Baveno, Italy June 22-24, 2012 The feasibility of a QA program for ISIORT Trials Frank W. Hensley 1, Don A. Goer 2, Sebastian Adamczyk 3, Falk Roeder 1, Felix Sedlmayer 4, Peter Kopp 4 1 University Clinics Heidelberg, Dept. of Radiation Oncology, D 69120 Heidelberg, Germany 2 Intraop Medical Company, 570 Del Rey Avenue, Sunnyvale, CA 94085, USA 3 Medical Physics Department, Greater Poland Cancer Centre, 61-866 Poznań, Poland 4 University Hospital Salzburg, Dept. of Radiation Oncology, 5020 Salzburg, Austria
Issue : Can we design a QA protocol for IORT trials which assures that IORT patients treated - at different centers - with different IORT and EBRT accelerators all recieve the protocol prescription so that the analysis of clinical results is meaningful? Example : QA protocol for HIOB trial FWH ISIORT Baveno 2012 2
HIOB trial: Hypofractionated Whole-Breast Irradiation preceded by Intra-Operative Radiotherapy with Electrons as anticipated Boost prospective, non- randomised multi-center trial to test the combination of an advanced IORT boost 11.1Gy @ Dmax ( = 10Gy @ 90%) combined with - consecutive hypofractionionated EBRT 15 x 2.7 Gy = 40.5 Gy FWH ISIORT Baveno 2012 3
The HIOB protocol requires QA for: Target preparation Selection of applicator and beam energy for IORT Documentation of IORT Documentation of standardized WBRT (and, of course, criteria for patient selection, combination with chemotherapy, etc.) Dosimetrical QA FWH ISIORT Baveno 2012 4
Target preparation Resection cavity Target coverage of complete target with prescribed dose at 90% isodose selection of applicator selection of beam energy + documentation of all steps FWH ISIORT Baveno 2012 5
HIOB: measure and report: target diameter = 3D volume of tissue reaching at least 2 cm beyond the former macroscopic tumor edge (excluding skin) pectoralis muscle ribs depth of distal margin of target ( = depth to pectoralis) measured preferably by intraoperative sonography or (mobile) CT depth of rib Dose limit to anterior rib surface: 5 Gy FWH ISIORT Baveno 2012 6
HIOB: dose prescription IOERT Dose (11.1 Gy) is specified at the point of maximum dose on the central axis depth dose curve. The PTV should be encompassed by 90% of the prescribed dose (i.e. 10 Gy). A dose inhomogeneity of -10% within the target volume is acceptable. In the beam entrance region, small volumes of underdosage down to 80% are acceptable FWH ISIORT Baveno 2012 7
HIOB : selection of applicator Typical electron dose distribution: 80-90% region ~ 1cm smaller than diam. of applicator Applicator diameter must be min. 1cm larger than target Different for different types of acclerators Hiob participants must therefore report parameters of dose distributions for all energies and applicators used FWH ISIORT Baveno 2012 8
HIOB: selection of electron energy R 80 - R 50 - d rib - d pectoralis governed by: - targe coverage by 90%-isodose - dose limit to anterior rib surface: 5 Gy thickness of pectoralis typiclly ~ 1cm FWH ISIORT Baveno 2012 9
HIOB: dosimetric QA Calibration of the EBRT & IOERT beams according to one of the dosimetry protocols: IAEA TRS 398, TG 51, OeNORM S5234-3 or DIN 6800-2, and identify which protocol is being used. Initial MU calibration - verified by transfer dosimetry (e.g. TLD) in cooperation with an accredited dosimetry laboratory. Participants in the USA encouraged to use the RPC mailed TLD program. Beam output constancy for mobile & stationary IOERT units - method and frequency of measurement varies depending on the type of system in use, but all methods assure the output is constant to +/- 3% per AAPM TG 72, and that the 90% depth dose is within 2 mm of the initial calibration. EBRT x-ray output of the energy used must be validated weekly to assure that the precision of dose to the reference point is within +/- 2%. FWH ISIORT Baveno 2012 10
