# Photon-counting CT for radiotherapy: Qualitative assessment of potential clinical value by semi-structured expert interviews

## TL;DR

This study explores how photon-counting CT could improve radiotherapy, finding it most valuable for head and neck, bone, and lung tumors due to spectral data and high-resolution imaging.

## Contribution

Novel insights into clinical applications of photon-counting CT in radiotherapy through expert interviews.

## Key findings

- Spectral data and high-resolution imaging are most valuable for clinical applications.
- Head and neck, bone, and lung tumors scored highest for added clinical value.
- Prostate tumors showed no added value from photon-counting CT.

## Abstract

•Semi-structured interviews provided insight in the potential added value of PCCT for radiotherapy.•Head and neck, bone and lung tumors had the highest potential of having added clinical value.•Availability of spectral data and high-resolution imaging contributed most to the added clinical value.

Semi-structured interviews provided insight in the potential added value of PCCT for radiotherapy.

Head and neck, bone and lung tumors had the highest potential of having added clinical value.

Availability of spectral data and high-resolution imaging contributed most to the added clinical value.

Photon-counting CT (PCCT) has several potential benefits that can considerably improve the radiotherapy workflow, like availability of intrinsic spectral data and high resolution imaging. It is unknown which treatment sites in radiotherapy will benefit the most from PCCT. This study aimed to identify clinical applications and treatment sites where PCCT may have the most clinical value.

Semi-structured interviews with expert teams were conducted about eight treatment sites. Each expert team consisted of 2 radiation oncologists and 1 radiologist with expertise in specific treatment site. During each session, PCCT images were shown to demonstrate specific PCCT features: instantly changing the energy from 40 to 190 keV with a slider, iodine maps, contrast-agent removal and high-resolution images. Next, the experts scored ten statements about clinical applications for added clinical value on a 5-point Likert scale, from 0=No added clinical value to 4 = Indispensable for the clinic.

A total of 80 scores were collected about ten statements and eight treatment sites. The statements about the use of spectral data scored highest for added clinical value, while reducing imaging dose scored lowest. The radiotherapy treatment sites with the highest scores were bone, head and neck and lung tumors, while lowest was prostate where no added value was found.

Semi-structured interviews identified advantages of PCCT that may have the most added clinical value for radiotherapy: the use of spectral data and increased resolution. Head and neck, bone and lung tumors are the clinical applications which were scored highest in terms of added clinical value and these could therefore be the first areas for clinical implementation.