TY - JOUR
T1 - A multi-layer strip ionization chamber (MLSIC) device for proton pencil beam scan quality assurance
AU - Zhou, Shuang
AU - Rao, Wei
AU - Chen, Qinghao
AU - Tan, Yuewen
AU - Smith, Winter
AU - Sun, Baozhou
AU - Zhou, Jun
AU - Chang, Chih Wei
AU - Lin, Liyong
AU - Darafsheh, Arash
AU - Zhao, Tianyu
AU - Zhang, Tiezhi
N1 - Publisher Copyright:
© 2022 Institute of Physics and Engineering in Medicine.
PY - 2022/9/7
Y1 - 2022/9/7
N2 - Objective. Proton pencil beam scanning (PBS) treatment fields needs to be verified before treatment deliveries to ensure patient safety. In current practice, treatment beam quality assurance (QA) is measured at a few selected depths using film or a 2D detector array, which is insensitive and time-consuming. A QA device that can measure all key dosimetric characteristics of treatment beams spot-by-spot within a single beam delivery is highly desired. Approach. We developed a multi-layer strip ionization chamber (MLSIC) prototype device that comprises of two layers of strip ionization chambers (IC) plates for spot position measurement and 64 layers of plate IC for beam energy measurement. The 768-channel strip ion chamber signals are integrated and sampled at a speed of 3.125 kHz. It has a 25.6 cm × 25.6 cm maximum measurement field size and 2 mm spatial resolution for spot position measurement. The depth resolution and maximum depth were 2.91 mm and 18.6 cm for 1.6 mm thick IC plate, respectively. The relative weight of each spot was determined from total charge by all IC detector channels. Main results. The MLSIC is able to measure ionization currents spot-by-spot. The depth dose measurement has a good agreement with the ground truth measured using a water tank and commercial one-dimensional (1D) multi-layer plate chamber. It can verify the spot position, energy, and relative weight of clinical PBS beams and compared with the treatment plans. Significance. The MLSIC is a highly efficient QA device that can measure the key dosimetric characteristics of proton treatment beams spot-by-spot with a single beam delivery. It may improve the quality and efficiency of clinical proton treatments.
AB - Objective. Proton pencil beam scanning (PBS) treatment fields needs to be verified before treatment deliveries to ensure patient safety. In current practice, treatment beam quality assurance (QA) is measured at a few selected depths using film or a 2D detector array, which is insensitive and time-consuming. A QA device that can measure all key dosimetric characteristics of treatment beams spot-by-spot within a single beam delivery is highly desired. Approach. We developed a multi-layer strip ionization chamber (MLSIC) prototype device that comprises of two layers of strip ionization chambers (IC) plates for spot position measurement and 64 layers of plate IC for beam energy measurement. The 768-channel strip ion chamber signals are integrated and sampled at a speed of 3.125 kHz. It has a 25.6 cm × 25.6 cm maximum measurement field size and 2 mm spatial resolution for spot position measurement. The depth resolution and maximum depth were 2.91 mm and 18.6 cm for 1.6 mm thick IC plate, respectively. The relative weight of each spot was determined from total charge by all IC detector channels. Main results. The MLSIC is able to measure ionization currents spot-by-spot. The depth dose measurement has a good agreement with the ground truth measured using a water tank and commercial one-dimensional (1D) multi-layer plate chamber. It can verify the spot position, energy, and relative weight of clinical PBS beams and compared with the treatment plans. Significance. The MLSIC is a highly efficient QA device that can measure the key dosimetric characteristics of proton treatment beams spot-by-spot with a single beam delivery. It may improve the quality and efficiency of clinical proton treatments.
KW - intensity modulated proton therapy
KW - multilayer ionization chamber
KW - proton therapy
KW - quality assurance
UR - http://www.scopus.com/inward/record.url?scp=85137101866&partnerID=8YFLogxK
U2 - 10.1088/1361-6560/ac8593
DO - 10.1088/1361-6560/ac8593
M3 - Article
C2 - 35905730
AN - SCOPUS:85137101866
SN - 0031-9155
VL - 67
JO - Physics in medicine and biology
JF - Physics in medicine and biology
IS - 17
M1 - 175006
ER -