Session Item

The Global Quality Assurance of Radiation Therapy Clinical Trials Harmonisation Group (GHG) (https://rtqaharmonization.com) is a collaborative group of Radiotherapy Quality Assurance (RTQA) organisations harmonizing and improving RTQA for multi-institutional clinical trials. The GHG identified an unmet need for consistent and optimal OAR contouring guidance alongside standardized nomenclature to combat variation in and between clinical trials with a radiation therapy component.

In August 2018 the GHG OAR multi-professional Working Group was formed, comprised of 22 members from 5 international RTQA Groups and affiliated organizations, EORTC, IROC, QUARTET, RTTQA, TROG, and IAEA. The objective was to unify OAR contouring guidance across the RTQA Groups, by compiling a single reference list of OAR in line with AAPM TG 263 standardised nomenclature and ASTRO normal tissue contouring consensus, with peer-reviewed contouring guidance for integration into future clinical trial protocols. The work consisted of 3 stages: (1)Clinical trial documentation review and identification of structures of interest (2)Review of existing contouring guidance and survey of proposed OAR contouring guidance (3)Analysis of survey feedback with recommendations for contouring guidance with OAR nomenclature.

157 clinical trials recruiting or in setup were examined. 206 structures were identified across the trial documentation. Duplicates, composite, non-anatomical, non-specific structures, and structures with more specific alternative nomenclature were excluded; leaving 112 structures of interest.  Of these, 47 (42.0%) were consistent with the ASTRO defined structures, which are either recommended or considered for contouring in site-specific clinical trials.  Of the 32 ASTRO structures recommended for contouring 30 (93.8%) were in use by 2 or more RTQA Groups; 17 structures (53.1%) were in use by all RTQA Groups (figure).



47 clinical trial investigators (41 radiation oncologists, 6 radiation therapy technologists) from 38 institutions across 15 countries responded to the survey. The mean number of responses per OAR was 16.6 (IQR 13–21). 6 OAR descriptions were accepted with no amendments, 46 required minor amendments, 5 major amendments, 14 were newly created as a result of feedback, and 41 were excluded as a result of feedback. The GHG OAR Working Group adopted AAPM TG 263 nomenclature for this work. The existing nomenclature choices did not fulfill requirements in 8 instances; new nomenclature was established to align with clinical trial contoured OAR (table).



The final GHG consensus recommendations include 71 OARs with associated nomenclature and optimal descriptions.

This report from an international collaborative network of RTQA Groups provides consensus recommendations on OAR descriptions and associated nomenclature for use in clinical trials. A more uniform dataset will support the delivery of clinically relevant, valid, and reliable conclusions from clinical trials.