Jenna Luscombe | Searcharxiv

arXiv2026

Generation of synthetic CT images from optical scanning for superficial mold brachytherapy

Optical 3D scanning systems allow the acquisition of accurate models of patient anatomy, suitable for use in the design of simple 3D-printable patient-matched medical devices with 3D modelling software. This study developed and demonstrated the use of superficial brachytherapy surface mold design workflow that utilizes data from optical 3D surface scanning and enables a commercial brachytherapy treatment planning system to be used for catheter positioning and dose optimization steps. Synthetic CT images were generated from 14 optically scanned anatomical models of human participants. Models and skin textures ac-quired from the optical scans were imported into Autodesk Meshmixer, where the treatment area was delineated, and treatment and device volumes produced. 3D Slicer was used to convert the body, treatment and device volumes to DICOM CT and RTSTRUCT data. The synthetic CT data and contoured volumes were imported into Varian Eclipse, where catheters were designed, and dwell positions and times optimised for dose coverage of the treatment volume. The lack of in-ternal anatomy did not compromise dose calculations, due to clinical use of a TG43 based algorithm. Once 3D printed, molds can be imaged in-situ during CT simulation, and reconstructed, for clinical dose calculation and plan approval.

physics.med-ph↗

arXiv2026

Patient-specific immobilisation for radiotherapy treatment of extensive lower-limb carcinoma

When non-melanoma skin cancers extend over large areas of skin, effective radiotherapy treatments can be delivered using volumetric modulated arc therapy (VMAT) beams with narrow segments that rotate around the affected surfaces. For lower-limb carcinoma treatments, careful immobilisation is needed to achieve the degree of reproducible and stable positioning required to ensure the narrow field segments treat the targeted tissue and avoid underlying anatomy. To meet this need, a 3D printed patient-specific foot support was created in the form of a solid box containing a deep ``footprint'', shaped to match the outline of the patient's relaxed foot when lying supine, supported by a vacuum bag. For our first patient treated with a 3D printed foot support, image guidance data and clinical notes were evaluated against corresponding information from all recent lower-leg VMAT treatments. The patient feedback was recorded as ``good'', with no complaints of discomfort or poor fit, and the proportion of treatment fractions requiring shifts greater than 5 mm after setup imaging (20\%) compared favourably to the proportions for patients without a patient-specific foot support (23\%-84\%). The patient-specific foot support was particularly useful for minimising longitudinal shifts and leg rotations. Evidently, 3D-printed patient-specific immobilisation devices have the potential to enhance positioning stability, and therefore potentially improve accuracy and effectiveness of VMAT treatments, for patients with extensive lower-limb carcinomas.

physics.med-ph↗