Types of deviation and review criteria in pretreatment central quality control of tumor bed boost in medulloblastoma—an analysis of the German Radiotherapy Quality Control Panel in the SIOP PNET5 MB trial

Abstract

Purpose In Germany, Austria, and Switzerland, pretreatment radiotherapy quality control (RT-QC) for tumor bed boost (TB) in non-metastatic medulloblastoma (MB) was not mandatory but was recommended for patients enrolled in the SIOP PNET5 MB trial between 2014 and 2018. This individual case review (ICR) analysis aimed to evaluate types of deviations in the initial plan proposals and develop uniform review criteria for TB boost. Patients and methods A total of 78 patients were registered in this trial, of whom a subgroup of 65 patients were available for evaluation of the TB treatment plans. Dose uniformity was evaluated according to the definitions of the protocol. Additional RT-QC criteria for standardized review of target contours were elaborated and data evaluated accordingly. Results Of 65 initial TB plan proposals, 27 (41.5%) revealed deviations of target volume delineation. Deviations according to the dose uniformity criteria were present in 14 (21.5%) TB plans. In 25 (38.5%) cases a modification of the RT plan was recommended. Rejection of the TB plans was rather related to unacceptable target volume delineation than to insufficient dose uniformity. Conclusion In this analysis of pretreatment RT-QC, protocol deviations were present in a high proportion of initial TB plan proposals. These findings emphasize the importance of pretreatment RT-QC in clinical trials for MB. Based on these data, a proposal for RT-QC criteria for tumor bed boost in non-metastatic MB was developed.

Radiotherapy quality assurance in paediatric clinical trials: first report from six QUARTET-affiliated trials

“…The initial QUARTET ICR outcomes show that inconsistency in planning, particularly due to (target) delineation remains a challenge, impacting the quality of radiotherapy treatments for children. This echoes the previous reports of protocol noncompliance rates and the importance of peer-review [5,6,13,14,[26][27][28] to this population of patients as well as adults. Prospective ICR will continue to be prioritised, but regular amendments to the RTQA guidelines and implementation of additional education resources will also be necessary to better support investigators to meet protocol requirements at first submission, and to monitor and standardise decision making in areas of conflict which result in justified variations.…”

Radiotherapy in Medulloblastoma—Evolution of Treatment, Current Concepts and Future Perspectives

“…First experiences of pre-treatment quality assurance in patients treated by 3D conformal radiotherapy within the SIOP-PNET5 MB trial in Italy, Germany, Austria, and Switzerland showed high rates of plan deviations. Plan modifications were recommended in approximately 40% of evaluated plans [ 72 , 77 , 78 , 79 ]. The SIOPE published a consensus guideline on craniospinal target volume delineation to improve the quality of contouring in high-precision radiotherapy [ 80 ].…”

SIOP PNET5 MB Trial: History and Concept of a Molecularly Stratified Clinical Trial of Risk-Adapted Therapies for Standard-Risk Medulloblastoma

“…Because quality of radiotherapy delivery is considered to be critical, pretreatment quality assurance of RT (RT-QA) is mandatory for SIOP PNET5 MB participants. First experiences of RT-QA have been published from the German and the Italian groups, showing that potentially clinically relevant deviations from the protocol are frequent [ 48 , 50 , 51 ] and decrease with increasing experience of the treatment site with the protocol [ 48 , 50 ].…”