Simulator Design and Operation Flashcards
Primary purpose of simulator
levels target volume
collect anatomic info
Basoc elements of simulator
- gantry: rotates 360
- PSA (patient support Assembly): couch where pt lays
- x ray tube
- collimater device
- imaging system of fluoro unit
- optical devices: lasers, light field
3 parts of treatment palnning
- tumor localization
- computation of dose distributions
- fabrication of treatment aids
What is DRR?
digital reconstructed radiograph
Set up functions of simulation
- tumor localization
- treatment verification
Who determines the extent and localization of tumor
the physician
Who sets the isocenter and field margins
dosimetrist
designed to simulate the mechanical, geometrical,a dn optical conditions of various treatment untis
conventional sim
What is is the tolerance for the gantry angle?
1 degree
Mechanical components:
gantry
arm
head
image intensifying/ film holder system
360 degrees
rotates along isocenter @ 100 cm
divergent edge
central axis is nondivergent
Gantry
patient’s right is always __ degrees
patient’s left is always ___ degrees
270
90
Varian machine, top is __ degrees
IEC machine, top is ___ degrees
180
0
Gantry head components:
collimator assembly
comprises gantry head and rotates
Gantry head components:
ODI
optical distance indicator
number readout
corresponds to SSD/ who deep we are going
Gantry head components:
field defining wires
represent diaphragms on machine
Gantry head components:
beam restricting diaphragms
determine size of x-ray beam
Gantry head components:
fudicial plate
plate with hashmarks, measurement
can also measure magnification
Gantry head components:
accessory holder
holds blocks and whatever needed for treatment
distance should be the same
OFD
object to field distance
SFD
source to film distance
TFD
target to film distance
SSD
source to skin distance
IFD
intrafield distance
IT
isocenter to table top
Positioning lasers
red or green
for positioning external landmarks (tattoos)
QA lasers
Types of Sim:
- conventional- old method
- conventional& CT- old method
- virtual- current method
Two main functions of CT sim:
- target localization and localization of clerical structures
- have DRR printed out
+ of CT sim
- mark patient
- able to transfer data from one system to another
multiple sources to get anatomical data for patient
fusion
when scan done in diagnostic position& one in treatment position
deformable fusion
attenuation rates or tissue density differences displayed as pixels of different shades of gray
range from +1,000 to -1,000
also called CT numbers
Hounsfield Units
examples of HU
-1,000: air
0: water
15: CSF
20: blood
40: gray matter
50: muscle
650: bone
+1,000: enamal