Provision of Organ at Risk Contouring Guidance in UK Radiotherapy Clinical Trials

Area of Science:

• Radiotherapy Quality Assurance
• Clinical Trial Design
• Medical Imaging and Radiation Oncology

Background:

• Accurate delineation of organs at risk (OAR) is critical for effective radiotherapy planning and preventing unintended dose delivery to healthy tissues.
• Imprecise anatomical definitions in OAR contouring can lead to suboptimal treatment plans and potential harm to patients.
• The National Institute of Health Research Clinical Research Network (NIHR CRN) portfolio includes numerous clinical trials requiring OAR contouring.

Purpose of the Study:

• To review the existing provision of OAR contouring guidance within NIHR CRN portfolio clinical trials.
• To identify inconsistencies and variations in OAR nomenclature and delineation across radiotherapy clinical trials.
• To inform the development of standardized OAR contouring guidelines for clinical trials.

Main Methods:

• A two-round Delphi assessment was conducted by the National Radiotherapy Quality Trials Assurance (RTTQA) Group.
• The assessment aimed to identify OAR descriptions that provide optimal contouring guidance.
• Eighty-four clinical trials within the NIHR CRN portfolio involving radiotherapy quality assurance were analyzed.

Main Results:

• Fifty-nine of the 84 identified trials mandated OAR contouring.
• Significant nomenclature variation was observed for 159 out of 412 OARs, with notable inconsistencies for the femoral head ± neck, parotid gland, and bowel.
• The Delphi assessment identified 42 OAR descriptions as providing optimal contouring guidance.

Conclusions:

• A clear need exists for consistent OAR nomenclature and contouring guidance across radiotherapy clinical trials.
• The RTTQA Group is collaborating with international partners to develop consensus recommendations for OAR delineation.
• These efforts aim to improve the harmonization of radiation therapy clinical trials through standardized OAR contouring.