A critical review of the practices of proton daily quality assurance programs

Demand for proton therapy (PT) continues to grow due to its dosimetric advantages over conventional radiotherapy. New PT facilities being constructed to meet this demand will need quality assurance (QA) programs to ensure that treatments are delivered safely and accurately. However, in contrast to conventional radiotherapy, proton QA practices are constantly evolving and few commercial solutions are available. As a result, QA programs at most operational proton facilities rely on a variety of in-house developed hardware and software. An important part of these QA programs is proton daily QA, which verifies clinically-acceptable proton delivery system operation each morning before starting patient treatment. In this review article, we summarize current proton daily QA practices by providing a brief introduction to PT, describing proton delivery techniques and their particular QA requirements, and then reviewing implementations of several proton daily QA programs. Although the QA instrumentation is quite heterogeneous, the literature shows that the dosimetric daily QA results among proton facilities are comparable. We also present a typical set of proton daily QA data from our institution that includes output, range, and spot position measurements. Based on the literature review and our institutional experience, we make recommendations for future proton daily QA programs.