A robust measurement point for dose verification in delivery quality assurance for a robotic radiosurgery system

Kurosu, Keita; Sumida, Iori; Shiomi, Hiroya; Mizuno, Hirokazu; Yamaguchi, Hiroko; Okubo, Hirofumi; Tamari, Keisuke; Seo, Yuji; Сузукі, Осаму; Ōta, Shōzō; Inoue, Shinichi; Ogawa, Kazuhiko

doi:10.1093/jrr/rrw103

Cited by 9 publications

(7 citation statements)

References 24 publications

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“…We confirmed that there were no steep dose gradients in the collecting volumes of the chambers in the different collimator types. However, a robust measurement point suggested by Kurosu et al30 may have some effect on the results of absolute dose verification. The maximum collimator sizes of the fixed collimators were smaller than that of the other collimators.…”

Section: Discussionmentioning

confidence: 99%

Clinical usefulness of MLCs in robotic radiosurgery systems for prostate SBRT

Tomida

Kamomae

Suzuki

et al. 2017

J Applied Clin Med Phys

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Stereotactic body radiation therapy (SBRT) using recently introduced multileaf collimators (MLC) is preferred over circular collimators in the treatment of localized prostate cancer. The objective of this study was to assess the clinical usefulness of MLCs in prostate SBRT by comparing the effectiveness of treatment plans using fixed collimators, variable collimators, and MLCs and by ensuring delivery quality assurance (DQA) for each. For each patient who underwent conventional radiation therapy for localized prostate cancer, mock SBRT plans were created using a fixed collimator, a variable collimator, and an MLC. The total MUs, treatment times, and dose–volume histograms of the planning target volumes and organs at risk for each treatment plan were compared. For DQA, a phantom with a radiochromic film or an ionization chamber was irradiated in each plan. We performed gamma‐index analysis to evaluate the consistency between the measured and calculated doses. The MLC‐based plans had an ~27% lower average total MU than the plans involving other collimators. Moreover, the average estimated treatment time for the MLC plan was 31% and 20% shorter than that for the fixed and variable collimator plans respectively. The gamma‐index passing rate in the DQA using film measurements was slightly lower for the MLC than for the other collimators. The DQA results acquired using the ionization chamber showed that the discrepancies between the measured and calculated doses were within 3% in all cases. The results reinforce the usefulness of MLCs in robotic radiosurgery for prostrate SBRT treatment planning; most notably, the total MU and treatment time were both reduced compared to the cases using other types of collimators. Moreover, although the DQA results based on film dosimetry yielded a slightly lower gamma‐index passing rate for the MLC than for the other collimators, the MLC accuracy was determined to be sufficient for clinical use.

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Section: Discussionmentioning

confidence: 99%

Clinical usefulness of MLCs in robotic radiosurgery systems for prostate SBRT

Tomida

Kamomae

Suzuki

et al. 2017

J Applied Clin Med Phys

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“…Heterogeneity corrections were considered only for the primary beam attenuation by using the equivalent path length for calculation of TPR. Dose calculation accuracy of the ShioRIS software has been reported elsewhere [ 18 ].…”

Section: Methodsmentioning

confidence: 99%

Development of raster scanning IMRT using a robotic radiosurgery system

Shiomi

Akino

Sumida

et al. 2021

Journal of Radiation Research

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Treatment time with the CyberKnife frameless radiosurgery system is prolonged due to the motion of the robotic arm. We have developed a novel scanning irradiation method to reduce treatment time. We generated treatment plans mimicking eight-field intensity-modulated radiotherapy (IMRT) plans generated for the Novalis radiosurgery system. 2D dose planes were generated with multiple static beam spots collimated by a fixed circular cone. The weights of the uniformly distributed beam spots in each dose plane were optimized using the attraction–repulsion model. The beam spots were converted to the scanning speed to generate the raster scanning plan. To shorten treatment time, we also developed a hybrid scanning method which combines static beams with larger cone sizes and the raster scanning method. Differences between the Novalis and the scanning plan’s dose planes were evaluated with the criterion of a 5% dose difference. The mean passing rates of three cases were > 85% for cone sizes ≤ 12.5 mm. Although the total monitor units (MU) increased for smaller cone sizes in an inverse-square manner, the hybrid scanning method greatly reduced the total MU, while maintaining dose distributions comparable to those with the Novalis plan. The estimated treatment time of the hybrid scanning with a 12.5 mm cone size was on average 22% shorter than that of the sequential plans. This technique will be useful in allowing the CyberKnife with conventional circular cones to achieve excellent dose distribution with a shortened treatment time.

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“…The dose distribution of each BED 2 in the liver was exported using the DICOM-RT image fusion software (ShioRIS TM 2.0, Osaka, Japan). 29 Additionally, we analyzed the relationship between the mean BED 2 values for the liver and the planning target volume (PTV), as well as those between the expected hepatic dysfunctional volume and the PTV in order to estimate the residual volume after radiotherapy. We defined the potential liver dysfunction volume as a liver volume that received a BED 2 of 50 Gy or greater when cirrhotic, or received 75 Gy or greater when normal.…”

Section: Methodsmentioning

confidence: 99%