Differences between Conventional and CT simulation
Differences
|
Conventional
simulation
|
Computed
tomography simulation
|
Treatment
position
|
Identified
with to bony landmarks under fluoroscopic condition
|
Identified
to bony landmarks through the use of scout+pilot
image
|
Identification
of target volume
|
Identified
from bony landmarks
|
Can get
directly from CT data
|
Determination
of beam geometry
|
-Verified
using fluoroscopic
-Doesn’t
have standard beam geometry
|
-Verified
from BEV/DRR
-Have
standard beam geometry
|
Contour acquisition
|
Patient
contour is obtained through the use of lead wire (manual)
|
Patient
contour is obtained from CT data
|
Shielding design
|
-From bony landmarks
-Cannot
use with beam geometry
|
-Conformal to target
-Can be
used together with the beam geometry
|
Virtual simulation
|
No
|
Yes
|
Image
of radiograph
|
Have limited soft
tissue contrast
|
Have good soft tissue contrast
|
Machine for Conventional and CT simulator
A conventional
treatment simulator
A dedicated
radiotherapy CT simulator
SUMMARY OF THE CONVENTIONAL SIMULATION
PROCEDURE FOR A TYPICAL PATIENT (SIX STEPS)
step
|
Conventional simulation
|
1
|
Determination of patient treatment position with
fluoroscopy
|
2
|
Determination of beam geometry
|
3
|
Determination of field limits and isocentre
|
4
|
Acquisition of contour
|
5
|
Acquisition of BEV and set-up radiographs
|
6
|
Marking of patient
|
SUMMARY OF THE PROCEDURE FOR A TYPICAL
PATIENT COMPUTED TOMOGRAPHY SIMULATION (NINE STEPS)
step
|
CT simulation
|
1
|
Determination of patient treatment position with
pilot/scout films
|
2
|
Determination and marking of reference isocentre
|
3
|
Acquisition of CT data and transfer to virtual
simulation workstation
|
4
|
Localization and contouring of targets and
critical structures
|
5
|
Determination of treatment isocentre with respect
to target and reference
isocentre
|
6
|
Determination of beam geometry
|
7
|
Determination of field limits and shielding
|
8
|
Transfer of CT and beam data to the TPS
|
9
|
Acquisition of BEV and set-up DRRs
|
Images
