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

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Presentation on theme: "RapidArc in Bergen Britt Nygaard, Harald Valen and Ellen Wasbø Haukeland University Hospital, Bergen, Norway."— Presentation transcript:

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

2 2 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

3 3 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.

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

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

6 Clinac 23EX (2004): T2 & T3

7 7 Trilogy (2007): T2 & T3

8 8 Clinac 23iX (2005): T2 & T3

9 9 TrueBeam (2011): T2 & T3

10 10 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

11 11

12 12 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

13 13 1 arc, 135° to 225°, TrueBeam 6MV photons

14 14

15 15 Clinac 23EX (2004), RapidArc in 2011: Failed T2 & T3 commissioning tests Patient QADose dev. within ±3% DTA < 3mmγ < 1 (3%, 3mm) PAB90,7%100% GB83,7%100% TER95,8%100%99,4% GDG85,5%100% EKGP85,9%100% MS83,0%100%

16 16 More patient QA Independent dose calculation Point check of dose Control of monitor units

17 17 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

18 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 19 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

20 20 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

21 21 5 fields IMRT: 574 MU (2.15 Gy x 35) RA: 1 arc 135-225° 494 MU (2.15 Gy x 35)

22 22 5 fields IMRT: 574 MU (2.15 Gy x 35 = 75.25) RA: 1 arc 135-225° 494 MU (2.15 Gy x 35)

23 23 5 fields IMRT: RA: 1 arc 135-225°

24 24 IMRT RA

25 25 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)

26 26

27 27 Gamma: 2mm 2% Measured with Delta4

28 28 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

29 29 IMRT RA

30 30 IMRTRA

31 31 Dose to rectum

32 32 IMRT

33 33 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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