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Ian Paddick of Medical Physics Limited


Gamma Knife, Intracranial Radiosurgery, MRI optimisation for SRS, Radiobiology, Commissioning

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Ian Paddick



MSc in Radiation Physics, University College London


Ian began his career as a Medical Physicist in 1989, working at the Hammersmith Hospital, London. Since 1998 he has worked almost exclusively with the Gamma Knife, being responsible for over 5,000 patient treatments using the B, 4C, Perfexion and Icon Gamma Knife models. He is a regular speaker and moderator at radiosurgery conferences, teaching on training courses and has helped start-up over 100 Gamma Knife centres worldwide. He is considered a world authority on treatment plan metrics, having formulated the Paddick Conformity Index and the Gradient Index. More recent research has been in the field of radiobiology as applied to radiosurgery.

Ian has an academic post at University College London and has published over 30 peer reviewed articles in the last five years.

In 2003, Ian formed Medical Physics Limited; a group of physicists providing expert radiosurgery physics services to SRS centres in the UK, Europe and the USA, as well as the manufacturers of the Gamma Knife, Elekta Instruments.

Ian is currently on the faculty of five Gamma Knife centres: Queen Square, London; Cromwell Hospital, London; Barts and the Royal London; Thornbury Radiosurgery Centre, Sheffield, and St. Elisabeth Hospital, Tilburg, Netherlands.

He was the first physicist to be elected as President of the International Stereotactic Radiosurgery Society (ISRS). He currently serves as Past President.

Contact Ian

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Gamma Knife,

Commissioning & End-to-End testing, Elekta Versa HD & Infinity, Varian TrueBeam, Elekta Monaco, Brainlab Elements, Varian Eclipse and Raystation TPS.

Diana Grishchuk MSc



MSc in Applied Nuclear Physics, Saint-Petersburg State Polytechnic University, St. Petersburg, Russian Federation



Diana obtained her first clinical experience as a medical physicist at the Russian Research Center for Radiology and Surgical Technologies; the lead radiotherapy centre in Saint-Petersburg. She was involved in a major department transition from 2D to 3D techniques, commissioning of Elekta Axesse and Precise linacs, Precise Plan, XiO, ERGO++ and Monaco planning systems and the implementation of IMRT and IGRT into clinical practice.


Later in her career she successfully applied her experience to acceptance testing and commissioning of Elekta Versa HD linacs and Monaco TPS at the Maltese Radiotherapy centre and then Varian TrueBeam STx linac, Raystation and Brainlab Elements TPSs at Imperial College Healthcare Trust, London.


Her extensive clinical experience also includes, but is not limited to, the clinical implementation of IBA and PTW dosimetry equipment and the development of department QA programs, while leading IGRT and SRS clinical teams. She has HCPC registration as a Clinical Scientist in the UK and, working for Medical Physics Limited, currently provides Radiosurgery physics services to four Gamma Knife centres in the UK.

In addition to clinical work, she has also worked as a contractor for Elekta as a Linac Hardware and Clinical Go-live Application specialist in Europe, Middle East and Africa.

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Treatment planning, brachytherapy, Quality Assurance

Anna Karanatsiou, MSc



MSc in Medical Physics, University of Surrey, UK



Anna started her career as a Medical Physicist Trainee at the Theageneion Cancer Hospital in Thessaloniki, Greece. There she worked in Radiotherapy, Nuclear Medicine and Diagnostics. She was involved in commissioning a CT scanner and two mammography units whilst gaining experience in treatment planning, QC and molecular treatments. After successfully completing the Medical Physicist (Greek) registration she moved to the United Kingdom. Anna was part of the Radiotherapy team in Bristol Haematology and Oncology Centre, UHB since 2017.  During the last few years she was involved in many different aspects of Radiotherapy; her clinical experience includes Gamma Knife planning, Linac dosimetry Quality Checks, Quality Assurance equipment, Brachytherapy, Total Body Irradiation, Molecular Physics and QMS. She also undertook the training for Radiation Protection Supervisors in 2019. 

She has HCPC registration as a Clinical Scientist in the United Kingdom and she is the newest member of the Medical Physicist Limited team.

Contact Anna



Gamma Knife, Intracranial Radiosurgery, commissioning, IORT

Phil Tapper MSc MIPEM



MSc in Radiation Physics, Medical College of St Bartholomew’s Hospital



Phil worked for a number of years in the NHS before moving into the private sector, eventually becoming Head of the Medical Physics Department including the London Gamma Knife Centre at the Harley Street Cancer Centre. He has extensive experience in the commissioning of treatment facilities and of running a successful, high quality medical physics department.

Since 2008 he has been providing radiosurgical physics support as a consultant, working for Medical Physics Limited, to three Gamma Knife centres in the UK and more recently providing a managed IORT service to two hospitals.

Our Team

Our dedicated team have a huge amount of experience in radiation therapy