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The Tomotherapy The Tomotherapy Experience at Experience at Advocate Good Advocate Good
Samaritan HospitalSamaritan Hospital
Mark PankuchMark Pankuch
Today’s DiscussionToday’s Discussion The History of Radiation at Good SamaritanThe History of Radiation at Good Samaritan
Quick Overview of the Tomotherapy UnitQuick Overview of the Tomotherapy Unit
Treatment population and Statistics of our Treatment population and Statistics of our experienceexperience
Results from ShieldingResults from Shielding
Comparison of plansComparison of plans
Advocate Good Advocate Good SamaritanSamaritan
Treated first patient on May 13, 2002Treated first patient on May 13, 2002
Single Linac Vault with a Seimens PrimusSingle Linac Vault with a Seimens Primus
Hand me down GE CT scannerHand me down GE CT scanner from radiologyfrom radiology
Paper-less / Film-less department Paper-less / Film-less department
Advocate Good Advocate Good SamaritanSamaritan
Within two years reached capacity Within two years reached capacity for a single Linac departmentfor a single Linac department
Began offering HDR treatmentsBegan offering HDR treatments
Strong administrative and physician Strong administrative and physician support for expansionsupport for expansion
Advocate Good Advocate Good SamaritanSamaritan
New Vault was neededNew Vault was needed
Doubling current patient volumes Doubling current patient volumes appeared as an over estimation for appeared as an over estimation for potential volumepotential volume
Present day IGRT with OBI not Present day IGRT with OBI not commonly availablecommonly available
What did Tomotherapy What did Tomotherapy Offer that Good Sam was Offer that Good Sam was
missing?missing?
IGRTIGRT
““Top End” IMRTTop End” IMRT
The Treatment ProcessThe Treatment Process
Patient is set up on table to Patient is set up on table to moveable lasers (2 min)moveable lasers (2 min)
High energy CT scan performed in High energy CT scan performed in the Tx Position (3 Min)the Tx Position (3 Min)
New images are fused with planning New images are fused with planning CT images (3 Min)CT images (3 Min)
Adjustments are made for patient Adjustments are made for patient position (2 min)position (2 min)
Treatment is delivered (10 Min)Treatment is delivered (10 Min)
Of Special Note on Of Special Note on Hardware:Hardware:
No flattening filter No flattening filter
Output ~ 900 MU / minOutput ~ 900 MU / min
Tx = 10,000 MUTx = 10,000 MU
MLC’s very, very fast (MLC’s very, very fast (uus)s)
Capable of MVCT exportCapable of MVCT export
MVCT ~ 2-3 cGyMVCT ~ 2-3 cGy
Planning SystemPlanning System Single workstation for planningSingle workstation for planning Cluster of 16 computers, w/ dual Cluster of 16 computers, w/ dual
processors for computing.processors for computing. Optimizations done on “beamlets” Optimizations done on “beamlets”
that can be calculated overnightthat can be calculated overnight Very few contouring tools, need Very few contouring tools, need
another system for contouring and another system for contouring and fusionsfusions
No planning review station, system No planning review station, system not multitaskingnot multitasking
What type of patients have What type of patients have we treated?we treated?
Tomotherapy Patient Breakdown to Oct 2006
0 10 20 30 40 50 60
Male Pelvis
Brain
Head / Neck
Thorax
Female Pelvis
Spine
Abdomen
Number of Patients
TomotherapyTomotherapy Not optimal for all treatment sitesNot optimal for all treatment sites
Rotational / Helical TreatmentsRotational / Helical Treatments
Need the capability to give low doses Need the capability to give low doses to large areas of normal tissuesto large areas of normal tissues
Ability of “cave out” dosesAbility of “cave out” doses
Very conformal, with good dose drop Very conformal, with good dose drop offoff
DQADQA Tomotherapy Supplied PhantomsTomotherapy Supplied Phantoms
Film and Point dose taken on every patientFilm and Point dose taken on every patient
Planning system has built-in QA toolsPlanning system has built-in QA tools
Film analysis evaluated by calculating Film analysis evaluated by calculating gamma index (Low et.al., Med Phys 25, gamma index (Low et.al., Med Phys 25, 1998)1998) 3% Dose3% Dose 3mm DTA3mm DTA
DQA Results For First 143 Procedures
0
10
20
30
40
4.0 to 3.5 3.5 to 2.5 2.5 to 1.5 1.5 to 0.5 0.5 to -0.5 -0.5 to -1.5 -1.5 to -2.5 -2.5 to -3.5 -3.5 to -4.0% Difference from Expected
QAQA
cGy / MUcGy / MU cGy / mincGy / min
