Evaluation of automated pre-treatment and transit in-vivo dosimetry in radiotherapy using empirically determined parameters

Background and purpose: First reports on clinical use of commercially automated systems for Electronic Portal Imaging Device (EPID)-based dosimetry in radiotherapy showed the capability to detect important changes in patient setup, anatomy and external device position. For this study, results for more than 3000 patients, for both pre-treatment verification and in-vivo transit dosimetry were analyzed. Materials and methods: For all Volumetric Modulated Arc Therapy (VMAT) plans, pre-treatment quality assurance (QA) with EPID images was performed. In-vivo dosimetry using transit EPID images was analyzed, including causes and actions for failed fractions for all patients receiving photon treatment (2018–2019). In total 3136 and 32,632 fractions were analyzed with pre-treatment and transit images respectively. Parameters for gamma analysis were empirically determined, balancing the rate between detection of clinically relevant problems and the number of false positive results. Results: Pre-treatment and in-vivo results depended on machine type. Causes for failed in-vivo analysis included deviations in patient positioning (32%) and anatomy change (28%). In addition, errors in planning, imaging, treatment delivery, simulation, breath hold and with immobilization devices were detected. Actions for failed fractions were mostly to repeat the measurement while taking extra care in positioning (54%) and to intensify imaging procedures (14%). Four percent initiated plan adjustments, showing the potential of the system as a basis for adaptive planning. Conclusions: EPID-based pre-treatment and in-vivo transit dosimetry using a commercially available automated system efficiently revealed a wide variety of deviations and showed potential to serve as a basis for adaptive planning

Favouring quality improvement initiatives: the experience of the Belgian College of Radiation Oncology

Radiation therapy (RT) is an essential treatment modality for cancer care and cure. Over the years, radiation treatments have become more complex and more computerized leading to highly precise treatment approaches maximising loco-regional control while minimizing toxicity. Safe and effective radiotherapy delivery however requires the implementation of adapted quality assurance (QA) programs and integral quality management (QM) systems, favouring continuous quality improvement. These improvements can arise within the local or departmental context, but they can also be favoured by national programs and incentives. The Belgian College of Physicians for Radiation Oncology Centres ('the College') is a federal entity-composed mainly of radiation oncologists, medical physicists, radiation therapists and quality managers-whose mission is to improve the quality of radiotherapy by organizing peer review activities. Throughout the past decades, the College has been the source of numerous national initiatives, which have fostered and accompanied radiotherapy departments in taking the steps towards increased quality of care. With this review, we aim to share these national quality-oriented projects instigated by the College. These include the introduction of peer-reviewed target volume contouring programs, the organisation of clinical audits and external beam dosimetry audits as well as the implementation of a national adverse event analysis system and the collection and analysis of RT-specific quality indicators