Hans Schiefer1, Konrad Buchauer2, Simon Heinze2, Guido Henke3, Ludwig Plasswilm3. 1. Department of Radiation Oncology, Medical Physics Group, Kantonsspital St. Gallen, 9007, St. Gallen, Switzerland. johann.schiefer@kssg.ch. 2. Department of Radiation Oncology, Medical Physics Group, Kantonsspital St. Gallen, 9007, St. Gallen, Switzerland. 3. Department of Radiation Oncology, Kantonsspital St. Gallen, 9007, St. Gallen, Switzerland.
Abstract
BACKGROUND: The unique beam-delivery technique of Tomotherapy machines (Accuray Inc., Sunnyvale, Calif.) necessitates tailored quality assurance. This requirement also applies to external dose intercomparisons. Therefore, the aim of the 2014 SSRMP (Swiss Society of Radiobiology and Medical Physics) dosimetry intercomparison was to compare two set-ups with different phantoms. MATERIALS AND METHODS: A small cylindrical Perspex phantom, which is similar to the IROC phantom (Imaging and Radiation Oncology Core, Houston, Tex.), and the "cheese" phantom, which is provided by the Tomotherapy manufacturer to all institutions, were used. The standard calibration plans for the TomoHelical and TomoDirect irradiation techniques were applied. These plans are routinely used for dose output calibration in Tomotherapy institutions. We tested 20 Tomotherapy machines in Germany and Switzerland. The ratio of the measured (Dm) to the calculated (Dc) dose was assessed for both phantoms and irradiation techniques. The Dm/Dc distributions were determined to compare the suitability of the measurement set-ups investigated. RESULTS: The standard deviations of the TLD-measured (thermoluminescent dosimetry) Dm/Dc ratios for the "cheese" phantom were 1.9 % for the TomoHelical (19 measurements) and 1.2 % (11 measurements) for the TomoDirect irradiation techniques. The corresponding ratios for the Perspex phantom were 2.8 % (18 measurements) and 1.8 % (11 measurements). CONCLUSION: Compared with the Perspex phantom-based set-up, the "cheese" phantom-based set-up without individual planning was demonstrated to be more suitable for Tomotherapy dose checks. Future SSRMP dosimetry intercomparisons for Tomotherapy machines will therefore be based on the "cheese" phantom set-up.
BACKGROUND: The unique beam-delivery technique of Tomotherapy machines (Accuray Inc., Sunnyvale, Calif.) necessitates tailored quality assurance. This requirement also applies to external dose intercomparisons. Therefore, the aim of the 2014 SSRMP (Swiss Society of Radiobiology and Medical Physics) dosimetry intercomparison was to compare two set-ups with different phantoms. MATERIALS AND METHODS: A small cylindrical Perspex phantom, which is similar to the IROC phantom (Imaging and Radiation Oncology Core, Houston, Tex.), and the "cheese" phantom, which is provided by the Tomotherapy manufacturer to all institutions, were used. The standard calibration plans for the TomoHelical and TomoDirect irradiation techniques were applied. These plans are routinely used for dose output calibration in Tomotherapy institutions. We tested 20 Tomotherapy machines in Germany and Switzerland. The ratio of the measured (Dm) to the calculated (Dc) dose was assessed for both phantoms and irradiation techniques. The Dm/Dc distributions were determined to compare the suitability of the measurement set-ups investigated. RESULTS: The standard deviations of the TLD-measured (thermoluminescent dosimetry) Dm/Dc ratios for the "cheese" phantom were 1.9 % for the TomoHelical (19 measurements) and 1.2 % (11 measurements) for the TomoDirect irradiation techniques. The corresponding ratios for the Perspex phantom were 2.8 % (18 measurements) and 1.8 % (11 measurements). CONCLUSION: Compared with the Perspex phantom-based set-up, the "cheese" phantom-based set-up without individual planning was demonstrated to be more suitable for Tomotherapy dose checks. Future SSRMP dosimetry intercomparisons for Tomotherapy machines will therefore be based on the "cheese" phantom set-up.
Authors: H Schiefer; A Fogliata; G Nicolini; L Cozzi; W W Seelentag; E Born; F Hasenbalg; J Roth; B Schnekenburger; K Münch-Berndl; V Vallet; M Pachoud; B Reiner; G Dipasquale; B Krusche; M K Fix Journal: Med Phys Date: 2010-08 Impact factor: 4.071
Authors: R Alfonso; P Andreo; R Capote; M Saiful Huq; W Kilby; P Kjäll; T R Mackie; H Palmans; K Rosser; J Seuntjens; W Ullrich; S Vatnitsky Journal: Med Phys Date: 2008-11 Impact factor: 4.071
Authors: T R Mackie; T Holmes; S Swerdloff; P Reckwerdt; J O Deasy; J Yang; B Paliwal; T Kinsella Journal: Med Phys Date: 1993 Nov-Dec Impact factor: 4.071
Authors: Nam P Nguyen; Shane P Krafft; Paul Vos; Vincent Vinh-Hung; Misty Ceizyk; Siyoung Jang; Anand Desai; Dave Abraham; Lars Ewell; Christopher Watchman; Russ Hamilton; Beng-Hoey Jo; Ulf Karlsson; Lexie Smith-Raymond Journal: Strahlenther Onkol Date: 2011-06-28 Impact factor: 3.621
Authors: Araceli Gago-Arias; Ruth Rodriguez-Romero; Patricia Sanchez-Rubio; Diego Miguel Gonzalez-Castano; Faustino Gomez; Luis Nunez; Hugo Palmans; Peter Sharpe; Juan Pardo-Montero Journal: Med Phys Date: 2012-04 Impact factor: 4.071
Authors: J D Fenwick; W A Tomé; H A Jaradat; S K Hui; J A James; J P Balog; C N DeSouza; D B Lucas; G H Olivera; T R Mackie; B R Paliwal Journal: Phys Med Biol Date: 2004-07-07 Impact factor: 3.609