The use of rigid carbon fiber couch inserts in radiotherapy treatment couches is a well-established method of reducing patient set-up errors associated with couch sag. Several published studies have described such inserts as radiotranslucent with negligible attenuation of the radiation field. Most of these studies were conducted with the radiation field normally incident on the couch and there appears to be no evidence in the literature of the effect of the gantry angle on the extent of beam attenuation by the carbon fiber insert alone during external beam radiotherapy. In this study we examined the magnitude of this effect over a range of posterior oblique gantry angles using a cylindrical solid water phantom containing an ionization chamber placed isocentrically. It was found that a 6 MV photon beam, field size 10 x 5 cm, was attenuated significantly as the gantry angle approached the plane of the couch, from 2% at normal incidence and reaching 9% attenuation at angle of incidence 70 degrees. This could have serious implications regarding dose to the treatment volume for treatments requiring posterior oblique angles of incidence with a possible correction factor necessary in monitor unit calculations.

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AimCancer research in the National Health Service has increased by 10·5% in 3 years since the formation of the National Cancer Research networks in 2000. The initial enthusiasm from clinical staffs to embark on a project has to be balanced against the implications of resources, costs and other developments. There is no standardised method to assess the impact of research projects on clinical practice. The aim of this project was to develop and implement a Radiotherapy Research Activity Assessment Tool (RAAT) to assess the feasibility of newly proposed projects within clinical settings.Methods and materialsA multi-step development method was used. The steps involved the principles of quality function deployment. The consecutive steps involved developing a user-friendly and replicable tool and would fit on one A4 page. The process involved multi-professionals and patients throughout the design process. The tool was preliminary tested on usability among eight stakeholders on a ten-point scale (1=poor; 10=very good). Percentage agreement was evaluated at 6 month post initial RAAT assessment scoring by the seven multi-disciplinary team (MDT) members.FindingsThe RAAT was developed in an e-form available in Microsoft Excel. The tool scored a mode of 6 for usability. Interrater reliability testing between the radiotherapy MDT resulted in 88% agreement. The RAAT seems to be feasible in clinical practice, and provide a framework to guide the decision-making process. The study calls for further testing of usability and review of long-term implications on all stakeholders.

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