ESTRO 2024 - Abstract Book

S4788

Physics - Quality assurance and auditing

ESTRO 2024

Investigating treatment plan quality for photon and proton RT in the clinical trial DAHANCA 35

Camilla P Nielsen 1,2 , Kenneth Jensen 3 , Simon L Krogh 1 , Carsten Brink 1,2 , Ebbe L Lorenzen 1,2 , Bob Smulders 3,4 , Anne I.S. Holm 5 , Eva Samsøe 3,6 , Martin S Nielsen 7 , Patrik Sibolt 8 , Peter S Skyt 3 , Ulrik V Elstrøm 3 , Jørgen Johansen 9 , Ruta Zukauskaite 2,9 , jesper G Eriksen 5,10 , Mohammad Farhadi 6 , Maria Andersen 7 , Christian Maare 8 , Jens Overgaard 10 , Cai Grau 3 , Jeppe Friborg 3,4 , Christian R Hansen 1,2,3 1 Odense University Hospital, Laboratory of Radiation Physics, Odense, Denmark. 2 University of Southern Denmark, Institute of Clinical Research, Odense, Denmark. 3 Aarhus University Hospital, Danish Centre for Particle Therapy, Aarhus, Denmark. 4 Rigshospitalet, University Hospital of Copenhagen, Department of Oncology, Copenhagen, Denmark. 5 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark. 6 Zealand University Hospital, Naestved, Department of Oncology, Næstved, Denmark. 7 Aalborg University Hospital, Department of Oncology, Aalborg, Denmark. 8 University Hospital Herlev, Department of Oncology, Herlev, Denmark. 9 Odense University Hospital, Department of Oncology, Odense, Denmark. 10 Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus, Denmark

Purpose/Objective:

The primary objective of radiotherapy treatment planning is to achieve optimal target coverage while minimising the radiation dose to critical Organs at Risk (OARs) following relevant guidelines. Ensuring consistently high-quality radiotherapy plans is crucial for patients’ survival chances and risk of side effects. The importance of treatment plan quality is emphasised in The Danish Head and Neck cancer Study Group (DAHANCA) 35 trial of proton versus photons, where patients are selected on treatment plan comparisons. As proton therapy may present a steep learning curve in treatment planning, this could influence the selection of patients for the study.

The present study aims to assess the development of quality of treatment plans for patients with head and neck cancer undergoing photon and proton radiotherapy in the context of the DAHANCA 35 trial (NCT04607694).

Material/Methods:

Between May 2019 and June 2023, 189 patients were enrolled in the ongoing DAHANCA 35 trial, with 63 patients in the pilot phase and 126 in the subsequent randomisation phase. A photon and a comparative proton treatment plan were developed for each patient. Patients could be included in the trial if there was an estimated benefit in Normal Tissue Complication Probability (NTCP) for proton therapy. During the pilot phase, all enrolled patients were offered proton therapy, and in the randomisation phase, patients were randomised 1:2 (photon:proton). For patients selected to receive proton therapy, a new clinical proton plan was made at the proton therapy centre, where the patients received treatment. All treatment plans were prepared following the DAHANCA guidelines [1]. This study analysed 189 photon plans, 189 comparative proton plans, and 140 clinical proton plans. The quality of the treatment plan was assessed individually for photon plans, comparative proton plans, and clinical proton plans. To assess any temporal development, three time intervals were used as follows: the first interval (Pilot phase) comprised 63 patients from the pilot phase, the second interval (Randomisation phase 1) encompassed the first 64 patients from the randomisation phase, and the third interval (Randomisation phase 2) included the remaining 62 patients from the randomisation phase. These intervals spanned 22, 19, and 14 months.