treatment planning parameters (tx dose and prescription)

what is the a document of the field parameters?

DRR

the physical radiation field size is delineated where on the isodose line

50%

(T/F) depth of the tumor determines the energy of the beam and the type of the treatment

T

(T/F) other terms for patient separation are patient thickness, intrafield distance, and innerfield distance

T

when a treatment is at “midplane” this means the isocenter is located where?

halfway btw the patient’s separation

what does SSD mean

source to skin distance

SSD techniques are more commonly used for what? (2)

single field

electron treatment

for SSD techniques, the SSD IS set at where

100 cm or another specific “fixed” SSD

what does SAD mean

source to axis distance

what is isocenteric technique

when the isocenter is located within the patient

secondary or primary collimating jaws?

moveable, asymmetric, and made of tungsten

secondary

fields larger than 40×40 cm require an extended ?

distance

(T/F) when a jaw is closed at 0 (half beam block), there is no beam divergence

T

only <0.? percent transmissioin through the jaws is permitted

0.5%

relationship btw

field size

collimator scatter

so then would we need less or more MU

up

up

less

(T/F) abutting fields meet at a determined depth within the patient bc of beam divergence

T

why does abutting fields meet at a determined depth within the patient?

bc of beam divergence

to avoid hot spots there must be a what?

gap on the skin surface

abutting fields is commonly used for what?

craniospinal irradiation

what is feathering?

it is a technique used to move or change the location of the gap throughout the treatment

the gap location on CSI is changed every what fax

5 fix

why do we do this?

blurs any inhomogeneous doses within the gap area