Impact of radiation attenuation by a carbon fiber couch on patient dose verification

Yu, Chun Yen; Chou, Wen Tsae; Liao, Yi Jen; Lee, Jeng Hung; Liang, Ji An; Hsu, Shih Ming

doi:10.1038/srep43336

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…In the present study, the average pass rate of 263 head and neck patients, and 154 pelvic patients was 98.03% and 98.36%, respectively.Yu et al used Delta phantom to verify 12 head and neck, and rectal plans, and the gamma index was almost the same, which is consistent with the results of the present study 15. In all the tumor sites, the lowest average pass rate was found in the head and neck IMRT group, probably because the head and neck plans were mostly for nasopharyngeal carcinomas, and the organs, optic nerves, parotid glands, and other critical organs were strictly constrained.…”

supporting

confidence: 91%

Analysis of dose verification results for 924 intensity‐modulated radiation therapy plans

Chen

et al. 2018

Precision Radiation Oncology

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Objective Intensity‐modulated radiation therapy (IMRT) plays an increasingly important role in clinical applications, and dose verification is particularly crucial for each patient. In the present study, we retrospectively analyzed the results of dose verification in 924 actual IMRT plans, including the relationship between gamma pass rates and the location of lesions, and the total number of monitor units, and the maximum area of the collected dose. Methods All the 924 IMRT plans implemented in a Varian Trilogy accelerator between 1 January 2014 and 31 March 2016 at Shandong Cancer Hospital were acquired. The Varian Eclipse planning system was used for all treatment planning and verification. Then, actual implemented plans were transplanted into a water phantom. Subsequently, the derived fluence was compared with the actual measured fluence by gamma analysis with the gamma criteria (3%/3 mm). Results A total of 924 IMRT plans were categorized into six groups, including the brain, head and neck, chest, abdomen, pelvis, and breast. The gamma pass rate average was >98% for 902 IMRT plans, whereas 22 plans did not pass the first time. A correlation was observed between the treatment site and gamma pass rate (P = 0.017). Meanwhile, a negative correlation was observed between the gamma pass rate and the total number of monitor units (P < 0.001), and the largest area of the acquisition dose (P < 0.001), respectively. Varian Trilogy accelerator IMRT QA data has a stable pass rate with a 100 confidence limit (CL) value of 95.19. Conclusion There was a correlation between the pass rate and the treatment site, the total number of monitor units, and the maximum area of collected dose. When using Mapcheck for patient plan dose verification, the gamma pass rate is very high, and only a few of them need to be analyzed.

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supporting

confidence: 91%

Analysis of dose verification results for 924 intensity‐modulated radiation therapy plans

Chen

et al. 2018

Precision Radiation Oncology

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“…Recent years the external photon beam radiotherapy delivery techniques and modalities have been undergone a rapid development, the method of radiation treatment has switched from the use of a single treatment beam to the utilization of multiple beams or rotation treatment. With the introduction of intensity modulated radiation therapy (IMRT) the number of fields used for patient treatment increases, the effect of treatment couches becomes more significant . Especially as the advanced volumetric modulated arc therapy (VMAT) delivery systems become a main role of treatment ways, which places even greater demands on delivering accuracy.…”

Section: Introductionmentioning

confidence: 99%

Quantification and comparison the dosimetric impact of two treatment couch model in VMAT

Zhang

Gao

Bai

2017

J Applied Clin Med Phys

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The use of Monte Carlo treatment planning systems (TPS) in radiation therapy has increased the dosimetric accuracy of VMAT treatment sequences. However, this accuracy is compromised by not including the treatment couch into the treatment planning process. Therefore, the impact of the treatment couch on radiation delivery output was determined, and two different couch models (uniform couch model A vs two components model B) were included and tested in the Monaco TPS to investigate which model can better quantify the couch influence on radiation dose. Relative attenuation measurements were performed following procedures outlined by TG‐176 with three phantom positions for A–B direction: on the left half (L), in the center (C) and on the right half (R) of the couch. As well as absolute dose comparison of static fields of 10 × 10 cm2 that were delivered through the couch tops with that calculated in the TPS with the couch model at 2 mm and 5 mm computing grid size respectively. The most severe percentage deviation was 4.60% for the phantom positioned at the left half of the couch with 5 mm grid size at gantry angle 120°. The couch model was included in the TPS with a uniform ED of 0.26 g/cm3 or a two component model with a fiber 0.52 g/cm3 and foam core 0.1 g/cm3. After including the treatment couch, the maximum mean dose attenuation was reduced from 3.68% without couch included to (0.60, 0.83, 0.72, and 1.02) % for model A and model B at 2 and 5 mm voxel grid size. The results obtained showed that Model A performed better than the model B, demonstrating lower deviations from measurements and better robustness against dose grid resolution changes. Considering the results of this study, we propose the systematic introduction of the couch Model A in clinical routine. All the reported findings are valid for the Elekta iBEAM ® evo Extension 415 couch and these methods can also be used for other couch model.

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“…Our medical physicist compensated for this effect by calculating the attenuation of the couch. 19 Furthermore, cone beam computed tomography ensured an accurate treatment location. Therefore, in this study, all treatment plans were designed using the supine position, which could make patients more comfortable, relaxed, and stable during treatment.…”

Section: Discussionmentioning

confidence: 99%

Dosimetry and efficiency comparison of knowledge-based and manual planning using volumetric modulated arc therapy for craniospinal irradiation

Tsai,

Hsieh,

Hung

et al. 2024

Radiology and Oncology

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Background Craniospinal irradiation (CSI) poses a challenge to treatment planning due to the large target, field junction, and multiple organs at risk (OARs) involved. The aim of this study was to evaluate the performance of knowledge-based planning (KBP) in CSI by comparing original manual plans (MP), KBP RapidPlan initial plans (RPI), and KBP RapidPlan final plans (RPF), which received further re-optimization to meet the dose constraints. Patients and methods Dose distributions in the target were evaluated in terms of coverage, mean dose, conformity index (CI), and homogeneity index (HI). The dosimetric results of OARs, planning time, and monitor unit (MU) were evaluated. Results All MP and RPF plans met the plan goals, and 89.36% of RPI plans met the plan goals. The Wilcoxon tests showed comparable target coverage, CI, and HI for the MP and RPF groups; however, worst plan quality was demonstrated in the RPI plans than in MP and RPF. For the OARs, RPF and RPI groups had better dosimetric results than the MP group (P < 0.05 for optic nerves, eyes, parotid glands, and heart). The planning time was significantly reduced by the KBP from an average of 677.80 min in MP to 227.66 min (P < 0.05) and 307.76 min (P < 0.05) in RPI, and RPF, respectively. MU was not significantly different between these three groups. Conclusions The KBP can significantly reduce planning time in CSI. Manual re-optimization after the initial KBP is recommended to enhance the plan quality.

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Impact of radiation attenuation by a carbon fiber couch on patient dose verification

Cited by 5 publications

References 10 publications

Analysis of dose verification results for 924 intensity‐modulated radiation therapy plans

Analysis of dose verification results for 924 intensity‐modulated radiation therapy plans

Quantification and comparison the dosimetric impact of two treatment couch model in VMAT

Dosimetry and efficiency comparison of knowledge-based and manual planning using volumetric modulated arc therapy for craniospinal irradiation

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