ESTRO 2024 - Abstract Book

S4093

Physics - Inter-fraction motion management and offline adaptive radiotherapy

ESTRO 2024

2577

Digital Poster

Clinical evaluation of H&N tumors adaptive proton therapy at CCB Krakow proton beam therapy center

Marzena Rydygier 1 , Tomasz Skora 2 , Kamil Kisielewicz 2 , Anna Spaleniak 1 , Eleonora Gora 2 , Jan Gajewski 1 , Magdalena Garbacz 1 , Gabriela Foltynska 1 , Natalia Mojzeszek 1 , Monika Lipa 1 , Karolina Sobkowicz 1 , Dawid Krzempek 1 , Renata Kopec 1 , Antoni Rucinski 1 1 Institute of Nuclear Physicis, Cyclotron Centre Bronowice, Krakow, Poland. 2 National Oncology Institute, National Research Institute, Krakow Branch, Kraków, Poland

Purpose/Objective:

Intensity modulated proton therapy (IMPT) using scanning pencil beams is planned on a computed tomography scan (CT), providing a ‘snapshot’ of the patient’s anatomy. The accuracy of IMPT delivery for head and neck (H&N) cancer may be compromised during the treatment course due to interfractional patient anatomy variations or setup errors, potentially affecting the therapeutic outcome. The goal of the adaptive proton therapy (APT) procedure is to ensure the delivery of the prescribed dose while maintaining healthy tissue constraints, even if the patient geometry changes during the course of a fractionated treatment. APT intends to improve radiation treatment by systematic monitoring of patient’s anatomy variations and incorporating them into the re-optimization of the treatment plan if needed. A major obstacle to the plan adaptation is the clinical workflow and available clinical resources, including time, personnel, and equipment costs. Adaptation requires imaging, contour definition, plan evaluation, plan adaptation, and, finally, plan verification [1]. Here we report on the APT protocol applied to proton patients considering dosimetry of the reference and adapted plan, therapy outcomes and resources required for adaptation.

Material/Methods:

At the Cyclotron Centre Bronowice (CCB) in Kraków, Poland, in cooperation with the National Oncology Institute (Kraków, Poland), control CT scans are typically taken weekly and are further used for APT if necessary. The CCB is equipped with two gantry rooms with dedicated proton scanning nozzles. In addition, a robotic patient positioning arm allows for any configuration of position and angle of tumor irradiation. At CCB, a 64-slice Siemens Somatom Definition AS Open is used to perform CT scans, and depending on the tumor location, an appropriate scanning protocol is used. The adaptive treatment plans were forward-calculated on the reference treatment planning CT. A group of 20 H&N patients was selected for analysis (see table 1). Patients were selected based on the location of the PTV for whom replan was performed due to dose distribution disorders in the PTV and/or OAR areas. Patients who had new immobilizations performed were not considered.

Table 1. List of patients who underwent APT in CCB Kraków and were selected for analysis.