Joint Department of Physics

Scientific Overview

Imaging and therapy are the two major areas of research and clinical service support in the Joint Department of Physics. The former involves the use of X-rays, radioisotopes, magnetic resonance, ultrasound and light, and the latter X-ray/gamma ray beams, brachytherapy, targeted radionuclides and focused ultrasound. These are multidisciplinary areas involving medical physicists, laboratory scientists, radiopharmacists and clinicians. Medical imaging provides morphological and physiological information that can be used for diagnosis, radiotherapy treatment planning and dosimetry, anticancer drug evaluation, assessment of treatment efficacy and the overall management of cancer. Therapy depends heavily on the availability of high quality imaging, as well as the use of computer controlled linear accelerators (LINACS), 3D planning systems, multileaf collimators to provide beam conformity and dosimetry methodology. The research in these areas involves collaborations with the Cancer Research UK Clinical Magnetic Resonance Research Group, The Royal Marsden Departments of Radiotherapy, Nuclear Medicine, Academic Radiology and the various clinical units, several of The Institute Sections including the Cancer Research UK Centre for Cancer Therapeutics, Paediatric Oncology, and Radiotherapy, in addition to other universities and commercial companies. The Joint Department also provides the radiation protection support for The Royal Marsden NHS Foundation and Royal Brompton & Harefield NHS Trusts, and a radiation monitoring service for The Royal Marsden and The Institute.

Relevance to the NHS Research and Development Programme

All of our developments are aimed at improving cancer treatment and diagnosis, which are central to the NHS R&D programme. Several areas of interest are also declared high priorities for the NHS - these include positron emission tomography (PET), magnetic resonance imaging (MRI), conformal radiotherapy and diagnostic methods for breast and skin cancer, which are part of the ultrasonic imaging research programme. This year we have strengthened our research staff in detector development and diagnostic X-ray imaging. Focused ultrasound has also made some significant progress.

Highlights from 2006:

RT physics (Chelsea and Sutton)

The Radiotherapy Physics teams play an active role in supporting the Trust's Capital Development Plan, and are key to the success of some of the larger schemes such as the Major Radiotherapy Development, brachytherapy and CT replacement programmes
Building works for Major Radiotherapy extension (Sutton) are nearly complete and have occupied all of 2006; completion is due in March 2007 with the installation of new accelerators commencing in January 2007
Installation, acceptance, commissioning and clinical handover of a dedicated CT Scanner for radiotherapy purposes at Sutton
Specification, technical evaluation, acceptance and clinical implementation of new Linear Accelerator and CT wide bore scanner for radiotherapy, both with gating facility (Chelsea)
Installation of Synergy on a Sutton linac
Installation of one of two proposed HDR brachytherapy units for use in new clinical trials in breast and rectal brachytherapy
Continuing to increase number of IMRT treatments, despite requirements for ‘out-of hours’ quality assurance and restricted LINACS access (Sutton and Chelsea)
Clinical implementation and support of new and ongoing multi-centre trials, eg, CHHIP, PARSPORT, FAST, pilot study for IMPORT HIGH
IMRT planning studies for new sites, eg, parotid, gynae
Implementation of treatment planning system developments, eg, breast planning optimisation programme, new electron calculation algorithm, CT based TBI lung compensator technique, new plan checking programme (Chelsea and Sutton)
Development of treatment planning capability for intensity-modulated arc therapy (IMAT), and initial testing of linear accelerator performance for dynamic arc therapy
Development of AutoBeam in-house treatment planning system for IMRT beam-orientation optimisation and IMRT breathing-motion compensation
Continuation of iodine seed prostate brachytherapy treatment service (Chelsea), using CT/MRI and ultrasound-based dosimetry
Planning ground floor facilities at Sutton for a new orthovoltage machine for skin cancer treatments and large bore CT scanner, including completion of competitive tenders for the scanner and micro-leaf collimator system for stereotactic radiotherapy
Collaboration with manufacturers to develop clinical implementation of technology, eg, VisionRT for patient set-up monitoring; Elekta for various projects including the ABC regulated breathing device, the next generation of RT imaging systems, IMRT QA/verification and IMAT delivery; Varian for the implementation of gating for the treatment of liver carcinoma; Wellhofer on software for IMRT QA/verification; QADOS on ultrasound and optical outlining and Medison on 3D cine ultrasound
Maintenance of ISO accreditation in radiotherapy and radiotherapy physics for the 11th year
Collaborated with radiotherapy to implement study into implanted markers for breast treatments with the aim of using this work in the IMPORT Trials (partial breast radiotherapy)
Further studies of tumour motion in relation to the delivery of IMRT have been carried out specifically investigating the effect of differential motion
The collaboration with UCL has expanded to combine the modelling work at ICR with the data processing abilities at UCL
The variable aperture collimator has been motorised and experiments at DKFZ are about to commence. 3D direct-aperture optimisation software is being constructed
The 2D target tracking theory has been worked out and experiments started to verify the results
A study was made with the Rotterdam Cyberknife to assess the accuracy of the Synchrony motion correction method
Developed method of MLC leaf position calibration using EPID
Quantified properties of EPID for dosimetry and developed new detector optimisation method
Evaluated automatic methods for finding fiducial markers in prostate
Development of combined dosimetry for radionuclide and external beam RT
Development of margin and gating model for RT of moving target
Completion of detailed statistical analysis of dose/volume data against mature clinical late rectal toxicity outcome data for RT01 prostate radiotherapy clinical trial ( in collaboration with MRC clinical trials unit)