Tägliche QA : Einfacher reproduzierbarer Aufbau schneller Aufbau möglichst geringer Dosisverbrauch beschränkte Betriebsbelastung des OP FWH 03 / 2012 IOERT _WS FFM 07.03.12 11
Arbeitstägliche QA Einfacher reproduzierbarer Aufbau FWH 03 / 2012 IOERT _WS FFM 07.03.12 12
Arbeitstägliche QA Notwendige Dosis für Prüfung hängt ab von: Linearität des Monitors Reproduzierbarkeit der Abschaltdosis Ziel : Dosisunsicherheit im Referenzpunkt < ± 2-2.5 % FWH 03 / 2012 IOERT _WS FFM 07.03.12 13
Arbeitstägliche QA Reproduzierbarkeit der Monitordosis ± 2.5% FWH 03 / 2012 IOERT _WS FFM 07.03.12 14
Arbeitstägliche QA Reproduzierbarkeit der Abschaltdosis Min. 3 Messungen bei jeder Energie Dosis 10Gy (wie therapeutische Dosis) 120 Gy QA-Dosis pro Tag bei Betriebsbelastung 380 Gy / Woche FWH 03 / 2012 IOERT _WS FFM 07.03.12 15
Arbeitstägliche QA Stabilität der Elektronenenergie Möglicherweise Änderungen aufgrund von Energieänderungen im flexiblen Hohlleiter regelmäßige Überprüfung der e - -Energie FWH 03 / 2012 IOERT _WS FFM 07.03.12 16
Filmdosimetrie mit Radiochrom- Filmen Dosis-Querverteilungen FWH 03 / 2012 IOERT _WS FFM 07.03.12 17
HIOB: WBRT Time factors WBRT starts after day 36 p.o. but until day 56 p.o.(in case of adjuvant hormonal treatment or no further tumor specific medication) In case of adjuvant chemotherapy, a time gap between IOERT and WBRT up to 6 months is allowed Treatment technique PTV - whole breast gland with the adjacent chest-wall 3D CRT (tangential wedged fields or IMRT) on individual CT-slices WBRT - delivered by photons with a minimum energy of 4 MV on Linacs Weekly patient set-up verification Dosage and duration of WBRT Single fx dose = 2,7 Gy (ICRU) 15 fx 5 fx/week with regular RT-breaks (weekend/feast days) V20 < 20 % of ipsilateral lung D50% < 5% of heart volume First WBRT treatment plan and portal images are analyze by the HIOB QA team to ensure compliance with the protocol. Subsequent treatment plans randomly review by the HIOB QA team. FWH ISIORT Baveno 2012 18
Example: dose distribution for a patient treated according to QA protocol IORT : Pat. 1 48y pt1 tumor Diameter : complete resection Target diameter target thickness : depth rib : 19 mm 40mm 20 mm 28 mm 28 mm 40 mm 20 mm Energy: Applicator: 10 MeV 5cm straight FWH ISIORT Baveno 2012 19
WBRT : FWH ISIORT Baveno 2012 20
Example: dose distribution for a patient treated according to QA protocol combination IORT - WBRT : FWH ISIORT Baveno 2012 21
Example: dose distribution for a patient treated according to QA protocol combination IORT - WBRT : FWH ISIORT Baveno 2012 22
Example: dose distribution for a patient treated according to QA protocol IORT : Pat. 2 66y pt1 tumor Diameter : complete resection Target diameter target thickness : 12 mm 40mm 16 mm 40 mm 16 mm Shielding plate diameter : Shielding plate thickness : Shielding plate H 2 O equivalent : 70 mm 5 mm 20 mm Energy: Applicator: 6 MeV 5cm straight FWH ISIORT Baveno 2012 23
Example: dose distribution for a patient treated according to QA protocol combination IORT - WBRT : FWH ISIORT Baveno 2012 24
Conclusion It is possible to develop a practical QA program to assure proper radiation delivery for an ISIORT protocol FWH ISIORT Baveno 2012 25
Thank you for your attention and Find also: Intraoperative radiotherapy in breast cancer treatment using high energy electrons four years of experience - Sebastian Adamczyk, Marcin Litoborski poster presentation FWH ISIORT Baveno 2012 26