Prior to starting as a Consultant Clinical Oncologist at The Royal Marsden NHS Foundation Trust, in December 2011, Dr Mandeville had undertaken a Cancer Research UK clinical research fellow position, with Professor Peter Hoskin at the Gray Cancer Institute at Mount Vernon Hospital. His thesis explored the clinical interaction between vascular targeting agents and radiotherapy utilising functional computerised tomography (CT) and Magnetic resonance imaging (MRI) techniques, and he was awarded an MD(Res) from University College London in 2011. Since 2010 he has been specialising in paediatric radiotherapy, previously working at University College London and Great Ormond Street Hospital.
Currently, his main research interests are in technical radiotherapy improvements for tumours in children and young people. These include: respiratory-related motion management, rotational intensity-modulated radiation therapy (IMRT), MRI-guided radiotherapy and proton therapy. He is also investigating the impact of local therapy on the quality of life of survivors. Since 2013, Dr Mandeville has been the Chair of the European Paediatric Soft Tissue Sarcoma Group (EpSSG) Radiotherapy Committee, and last year was appointed to the EpSSG Board. He is the Local Therapy lead for the new EpSSG Frontline and Relapsed Rhabdomyosarcoma (FaR-RMS) study.
Dr Mandeville is Team Leader of the Radiotherapy for Children, Teenagers and Young Adults Team.