Radiological Physics

Security provisions for sealed sources have been met under the new HASS (High Activity Sealed Sources) regulations
Numerous sealed sources have been disposed of with a grant from the Environment Agency under their Sealed Sources Disposal Programme
Detailed environmental impact assessment and habits surveys have been conducted for radioactive waste disposals from the Sutton site
A changeover from film to thermoluminescent dosimeters (TLDs) for personal monitoring is underway
Courses on radiological protection for a range of Trust staff groups and on X-ray medical imaging have been provided
We have participated in the procurement and acceptance of digital X-ray systems multi-slice CT scanners and digital fluoroscopy systems
We have developed software tools for the automated analysis of CT image quality
We have established scanning protocols for CT perfusion which generate images of comparable quality to those produced by the manufacturer's own protocol, but at half the radiation dose to the patient
We have used our Monte Carlo model for CT to calculate radiation doses for cardiac imaging using electron beam CT and for paediatric chest imaging, and to determine how commercial dosimetry packages can best be used despite the shortcomings of the patient model used
Development of a state-of-the-art system based on large area a-Se detectors for low-dose 3D X-ray digital mammography tomosynthesis. This is a collaboration with Dexela Imaging Ltd and the X-ray Department of RMH and is funded by the DTI through the KTP programme
Detailed modelling of novel pixellated CdZnTe detectors for an accurate performance characterisation of a truly integrated multi-modality imaging system (SPECT/PET/CT) using the GATE Monte Carlo code

Therapeutic Ultrasound Team

Clinical trials for the transrectal treatment of recurrent prostate cancer with high-intensity focused ultrasound (HIFU) using the “Ablatherm” on loan from EDAP Technomed began in 2006 and are showing promising results
Our EPSRC funded project to design and test a new non-invasive clinical HIFU device for use in the treatment of soft-tissue tumours of liver and kidney continues, with the design of many critical components required for the new Teleson II clinical system completed
A 3D numerical model is nearly completed that will allow us to model the ultrasonic fields from complex geometry HIFU sources, including multi-element phased arrays, with the aim of exploring methods of reducing treatment times significantly
The collaboration with the HIFU Unit, Churchill Hospital continues with new clinical trials to investigate the treatment of liver, kidney and pancreatic cancer using HIFU
Methods have been developed for improving the reproducibility of HIFU damage formation based on standard ultrasound imaging. These involve both backscatter estimation of tissue attenuation and backscatter temperature imaging to help identify optimal exposure intensities
New methods of monitoring temperature rise and acoustic cavitation in the clinic are being developed to ensure greater safety and efficacy through optimal exposure
A fruitful collaboration continues between the Therapy Ultrasound Team and the Quality-of- Life Division of the National Physical Laboratory following the successful secondment of Adam Shaw to work on aspects of HIFU field characterisation
Quantitative high field magnetic resonance imaging and detail histological investigation are being investigated as a means of understanding the tissue changes associated with HIFU exposures
We organised the 4 day meeting of the International Society of Therapeutic Ultrasound (ISTU6) in Oxford in 2006 which was attended by 300 delegates from all over the world
James McLaughlan won the Bob Clarke Best Student presentation award at ISTU6, with Hugh Morris collecting a merit award

