Numerous commercial technologies for online treatment monitoring (OTM) in radiotherapy (RT) are currently available including electronic portal imaging device (EPID) in vivo dosimetry (IVD), transmission detectors and log files analysis. Despite this, in the UK there exists limited guidance on how to implement and commission a system for clinical use or information about the resources required to set up and maintain a service. A Radiotherapy Special Interest Group working party, established by Institute of Physics and Engineering in Medicine was formed with a view to reassess the current practice for OTM in the UK and an aim to develop consensus guidelines for the implementation of a system. A survey distributed to Heads of Medical Physics at 71 UK RT departments investigated: availability of OTM in the UK; estimates of workload; clinical implementation; methods of analysis; quality assurance; and opinions on future directions. The survey achieved a 76% response rate and demonstrated that OTM is widely supported in the UK, with 87% of respondents indicating all patients should undergo OTM. EPID IVD (EIVD) was the most popular form of OTM. An active EIVD service was reported by 37% of respondents, with 84% believing it was the optimal solution. This demonstrates a steady increase in adoption since 2012. Other forms of OTM were in use but they had only been adopted by a minority of centres. Financial barriers and the increase of staff workload continue to hinder wider implementation in other centres. Device automation and integration is a key factor for successful future adoption and requires support between treatment machine and OTM manufacturers. The survey has provided an updated analysis on the use of OTM methods across the UK. Future guidance is recommended on commissioning, adoption of local tolerances and root-cause analysis strategies to assist departments intending to implement OTM.
This report provides guidance for the implementation of online treatment monitoring (OTM) solutions in radiotherapy (RT), with a focus on modulated treatments. Support is provided covering the implementation process, from identification of an OTM solution to local implementation strategy. Guidance has been developed by a RT special interest group (RTSIG) working party (WP) on behalf of the Institute of Physics and Engineering in Medicine (IPEM). Recommendations within the report are derived from the experience of the WP members (in consultation with manufacturers, vendors and user groups), existing guidance or legislation and a UK survey conducted in 2020 (Stevens et al., 2021).

OTM is an inclusive term representing any system capable of providing a direct or inferred measurement of the delivered dose to a RT patient. Information on each type of OTM is provided but, commensurate with UK demand, guidance is largely influenced by in vivo dosimetry (IVD) methods utilising the electronic portal imager device (EPID).

Sections are included on the choice of OTM solutions, acceptance and commissioning methods with recommendations on routine quality control, analytical methods and tolerance setting, clinical introduction and staffing/resource requirements. The guidance aims to give a practical solution to sensitivity and specificity testing. Functionality is provided for the user to introduce known errors into treatment plans for local testing. Receiver operating characteristic (ROC) analysis is discussed as a tool to performance assess OTM systems. 

OTM solutions can help verify the correct delivery of radiotherapy treatment. Furthermore, modern systems are increasingly capable of providing clinical decision-making information which can impact the course of a patient’s treatment. However, technical limitations persist. It is not within the scope of this guidance to critique each available solution, but the user is encouraged to carefully consider workflow and engage with manufacturers in resolving compatibility issues. 
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.