Simulation Flashcards
types of simulations
- initial
- verification
- adaptive
- boost
what happens during initial sim
starts the radiation treatment process, also the first sim
what happens during the verification sim
sim done in same postitioning as initial, done if patient has lost markings or setup at treatment unit is not optimal
what happens during adaptive sim
done in same pos as initial, done if patient has lost weight of tumor volume has changed and a new plan is required
what happens during boost sim
may or may not be in the same pos as initial sim. done to define possible smaller target volumes to bring to higher doses
Conventional simulators
simulates the geometry of LINAC (gantry angles, field size, coll angles, couch angles)
films are taken to localize and identify area of treatment
what type of collimator is used for conventional simulators
MLC or cerrobend blocks
what kind of image is conventional sim
2D radiographs
CT bases sim
patient is marked according to the isocenter coordinates
target volumes and field placement occurs after the patient has left the department
Slice thickness of CT sim
1mm-5mm increments (2.5mm)
How is data acquired for CT sim
digitally data is acquired and then reconstructed to allow for 3D visualization of patient’s anatomy
what is an isocenter
geometric location, often placed in the center of target
what are lasers for
display and mark the isocenter on patient’s surface
what happens at the site of marked isocenter
point from where all of the patients planning parameters will start
how often is laser accuracy checked
daily
what is CT table made of
carbon fiber
what are attached on the sides of CT table
notches- allows for “lockdown bar”
process of PET/CT sim
2 scans are taken
CT is taken first- then PET
both scans are merged to show info form each
what type of PET is used during sim
Fluorodeoxyglucose (FDG) is a radio pharmaceutical
what is PET specialized in
biology/ functioning
what is CT specialized in
anatomic structure
MRI simulators
high soft tissue definitions
utilizes a very strong magnet
simulation workflow
- prepare patient for treatment
- patient positioning
- patient immobilization
- isocenter placement
- patient marking
- field arrangement
- field delineation
- field blocking determined
- dosage, plan objectives determined
free breathing
planning scan is acquired without monitoring or tracking device
used when breathing cycle does not affect target motion
breath hold (DIBH)
planning scan is acquired while patient inhales and holds breath
monitored and recorded
benefits: enlarge lung volume, pull organs away from high dose regions, decrease tumor motion
4D
planning scan is acquired when patient is free breathing
image reconstructed for each phase of breathing cycle- accounts for respirator cycle with images a multiple or all breathing phase
Breast compression device
- boost re-sim required
- compresses breast tissue
- useful when tumor bed is deep
- can reduce electron energy
- can reduce dose to underlined structures (ribs, lung)
Pelvis
- mini scan for isocenter placement, check bladder filling, rectal gas
- BBs placed and determined isocenter
head and neck
- aquaplasst for head and shoulder
- stent, bolus, pull straps, etc
