Radiation Treatment Techniques Flashcards
what radiation therapy technique requires 3D imaging? – IMRT or 3D-CRT
3D-CRT
T/F: 3D-CRT is more accurate than 2D
true
2D is technique used for _____
fluoro
3D-CRT fields conform to what _______?
target volume
which treatment technique has uniform intensity? IMRT or 3D-CRT
3D-CRT
what planning (Forward or Inverse) does 3D-CRT use?
Forward planning
T/F: MLCs, jaws, wedges, compensators can all be used still by 3D-CRT
true
____ treatment planning creates DRRs
3D
what does 3D-CRT stand for?
3D Conformal Radiation Therapy
what does IMRT stand for?
Intensity Modulated Radiation Therapy
________ varies throughout an IMRT beam, intentionally
intensity
_______ = smaller beams
beamlets
how does a non-uniform dose (like with IMRT) optimize dose to target volume?
higher doses can get to tumor while minimizing dose to surrounding tissues
IMRT uses what planning? Forward or Inverse
INVERSE planning
choppy starfish represents IMRT step n shoot, or IMRT dynamic
IMRT step n shoot
static/step n shoot IMRT gantry is _____ while beam is ON
not moving
rotating/VMAT gantry is _____ while beam is ON
moving … MLCs going too
Step n Shoot MLCs can also be referred to as ________ MLCs
segmental MLCs
when MLCs move while beam is PAUSED or OFF, what do we call this?
segmental MLCs/Step n Shoot
when MLCs move while beam is ON and delivering treatment, what do we call this?
dynamic
what is one way we can identify if the technique is VMAT on a plan?
we would typically see arrows, which represent the ARCS/ROTATION of VMAT
the following depicts 3D-CRT or IMRT?
3D-CRT
the following depicts Dynamic IMRT or Step n Shoot IMRT
Step n Shoot
the following depicts 3D-CRT or VMAT?
VMAT
each time MLCs re-shape during step n shoot, it is considered what?
a sub-field
MLCs move at speeds of ____ per second
2 cm per second
T/F: MLCs are controlled by a computer system which is simultaneously monitoring leaf position as well
true
what is it called when the gantry is rotating but MLCS are NOT moving?
Non-Volumetric ARC therapy
Non-Volumetric ARC therapy can also be called what?
Dynamic Conformal ARC Therapy; DCA or DAT for short
what is difference between VMAT and Non-Conformal ARC Therapy?
VMAT - both gantry and MLCs move
DCA/DAT - gantry moves but MLCs are stationary
Non-volumetric ARC therapy uses what type of plan?
3D; planned like a 3D plan using FORWARD planning - but dose distributions are much better than stationary 3D plans
Non- Volumetric ARC therapy is used for what type of tumors?
typically used for deep seated tumors, that are NOT located near OARs w/ low tolerance doses
electrons are/use ______ beams
monoenergetic
electrons treat ___deep/superficial___ tumors
superficial
electrons treat tumors that are ____ cm deep
<5cm deep
clinically electrons have an energy range of ___-___ MeV
6-20 MeV
electrons lose _____ quickly in matter
energy
_____ have a sharp dose reduction/fall off after dmax
electrons
electrons _____ easily in air
scatter
since electrons scatter easily in air, what do they require for treatment?
*hint - it is an accessory
they require electron cones to combat the scatter
PDD at skin surface is __-__& for electrons , whereas it is _____ at skin surface for photons
electrons have a 80-90% PDD at skin surface; photons have 30% PDD at skin surface
practical range depth of electrons is calculated using what formula?
MeV / 2
T/F: range and penetration are interchangeable and are same thing
true
as energy increases, so will range/penetration in patient, BUT electrons have ___________ so deeper organs and tissues will receive little to no dose
rapid dose fall off
the following depicts what treatment technique? - electron or photon
electron
SRS treatments are typically treated on ________ and __________, but can still be on LINACs
gammaknife and cyberknife
SRS is typically used for brain, but what can be an exception?
spine
______ treatment technique treats tumors in cranium at very high doses
SRS
SRS stands for what? -
Stereotactic Radiosurgery
SRS treats tumors that are ___ in size
< 3 cm
how many fractions is an SRS treatment?
1
what is the dosimetric accuracy needed for SRS?
+/- 5%
what is the positional accuracy needed for SRS?
+/- 1 mm
for what treatment is a rigid frame attached to patient’s skull?
SRS
an SRS frame creates what?
a coordinate system
when are MRIs and CTs taken when an SRS frame is used?
after the frame is attached to patient’s skull
what are possible trts for SRS?; cancers/diseases that call for SRS (7)
AVMs, trigeminal neuralgia, acoustic neuromas, meningiomas, pituitary adenomas, Parkinsons, epilepsy
what does AVM stand for?
arterial venous malformations
AVMs are an abnormal __________of _________ in the brain
abnormal tangle of blood vessels in the brain
what is trigeminal neuralgia?
functional disorder of the face
what is typical dose for an SRS treatment? and fractionation
25 Gy or 2500 cGy in 1 fraction
SBRT stands for what?
Stereotactic Body Radiation Therapy
what does SBRT typically treat? (6)
spine, lung, liver, pancreas, kidney, prostate
what is typical SBRT dose? __-__ Gy … And how many fractions typically?
6-30 Gy, and 3-5 fractions
what radiation treatment technique is used to treat small tumors outside the cranium at high doses?
SBRT
how large are the tumors that get treated by SBRT?
less than or equal to 5cm
for an SBRT treatment what extra element can be very important to reduce intrafraction motion?
motion management like abdominal compressions, breath hold, or respiratory gating
TBI stands for what?
Total Body Irradiation
TBI dose rates are ___% of normal dose rates
10%
TBI treatments are done ____quickly/slowly___
slowly; they take a long time
TBI uses blocks for what areas?
lung, kidney, and head
T/F: TBI treatments use blocks
true
TBI targets what area?
whole body
____ treatment prepares patient for BMT (bone marrow transplant)
TBI
a Bone Marrow Transplant is a type of treatment for what cancer?
Leukemia
what is main goal of a TBI trt?
destroy bone marrow & immunosuppress patient enough their body won’t reject new bone marrow that will come from transplant; to prep patient for a BMT
what does BMT stand for?
Bone Marrow Transplant
in what two ways can a patient be positioned for TBI?
standing or lying down
if a patient is standing for their TBI treatment what must be implemented?
lung blocks to prevent overdose
if patient is standing for TBI, what are the gantry angles?
AP/PA
if a patient is lying down for TBI, what are the gantry angles?
RT lat/LT lat; bilateral fields
what is the typical distance a patient getting TBI is positioned away from the gantry? In meters, feet, and cm
4 meters; 13 feet; 400-411 cm approx
how do we treat the whole body for a TBI? - ie. how do we fit it in field
rotate collimator and use extended SSDs
for TBI treatments what is positioned between patient and source that reduce skin sparing?
beam spoiler
beam spoilers are made of materials with __high/low___ atomic #s
low
what dose is typical of TBI?
8-10 Gy
what is used to reduce skin sparing in TBI?
beam spoiler
beam spoilers are placed as close, or as far away from patient?
as close to patient as possible
label the following TBI treatment diagram - label A, B, C
A = 400-411 cm
B = central axis
C = beam spoiler
the following diagram represents what treatment?
TBI
