ESTRO 2025 - Abstract Book

S69

Invited Speaker

ESTRO 2025

preferences for non-invasive alternatives, and the expanding accessibility of SBRT.

Trials such as ASCENDE-SBRT are evaluating its efficacy, and it is possible that this modality will integrate into the therapeutic arsenal. However, the brachytherapy community is responding by integrating functional imaging (MRI, PET) to refine target delineation, optimizing volume definitions (e.g., focal boost strategies), and developing more efficient treatment regimens. To ensure the continued role of BT boost, major efforts are underway to expand training programs, foster collaborative networks, and reinforce its unique advantages in prostate cancer management. Initiatives such as ENCOMPASS demonstrate how coordinated efforts can preserve expertise, optimize treatment strategies, and secure BT boost’s place in modern radiation oncology. While SBRT’s rise presents a challenge, the future of BT boost will depend on its ability to evolve, adapt, and assert its distinct clinical value. The coming years will determine whether its trajectory leads to clear skies or an uncertain horizon.

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Speaker Abstracts Medical physicists in skin radiotherapy: Working behind the scene Anysja Zuchora Medical Physics and Clinical Engineering, University Hospital Galway, Galway, Ireland

Abstract: The medical physicist is a part of multidisciplinary radiotherapy team with a special role dedicated to machine Quality Control, treatment planning and involvement in treatment delivery. Well-established Radiotherapy techniques can be propose for patients when they are starting their journey in the oncology word. Each type of proposed treatment technique needs a different workflow. Each patient need individual care and treatment. For non-melanoma skin cancer treatment options include: X-ray low energy (superficial/orthovoltage), electrons and high energy photons treatment, interventional radiotherapy (brachytherapy), Diffusing Alpha-emitting Radiation Therapy (Alpha DaRT /224Radium) and 188Rhenium Skin Cancer Therapy (SCT). Available techniques in External Beam Radiation are: 3D Conformal Radiotherapy (3DCRT), Intensity Modulated Radiotherapy (IMRT)/Volumetric Modulated Arc Therapy (VMAT), Stereotactic Body Radiation Therapy (SBRT) and FLASH Radiotherapy (delivers a high dose of radiation in an ultra-short time frame). These treatments usually require treatment aids such as: 3-Dimensionally (3-D) printed patient moulds, commercial applicators, surface flaps, bolus or patient specific cut-outs. In many of these cases, the physicist works alongside the radiation therapist. Some treatments require further input from the physicist prior to delivery such as: cut-out factor verifications for electrons and orthovoltage with stand-in or stand-off calculation, patient specific quality assurance, decision regarding bolus thickness, patient specifics or 3D printed mould preparation. X-ray low energy skin treatment is sometimes ignore due to a focus on more advanced radiotherapy technique. This treatment is especially useful for small surface lesions with shallow treatment thicknesses. Simple and short treatment delivery is usually acceptable for older patients even with comorbidities. The physicist measures applicators or cut-out size before starting treatment and prepares individual calculation depends on x-ray energy, applicator size and applicator distance from the skin. They also contribute to discussion on additional shielding locations i.e. the eyes Standard bolus, custom bolus or 3-D modelled printing bolus are available for MV photon and electron treatments. For skin treatments by electrons, bolus on the skin surface, cut-outs on the patient surface or individual cut-outs in electron applicators are frequently used. Minimum cut-out size and the cut-out factors depend on electron energy, requiring physicist input. When interventional radiotherapy is an option for skin treatments sometimes individual moulds or 3-D printed moulds are necessary. In 3-D moulds it is possible to create locations for catheter based on the pre-planning process. This is possible with strong cooperation between Radiation