Positioning accuracy and daily dose assessment for prostate cancer treatment using in‐room CT image guidance at a proton therapy facility

Maeda, Yoshikazu; Sato, Yoshitaka; Minami, Hiroki; Yasukawa, Y.; Yamamoto, Kazutaka; Tamamura, Hiroyasu; Shibata, Satoshi; Bou, Sayuri; Sasaki, Makoto; Tameshige, Y.; Kume, Kazuhiko; Ooto, Hiroshi; Kasahara, Shigeru; Shimizu, Yasuhiro; Saga, Yusuke; Omoya, Akira; Saitou, Makoto

doi:10.1002/mp.12858

Cited by 22 publications

(57 citation statements)

References 28 publications

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“…The treatment planning created initially based on above conditions was used through entire treatment with our CT image guidance. More detailed information was described in our report …”

Section: Methodsmentioning

confidence: 95%

“…In this study, we analyzed the interfractional variation in the prostate, rectum, and SVs utilizing almost full sets of in‐room CT images acquired throughout prostate cancer treatment at a proton therapy facility . We directly measured the movements of the different portions of each anatomical structure along the relevant coordinate axes for proton therapy with opposed lateral beams.…”

Section: Introductionmentioning

confidence: 99%

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Effects of organ motion on proton prostate treatments, as determined from analysis of daily CT imaging for patient positioning

et al. 2018

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The positional deviations for the prostate on the posterior side and the SVs were smaller by PRB matching than the other strategies and effectively reduced the rectal dose. 3D dose calculations indicate that PRB matching with CT image guidance may do a better job relative to other positioning methods to effectively reduce the rectal complications. The WEL variation was quite large, and the appropriate margin (approx. 10 mm) must be adapted to the proton range in an initial planning to maintain the coverage of target volumes throughout entire treatment.

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“…The treatment planning created initially based on above conditions was used through entire treatment with our CT image guidance. More detailed information was described in our report …”

Section: Methodsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Effects of organ motion on proton prostate treatments, as determined from analysis of daily CT imaging for patient positioning

et al. 2018

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“…27 When comparing image guidance on BA versus guidance on the prostate-rectal wall, Maeda et al found superior or comparable target coverage for the latter. 28 In their study, the passive scattering technique was, however, planned to compensate for prostate motion of AE10 mm in relation to the BA, which was more than the recorded differences between the 2 setup techniques in their patient material. In our training material, such large motion was rare (2.5%) and nonexistent among the testing patients Pat.20 Pat.…”

Section: Discussionmentioning

confidence: 99%

Plan Selection in Proton Therapy of Locally Advanced Prostate Cancer with Simultaneous Treatment of Multiple Targets

Pilskog

Abal

Øvrelid

et al. 2020

International Journal of Radiation Oncology*Biology*Physics

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This study presented a method of plan selection in intensity modulated proton therapy to address the challenge of delivering treatment to the prostate and the pelvic lymph nodes with different motion patterns. The plan library used different positions of the prostate created from a population model of day-to-day target motion. Plan selection from this library reduced the dose to the rectum and bladder without compromising target coverage compared with nonadaptive delivery.

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“…Previous analyses have employed varying strategies to accumulate fractional doses for prostate cancer radiotherapy on the basis of widely available but low-quality CBCT imaging, including enhanced or iterative CBCT approaches, portal dose measurements or rigid registration strategies, albeit with limitations regarding dose mapping ( 12 , 15 , 31 , 32 ). Dosimetric analyses based on daily diagnostic CT imaging have only been reported for proton radiotherapy, as in-room CT scanners are more widely available at the respective facilities, given the necessity for high-resolution imaging to compensate for higher proton range uncertainties due to anatomic alterations ( 33 , 34 ).…”

Section: Discussionmentioning

confidence: 99%

Dosimetric Impact of the Positional Imaging Frequency for Hypofractionated Prostate Radiotherapy – A Voxel-by-Voxel Analysis

et al. 2020

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Background To investigate deviations between planned and applied treatment doses for hypofractionated prostate radiotherapy and to quantify dosimetric accuracy in dependence of the image guidance frequency. Methods Daily diagnostic in-room CTs were carried out in 10 patients in treatment position as image guidance for hypofractionated prostate radiotherapy. Fraction doses were mapped to the planning CTs and recalculated, and applied doses were accumulated voxel-wise using deformable registration. Non-daily imaging schedules were simulated by deriving position correction vectors from individual scans and used to rigidly register the following scans until the next repositioning before dose recalculation and accumulation. Planned and applied doses were compared regarding dose-volume indices and TCP and NTCP values in dependence of the imaging and repositioning frequency. Results Daily image-guided repositioning was associated with only negligible deviations of analyzed dose-volume parameters and conformity/homogeneity indices for the prostate, bladder and rectum. Average CTV T did not significantly deviate from the plan values, and rectum NTCPs were highly comparable, while bladder NTCPs were reduced. For non-daily image-guided repositioning, there were significant deviations in the high-dose range from the planned values. Similarly, CTV dose conformity and homogeneity were reduced. While TCPs and rectal NTCPs did not significantly deteriorate for non-daily repositioning, bladder NTCPs appeared falsely diminished in dependence of the imaging frequency. Conclusion Using voxel-by-voxel dose accumulation, we showed for the first time that daily image-guided repositioning resulted in only negligible dosimetric deviations for hypofractionated prostate radiotherapy. Regarding dosimetric aberrations for non-daily imaging, daily imaging is required to adequately deliver treatment.

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Positioning accuracy and daily dose assessment for prostate cancer treatment using in‐room CT image guidance at a proton therapy facility

Cited by 22 publications

References 28 publications

Effects of organ motion on proton prostate treatments, as determined from analysis of daily CT imaging for patient positioning

Effects of organ motion on proton prostate treatments, as determined from analysis of daily CT imaging for patient positioning

Plan Selection in Proton Therapy of Locally Advanced Prostate Cancer with Simultaneous Treatment of Multiple Targets

Dosimetric Impact of the Positional Imaging Frequency for Hypofractionated Prostate Radiotherapy – A Voxel-by-Voxel Analysis

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