Mark Warren

An isotoxic planning comparison study for stage II-III non-small cell lung cancer: is intensity-modulated radiotherapy the answer?

AIMS Recent clinical series suggest that treating patients with isotoxic twice-daily radiotherapy may be beneficial. This dosimetric planning study compared the use of intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DRT) to deliver isotoxic treatment for non-small cell lung cancer (NSCLC) patients. MATERIALS AND METHODS Twenty patients with stage II/III NSCLC were selected. A dose-escalated plan was produced retrospectively for each using three different methods: (i) three to five beams 3DRT; (ii) seven beams inverse-planned conformal radiotherapy; (iii) seven beams IMRT. The starting point for dose escalation was 55.8 Gy in 1.8 Gy per fraction twice-daily. The number of fractions was then increased until one or more organ at risk tolerance dose was exceeded or a maximum dose of 79.2 Gy was reached. RESULTS The median escalated doses were 70.2, 66.6 and 64.8 Gy for IMRT, 3DRT and inverse-planned conformal radiotherapy, respectively. IMRT allowed a significant dose increase in comparison with the other two methods (P < 0.05), whereas no significant difference was found between 3DRT and inverse-planned conformal radiotherapy. IMRT was more successful at escalating dose in patients where the brachial plexus and spinal canal were close to the planning target volume. IMRT did not allow the escalation of dose beyond 70.2 Gy (82.8 Gy BED10, 69 Gy EQD2) due to the proximity of disease to the great vessels and the proximal bronchial tree. CONCLUSIONS IMRT allows increased dose escalation compared with conformal radiotherapy. However, there is limited opportunity to escalate the prescription dose beyond 70.2 Gy twice-daily in disease close to the central mediastinal structures.

The departmental impact of magnetic resonance imaging in the management of cervical cancer brachytherapy: a discussion paper

This discussion paper will explore the impact of using Magnetic Resonance Imaging (MRI) in the treatment of cervical cancer with brachytherapy. It is written from the perspective of current departmental practice in the UK and aims to highlight the issues associated with using MRI as a tool for image guided brachytherapy planning. To support the discussion, a literature review was undertaken focussing specifically on the use of MRI in brachytherapy treatment planning for cervical cancer. Results from planning case studies and clinical series were analysed, and the literature showed that image guided brachytherapy treatment planning is a promising development. MRI assisted planning could theoretically be implemented in centres that have access to a MRI scanner. Alternative brachytherapy technologies (e.g. Computed Tomography (CT) assisted planning), and alternative radiotherapy modalities (e.g. an external beam radiotherapy boost), were not found to be superior in effect or of implementation. Although MRI shows great promise, the evidence base for MRI in brachytherapy planning for cervical cancer is currently limited and therefore careful implementation and evaluation is required. It is suggested by the authors that new methods of working are devised to ensure consistency and quality in implementation and delivery, and that outcomes are measured and audited to evaluate efficacy.

What are the current and future requirements for magnetic resonance imaging interpretation skills in radiotherapy? A critical review

Abstract Purpose Increasing usage of magnetic resonance imaging (MRI) in radiotherapy (RT) and the advent of MRI-based image-guided radiotherapy (IGRT) suggests a need for additional training within the RT profession. This critical review aimed to identify potential gaps in knowledge by evaluating the current skill base in MRI among therapeutic radiographers as evidenced by published research. Methods Papers related to MRI usage were retrieved. Topic areas included outlining, planning and IGRT; diagnosis, follow-up and staging-related papers were excluded. After selection and further text analysis, papers were grouped by tumour site and year of publication. Results The literature search and filtering resulted in a total of 123 papers, of which 66 were related to ‘outlining’, 37 to ‘planning’ and 20 to ‘IGRT’. The main sites of existing MRI expertise in RT were brain, central nervous system, prostate, and head and neck tumours. Expertise was clearly related to regions where MRI offered improved soft-tissue contrast. MRI studies within RT have been published from 2007 onwards at a steadily increasing rate. Conclusion Current use of MRI in RT is mainly restricted to sites where MRI offers a considerable imaging advantage over computed tomography. Given the changing use of MRI for image guidance, emerging therapeutic radiographers will require training in MRI interpretation across a wider range of anatomical regions.

Use of planning metrics software for automated feedback to radiotherapy students

Abstract Background and purpose Pre-registration teaching of radiotherapy planning in a non-clinical setting should allow students the opportunity to develop clinical decision-making skills. Students frequently struggle with their ability to prioritise and optimise multiple objectives when producing a clinically acceptable plan. Emerging software applications providing quantitative assessment of plan quality are designed for clinical use but may have value for teaching these skills. This project aimed to evaluate the potential value of automated feedback to second year BSc (Hons) Radiotherapy students. Materials and methods All 26 students studying a pre-registration radiotherapy planning module were provided with automated prediction of relative feasibility for left lung tumour planning targets by planning metrics software. Students were also provided with interim quantitative reports during the development of their plan. Student perceptions of the software were gathered using an anonymous questionnaire. Independent blinded marking of plans was performed after module completion and analysed for correlation with software-assigned marks. Results In total, 25 plans were utilised for marking comparison and 16 students submitted feedback relating to the software. Overall, student feedback was positive regarding the software. A ‘strong’ Spearman’s rank-order correlation ( r s =0·7165) was evident between human and computer marks ( p =0·000055). Conclusions Automated software is capable of providing useful feedback to students as a teaching aid, in particular with regard to relative feasibility of goals. The strong correlation between human and computer marks suggests a role in benchmarking or moderation; however, the narrow scope of assessment parameters suggests value as an adjunct and not a replacement to human marking.