Phase-insensitive Ultrasonic Computed Tomography (pi-UCT) for the diagnosis of breast disease. 

Funded by Innovate UK (formerly the Technology Strategy Board - TSB).  Funding started Feb 2014.

The first prototype ultrasound sensors for a new improved breast screening technique have been developed as part of a collaboration between the National Physical Laboratory (NPL), University Hospitals Bristol and Weston  (UHBW), North Bristol NHS Trust (NBT), Precision Acoustics Limited and Designworks The team is now looking for commercial partners to translate the novel development into a clinical device.

NHS breast cancer screening in England is currently conducted using X-ray mammography, and further investigations may involve a clinical examination, more X-ray mammograms and conventional ultrasound.

During mammography, each breast is compressed between the two plates of an X-ray machine, which some women find very uncomfortable, and two X-rays are taken at different angles. However, the inability of 2D X-ray mammography to separate overlying tissue can lead to false positives and false negatives, and the hazards associated with ionising radiation limit the frequency with which X-rays can be performed. Conventional ultrasound is highly operator-dependent and suffers from imaging problems, making cancerous tissue difficult to distinguish from healthy tissue.

NPL, UHB, NBT, Precision Acoustics and Designworks are developing a prototype clinical system for a new breast screening technique - using ultrasound computed tomography (UCT) - that may overcome the problems of diagnosing breast disease using conventional X-ray mammography and ultrasound scans. The new ultrasound method will be safer and lower cost than currently-used screening techniques, and the results should be easier for clinicians to interpret.

Fig. 1: The proposed breast screening system (Image courtesy of Designworks)

NPL has developed and patented a novel detection method employing pyroelectric sensors, which convert ultrasonic energy into heat, generating electrical signals which are eventually used to form the ultrasound image. These large-area thermal sensors should generate far fewer image artefacts than conventional piezoelectric detectors, which are sensitive to the phase of the arriving ultrasound waves.

In the new procedure (Fig. 1), the patient's breast will be placed in a warm water bath between an ultrasound transmitter and receiver. Ultrasonic waves are sent through the breast and the amount of energy emerging is measured using the prototype ultrasound sensor. The ultrasound transmitter array and the receiver are rotated around the breast, and the resulting measurements are combined to produce a 3D image of breast tissue properties. Different tissue types, including those that are cancerous, can then be identified from this image.

The first prototype pyroelectric sensors have been manufactured by Precision Acoustics and are currently being tested and optimised at NPL. Next, the team will develop a platform combining all the project components into a breast screening system ready for clinical evaluation. The system will then be deployed at the Bristol Breast Care Centre Service (NBT) for clinical evaluation on a small number of patients, providing the potential for an accurate, safe and comfortable method of screening for breast cancer.

Dr Lis Kutt and Dr Mike Shere from the Bristol Breast Care Centre Service (NBT) said: "We are evaluating this tool for imaging purposes with a view to looking at using it for screening should it prove to have the required sensitivity, specificity, patient acceptance and reproducibility of conventional mammography."

Transmission - Radiotherapy Active Pixel System (TRAPS): Towards a Clinical Prototype for Real-Time 2D Verification of Intensity Modulated Radiotherapy.

Background

Many cancer patients are treated using X-ray irradiation. For some cancers this is very difficult if the tumour is located close to organs sensitive to radiation. Advances in the way radiotherapy is delivered to patients means that tumours can be much more accurately targeted, greatly reducing the damage to surrounding tissue and sensitive organs.  Finely engineered components in the treatment machine shape the radiation field directed at the tumour; if the beam components are misaligned or are delivered in the wrong sequence, it may not be easily recognised or immediately spotted. Errors can result in the wrong treatment being delivered, or as in some high-profile cases, delivery of a fatal overdose. Checks are made before, and ideally during, treatments to avoid such errors. The patient radiation dose needs reporting across the whole radiation field and the radiation beam monitored without perturbing it.

Our project team has developed a novel method for detecting errors during treatment using a thin silicon panel that does not interfere with the upstream radiation beam. The system, related to digital camera technology, is fast and cost-effective, has been proven to work for a range of standard radiotherapy treatments and will now be extended to work for new radiation delivery systems which move during treatment. The aim is to speed up data collection and validate the system for real-time intervention in cases of error. This will enable reporting of serious deviations from the planned treatment and provision of detailed dose distribution reports. Any errors can then be dealt with prior to treatment completion.

Team

This project was a collaboration between clinical scientists, medical physicists, radiographers and academics in the Medical Physics & Bioengineering Department (MPB) in UH Bristol & Weston NHS Foundation Trust, the HH Wills Physics Laboratory at the University of Bristol, the College of Medicine in Swansea University, the Rutherford Appleton Laboratory (STFC) and industrial partners, IBA and vivaMOS.  The project was led by Dr Diane Crawford who is now retired but was a former Director of MPB.  The focus of the project was on further development of the detector, covering a larger radiation field, extending from a static to a dynamic system, commercial collaboration and clinical application.

