Adam Yeo
Peter MacCallum Cancer Centre & RMIT University
Senior Medical Physicist

Adam Yeo
Senior Medical Physicist
Peter MacCallum Cancer Centre & RMIT University

Kurian George
Medical Physicist
Peter MacCallum Cancer Centre

Tomas Kron
Director of Physical Sciences
Peter MacCallum Cancer Centre & RMIT University

Nonmelanoma skin cancer (NMSC) is one of the most common malignancies and there is an increasing clinical need in our department, Peter MacCallum Cancer Centre (PeterMac), to seek the use of surface mould brachytherapy (SMBT). In this study we sought to describe application of SMBT using 3D-printing technique for NMSC. This feasibility study considered two clinical scenarios: i) a large scalp lesion, and ii) a circumferentially shaped lesion around arms or legs, which can maximally benefit SMBT in terms of target coverage and OAR sparing, compared to external beam radiotherapy (EBRT) such as electron beam or VMAT techniques. Customised mould structures and catheter channels are defined in MIM Maestro®, which can efficiently creating such structures. RT structure files are converted to STL file format which can be readable by 3D printer. The same RT structure files are transferred to brachytherapy treatment planning systems (Oncentra Brachy and Oncentra Prostate, Nucletron), which does not require any patient-specific anatomy as per water equivalency assumption used in TG43 formalism. Treatment planning is performed using both systems which use different optimisation algorithms (IPSA vs HIPO). It is evident that treatment quality with SMBT is preferable over electron beam or VMAT techniques for the two cases studied in this work. CT scan of surface moulds shows HU variation up to 15% compared to water, depending on print parameters (nozzle size, print speed, layer thickness, percentage infill). Film measurements verify SMBT can accurately deliver planned dose distribution within 5% dose uncertainty. This application has potential to provide an additional treatment modality for skin cancer, which can be more efficient and effective over EBRT for multiple clinical scenarios, such as i) for large targets overlying irregular or curved surfaces, ii) for avoidance of deep structures and sparing underlying normal tissue, and iii) treatment of small fields where other radiation therapy modalities are not practical.


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