Simulation

Question 1

types of simulations

Answer 1

1. initial
2. verification
3. adaptive
4. boost

Question 2

what happens during initial sim

Answer 2

starts the radiation treatment process, also the first sim

Question 3

what happens during the verification sim

Answer 3

sim done in same postitioning as initial, done if patient has lost markings or setup at treatment unit is not optimal

Question 4

what happens during adaptive sim

Answer 4

done in same pos as initial, done if patient has lost weight of tumor volume has changed and a new plan is required

Question 5

what happens during boost sim

Answer 5

may or may not be in the same pos as initial sim. done to define possible smaller target volumes to bring to higher doses

Question 6

Conventional simulators

Answer 6

simulates the geometry of LINAC (gantry angles, field size, coll angles, couch angles)

films are taken to localize and identify area of treatment

Question 7

what type of collimator is used for conventional simulators

Answer 7

MLC or cerrobend blocks

Question 8

what kind of image is conventional sim

Answer 8

2D radiographs

Question 9

CT bases sim

Answer 9

patient is marked according to the isocenter coordinates

target volumes and field placement occurs after the patient has left the department

Question 10

Slice thickness of CT sim

Answer 10

1mm-5mm increments (2.5mm)

Question 11

How is data acquired for CT sim

Answer 11

digitally data is acquired and then reconstructed to allow for 3D visualization of patient’s anatomy

Question 12

what is an isocenter

Answer 12

geometric location, often placed in the center of target

Question 13

what are lasers for

Answer 13

display and mark the isocenter on patient’s surface

Question 14

what happens at the site of marked isocenter

Answer 14

point from where all of the patients planning parameters will start

Question 15

how often is laser accuracy checked

Answer 15

daily

Question 16

what is CT table made of

Answer 16

carbon fiber

Question 17

what are attached on the sides of CT table

Answer 17

notches- allows for “lockdown bar”

Question 18

process of PET/CT sim

Answer 18

2 scans are taken

CT is taken first- then PET

both scans are merged to show info form each

Question 19

what type of PET is used during sim

Answer 19

Fluorodeoxyglucose (FDG) is a radio pharmaceutical

Question 20

what is PET specialized in

Answer 20

biology/ functioning

Question 21

what is CT specialized in

Answer 21

anatomic structure

Question 22

MRI simulators

Answer 22

high soft tissue definitions

utilizes a very strong magnet

Question 23

simulation workflow

Answer 23

1. prepare patient for treatment
2. patient positioning
3. patient immobilization
4. isocenter placement
5. patient marking
6. field arrangement
7. field delineation
8. field blocking determined
9. dosage, plan objectives determined

Question 24

free breathing

Answer 24

planning scan is acquired without monitoring or tracking device

used when breathing cycle does not affect target motion

Question 25

breath hold (DIBH)

Answer 25

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

Question 26

4D

Answer 26

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

Question 27

Breast compression device

Answer 27

• 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)

Question 28

Pelvis

Answer 28

• mini scan for isocenter placement, check bladder filling, rectal gas
• BBs placed and determined isocenter

Question 29

head and neck

Answer 29

• aquaplasst for head and shoulder

- stent, bolus, pull straps, etc