Michael Lempart1, Börje Blad1, Gabriel Adrian2, Sven Bäck3, Tommy Knöös3, Crister Ceberg4, Kristoffer Petersson5. 1. Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund University, Sweden. 2. Division of Oncology and Pathology, Clinical Sciences, Lund, Skåne University Hospital, Lund University, Sweden. 3. Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund University, Sweden; Department of Medical Radiation Physics, Clinical Sciences, Lund, Lund University, Sweden. 4. Department of Medical Radiation Physics, Clinical Sciences, Lund, Lund University, Sweden. 5. Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund University, Sweden. Electronic address: kristoffer.petersson@med.lu.se.
Abstract
OBJECTIVES: The purpose of this study was to modify a clinical linear accelerator, making it capable of electron beam ultra-high dose rate (FLASH) irradiation. Modifications had to be quick, reversible, and without interfering with clinical treatments. METHODS: Performed modifications: (1) reduced distance with three setup positions, (2) adjusted/optimized gun current, modulator charge rate and beam steering values for a high dose rate, (3) delivery was controlled with a microcontroller on an electron pulse level, and (4) moving the primary and/or secondary scattering foils from the beam path. RESULTS: The variation in dose for a five-pulse delivery was measured to be 1% (using a diode, 4% using film) during 10 minutes after a warm-up procedure, later increasing to 7% (11% using film). A FLASH irradiation dose rate was reached at the cross-hair foil, MLC, and wedge position, with ≥30, ≥80, and ≥300 Gy/s, respectively. Moving the scattering foils resulted in an increased output of ≥120, ≥250, and ≥1000 Gy/s, at the three positions. The beam flatness was 5% at the cross-hair position for a 20 × 20 and a 10 × 10 cm2 area, with and without both scattering foils in the beam. The beam flatness was 10% at the wedge position for a 6 and 2.5 cm diametric area, with and without the scattering foils in the beam path. CONCLUSIONS: A clinical accelerator was modified to produce ultra-high dose rates, high enough for FLASH irradiation. Future work aims to fine-tune the dose delivery, using the on-board transmission chamber signal and adjusting the dose-per-pulse.
OBJECTIVES: The purpose of this study was to modify a clinical linear accelerator, making it capable of electron beam ultra-high dose rate (FLASH) irradiation. Modifications had to be quick, reversible, and without interfering with clinical treatments. METHODS: Performed modifications: (1) reduced distance with three setup positions, (2) adjusted/optimized gun current, modulator charge rate and beam steering values for a high dose rate, (3) delivery was controlled with a microcontroller on an electron pulse level, and (4) moving the primary and/or secondary scattering foils from the beam path. RESULTS: The variation in dose for a five-pulse delivery was measured to be 1% (using a diode, 4% using film) during 10 minutes after a warm-up procedure, later increasing to 7% (11% using film). A FLASH irradiation dose rate was reached at the cross-hair foil, MLC, and wedge position, with ≥30, ≥80, and ≥300 Gy/s, respectively. Moving the scattering foils resulted in an increased output of ≥120, ≥250, and ≥1000 Gy/s, at the three positions. The beam flatness was 5% at the cross-hair position for a 20 × 20 and a 10 × 10 cm2 area, with and without both scattering foils in the beam. The beam flatness was 10% at the wedge position for a 6 and 2.5 cm diametric area, with and without the scattering foils in the beam path. CONCLUSIONS: A clinical accelerator was modified to produce ultra-high dose rates, high enough for FLASH irradiation. Future work aims to fine-tune the dose delivery, using the on-board transmission chamber signal and adjusting the dose-per-pulse.
Authors: Noora H Ba Sunbul; Wei Zhang; Ibrahim Oraiqat; Dale W Litzenberg; Kwok L Lam; Kyle Cuneo; Jean M Moran; Paul L Carson; Xueding Wang; Shaun D Clarke; Martha M Matuszak; Sara A Pozzi; Issam El Naqa Journal: Med Phys Date: 2021-09-08 Impact factor: 4.071
Authors: Michele M Kim; Arash Darafsheh; Jan Schuemann; Ivana Dokic; Olle Lundh; Tianyu Zhao; José Ramos-Méndez; Lei Dong; Kristoffer Petersson Journal: IEEE Trans Radiat Plasma Med Sci Date: 2021-06-22
Authors: Ryan B Ko; Luis A Soto; Rie von Eyben; Stavros Melemenidis; Erinn B Rankin; Peter G Maxim; Edward E Graves; Billy W Loo Journal: Radiat Res Date: 2020-12-01 Impact factor: 2.841
Authors: Elise Konradsson; Maja L Arendt; Kristine Bastholm Jensen; Betina Børresen; Anders E Hansen; Sven Bäck; Annemarie T Kristensen; Per Munck Af Rosenschöld; Crister Ceberg; Kristoffer Petersson Journal: Front Oncol Date: 2021-05-13 Impact factor: 6.244
Authors: Alexander Berne; Kristoffer Petersson; Iain D C Tullis; Robert G Newman; Borivoj Vojnovic Journal: Phys Med Biol Date: 2021-02-09 Impact factor: 3.609