Patient-specific quality assurance for proton depth dose distribution using a multi-layer ionization chamber in a single-ring wobbling method

Katō, Takahiro; Arai, Kazuhiro; Sagara, Tatsuhiko; Kato, Ryohei; Yamazaki, Yoshitake; Oyama, Sho

doi:10.1007/s12194-019-00524-8

Cited by 8 publications

(5 citation statements)

References 12 publications

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“…The irradiation method was the wobbler method, which is one of the passive scattering methods [ 14 ]. The prescribed dose was determined as 19.8 Gy relative biological effectiveness (RBE)/11 fractions or 30.6 Gy (RBE)/17 fractions at the isocenter for the standard protocol according to the Japan Childhood Cancer Group Neuroblastoma Committee [ 2 ].…”

Section: Methodsmentioning

confidence: 99%

Evaluation of Diaphragm Position Variations During Proton Therapy for Pediatric Patients With Neuroblastoma

Kato,

Narita,

Takemasa

et al. 2024

Cureus

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Background To evaluate the respiratory-induced intrafractional diaphragm motion and interfractional diaphragm displacement in pediatric patients with neuroblastoma (NBL). Materials and methods Ten pediatric patients with a mean age of 4.5 years (range: 1.8-8.7 years) with abdominal NBL treated with proton therapy (PT) have been evaluated. Intrafractional motion and interfractional displacement have been analyzed by using cine radiography and orthogonal X-ray images, respectively. In each case, the cranio-caudal positions of the diaphragm have been measured as an index. This study has investigated the possible correlations between intrafractional diaphragm motion and height. Additionally, interfractional displacement and its time trend during the treatment course have been analyzed. Results The average right and left diaphragm intrafractional motions of 8.3 mm (range: 4.4-11.5 mm) and 6.4 mm (range: 2.2-11.8 mm) were observed, respectively; however, no significant correlation has been observed with height. An interfractional displacement of 5 mm or more has been observed in 20 out of 152 fractions (13%). The average absolute value of the interfractional displacement was 2.5 mm (range: 0-8.6 mm). Interfractional displacement did not show a peculiar tendency throughout the treatment period. Conclusions It was suggested that respiratory-induced diaphragm position variation in children varies greatly among individuals, and accurately estimating it based on height is difficult. Thus, these individual evaluations are considered indispensable.

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Section: Methodsmentioning

confidence: 99%

Evaluation of Diaphragm Position Variations During Proton Therapy for Pediatric Patients With Neuroblastoma

Kato,

Narita,

Takemasa

et al. 2024

Cureus

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“…The irradiation method was the wobbler method, one of the passive scattering methods. 14 A plan was created for the beam direction by using the method described by Moyers et al. 15 The RBE value of 1.1 was used in this study.…”

Section: Methodsmentioning

confidence: 99%

“…The irradiation method was the wobbler method, one of the passive scattering methods. 14 A plan was created for the beam direction by using the method described by Moyers et al 15 The RBE value of 1.1 was used in this study. Hitachi's proton-type Particle Therapy System (Hitachi, Kashiwa, Japan) was F I G U R E 2 Differences in the water equivalent path length (WEPL) with different large bowel densities.…”

Section: Treatment Planning With Sib Approachmentioning

confidence: 99%

Dosimetric impact of simulated changes in large bowel content during proton therapy with simultaneous integrated boost for locally advanced pancreatic cancer