Results

The outcome of the project was the development of a novel radiation detector with low beam attenuation (ie minimal reduction in treatment beam intensity) and improved resolution, compared with competing devices capable of monitoring errors during the treatment of cancer with radiation (radiotherapy).  This project focused on redesigning our earlier device to demonstrate our ability to monitor treatment of new dynamic radiation delivery systems that move during beam delivery e.g. Volume Modulated Arc Therapy (VMAT), and cover larger treatment areas, more typically required clinically.  We also developed methods to speed up data collection and determined that the system is capable of real-time intervention in cases of error.  This will enable reporting of serious deviations from the planned treatment and provision of detailed dose distribution reports. Any errors can then be dealt with prior to treatment completion. 

During the project we sought input from patient and clinical users and there was keen interest in this project at two focus group workshops which we hosted.  Understanding how this device is viewed by patients has enabled us to establish key design features for the final detector design.  Patient and user representatives also contributed to project steering group meetings and their desire to ensure this development becomes a clinical reality has also been a key motivator for the project team.

Team expertise in fabrication of radiation detectors and modelling of clinical radiation equipment enabled us to achieve the major project objectives.  For 2 years the project work focused on using Achilles sensors (6 x 6 cm) available for purchase when the project work started.  Subsequently a larger sensor (LASSENA) became available for purchase which could cover a greater treatment field area. NIHR agreed to our extending the project time to enable us to demonstrate the potential for using this sensor within the TRAPS system. Our results have been encouraging and detailed discussions continue post-project with key commercial companies who are actively considering bringing the device to market.

The Bristol Dose Painting Study

	VMAT device and software used to calculate the dose to the patient so the tumour gets the highest dose whilst limiting the dose to the surrounding tissues
	This figure shows the dose distribution around the tumours and surrounding tissue.

This study is a collaboration between Medical Physics and Oncology staff at UHBW (University Hospitals Bristol and Weston NHS Foundation Trust) and NBT (North Bristol NHS Trust), and CRIC Bristol, with support from Above & Beyond.

This study is to determine if a technique known as dose painting is feasible. Dose painting involves boosting the dose of radiation to tumours presenting as isolated nodules without increasing the dose to the surrounding healthy tissues, focusing on the prostate. The study focusses on the prostate because prostate tumours tend to be close to healthy tissues such as the bladder, rectum and urethra, and if you increase the dose to the whole prostate this leads to higher rates of toxicity in the normal tissues, so if dose painting is a feasible technique we could reduce reoccurrence rate without decreasing quality of life.

20 patients participated in this study, and MRI scans were obtained for 19 of them. Of these, 14 had these isolated nodules and 6 of those were able to receive the elevated dose, whilst in 6 of the 8 remaining they received a limited elevated dose due to their position close to the urethra. In the other 2 patients there were registration issues due to changes in their internal anatomy.

This study has been very helpful in identifying the issues involved in implementing this technique and current results are positive regarding the feasibility of using dose painting in Bristol. In the future the plan is to enter a clinical trial involving dose painting, as currently this study has successfully delivered an elevated dose to the tumour with no difference in toxicity and quality of life between standard treatment and using dose painting.

For more information on the study click here.

3D versus 2D neonatal cranial ultrasound

Joao Alves Rosa, Rachel Roberts, Adam Smith-Collins, Sian Curtis, Savvas Andronikou, David Grier

A standard 2D coronal image of the frontal lobe, showing the 'bull horns'.

A 3D coronal image of the frontal lobe taken during the study for comparison.

A standard 2D sagittal image of the left temporal lobe.

Patients on the neonatal intensive care unit (NICU) often require imaging of their brain to look for intracranial haemorrhage or other complications.

These are commonly seen in pre-term babies, or term infants with birth asphyxia, seizures, or congenital infections.

Ultrasound is the imaging modality of choice as it does not use ionising radiation, and is easily performed at the bedside. 2-dimensional (2D) ultrasound requires significant training to obtain adequate quality images in the standard planes.  3-dimensional (3D) ultrasound images are easier and quicker to acquire, which may be of benefit to patients that are sick and immobilised by medical paraphernalia such as ventilators. These images can be reconstructed using computer software into the 2-dimensional images in the standard planes.

If the image quality of these reconstructions is equal to a 2D-acquired scan for diagnostic purposes, then these could be performed at remote sites. The resultant images could then be sent on to tertiary referral centres and interpreted by specialists without the need for the infant to travel hundreds of miles in a sub-optimal clinical condition.

To find out whether this is possible we first want to carry out a proof of concept study (20 patients) to ensure that the 3D scans can be reconstructed to provide a 2D image, without loss of quality, or loss of features over that seen in the 2D scan.  We will also validate the anecdotal evidence that the 3D scan can be performed more quickly and easily than the 2D scan. 

The aim of the study is to compare the presence and quality of key anatomical landmarks in standard images of the brain in the neonatal population produced by 2D and 2D cross-sectional reconstructions from a 3D data set.

The primary endpoint of this study is the adequacy of reconstructed 3D data to display at least 90% of the key anatomical landmarks with similar quality to the 2D acquires standard images.