143 A review of changes in lung radiotherapy treatment techniques during the CONVERT trial

Radiotherapy 143 A review of changes in lung radiotherapy treatment techniques during the CONVERT trial N. Groom1 *, E. Wilson2, C. Faivre-Finn3, E. Lyn4, A. Price5, M. Snee6, R. McMenemin7, N. Mohammed8. 1Mount Vernon Cancer Centre, UK, 2University College London Hospitals NHS Foundation Trust, UK, 3The Christie NHS Foundation Trust, Manchester, UK, 4CancerCare Manitoba, Canada, 5Edinburgh Cancer Centre, UK, 6St James’s Hospital Leeds, UK, 7 Freeman Hospital Newcastle, UK, 8Beatson Cancer centre, UK Background: CONVERT is an international randomised phase III trial, comparing 45 Gy in 30 fractions twice-daily or 66 Gy in 33 fractions once-daily (given concurrently with cisplatin/etoposide) for good performance status patients with limited stage small cell lung cancer. A survey was sent out to 69 clinicians who had randomised patients into the trial with the aim of establishing how radiotherapy techniques for lung cancer have evolved during the trial. Method: In 2008, as part of the pre-trial quality assurance process, each centre was asked to complete a facility questionnaire giving details of treatment planning, delivery and verification techniques. In January 2013, a further facility questionnaire was sent to centres. Results: This analysis includes answers from the 34 clinicians who responded to the questionnaire. Changes in treatment planning techniques and verification since the beginning of the trial are summarised in Table 1. Table 1. Changes in treatment planning techniques and verification 2008 2013 FDG-PET imaging for GTV delineation 20 (58.8%) 28 (82.35%) Multileaf collimators 25 (73.5%) 28 (82.35%) Intensity Modulated Radiotherapy 3 (8.8%) 14 (41.2%) Volumetric Arc Therapy 0 2 (5.88%) Beam Energy 10 MV 33 (97.1%) 34 (100%) >10 MV 9 (26.5%) 11 (32.4%) Treatment planning algorithms Type A treatment planning algorithm 9 (26.5%) 1 (2.94%) Type B treatment planning algorithm 24 (70.6%) 33 (97.1%) Clarkson algorithm 1 (2.94%) 0 Monte Carlo algorithm 0 2 (5.88%) Treatment verification Megavoltage electronic portal imaging 17 (50%) 17 (50%) Cone beam CT (CBCT) 6 (17.64%) 17 (50%) Kilovoltage planar imaging 2 (5.88%) 8 (23.5%) Radiographic portal films 4 (11.76%) 0 Out of the 34 clinicians who answered the 2013 questionnaire, 14 (41.1%) are currently using 4DCT, 3 (8.8%) are using breath-hold techniques and 16 (47.1%) are not using any technique to account for respiratory motion for simulation and treatment planning of lung patients. Data on management of respiratory motion was not available in 2008. Conclusion: During the 5 years the Convert Trial has been open there have been significant advances in radiotherapy treatment technology. Major changes include the use of Type B treatment planning algorithms and PET CT for planning, IMRT for treatment and CBCT for treatment verification of patients with small cell lung cancer.