Narita

Katō

Takemasa

et al. 2021

J Applied Clin Med Phys

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To investigate the dosimetric impact of changes in the large bowel content during proton therapy (PT) with simultaneous integrated boost (SIB) for locally advanced pancreatic cancer (LAPC). Materials and methods: Fifteen patients with LAPC were included in this study. The SIB method was performed using five fields according to our standard protocol. A total dose of 67.5 Gy(relative biological effectiveness [RBE]) was prescribed in 25 fractions using the SIB method. A dose of 45 Gy(RBE) was prescribed for the entire planning target volume (PTV) by using four main fields. The remaining 22.5 Gy(RBE) was prescribed to the PTV excluding for the gastrointestinal tract using one subfield. Five simulated doses were obtained by the forward dose calculations with the Hounsfield units (HU) override to the large bowel to 50, 0, −100, −500, and −1000, respectively. The dose-volume indices in each plan were compared using the 50 HU plan as a reference. Results: At D 98 of the clinical target volume (CTV) and spinal cord-D 2cc , when the density of the large bowel was close to that of gas, there were significant differences compared to the reference plan (p < 0.05). By contrast, no significant difference was observed in stomach-D 2cc duodenum-D 2cc , small bowel-D 2cc , kidneys-V 18 , and liver-D mean under any of the conditions. There were no cases in which the dose constraint of organs at risk, specified by our institution, was exceeded. Conclusion: Density change in the large bowel was revealed to significantly affect the doses of the CTV and spinal cord during PT with SIB for LAPC. For beam arrangement,it is important to select a gantry angle that prevents the large bowel from passing as much as possible. If this is unavoidable, it is important to carefully observe the gas image on the beam path during daily image guidance and to provide adaptive re-planning as needed.

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“…The planning target volume (PTV) was defined as additionally a 5‐mm isotropic margin except 7 mm inferiorly aiming in consideration of the movement within the gating window on respiratory movement. The irradiation method was the wobbler method, which is one of the passive scattering methods, 14 and a plan was created for the beam direction by using the Method described by Moyers et al 15 The number of beam angles was determined according to our standard protocol, with two to four angles depending on the tumor location. Although there were no restrictions on the size or location of the target in this study, this is a relative planning study, the prescribed dose was determined as 66 Gy relative biological effectiveness (RBE)/10 fractions at the isocenter for the peripheral type protocol in accordance with the Japanese Society for Radiation Oncology treatment policy of PT (ver 1.0) 16 .…”

Section: Methodsmentioning

confidence: 99%

The impact of different setup methods on the dose distribution in proton therapy for hepatocellular carcinoma

Takemasa

Katō

Narita

et al. 2021

J Applied Clin Med Phys

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To investigate the impact of different setup methods, vertebral body matching (VM), diaphragm matching (DM), and marker matching (MM), on the dose distribution in proton therapy (PT) for hepatocellular carcinoma (HCC). Materials and Methods: Thirty-eight HCC lesions were studied retrospectively to assess changes in the dose distribution on two computed tomography (CT) scans. One was for treatment planning (1st-CT), and the other was for dose confirmation acquired during the course of PT (2nd-CT). The dose coverage of the clinical target volume (CTV-D 98) and normal liver volume that received 30 Gy relative biological effectiveness (RBE) (liver-V 30) were evaluated under each condition. Initial treatment planning on the 1st-CT was defined as reference, and three dose distributions recalculated using VM, DM, and MM on the 2nd-CT, were compared to it, respectively. In addition, the relationship between the CTV-D 98 of each method and the distance between the center of mass (COM) of the CTV and the right diaphragm top was evaluated. Results: For CTV-D 98 , significant differences were observed between the reference and VM and DM, respectively (P = 0.013, P = 0.015). There were also significant differences between MM and VM and DM, respectively (P = 0.018, P = 0.036). Regarding liver-V 30 , there was no significant difference in any of the methods, and there were no discernable difference due to the different setup methods. In DM, only two out of 34 cases with a distance from right diaphragm top to COM of CTV of 90 mm or less that CTV-D 98 difference was 5% or more and CTV-D 98 was worse than VM were confirmed. Conclusion: Although MM is obviously the most effective method, it is suggested that DM may be particularly effective in cases where the distance from right diaphragm top to COM of CTV of 90 mm or less.

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Patient-specific quality assurance for proton depth dose distribution using a multi-layer ionization chamber in a single-ring wobbling method

Cited by 8 publications

References 12 publications

Evaluation of Diaphragm Position Variations During Proton Therapy for Pediatric Patients With Neuroblastoma

Evaluation of Diaphragm Position Variations During Proton Therapy for Pediatric Patients With Neuroblastoma

Dosimetric impact of simulated changes in large bowel content during proton therapy with simultaneous integrated boost for locally advanced pancreatic cancer

The impact of different setup methods on the dose distribution in proton therapy for hepatocellular carcinoma

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