Language：English   Publishing type：Research paper (scientific journal)   Publisher：Radiotherapy and Oncology  

Background and purpose: In external beam radiotherapy for prostate cancer, inclusion of the seminal vesicles (SV) in the clinical target volume (CTV) is often complicated by considerable SV motion and deformation. This study aimed to investigate the feasibility of predicting patient-specific SV motion using anatomical features surrounding the prostate on planning CT (pCT) images. Materials and methods: Interfractional SV motion was quantified using five pretreatment cone-beam CT (CBCT) scans per patient from a cohort of 191 prostate cancer patients. Patients whose SV was not fully covered by a 3-mm margin were assigned to the High SV Motion Group, which served as the target for prediction. A total of 42 anatomical features were extracted from the contours of the prostate, SV, bladder, and rectum on the pCT. Feature selection was performed using Random-Forest Recursive Feature Elimination, and a machine learning model was developed and evaluated using both internal and external patient cohorts. Results: Four anatomical features were selected, including those based on the anatomical relationship between the prostate and the SV. Using these features, the best-performing light gradient boosting machine model achieved an area under the receiver operating characteristic curve of 0.724 in the internal test and 0.632 in the external test for identifying patients in the High SV Motion Group. Conclusion: This study suggests an association between anatomical features derived from pCT and patient-specific SV motion. Although the current predictive performance is moderate, this approach may help support radiotherapy strategies when the SV is included in the CTV.

DOI： 10.1016/j.radonc.2026.111368

Open Access

Web of Science

Scopus

PubMed

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.25259/JCIS_255_2025

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Applied Clinical Medical Physics  

Purpose: Cardiac motion may degrade dose distribution during stereotactic arrhythmia radioablation using the CyberKnife system, a robotic radiosurgery system. This study evaluated the dose distribution changes using a self-made cardiac dynamic platform that mimics cardiac motion. Methods: The cardiac dynamic platform was operated with amplitudes of 5 and 3.5 mm along the superior–inferior (SI) and left–right (LR) directions, respectively. The respiratory motion tracking of the CyberKnife system was applied when respiratory motion, simulated using a commercial platform, was introduced. The accuracy of respiratory motion tracking was evaluated by the correlation error between infrared markers and a fiducial marker. The dose distribution was compared with and without cardiac motion. The evaluations included error in the centroid analysis of the irradiated dose distribution, dose profile analysis in the SI and LR directions, and dose distribution analysis comparing the irradiated and planned dose distributions. Results: Cardiac motion increased the correlation error in the direction of motion. Cardiac motion displaced the centroid by up to 0.23 and 0.19 mm in the SI and LR directions, respectively. Cardiac motion blurring caused the distance of the isodose lines to become smaller (bigger) at higher (lower) doses in the SI direction. The gamma pass rate was reduced by cardiac motion but exceeded 94.1% with 1 mm/3% for all conditions. Respiratory motion tracking was also effective under cardiac motion. The cardiac motion slightly varied the dose at the edges of the irradiation volume. Conclusion: While cardiac motion increased respiratory tracking correlation errors, its effects on dose distribution were limited in this study. Further studies using motion phantoms that are close to a human or individual patient are necessary for a more detailed understanding of the effects of cardiac motion.

DOI： 10.1002/acm2.70021

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Scopus

PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Radiation Research  

Dynamic WaveArc (DWA) is a technique used for continuous, non-coplanar volumetric-modulated arc therapy on the Vero4DRT platform. This study aimed to evaluate the application of single-isocenter DWA (SI-DWA) for treating multiple brain metastases by comparing dose distribution and irradiation time with multi-isocenter DWA (MI-DWA) through retrospective treatment planning. Treatment plans were developed for SI-DWA and MI-DWA in 14 cases with 3-5 brain metastases. Parameters assessed included target dose indices, such as conformity index (CI) of the planning target volume (PTV), volumes of normal brain excluding gross tumor volumes (GTVs) receiving a single dose equivalent of 14 Gy (V14), V30%, V20%, V10%, volumes of normal brain, including GTVs receiving a single dose equivalent of 12 Gy (V12), D2% for other organs at risk, and beam-on time. SI-DWA showed inferior CI, V14, and V12 values for lesions with PTV volumes <1 cc, whereas it performed equivalently to MI-DWA for lesions with PTV volumes ≥1 cc. SI-DWA resulted in higher volumes of normal brain receiving low doses compared to MI-DWA. SI-DWA exhibited significantly shorter beam-on times than MI-DWA. In conclusion, SI-DWA is an effective method for treating multiple brain metastases with PTV volumes ≥1 cc, offering an index of radiation-induced brain necrosis comparable with MI-DWA while allowing for shorter irradiation times.

DOI： 10.1093/jrr/rrae098

Open Access

Web of Science

Scopus

PubMed

Event date： 2025.4

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：ホテルメルパルク名古屋   Country：Japan  

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：ウインクあいち   Country：Japan  

Event date： 2024.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya Congress Center   Country：Japan  

Event date： 2024.6

Language：Japanese   Presentation type：Symposium, workshop panel (nominated)  

Venue：Online開催   Country：Japan  

Event date： 2023.11 - 2023.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：パシフィコ横浜 ノース   Country：Japan  

Type：Academic society, research group, etc.