Lasers coincidenceLasers coincidence Table AccuracyTable Accuracy Field ConsistencyField Consistency MLC accuracyMLC accuracy
Clinical OutcomesClinical Outcomes Pelvis patients decreased side effectsPelvis patients decreased side effects
Prostate patients no side effects Prostate patients no side effects (78Gy)(78Gy)
Brain Patients get ring shape hair lossBrain Patients get ring shape hair loss
Head / Neck patientsHead / Neck patients Still have skin reactionsStill have skin reactions Considerably reduces reaction in mouthConsiderably reduces reaction in mouth Need more time for long term resultsNeed more time for long term results
Shielding ConsiderationsShielding Considerations
Large majority of shielding needed Large majority of shielding needed because of leakagebecause of leakage
Scatter RadiationScatter Radiation
Primary beamPrimary beam
Shielding ConsiderationsShielding Considerations X = W * U * T * ISFX = W * U * T * ISF Workload:Workload:
30 Patients/day30 Patients/day 10 min Tx time10 min Tx time 880MU/min880MU/min 66,000,000 MU/year 66,000,000 MU/year
Usage Factors = 1Usage Factors = 1 Occupancy Factor as usualOccupancy Factor as usual Occupational areas kept to 10% of Occupational areas kept to 10% of
limitslimits ISF from 3 metersISF from 3 meters
Shielding Considerations, Shielding Considerations, LeakageLeakage
Leakage levels obtained from chart like CT Leakage levels obtained from chart like CT scanner scanner
Leakage was measured and plotted as a Leakage was measured and plotted as a function of position around the gantry and function of position around the gantry and radial distanceradial distance
All leaves closed for measurementsAll leaves closed for measurements
Leakage fraction at 3 meters was usedLeakage fraction at 3 meters was used
ISF from 3 metersISF from 3 meters
Shielding Shielding Considerations, ScatterConsiderations, Scatter
Scatter levels a function of position around gantry Scatter levels a function of position around gantry
Greatest at opening of couchGreatest at opening of couch
With all leaves open, can be 186% of leakage With all leaves open, can be 186% of leakage exposureexposure
Clinically, the exposure can be reduced by a Clinically, the exposure can be reduced by a factor of 16 factor of 16
Maximum % scatter increase = 12%, I used 15%Maximum % scatter increase = 12%, I used 15%
Shielding Considerations, Shielding Considerations, PrimaryPrimary
Unit has a built in Primary Beam Block, Unit has a built in Primary Beam Block, 13cm Pb 13cm Pb
The primary beam was 6.3% of the overall The primary beam was 6.3% of the overall radiation at 2.5 cm from the isocenterradiation at 2.5 cm from the isocenter
Clinically, the exposure can be reduced by a Clinically, the exposure can be reduced by a factor similar to scatter due to closed leaves factor similar to scatter due to closed leaves
I ignored reduction factor, and increased I ignored reduction factor, and increased exposure by 6.3%.exposure by 6.3%.
Shielding ResultsShielding 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 0.012 0.188
Ratio of Measured / Calculated
141% 22% 26% 117% 17% 54%
Ratio of Measured / Required
58% 12% 5% 3% 12% 38%
Plan ComparisonPlan Comparison
TomotherapyTomotherapy
CMS XIO, Step and ShootCMS XIO, Step and Shoot
Varian Eclipse, Sliding WindowVarian Eclipse, Sliding Window
Rt Parotid
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10 20 30 40 50 60
Dose (Gy)
Vo
lum
e
Tomotherapy
XIO
Eclipse
Lt Parotid
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10 20 30 40 50 60
Dose (Gy)
Vo
lum
e
Tomotherapy
XIO
Eclipse
Spinal Cord
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10 20 30 40 50 60
Dose (Gy)
Vo
lum
e
Tomotherapy
XIO
Eclipse
Brain Stem
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10 20 30 40 50 60
Dose (Gy)
Vo
lum
e
Tomotherapy
XIO
Eclipse
PTV
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10 20 30 40 50 60
Dose (Gy)
Vo
lum
e
Tomotherapy
XIO
Eclipse
Which is best??Which is best??
Depends ……..Depends …….. WorkloadWorkload NeedsNeeds Patient sitesPatient sites
Many systems now have IGRTMany systems now have IGRT Where is IGRT going?Where is IGRT going?
No Breath Gateing on TomotherapyNo Breath Gateing on Tomotherapy Where is gateing doing?Where is gateing doing?
In the future for In the future for TomotherapyTomotherapy
Adaptive treatmentsAdaptive treatments
Live time optimizationsLive time optimizations
Conductivity with IMPACConductivity with IMPAC
Live time QCLive time QC
Breath Coaching MethodsBreath Coaching Methods