calculated for 6MV and then is moved to 16 MV, the effective equivalent square for the 6 MV would: a. increase b. decrease c. remain the same d. do not know - answer - a. increase photon energy increases the contribution due to scatter decreases purpose of beam spoiler in TBI is to eliminate - answer - skin sparing non coplanar arcs are used for radiosurgery because? a. calculation is easier b. geometric accuracy is more easily achieved c. dose distribution can be made to conform to irregular target shapes d. they produce relatively rapid and symmetric dose fall off outside of the target e. treatment time is faster - answer - d. they produce relatively rapid and symmetric dose fall off outside of the target produce sharp dose gradient in all directions requires large number of directions and a small target which of the following are true for surface dose of electrons? a. as energy increases the surface dose decreases b. same as orthovoltage with beam HVL =0.5 mm Cu c. depends on the design of the collimator d. less for scattering foil than for scanning beam - answer - c. depends on the design of the collimator scanned have less low energy scattered electrons compared to scattering foil & orthovoltage is 100% skin dose an electron field size required to treat a 5cm volume is a. 5 cm b. greater than 5 cm c. less than 5 cm - answer - b. greater than 5 cm field size on skin must always be wider than the volume width at depth. 90% isodose curve decreases in width with depth treatment to the nose is done with superficial Xray and electrons. which will have a higher dose to the nose bone - answer - xrays xray delivers high dose to the bone because of the photoelectric effect Z^3 when compared to an open field a 2cm ocular lead cut out would result in ________ PDD and ________ output - answer - decreased PDD & decreased output posterior cervical nodes are treated with increased SSD, what is affected 1. increased penumbra 2. decreased PDD 3. decreased output ased beam energy a. 1,2,3 b. 1,3 c. 2,4 d. 4 only e. all of the above - answ