1. Stereotac(c
Radiosurgery
(Rota(on
#
9)
Mentor:
Edward
C
Pennington
(01/19/2010
–
03/05/2010)
By
Vibha
Chaswal,
Ph.D.

2. Contents

3. Ac(vi(es
• Es(ma(on
of
mechanical
accuracy
of
the
floor-­‐
stand
• End-­‐to-­‐end
process
tes(ng:
Absolute
phantom
based
QA:
Frame-­‐based
and
Frame-­‐less
SRS
• Small
field
dosimetry
measurements:
TMRs,
output
factors,
profiles,
off-­‐axis
factors
• CT
to
MRI
image
registra(on
• SRS
treatment
planning
• Pre-­‐treatment
SRS
floor-­‐stand
QA
• Par(cipa(on
in
treatment
delivery

4. Mechanical
QA:
Floor-­‐stand

5. End-­‐to-­‐End:
CT-­‐
Localiza1on
(Frame-­‐based)
TILT
and
SPIN
Adjusted
on
Frame.
CT-­‐Localiza(on
with
(lt
and
spin
correc(on
Max
error:
Ax
(0.4
mm)
Lat
(0.3
mm)
A-­‐P
(0.5
mm)
3D
(0.6
mm)

6. Frame-­‐based
End-­‐to-­‐End
tes(ng:
Floor-­‐stand
isocentric
localiza(on

7. Frame-­‐Less
SRS
End-­‐to-­‐End
isocentric
localiza(on
:

8. SRS
Commissioning:
Small
field
dosimetry
TMR
and
Out-­‐put
measurement
set-­‐up
NOT
A
TRIVIAL
AFFAIR
!!!!!!!!!

9. ~
3.5
%
lower
TMR
And
dmax
~
1
cm

11. Re-­‐measurement
of
TMRs
Stereotac1c
Chamber-­‐valida1on

12. TMR’s
s(ll
off
but
d-­‐max
depth
=
1.5
cm

13. OUT-­‐PUT
Factor
measurements

14. Off-­‐Axis-­‐Factors

16. Recommenda(on
of
independent
Physics
check
on
TMR
measurements
of
small
fields.
Iden(fied
pit-­‐falls:
SRS
stereotac(c
chamber
response
with
depth
L-­‐R
(lt
on
the
SRS
phantom
base
(resolved
with
a
(ssue
propped
at
led
side)

17. Par(cipa(on
and
observa(on
in
SRS
work-­‐
flow:
Iden(fica(on
of
Physics
QA
at
all
steps

19. ThankYou!!!!!