Presenter(s)
C. Jeon1, K. Park2, J. E. Rah3, J. Kim4, U. J. Hwang5, S. H. Choi6, and Y. K. Lim7; 1Korea National Cancer Center, Gyeonggi-Do, Korea, Republic of (South), 2Department of Radiation Oncology, Asan Medical Center, Seoul, Republic of Korea, Seoul, Korea, Republic of (South), 3Myongji Hospital, Goyang, Korea, Republic of (South), 4Proton Therapy Center, National Cancer Center, Goyang, BUS, Korea, Republic Of, 5Department of Radiation Oncology, Chungnam National University Sejong Hospital, Daejon, Korea, Republic Of, 6Korea Institute of Radiological & Medical Sciences (KIRAMS), Seoul, Korea, Republic of (South), 7Proton Therapy Center, National Cancer Center, Goyang-si, Korea, Republic of (South)
Purpose/Objective(s):
Conventional brachytherapy delivers dose isotropically, which can lead to target dose inhomogeneity, limited conformality for irregular targets, and suboptimal sparing of adjacent organs at risk (OARs). This study aimed to design and develop a novel dual-channel cylinder applicator for intensity-modulated brachytherapy (IMBT) for vaginal cancer.Materials/Methods:
A dual-channel cylinder applicator was designed and fabricated with a shield diameter and a effective treatment length. The applicator comprises an outer and an inner channel intended to generate broad and narrow radiation fields, respectively. Each channel enables independent irradiation at 36 angular positions, allowing modulation of emission angle and intensity to achieve highly conformal dose delivery. A motorized rotation system was implemented to deliver radiation at predefined azimuthal positions in increments. Operational performance and angular dose characteristics were evaluated by measuring 2D dose distributions from each channel in a water phantom using radiochromic film, with the film positioned perpendicular to the cylinder applicator axis. The measured results were compared with the designed dosimetric characteristics from Monte Carlo simulations.Results:
The fabricated dual-channel applicator demonstrated dosimetric behavior consistent with the intended design. The inner channel produced a highly collimated angular distribution with an azimuthal spread within approximately , while the outer channel generated a broad field with an angular spread of approximately ; both angular spreads were defined at the level of the maximum dose. Superposition of the two dose components enabled asymmetric and highly conformal dose distributions suitable for irregular target geometries.Conclusion:
A dual-channel cylinder applicator for IMBT was successfully developed, and its potential clinical utility was supported by 2D dose distribution measurements for vaginal cancer applications. Future work will include comprehensive validation in anthropomorphic geometries and device optimization, including the selective use of cylindrical plastic caps of various sizes or patient-specific molds to minimize air gaps around the applicator.