1. The Tomotherapy Experience at Advocate Good Samaritan Hospital
Mark Pankuch

2. Today’s Discussion The History of Radiation at Good Samaritan
Quick Overview of the Tomotherapy Unit
Treatment population and Statistics of our experience
Results from Shielding
Comparison of plans

3. Advocate Good Samaritan
Treated first patient on May 13, 2002
Single Linac Vault with a Seimens Primus
Hand me down GE CT scanner
from radiology
Paper-less / Film-less department

4. Advocate Good Samaritan
Within two years reached capacity for a single Linac department
Began offering HDR treatments
Strong administrative and physician support for expansion

5. Advocate Good Samaritan
New Vault was needed
Doubling current patient volumes appeared as an over estimation for potential volume
Present day IGRT with OBI not commonly available

7. What did Tomotherapy Offer that Good Sam was missing?
IGRT
“Top End” IMRT

8. The Answer For Good Sam?

9. Tomotherapy

10. Tomotherapy MLC

11. MLC’s Oriented in the Sagital Plane

12. The Treatment Process
Patient is set up on table to moveable lasers (2 min)
High energy CT scan performed in the Tx Position (3 Min)
New images are fused with planning CT images (3 Min)
Adjustments are made for patient position (2 min)
Treatment is delivered (10 Min)

13. Of Special Note on Hardware:
No flattening filter
Output ~ 900 MU / min
Tx = 10,000 MU
MLC’s very, very fast (us)
Capable of MVCT export
MVCT ~ 2-3 cGy

14. Planning System Single workstation for planning
Cluster of 16 computers, w/ dual processors for computing.
Optimizations done on “beamlets” that can be calculated overnight
Very few contouring tools, need another system for contouring and fusions
No planning review station, system not multitasking

15. What type of patients have we treated?

16. Tomotherapy Not optimal for all treatment sites
Rotational / Helical Treatments
Need the capability to give low doses to large areas of normal tissues
Ability of “cave out” doses
Very conformal, with good dose drop off

20. Simultaneous Boost

24. DQA Tomotherapy Supplied Phantoms
Film and Point dose taken on every patient
Planning system has built-in QA tools
Film analysis evaluated by calculating gamma index (Low et.al., Med Phys 25, 1998)
3% Dose
3mm DTA

28. QA cGy / MU cGy / min Lasers coincidence Table Accuracy
Field Consistency
MLC accuracy

29. Clinical Outcomes Pelvis patients decreased side effects
Prostate patients no side effects (78Gy)
Brain Patients get ring shape hair loss
Head / Neck patients
Still have skin reactions
Considerably reduces reaction in mouth
Need more time for long term results

30. Skin Reactions

31. Shielding Considerations
Large majority of shielding needed because of leakage
Scatter Radiation
Primary beam

32. Shielding Considerations
X = W * U * T * ISF
Workload:
30 Patients/day
10 min Tx time
880MU/min
66,000,000 MU/year
Usage Factors = 1
Occupancy Factor as usual
Occupational areas kept to 10% of limits
ISF from 3 meters

33. Shielding Considerations, Leakage
Leakage levels obtained from chart like CT scanner
Leakage was measured and plotted as a function of position around the gantry and radial distance
All leaves closed for measurements
Leakage fraction at 3 meters was used
ISF from 3 meters

34. Shielding Considerations, Scatter
Scatter levels a function of position around gantry
Greatest at opening of couch
With all leaves open, can be 186% of leakage exposure
Clinically, the exposure can be reduced by a factor of 16
Maximum % scatter increase = 12%, I used 15%

35. Shielding Considerations, Primary
Unit has a built in Primary Beam Block, 13cm Pb
The primary beam was 6.3% of the overall radiation at 2.5 cm from the isocenter
Clinically, the exposure can be reduced by a factor similar to scatter due to closed leaves
I ignored reduction factor, and increased exposure by 6.3%.

36. Shielding Results North Wall South Wall West Wall East Wall Ceiling
Door
Calculated Exposure (mR/hr)
0.163
0.042
0.017
0.009
0.058
0.278
Measured Exposure (mR/hr)
0.288
0.012
0.005
0.013
0.188
Ratio of Measured / Calculated
141%
22%
26%
117%
17%
54%
Ratio of Measured / Required
58%
12% 5% 3%
38%

37. Plan Comparison Tomotherapy CMS XIO, Step and Shoot
Varian Eclipse, Sliding Window

44. Which is best?? Depends …….. Many systems now have IGRT
Workload
Needs
Patient sites
Many systems now have IGRT
Where is IGRT going?
No Breath Gateing on Tomotherapy
Where is gateing doing?

45. In the future for Tomotherapy
Adaptive treatments
Live time optimizations
Conductivity with IMPAC
Live time QC
Breath Coaching Methods

46. Questions ?? Thanks for your attention!
Free tour of the Cancer Center after lunch
Questions ???