TY - JOUR
T1 - Clinical Linear Accelerator-Based Electron FLASH
T2 - Pathway for Practical Translation to FLASH Clinical Trials
AU - No, Hyunsoo Joshua
AU - Wu, Yufan (Fred)
AU - Dworkin, Michael Louis
AU - Manjappa, Rakesh
AU - Skinner, Lawrie
AU - Ashraf, M. Ramish
AU - Lau, Brianna
AU - Melemenidis, Stavros
AU - Viswanathan, Vignesh
AU - Yu, Amy Shu Jung
AU - Surucu, Murat
AU - Schüler, Emil
AU - Graves, Edward Elliot
AU - Maxim, Peter Gregor
AU - Loo, Billy W.
N1 - Publisher Copyright:
© 2023 Elsevier Inc.
PY - 2023/10/1
Y1 - 2023/10/1
N2 - Purpose: Ultrahigh-dose-rate (UHDR) radiation therapy (RT) has produced the FLASH effect in preclinical models: reduced toxicity with comparable tumor control compared with conventional-dose-rate RT. Early clinical trials focused on UHDR RT feasibility using specialized devices. We explore the technical feasibility of practical electron UHDR RT on a standard clinical linear accelerator (LINAC). Methods and Materials: We tuned the program board of a decommissioned electron energy for UHDR electron delivery on a clinical LINAC without hardware modification. Pulse delivery was controlled using the respiratory gating interface. A short source-to-surface distance (SSD) electron setup with a standard scattering foil was configured and tested on an anthropomorphic phantom using circular blocks with 3- to 20-cm field sizes. Dosimetry was evaluated using radiochromic film and an ion chamber profiler. Results: UHDR open-field mean dose rates at 100, 80, 70, and 59 cm SSD were 36.82, 59.52, 82.01, and 112.83 Gy/s, respectively. At 80 cm SSD, mean dose rate was ∼60 Gy/s for all collimated field sizes, with an R80 depth of 6.1 cm corresponding to an energy of 17.5 MeV. Heterogeneity was <5.0% with asymmetry of 2.2% to 6.2%. The short SSD setup was feasible under realistic treatment conditions simulating broad clinical indications on an anthropomorphic phantom. Conclusions: Short SSD and tuning for high electron beam current on a standard clinical LINAC can deliver flat, homogenous UHDR electrons over a broad, clinically relevant range of field sizes and depths with practical working distances in a configuration easily reversible to standard clinical use.
AB - Purpose: Ultrahigh-dose-rate (UHDR) radiation therapy (RT) has produced the FLASH effect in preclinical models: reduced toxicity with comparable tumor control compared with conventional-dose-rate RT. Early clinical trials focused on UHDR RT feasibility using specialized devices. We explore the technical feasibility of practical electron UHDR RT on a standard clinical linear accelerator (LINAC). Methods and Materials: We tuned the program board of a decommissioned electron energy for UHDR electron delivery on a clinical LINAC without hardware modification. Pulse delivery was controlled using the respiratory gating interface. A short source-to-surface distance (SSD) electron setup with a standard scattering foil was configured and tested on an anthropomorphic phantom using circular blocks with 3- to 20-cm field sizes. Dosimetry was evaluated using radiochromic film and an ion chamber profiler. Results: UHDR open-field mean dose rates at 100, 80, 70, and 59 cm SSD were 36.82, 59.52, 82.01, and 112.83 Gy/s, respectively. At 80 cm SSD, mean dose rate was ∼60 Gy/s for all collimated field sizes, with an R80 depth of 6.1 cm corresponding to an energy of 17.5 MeV. Heterogeneity was <5.0% with asymmetry of 2.2% to 6.2%. The short SSD setup was feasible under realistic treatment conditions simulating broad clinical indications on an anthropomorphic phantom. Conclusions: Short SSD and tuning for high electron beam current on a standard clinical LINAC can deliver flat, homogenous UHDR electrons over a broad, clinically relevant range of field sizes and depths with practical working distances in a configuration easily reversible to standard clinical use.
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U2 - 10.1016/j.ijrobp.2023.04.011
DO - 10.1016/j.ijrobp.2023.04.011
M3 - Article
C2 - 37105403
AN - SCOPUS:85160068566
SN - 0360-3016
VL - 117
SP - 482
EP - 492
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 2
ER -