RapidArc in Bergen - Ra

Report
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
– 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
3
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.
Dose rate and Gantry
speed variation
during RapidArc
MLC speed variation
during RapidArc
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Analyse results
• Dose rate and Gantry speed variation
(”Test2”)
• MLC speed variation (”Test3”)
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Clinac 23EX (2004): T2 & T3
Trilogy (2007): T2 & T3
7
Clinac 23iX (2005): T2 & T3
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TrueBeam (2011): T2 & T3
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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
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
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1 arc, 135° to 225°, TrueBeam 6MV photons
13
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Clinac 23EX (2004), RapidArc in 2011:
Failed T2 & T3 commissioning tests
DTA < 3mm
γ < 1 (3%, 3mm)
PAB
Dose dev.
within ±3%
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%
Patient QA
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
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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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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 (EQD2= 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
2 full arc RA
1499 MU (2.7 Gy)
611 MU (2.7 Gy)
555 MU/Gy
(calibration factor 130MU/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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