Assessing the need for adaptive radiotherapy in head and neck cancer patients using an automatic planning tool

Natália Alves; Joana Matos Dias; Humberto Rocha; Tiago Ventura; Josefina Mateus; Miguel Capela; Leila Khouri; Maria do Carmo Lopes

doi:10.5603/RPOR.a2021.0056

Assessing the need for adaptive radiotherapy in head and neck cancer patients using an automatic planning tool

Rep Pract Oncol Radiother. 2021 Jun 9;26(3):423-432. doi: 10.5603/RPOR.a2021.0056. eCollection 2021.

Authors

Natália Alves¹, Joana Matos Dias^{2

3}, Humberto Rocha^{2

3}, Tiago Ventura^{2

4}, Josefina Mateus⁴, Miguel Capela⁴, Leila Khouri⁵, Maria do Carmo Lopes^{2

4}

Affiliations

¹ Physics Department, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal.
² Instituto de Engenharia de Sistemas e Computadores de Coimbra, Coimbra, Portugal.
³ Faculty of Economics, University of Coimbra, Coimbra, Portugal.
⁴ Medical Physics Department, Instituto Português de Oncologia de Coimbra Francisco Gentil, EPE, Coimbra, Portugal.
⁵ Radiotherapy Department, Instituto Português de Oncologia de Coimbra Francisco Gentil, EPE, Coimbra, Portugal.

Abstract

Background: Unbiased analysis of the impact of adaptive radiotherapy (ART) is necessary to evaluate dosimetric benefit and optimize clinics' workflows. The aim of the study was to assess the need for adaptive radiotherapy (ART) in head and neck (H&N) cancer patients using an automatic planning tool in a retrospective planning study.

Materials and methods: Thirty H&N patients treated with adaptive radiotherapy were analysed. Patients had a CT scan for treatment planning and a verification CT during treatment according to the clinic's protocol. Considering these images, three plans were retrospectively generated using the iCycle tool to simulate the scenarios with and without adaptation: 1) the optimized plan based on the planning CT; 2) the optimized plan based on the verification CT (ART-plan); 3) the plan obtained by considering treatment plan 1 re-calculated in the verification CT (non-ART plan). The dosimetric endpoints for both target volumes and OAR were compared between scenarios 2 and 3 and the SPIDERplan used to evaluate plan quality.

Results: The most significant impact of ART was found for the PTVs, which demonstrated decreased D98% in the non-ART plan. A general increase in the dose was observed for the OAR but only the spinal cord showed a statistical significance. The SPIDERplan analysis indicated an overall loss of plan quality in the absence of ART.

Conclusion: These results confirm the advantages of ART in H&N patients, especially for the coverage of target volumes. The usage of an automatic planning tool reduces planner-induced bias in the results, guaranteeing that the observed changes derive from the application of ART.

Keywords: adaptive radiotherapy; automatic planning; head and neck cancer; radiotherapy.