TY - JOUR
T1 - Proton FLASH
T2 - passive scattering or pencil beam scanning?
AU - Zhang, Guoliang
AU - Wang, Junliang
AU - Wang, Yuenan
AU - Peng, Hao
N1 - Publisher Copyright:
© 2021 Institute of Physics and Engineering in Medicine.
PY - 2021/2/7
Y1 - 2021/2/7
N2 - This study focused on a direct comparison of dose delivery efficiency between two proton FLASH delivery modes: passive scattering and pencil beam scanning (PBS). Monte-Carlo simulation of the beamline was performed using the Geant4 package. Two proton energies (63 and 230 MeV) were selected, targeting for shallow and deep-seated tumors, respectively. Two irradiation field sizes were selected: 13 × 13 mm2 and 50 × 50 mm2. For each delivery mode, two cases were investigated: shoot-through and Bragg peak, yielding a total of 4 delivery scenarios. For the passive scattering mode, the impact on dose rate by multiple components along the beamline were investigated, including ridge-filter, scatterer, range shifter and collimator. A quantitative comparison among four scenarios was made in terms of field size, dose, dose rate and treatment plan quality (dose volume histogram). For the 230 MeV case, the dose rate (for 1 nA current) is 0.05 Gy s−1 (passive with Bragg peak, field size: 50 × 50 mm2) and 2.6 Gy s−1 (PBS with shoot-through). Dose rate comparison is made between passive scattering and PBS as the delivery changes from spot-layer to shoot-through. In conclusion, the study successfully established a benchmark reference for dose rate performance for different scenarios, taking into account components along the beamline, field size and beam current. The results allow us to predict and compare the required beam current to yield a dose rate sufficiently high, above the threshold of the FLASH effect.
AB - This study focused on a direct comparison of dose delivery efficiency between two proton FLASH delivery modes: passive scattering and pencil beam scanning (PBS). Monte-Carlo simulation of the beamline was performed using the Geant4 package. Two proton energies (63 and 230 MeV) were selected, targeting for shallow and deep-seated tumors, respectively. Two irradiation field sizes were selected: 13 × 13 mm2 and 50 × 50 mm2. For each delivery mode, two cases were investigated: shoot-through and Bragg peak, yielding a total of 4 delivery scenarios. For the passive scattering mode, the impact on dose rate by multiple components along the beamline were investigated, including ridge-filter, scatterer, range shifter and collimator. A quantitative comparison among four scenarios was made in terms of field size, dose, dose rate and treatment plan quality (dose volume histogram). For the 230 MeV case, the dose rate (for 1 nA current) is 0.05 Gy s−1 (passive with Bragg peak, field size: 50 × 50 mm2) and 2.6 Gy s−1 (PBS with shoot-through). Dose rate comparison is made between passive scattering and PBS as the delivery changes from spot-layer to shoot-through. In conclusion, the study successfully established a benchmark reference for dose rate performance for different scenarios, taking into account components along the beamline, field size and beam current. The results allow us to predict and compare the required beam current to yield a dose rate sufficiently high, above the threshold of the FLASH effect.
KW - Dose rate
KW - FLASH
KW - Proton therapy
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U2 - 10.1088/1361-6560/abd22d
DO - 10.1088/1361-6560/abd22d
M3 - Article
C2 - 33296881
AN - SCOPUS:85100954365
SN - 0031-9155
VL - 66
JO - Physics in medicine and biology
JF - Physics in medicine and biology
IS - 3
M1 - 03NT01
ER -