Improving Radiotherapy Treatments for Head and Neck Cancer Patients

Abstract

Radiotherapy for head and neck cancer is a highly complex, multi-step process that requires input from many different staff groups. The timeliness and quality of radiotherapy for head and neck cancer patients is essential in reaching the aims set out in the radiotherapy operational delivery network service specifications (NHS England, 2019). This thesis addresses the issues of timeliness and quality in radiotherapy for head and neck cancer patients. Timeliness has been addressed in a study of the impact waiting for radiotherapy to start has on overall survival and patient experience. The time between decision to treat with radiotherapy and the start of radiotherapy (TTS) was studied. A TTS greater than 30 days was found to be associated with a significant increase in death when compared to a TTS of less than 15 days. Patient responses to a questionnaire showed that the effect of waiting for radiotherapy to start is patient dependent and not time dependent. This study shows that focus should be on ensuring all patients are treated within a TTS of 30 days. In radiotherapy of the head and neck it is common for the clinical target volume (CTV) to extend to the patient’s skin. For inverse planning this results in excessive fluence being delivered to the build-up region and therefore the skin. A study has been carried out to determine a planning solution that gives superior plan quality when considering CTV coverage, skin dose and plan robustness. This study shows that a virtual bolus planning method was superior to the other common techniques considered. In the planning study an accurate Eclipse Acuros XB calculation of dose at the surface and in the build-up region was assumed. A novel dosimeter for surface dosimetry has been used to study the differences in skin dose found in the planning study. DOSEmappersTM are a 2D array of Micro Silica Bead TLDs. This study has shown that the Bead TLDs have an effective depth of measurement of 0.7 mm and when constructed as a DOSEmapperTM make an ideal near surface dosimeter. Measurements using DOSEmappersTM confirm the dose differences from different planning approaches used in the planning study. This gives confidence in determining the most superior planning method for head and neck VMAT planning. This work contributes to the field of head and neck cancer radiotherapy. The time head and neck cancer patients should be treated within and a planning method that gives superior plan quality have been determined and validated.

Date of Award	1 Aug 2023
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Julia-Claire Handley (Supervisor)