Dosimetric effects of the ipsilateral shoulder position variations in the sitting-positioned boron neutron capture therapy for lower neck tumor

Kato, Ryohei; Hirose, Katsumi; Katō, Takahiro; Motoyanagi, Tomoaki; Arai, Kazuhiro; Harada, Tohru; Takeuchi, Akihiko; Yamazaki, Yoshitake; Narita, Yuki; Komori, Shinya; Sato, Mariko; Takai, Yoshihiro

doi:10.1016/j.apradiso.2022.110397

Cited by 2 publications

(2 citation statements)

References 20 publications

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“…The principal of BNCT is the local energy deposition by the alpha particles and 7 Li ions produced from the thermal neutron capture reaction, 10 B(n,α) 7 Li. 1 In addition, protons are generated from the thermal neutron capture reaction of nitrogen atoms 14 N(n,p) 14 C and fast neutrons causing recoil protons from hydrogen in tissue. Furthermore, gamma rays are produced from the thermal neutron capture reaction of hydrogen atoms 1 H(n,γ) 2 H and from the primary beam itself.…”

Section: Introductionmentioning

confidence: 99%

“…[10][11][12][13] The current BNCT treatment planning process utilises a "simple method", where the mass density and elemental composition of the defined regions (region of interest: ROI) are set and assumed to be a homogeneous material composition. 14,15 Some studies have applied voxel-by-voxel dose calculation method where the CT images are converted into a voxel phantom and each individual voxel is assigned an elemental composition, but have either directly used the Schneider database, 16 or have used their own CT number to material conversion process without information on the fine details on the process and how the CT numbers were calibrated. [17][18][19] In a recent study by account for the difference in the x-ray tube voltage.…”

Section: Introductionmentioning

confidence: 99%

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Application of stoichiometric CT number calibration method for dose calculation of tissue heterogeneous volumes in boron neutron capture therapy

Hu,

Nakao,

Ozawa

et al. 2024

Medical Physics

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BackgroundMonte Carlo simulation code is commonly used for the dose calculation of boron neutron capture therapy. In the past, dose calculation was performed assuming a homogeneous mass density and elemental composition inside the tissue, regardless of the patient's age or sex. Studies have shown that the mass density varies with patient to patient, particularly for those that have undergone surgery or radiotherapy. A method to convert computed tomography numbers into mass density and elemental weights of tissues has been developed and applied in the dose calculation process using Monte Carlo codes. A recent study has shown the variation in the computed tomography number between different scanners for low‐ and high‐density materials.PurposeThe aim of this study is to investigate the effect of the elemental composition inside each calculation voxel on the dose calculation and the application of the stoichiometric CT number calibration method for boron neutron capture therapy planning.MethodsMonte Carlo simulation package Particle and Heavy Ion Transport code System was used for the dose calculation. Firstly, a homogeneous cubic phantom with the material set to ICRU soft tissue (four component), muscle, fat, and brain was modelled and the NeuCure BNCT system accelerator‐based neutron source was used. The central axis depth dose distribution was simulated and compared between the four materials. Secondly, a treatment plan of the brain and the head and neck region was simulated using a dummy patient dataset. Three models were generated; (1) a model where only the fundamental materials were considered (simple model), a model where each voxel was assigned a mass density and elemental weight using (2) the Nakao20 model, and (3) the Schneider00 model. The irradiation conditions were kept the same between the different models (irradiation time and irradiation field size) and the near maximum (D1%) and mean dose to the organs at risk were calculated and compared.ResultsA maximum percentage difference of approximately 5% was observed between the different materials for the homogeneous phantom. With the dummy patient plan, a large dose difference in the bone (greater than 12%) and region near the low‐density material (mucosal membrane, 7%–11%) was found between the different models.ConclusionsA stoichiometric CT number calibration method using the newly developed Nakao20 model was applied to BNCT dose calculation. The results indicate the importance of calibrating the CT number to elemental composition for each individual CT scanner for the purpose of BNCT dose calculation along with the consideration of heterogeneity of the material composition inside the defined region of interest.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Application of stoichiometric CT number calibration method for dose calculation of tissue heterogeneous volumes in boron neutron capture therapy

Hu,

Nakao,

Ozawa

et al. 2024

Medical Physics

View full text Add to dashboard Cite

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Opportunities and challenges of upright patient positioning in radiotherapy

Volz,

Korte,

Martire

et al. 2024

Phys. Med. Biol.

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Upright positioning has seen a surge in interest recently as a means to reduce radiotherapy (RT) cost, improve patient comfort, and, in selected cases, benefit treatment quality. In particle therapy, eliminating the need for a gantry can present massive reduction of upfront investment, and would drastically reduce the facility footprint. For patients with pre-existing conditions that make lying down uncomfortable, or for target sites in intimate body regions, upright RT presents a promising option toward a more comfortable, patient centred treatment. With more evidence for benefits of upright patient postures in RT emerging, several centres across the globe, mainly in particle therapy, are currently in the process of installing commercially available or prototype upright positioning devices or have already commenced treatment with upright patient postures. Yet, there remain many challenges and open questions to embed upright positioning in the modern RT workflow, no international guidelines exist to support clinical practice in upright RT, and there is a lack of professionals trained for upright patient positioning. Much work is still needed to justify the many changes necessary for upright RT. Modern image guidance is paramount to upright RT, and it is yet unclear which imaging modalities are necessary to support upright postures with the same quality as recumbent positioning. In works on prototype upright positioning systems, external alignment similar to recumbent positioning was reported for small patient or volunteer cohorts. Certain clinical advantages, such as reduced breathing motion in upright position, have been reported, but limited cohort sizes do not allow resilient conclusions on the expected treatment quality yes. Redesign of RT equipment for upright positioning, such as immobilization accessories for various body regions, is necessary, where innovations have been presented in recent literature. This review discusses the opportunities of upright RT and puts them in perspective to the current challenges.

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Dosimetric effects of the ipsilateral shoulder position variations in the sitting-positioned boron neutron capture therapy for lower neck tumor

Cited by 2 publications

References 20 publications

Application of stoichiometric CT number calibration method for dose calculation of tissue heterogeneous volumes in boron neutron capture therapy

Application of stoichiometric CT number calibration method for dose calculation of tissue heterogeneous volumes in boron neutron capture therapy

Opportunities and challenges of upright patient positioning in radiotherapy

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