rapidarc in bergen britt nygaard, harald valen and ellen wasbø haukeland university hospital,...
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RapidArc in Bergen
Britt Nygaard, Harald Valen and Ellen Wasbø
Haukeland University Hospital, Bergen, Norway
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• 2007: – Trilogy with RapidArc option
• 2008: – Scandidos Delta4 QA tool– Aria upgrade: RapidArc on the Trilogy and 23iX
• Autumn 2009: – Course in Bellinzona and Zug– Stay-and-learn in Copenhagen– Eclipse AAA configuration– Machine QA and patient QA procedures
• 2010:– Decisions, decisions.. Which category of patients?– Learning RapidArc doseplanning in Eclipse– 1st patient on 14th of June – 2nd on 22nd of November
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Quality control
• Commisioning tests as suggested by Memorial Sloan-Kettering CC and Varian– A picket fence test during RapidArc– 7 adjacent fields with varying Dose rate & Gantry
speed– 4 adjacent fields with varying MLC speed & Gantry
speed
– Possible to study combined effect of • dose rate and gantry speed• dynamic MLC and variable dose rate
C. C. Ling et. al: Commissioning and Quality Assurance of RapidArc Delivery System. Radiotherapy, Int. J. Radiation Oncology Biol. Phys., Vol. 72, No. 2, pp. 575–581, 2008.
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Analyse results• Dynalog files
– Log planned and actual leaf positions and leaf speed vs. time
– Log gantry speed vs. Time– How TrueBeam
• Tool: ”Analyse Dynalog”– In-house developed (EW)– Language: IDL
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Patient QA
• Delta4– Daily dose correction– Run and measure Verification plan– Pass / Fail criteria
• Dose deviation– > 85% within ±3% deviation
• Distance to agreement– > 98% with DTA ≤ 3mm
• Gamma index 3%, 3mm– > 95% with index ≤ 1
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Clinac 23EX (2004), RapidArc in 2011: Failed T2 & T3 commissioning tests
Patient QA Dose dev. within ±3%
DTA < 3mm γ < 1 (3%, 3mm)
PAB 90,7% 100% 100%
GB 83,7% 100% 100%
TER 95,8% 100% 99,4%
GDG 85,5% 100% 100%
EKGP 85,9% 100% 100%
MS 83,0% 100% 100%
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Treatment planning, Autumn 2010:
• 5 years experience with IMRT– head and neck– prostate with and without lymph nodes (LN)– ani (and gyn) with LN – Sarcoma, lymphoma and other
• RA configuration and acceptance tests OK • RA installed on 2 Clinacs • Patient start up
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Which patient groups?
• Increased efficiency for the department – Prostate with LN, 7 splitted fields
• Patients unable to keep the supine position for 10-15 min– Head and neck
• Less MU and less risk for secondary cancer• A category that is easy to create acceptable and
standardized plans for– Prostate intermediate risk
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Which patient groups?
• Increased efficiency for the department – Prostate with LN, 7 splitted fields
• Patients unable to keep the supine position for 10-15 min– Head and neck
• Less MU and less risk for secondary cancer• A category that is easy to create acceptable and
standardized plans for– Prostate intermediate risk
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Prostate intermediate risk, criteria:• Treatment of prostate and seminal vesicles
• Equal plan or better than IMRT (PTV and rectum)
• We made two plans, one IMRT (backup) and one RA, 1 arc 135-225° (avoid couch slides) for the 10 first patients
• PTV 95%-107%, median 100%,
• Rectum: max 10ml >60 Gy and less than 50 Gy to half the circumference
• Delta4 measurements OK; • Gamma index 3%, 3mm
– > 95% with index ≤ 1
• Dose deviation– > 85% within ±3% deviation
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RA today: (2.4 Gy sem.ves. and integrated boost 2.7 Gy prostate) x 25 = 67.5 Gy (EQD2= 81 Gy if α/β=1.5)
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7 field-IMRT
1499 MU (2.7 Gy)
555 MU/Gy
(calibration factor 130MU/Gy)
2 full arc RA
611 MU (2.7 Gy)
Prostate high risk: 2 Gy to the lymph nodes, integrated boost; 2.4 Gy sem.ves. and 2.7 Gy prost, 25 fractions