A Proton Beam Therapy System Dedicated to Spot-Scanning Increases Accuracy with Moving Tumors by Real-Time Imaging and Gating and Reduces Equipment Size

Shimizu, Satoru; Miyamoto, Naoki; Matsuura, Tetsuya; Fujii, Yusuke; Umezawa, M.; Umegaki, Kikuo; Hiramoto, Kazuo; Shirato, Hiroki

doi:10.1371/journal.pone.0094971

Cited by 82 publications

(89 citation statements)

References 15 publications

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“…Respiratory gating is a non-invasive technique for addressing the problem posed by the respiratory motion of tumors including lung cancers [5]–[10]. Based on the results of our earlier simulation studies that compared respiratory gating techniques [11], [12] we used phase-based gating in patients with lung cancer to set the gating window to cover a 30% duty cycle around end-expiration.…”

Section: Introductionmentioning

confidence: 99%

Respiratory Gating during Stereotactic Body Radiotherapy for Lung Cancer Reduces Tumor Position Variability

et al. 2014

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PurposeWe evaluated the effects of respiratory gating on treatment accuracy in lung cancer patients undergoing lung stereotactic body radiotherapy by using electronic portal imaging device (EPID) images.Materials and MethodsOur study population consisted of 30 lung cancer patients treated with stereotactic body radiotherapy (48 Gy/4 fractions/4 to 9 days). Of these, 14 were treated with- (group A) and 16 without gating (group B); typically the patients whose tumors showed three-dimensional respiratory motion ≧5 mm were selected for gating. Tumor respiratory motion was estimated using four-dimensional computed tomography images acquired during treatment simulation. Tumor position variability during all treatment sessions was assessed by measuring the standard deviation (SD) and range of tumor displacement on EPID images. The two groups were compared for tumor respiratory motion and position variability using the Mann-Whitney U test.ResultsThe median three-dimensional tumor motion during simulation was greater in group A than group B (9 mm, range 3–30 mm vs. 2 mm, range 0–4 mm; p<0.001). In groups A and B the median SD of the tumor position was 1.1 mm and 0.9 mm in the craniocaudal- (p = 0.24) and 0.7 mm and 0.6 mm in the mediolateral direction (p = 0.89), respectively. The median range of the tumor position was 4.0 mm and 3.0 mm in the craniocaudal- (p = 0.21) and 2.0 mm and 1.5 mm in the mediolateral direction (p = 0.20), respectively.ConclusionsAlthough patients treated with respiratory gating exhibited greater respiratory tumor motion during treatment simulation, tumor position variability in the EPID images was low and comparable to patients treated without gating. This demonstrates the benefit of respiratory gating.

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Section: Introductionmentioning

confidence: 99%

Respiratory Gating during Stereotactic Body Radiotherapy for Lung Cancer Reduces Tumor Position Variability

et al. 2014

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“…Despite many advantages, PBS has an inherent limitation with respect to moving targets. Compared to passive scattering proton beam therapy, PBS is subject to the dosimetric “interplay effect.” Many studies have been focused on how to mitigate dose uncertainties due to target motion; mitigation strategies include gating, rescanning, robust optimization, as well as optimization of the spot delivery sequence . With each of these techniques, the patients’ breathing phases at the start of the beam delivery have theoretical relevance (especially in the case of reproducible breathing periods).…”

Section: Discussionmentioning

confidence: 99%

Technical Note: Using experimentally determined proton spot scanning timing parameters to accurately model beam delivery time

et al. 2017

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“…In addition, internal tumor motion includes interfractional variation [27]. Here, we ignored the baseline shift/drift during the therapeutic beam delivery, which also depends on the tumor motion [23] and consequently changes the gate signal patterns and the system efficiency. These biases may be significant but cannot be compensated by the multiple gated-irradiation function.…”

Section: Discussionmentioning

confidence: 99%

“…The resulting fluctuations in the gating signal can significantly reduce the gated irradiation efficiency in variable flat top phase synchrotron operation [21]. To improve the gated irradiation efficiency, we have developed a real-time-image gated proton beam therapy (RGPT) system [22][23][24] which has a new function, called the multiple gated-irradiation function [20,25]. The combination of variable flat top phase operation and multiple gated-irradiation function was realized in the first in RGPT.…”

Section: Introductionmentioning

confidence: 99%

Optimization and evaluation of multiple gating beam delivery in a synchrotron-based proton beam scanning system using a real-time imaging technique

et al. 2016

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(Naoki Miyamoto) Purpose:To find the optimum parameter of a new beam control function installed in a synchrotron-based proton therapy system. Methods:A function enabling multiple gated irradiation in the flat top phase has been installed in a real-time-image gated proton beam therapy (RGPT) system. This function is realized by a waiting timer that monitors the elapsed time from the last gate-off signal in the flat top phase. The gated irradiation efficiency depends on the timer value, T w . To find the optimum T w value, gated irradiation efficiency was evaluated for each configurable T w value. 271 gate signal data sets from 58 patients were used for the simulation. Results:The highest mean efficiency 0.52 was obtained in T W = 0.2 s. The irradiation efficiency was approximately 21% higher than at T W = 0 s, which corresponds to ordinary synchrotron operation. The irradiation efficiency was improved in 154 (57%) of the 271 cases. The irradiation efficiency was reduced in 117 cases because the T W value was insufficient or the function introduced an unutilized wait time for the next gate-on signal in the flat top phase. In the actual treatment of a patient with a hepatic tumor at T w = 0.2 s, 4.48 GyE irradiation was completed within 250 s. In contrast, the treatment time of ordinary synchrotron operation was estimated to be 420 s. Conclusions:The results suggest that the multiple gated-irradiation function has potential to improve the gated irradiation efficiency and to reduce the treatment time.

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A Proton Beam Therapy System Dedicated to Spot-Scanning Increases Accuracy with Moving Tumors by Real-Time Imaging and Gating and Reduces Equipment Size

Cited by 82 publications

References 15 publications

Respiratory Gating during Stereotactic Body Radiotherapy for Lung Cancer Reduces Tumor Position Variability

Respiratory Gating during Stereotactic Body Radiotherapy for Lung Cancer Reduces Tumor Position Variability

Technical Note: Using experimentally determined proton spot scanning timing parameters to accurately model beam delivery time

Optimization and evaluation of multiple gating beam delivery in a synchrotron-based proton beam scanning system using a real-time imaging technique

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