RapidArc in Bergen

Britt Nygaard, Harald Valen and Ellen Wasbø Haukeland University Hospital, Bergen, Norway

• • • • 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 1 st patient on 14 th of June – 2 nd on 22 nd of November 2

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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Dose rate and Gantry speed variation during RapidArc MLC speed variation during RapidArc 4

Analyse results

• Dose rate and Gantry speed variation (”Test2”) • MLC speed variation (”Test3”) 5

Clinac 23EX (2004): T2 & T3

Trilogy (2007): T2 & T3

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Clinac 23iX (2005): T2 & T3

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TrueBeam (2011): T2 & T3

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Analyse results

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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 10

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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 12

1 arc, 135 ° to 225°, TrueBeam 6MV photons

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Clinac 23EX (2004), RapidArc in 2011: Failed T2 & T3 commissioning tests Patient QA

DTA < 3mm γ < 1 (3%, 3mm) PAB GB TER GDG EKGP MS Dose dev. within ±3% 90,7% 83,7% 95,8% 85,5% 85,9% 83,0% 100% 100% 100% 100% 100% 100% 100% 100% 99,4% 100% 100% 100% 15

More patient QA

• • • Independent dose calculation Point check of dose Control of monitor units 16

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 17

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 18

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 19

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 20

5 fields IMRT: 574 MU (2.15 Gy x 35) RA: 1 arc 135-225 ° 494 MU (2.15 Gy x 35)

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5 fields IMRT: 574 MU (2.15 Gy x 35 = 75.25) RA: 1 arc 135-225 ° 494 MU (2.15 Gy x 35)

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5 fields IMRT: RA: 1 arc 135-225 °

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IMRT RA

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RA today: (2.4 Gy sem.ves. and integrated boost 2.7 Gy prostate) x 25 = 67.5 Gy (EQD 2 = 81 Gy if α/β=1.5)

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Measured with Delta4 Gamma: 2mm 2%

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Prostate high risk: 2 Gy to the lymph nodes, integrated boost; 2.4 Gy sem.ves. and 2.7 Gy prost, 25 fractions 7 field-IMRT 1499 MU (2.7 Gy) 555 MU/Gy (calibration factor 130MU/Gy) 2 full arc RA 611 MU (2.7 Gy)

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IMRT RA

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IMRT RA

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Dose to rectum

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IMRT

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Future:

• • We would like to treat our high risk protate with LN with two arcs – Prerequisite: RA plan equal or better than IMRT (PTV and rectum) This autumn we have been focusing on commissioning TrueBeam..

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