Modifying a clinical linear accelerator for delivery of ultra-high dose rate irradiation
(2019) In Radiotherapy and Oncology 139. p.40-45- 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... (More)
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.
(Less)
- author
- Lempart, Michael LU ; Blad, Börje LU ; Adrian, Gabriel LU ; Bäck, Sven LU ; Knöös, Tommy LU ; Ceberg, Crister LU and Petersson, Kristoffer LU
- organization
- publishing date
- 2019-02-10
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- FLASH, Irradiation, Linac, Ultra-high dose rate
- in
- Radiotherapy and Oncology
- volume
- 139
- pages
- 40 - 45
- publisher
- Elsevier
- external identifiers
-
- scopus:85061177418
- pmid:30755324
- ISSN
- 0167-8140
- DOI
- 10.1016/j.radonc.2019.01.031
- language
- English
- LU publication?
- yes
- id
- c58cf1bf-e057-4f32-a7ec-1e8701b50a0c
- date added to LUP
- 2019-02-20 09:26:51
- date last changed
- 2024-04-16 00:45:57
@article{c58cf1bf-e057-4f32-a7ec-1e8701b50a0c, abstract = {{<p>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 cm<sup>2</sup> 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.</p>}}, author = {{Lempart, Michael and Blad, Börje and Adrian, Gabriel and Bäck, Sven and Knöös, Tommy and Ceberg, Crister and Petersson, Kristoffer}}, issn = {{0167-8140}}, keywords = {{FLASH; Irradiation; Linac; Ultra-high dose rate}}, language = {{eng}}, month = {{02}}, pages = {{40--45}}, publisher = {{Elsevier}}, series = {{Radiotherapy and Oncology}}, title = {{Modifying a clinical linear accelerator for delivery of ultra-high dose rate irradiation}}, url = {{http://dx.doi.org/10.1016/j.radonc.2019.01.031}}, doi = {{10.1016/j.radonc.2019.01.031}}, volume = {{139}}, year = {{2019}}, }