Ultrasound and Optical Imaging

Continued collaboration with the University of the West of England to develop a novel photometric stereo camera for skin imaging that provides separate but registered images of colour reflectance and surface gradient profile
Colour reflectance images produced using photometric stereo were demonstrated in clinical tests to provide, relative to conventional diffuse lighting, improved visibility of subsurface pigmentation important for visual diagnosis of malignant melanoma
Skin surface profilometry using photometric stereo was demonstrated clinically to be superior to reflected intensity images for tracking and hence creation of optical elasticity (strain) images of skin and skin tumours
Completed acquiring data for a preliminary clinical trial of optical elastography and ultrasound elastography of the skin under surface tensile strain, for evaluation of elastographic parameters as diagnostic measures in breast cancer related lymphoedema (BCRL)
Preliminary clinical data collection completed for assessment of optical tensile strain elastography in visualising skin tumours
Constructed, in collaboration with Bath Royal United Hospital, mechanical and electronic 3D scanning hardware that will provide a bench-top demonstrator of the application of our novel transient acoustic radiation force elastography to breast cancer diagnosis
Constructed, in collaboration with the Therapeutic Ultrasound Team, a 2D scanning and frame interleaving system for applying transient acoustic radiation force elastography to monitoring focused ultrasound surgical treatment of cancer
Demonstrated in phantoms that elastograms made using transient focused acoustic radiation force have improved image signal to noise ratio and spatial resolution, and suffer less from artefacts, than those made using quasi-static surface loading
Carried out a preliminary trial of intraoperative freehand elastography for assisting resection of brain tumours at the Royal Free Hospital. Both Medison Accuvix XQ™ real-time elastography and our own off-line elastography showed relative stiffness of tumour to brain, and tumour stiffness heterogeneity
In collaboration with the Royal Free Hospital, transferred to the clinic our novel ‘slip elastography’, a method to non-invasively assess frictional resistance to slip at the tumour-normal tissue interface, for provision of intraoperative information on adherence of tumour to brain
Using a combination of theoretical modelling and experimental confirmation using elastography, an understanding was gained of the spatio- temporal dependence of strain inside a relaxing medium consisting of a layer of fluid-filled highly porous tissue sandwiched between two layers of relatively elastic non-porous regions, and experimental confirmation was obtained of their correctness
Completed a preliminary clinical elastographic study of BCRL, showing that under sustained compression (a) the spatio- temporal pattern of strain inside the tissues of the forearm is similar to that for a layered medium, and (b) such a pattern is more apparent in arms affected by BCRL than in the contralateral arms
The Institute of Physics awarded “select status” to a publication in collaboration with the University of Boston, of new theoretical predictions for the spatio- temporal dependence of strain inside a multi-compartmental medium undergoing stress relaxation, which models a tumour and a background normal tissue in terms of their relative stiffness, resistance to fluid flow within the interstitial and microvascular compartments, and resistance to fluid exchange between these compartments
In collaboration with the Therapeutic Ultrasound Team, backscatter methods for estimating ultrasound attenuation and temperature rise in tissue, implemented on commercial ultrasound scanners, were shown in vitro to provide a small improvement in the consistency of focused ultrasound tissue ablation
In collaboration with the Gene Therapy Team of the Section of Cell and Molecular Biology, extended our novel experimental techniques for studying ultrasound and microbubble mediated gene transfection of cells in vitro to enable a luminescence readout of a marker gene, allowing rapid determination of the combined effects of acoustic frequency and pressure as determinants of transfection efficiency
With the Gene Therapy Team, continued development and in vitro demonstration of our patented highly targeted ultrasound gene transfection method using microbubbles and modified retroviruses
A new PhD project was begun to study possible ultrasonic read-out signals from nanoparticles that could eventually be used for molecular imaging of extravascular targets
The frequency dependence of ultrasonic attenuation and the Young’s modulus were measured in radiation sensitive gels and shown to vary as a function of radiation dose, demonstrating potential of these variables for eventual use in a 3D radiotherapy dose imaging system
Continued work with European partners, and with The Institute’s Sections of Medicine and Cancer Therapeutics, on the ADONIS project, which will evaluate the feasibility of preclinical opto-acoustic molecular imaging of prostate cancer using PSMA-targeted gold nanoparticles
In collaboration with the Radiotherapy Team, 4D ultrasound (Medison) echo tracking has been evaluated in phantoms to determine the limits of accuracy and precision of rigid tissue displacement measurement, for eventual use in motion compensated radiotherapy
Continued collaboration with Zonare Ltd to explore research applications of the unique Z.one ultrasound imaging platform

Radioisotope Physics

New image processing systems were installed and tested for routine analysis of nuclear medicine scans
Software upgrades were carried out for all existing systems
A picture archiving and communications system (PACS) was installed to enable image retrieval networking of nuclear medicine and physics systems
Quantification procedures for In-111 and Y-90 imaging have been further developed to enable dosimetry for radiolabelled antibody treatment of lymphoma
A phantom imaging study to optimise acquisition and processing protocols for Ra-223 imaging was conducted. This will form the basis for a clinical dosimetry study in 2007
New methodology was developed to apply polymer gel dosimeters to the verification of quantification techniques to I131 imaging
Upgrades to the whole-body monitoring unit have been installed and tested in the paediatric department. Multiple treatments were performed based on whole-body dosimetry prior to a European clinical trial. Physics procedures have been put in place to permit the use of radioisotope localisation for Sentinel Lymph Node Biopsy. This has included testing and QA of the probe used by the surgeon, training of the theatre staff and radiation protection issues
An interventional clinical trial investigating the use of PET/CT for external beam radiotherapy treatment planning in the oesophagus is in progress
An IMRT planning study of the effect of SPECT lung perfusion maps on radiotherapy planning for primary lung cancer is in progress
An international PET/CT Symposium has been organised
Performance testing has been carried out for a small animal PET scanner
Detailed plans for a cyclotron and radiochemistry research facilities have been finalised, ready for construction in early 2007
New PhD projects were commenced to explore the use of Monte Carlo methods for patient dosimetry and to optimise image quantification for I131 mIBG therapy

In the Joint Department of Physics

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