ESTRO 2025 - Abstract Book

S2959

Physics - Image acquisition and processing

ESTRO 2025

935

Proffered Paper Photon-counting CT for radiotherapy purposes – where are the clinical benefits?

Thiele Kroes-Kobus 1 , Linda Rossi 1 , Joost Nuyttens 1 , Dirk de Ruysscher 1 , Arlette Odink 2 , Manouk Olofsen-van Acht 1 , Ilse de Pree 1 , Edwin Oei 2 , Jos Elbers 1 , Michiel Kroesen 1 , Anke W van der Eerden 2 , Jan Willem Mens 1 , Steven Nagtegaal 1 , Martine Franckena 1 , Kim de Vries 1 , Sophie Vermaas – Fricot 2 , Judith Middelburg - van Rijn 1 , Patrick Wohlfahrt 3 , Marcel van Straten 2 , Mischa Hoogeman 1 1 Radiotherapy, Erasmus MC Cancer Institute, Rotterdam, Netherlands. 2 Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, Netherlands. 3 Cancer Therapy, Siemens Healthineers, Forchheim, Germany Purpose/Objective: The use and applications of photon-counting CT (PCCT) are emerging within radiology [1,2]. Using advanced detectors, PCCT enables a higher resolution, removal of electronic noise and acquisition of intrinsic spectral information (Figure 1). As CT is the primary imaging modality in radiotherapy, advancements in CT can significantly affect radiotherapy workflow. Prior to clinical implementation of PCCT, it is essential to explore and identify its potential clinical benefits. This study examines which applications may have most widespread clinical value for radiotherapy targets.

Material/Methods: PCCT-images of 27 patients who underwent a diagnostic PCCT-scan (NAEOTOM Alpha, Siemens Healthineers) before their radiotherapy treatment were included. The local ethics committee approved this retrospective study and written informed consent was obtained. Six structured interviews were held during which PCCT-images of 4 to 6 patients were presented to expert teams specialized in breast, gynecology, head & neck, lung, palliation or urology. Each expert team consisted of two radiation oncologists and a radiologist. Specific PCCT features were demonstrated: mono-energetic images from 40 to 190 keV, iodine maps, contrast removal and high-resolution images (when available). After image review and discussion, the experts were asked to rate statements on features and potential applications on a 5-point scale from ‘no clinical value’ to ‘indispensable' (x-axis Figure 2). The discussion of palliation experts focused on bone metastasis, for gynecology on cervical cancers, and for urology on prostate and bladder cancer. Results: The scored rates for clinical value of spectral data varied, but were greatest for mono-energetic images, and less for contrast agent removal, or iodine maps (Figure 2B-D). High-resolution images scored the most additional clinical value for bone and head & neck cancers (Figure 2A). No expert team scored added value in reducing imaging dose on the planning CT (Figure 2E).