Clinical Research

The Queen Square Radiosurgery Centre, as well as providing a radiosurgery service for NHS, private an international patients is committed to research and dissemination of knowledge, working with  groups from around the world. Research is a key focus and the trials we are currently designing and conducting will provide invaluable data to optimise the methods currently used to plan and deliver Gamma Knife Radiosurgery as well as to assess its effectiveness and safety.

A series of research projects are currently being undertaken and their results are expected to positively impact the quality of the service we offer. The research questions being addressed are based from local obesrvations and will provide invaluable data both for local use and comparison to global practice. The research being undertaken includes studies on all stages of Gamma Knife Radiosurgery, from pre-treatment MRI imaging, to long term evaluation of efficacy and possible side effects.

Thus, research subjects are heterogeneous and include: optimisation of sequences for MRI pre-treatment imaging, evaluation of algorithms to calculate the radiation dose, trial of different beam sizes to deliver radiation to brain metastases, comparison of Gamma Knife with other therapeutic options for trigeminal neuralgia, comparison of Gamma Knife with other Radio surgical tools, and long term evaluation of efficacy and side effects of the treatment. This requires constant input from a multidisciplinary team that assesses the relevance of the research as well as the design and methods, so as to accurately provide answers to the research questions.

The research work is led by Mr Neil Kitchen, consultant neurosurgeon and Ian Paddick, chief medical physicist; both well experienced practitioners and renowned researchers and co-ordinated by Cornel Tancu, Clinical Research Fellow. The projects are designed and conducted in collaboration with consultants from other relevant specialties, such as Dr Naomi Fersht, Clinical oncologist and Dr Rolf Jager, Consultant Neuroradiologist.

We aim to include all of our patients in our research. We have a variety of trials which are suitable for multi diseases, but also others specific for diseases such as Brain Metastasis and Trigeminal Neuralgia.

If you are a patient interested in enrolling in any of our research projects, please don’t hesitate to contact us for further information.

If you would like to work in collaboration with us on research projects or trials please get in touch.


Our current key research projects include:-


Convolution Algorithm evaluation

Full title: Evaluation of dosimetric differences between the TMR 10 and convolution algorithm for Gamma Knife Radiosurgery planning

Gamma Knife Radiosurgery (GKR) relies on mathematical algorithms to predict dose distribution and to calculate the radiation dose at arbitrary points in the head. For the last 25 years, doses applied using Gamma Knife Radiosurgery have been calculated using a simple algorithm, called the Tissue Maximum Ratio algorithm (TMR). Dose planning using this algorithm, relies on a number of approximations to enable fast computation during treatment planning. One of the most significant of these is the approximation of the head to water-equivalent density. The increased electron density of brain and bone and the near-zero density of air cavities in the skull may make significant perturbations to isodose and beam-on time calculations.

With the advent of faster workstations, the effect of tissue in-homogeneities can finally be calculated in reasonable time during the treatment planning process; a newer, more modern algorithm known as convolution algorithm is now commercially available. It uses the values of density indicated in the CT scan to predict the dose distribution and is expected to more accurately calculate radiation dose, although it needs further investigation before clinical implementation. Inter- and intra-indication differences between the old and new algorithms need to be understood before this method can be confidently employed in a clinical setting.

The aim of this study is to understand the dosimetric differences between these dose calculation algorithms and to evaluate the implications of using the convolution algorithm for GKR. A large number of treatments will be re-planned using the convolution algorithm and compared to the TMR plans used to treat the patients.  This study involves the patient undergoing a stereotactic CT scan of the head after the treatment has being delivered with TMR 10, which is the current standard practise. Then, information from the CT scan will be used to re-plan the treatment using the new Convolution algorithm; the treatment plans will be compared and the potential implications on treatment planning will be elucidated.

Recruitment for this study is now open and all the patients receiving Gamma Knife treatment in Queen Square will be invited to participate.

For further information please click here. Some of the results from this research have been published and can be found  here.

Trigeminal Neuralgia Cohort

Full title: The natural history of trigeminal Neuralgia, a long term cohort study.

This is a long term observational study to evaluate the natural history of trigeminal neuralgia and to assess the efficacy and safety of Gamma Knife Radiosurgery.  As the long-term history, outcomes and responses to various treatments of trigeminal neuralgia are largely unknown, the information collected from this study will be  important to support future advice for patients and development of treatment protocols.

This project is being conducted in collaboration with Prof. Joanna Zakrzewska, Lead Facial Pain Specialist in the Eastman Dental Hospital. All patients receiving Gamma Knife treatment for Trigeminal Neuralgia will be invited to take part. The study involves patients completing an initial pain questionnaire on the day of Gamma Knife treatment, and then completion of the same form posted regularly for 5 years.

This study is currently recruiting subjects.

For further information please click here.

Brain Micrometastases

Full title: Optimal radiation method for Gamma Knife Radiosurgery of brain micro-metastases:  A Randomized Clinical Trial of the 4mm vs. the 8mm collimator.

There is controversy over which collimator (beam size) should be used when treating brain micrometastases (very small lesions up to 0.140 cc). These lesions can either be treated with the 4mm collimator at an isodose between the 40% and 90%, or the 8mm collimator at an isodose between 90% and above. While the 4mm collimator gives a very steep dose gradient outside the target, some have argued that the dose gradient is too steep, leaving inadequately treated invisible micro-metastatic spread outside the radiological target. The 8mm collimator provides shorter treatment times, which is important especially for patients with multiple brain metastases, but it yields a very poor dose fall off, which may needlessly irradiate healthy brain tissue. The aim of the trial is to investigate if a difference in clinical efficacy exists between treating micrometastases with Gamma Knife Radiosurgery using the 4 mm or the 8 mm collimator.

Working in collaboration with the Cromwell Gamma Knife Centre approaching 300 patients are included in the study which was recently reviewed positively by the ethics committee.

Optimization of MRI imaging for Gamma Knife Radiosurgery of Brain AVM

To optimise MRA techniques and MRI perfusion sequences to facilitate non invasive planning of Gamma Knife Radiosurgery and subsequent evaluation of treatment response avoiding the need of two Digital Substraction Angiograms (DSA). MRI perfusion techniques such as TOF angiography, TRICKS, ASL and DCE will be optimised to facilitate non invasive planning and follow up of patients undergoing Gamma Knife treatment. This study should enable adequate planning of AVM treatment on non invasive imaging techniques, avoiding the use of invasive angiograms.

Evaluation of the stability of the stereotactic Leksell G frame

To confirm the stability of the Leksell G frame in the clinical settings. The stereotactic location of well defined targets is evaluated in the MRI scan performed before treatment and a CT scan performed after Gamma Knife is completed. This study will re-assure the accuracy of Gamma Knife Radiosurgery and will work as a quality assessment/audit evaluation of the treatment plans delivered at QSRC.

Further information can be found here.

Further information including summaries of retrospective studies and presentations can be found below:

Brain Metastases retrospective study

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AVM treatment at QSRC

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Vestibular Schwannoma retrospective study

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