S127
Brachytherapy - Physics
ESTRO 2026
doi:10.1016/j.brachy.2015.08.0035. Peppa V, et al. Brachytherapy. 2016;15(2):252-262. doi:10.1016/j.brachy.2015.11.0016. Berumen F, et al. Brachytherapy. 2021;20(4):911-921. doi:10.1016/j.brachy.2020.12.0077. Beaulieu L, et al. Medical Physics. 2023;50(8):e946-e960. doi:10.1002/mp.165718. Peppa V, et al. Medical Physics. 2023;50(7):4675-4687. doi:10.1002/mp.16455
accordance with the TG-186 report,3 using uniform densities, for both ACE and MC. Plans were calculated with TG-43, ACE, and MC. The resolution and position of the dose reporting grids were set to equal the grid of the CTs, hence facilitating future repetition of our dose calculations with other MBDCA and MC codes.To evaluate the accuracy of ACE and TG-43 against MC, the MC-dose distribution was imported to OcB, and DVH parameters were compared. Results: Figure 1 shows the dose for case 1. Preliminary results show ACE to be in agreement with MC for the CTV. The same was true for TG-43 in the CTV, although a slightly higher discrepancy was noticed. Differences between TG-43 and MC were higher in low-dose regions, such as the eyes, where ACE showed closer agreement with MC, see Figure 2. Our results agree with the findings by Rossi et. al.1
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Automated catheter placement and treatment planning for scalp brachytherapy with 3D-printed applicators Björn Morén 1 , Freja Alpsten 2,3 , Apostolos Raptis 2 , Michael Gubanski 4,3 , Åsa Carlsson Tedgren 2,3 1 Linköping University, Department of Mathematics, Linköping, Sweden. 2 Karolinska University Hospital, Department of Nuclear Medicine and Medical Physics, Stockholm, Sweden. 3 Karolinska Institute, Department of Oncology-Pathology, Stockholm, Sweden. 4 Karolinska University Hospital, Radiation Therapy, Theme Cancer, Stockholm, Sweden Purpose/Objective: There is a rising incidence of non-melanoma skin cancer for which brachytherapy has been shown to provide excellent treatment results [1,2]. The use of 3D-printed applicators in contact brachytherapy of the skin increases the degrees of freedom in treatment planning. With the new applicators, treatment plan optimization includes not only dwell positions and times in pre-defined catheters, but also the generation of the catheter trajectories themselves. Compared to the commercially available applicators, which have fixed trajectories and source to skin distance, the obtained dose distributions can be more conformal to the target, and brachytherapy can be used for targets with a larger variation in sizes and thicknesses [3]. However, manual optimization of catheter placement is an impractical, time-consuming task. Therefore, we aim to automate catheter placement and treatment plan optimization for contact brachytherapy of the scalp with 3D-printed applicators. Material/Methods: The CTV of two scalp lesions and nearby organs of interest were delineated on CT images of a head phantom. Additionally, a large bolus-like structure and two 2D-planes were contoured. These structures were used to define the area allowed for catheter placement as well as the catheter starting and end points. We consider two common clinical scenarios: (i) uniform target coverage, and (ii) non-radical surgery, where the priority is to irradiate the margins. The clinical goals include dose guidance on target coverage, and on dose to the organs of interest. A
Conclusion: We have validated ACE against MC in skin brachytherapy for targets of various sizes; findings here thus help to fill that gap. The cases were designed to ease additional verification with other MC codes and MBDCAs. Future work will aim to provide a skin test case on the AAPM WGDCAB registry. Keywords: MBDCA, skin brachytherapy, contact
brachytheapy References: 1. Rossi G, et al. phiRO. 2024;32.
doi:10.1016/j.phro.2024.1006732. Szlag M, et al. J Contemp Brachytherapy. 2021;13(4):441-446. doi:10.5114/jcb.2021.1065413. Beaulieu L, et al. Med Phys. 2012;39(10):6208-6236. doi:10.1118/1.47472644. Ma Y, et al. Brachytherapy. 2015;14(6):939-952.
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