Imaging for Radiotherapy Adaptation Group

Dr Emma Harris and her group are developing imaging techniques to increase the effectiveness of radiation oncology to treat a number of different cancer sites. Her main focus is the development of various novel ultrasonic imaging techniques to locate the radiotherapy target volume, to guide the delivery of radiotherapy and to help predict, and monitor, treatment response.

Quantification of Radiation-Induced Tissue Fibrosis using Ultrasound Imaging

Radiation-induced fibrosis is a chronic side effect of radiotherapy given to patients with cancer and may limit the dose that is given. Fibrosis is a genetically regulated response to tissue injury and drugs may be given to reduce its severity. Reliable measures of fibrosis are required to support research in three specific areas: i) radiotherapy dose scheduling, ii) identification of patients’ genetic susceptibility to fibrosis, and iii) clinical evaluation of anti-fibrotic therapies. Quantitative in vivo measures of treatment response are needed to support the investigation of genetic and physiological susceptibility to radiation toxicity and clinical trials evaluating anti-fibrotic, anti-angiogenic and anti-hypoxia therapies.

This research project investigates the potential of new ultrasound based tools in vivo for assessment of radiation induced fibrosis in women following radiotherapy for breast cancer.

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Development of ultrasound motion estimation techniques to optimise radiation therapy delivery

Dr Tuathan O’Shea is researching novel ways to use imaging techniques to improve radiation therapy delivery. It is well known that for many anatomical sites the tumour remains mobile during radiation therapy (RT) requiring margins around the target to account for motion (known as intra-fraction motion). With the application of imaging and improved information on tumour position, margins can be decreased, reducing radiation to surrounding healthy tissue and potentially allowing increased tumour dosage.

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Development of ultrasound guided radiotherapy of the cervix and kidneys

Highly conformal radiotherapy planning techniques such as IMRT and VMAT are only possible if the precise positions of the target volume and organs at risk are known. However, the motile and deformable characteristics of soft tissue organs make it extremely difficult to ascertain their position (despite daily x-ray imaging and careful patient set up) prior to and during radiation delivery. Therefore, large treatment margins are required to ensure adequate coverage of the target area at the expense of including healthy tissues in the treatment field. Daily soft-tissue imaging using ultrasound is a promising solution for determining the precise location of the target organ and surrounding tissues for radiotherapy, which could ultimately allow a more widespread use of highly conformal delivery plans.

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Multi-parametric ultrasound imaging for assessment of tumour response to radiotherapy

Radiotherapy is an important treatment for cancer with around 50% of cancer patients receiving radiotherapy. Unfortunately, not all tumours respond in the same way. Some tumours may be radiation resistant resulting in treatment failure. It is important that we find accurate and cost effective methods to monitor the response of tumours to radiotherapy at multiple times throughout treatment. That way, the clinician can know if the treatment is failing and this allows them to change the patient’s treatment accordingly and quickly. Functional ultrasound imaging techniques such as contrast enhanced ultrasound, molecular ultrasound and elastography, show great promise for the evaluation of tumour response to therapy. They are also affordable and quick to perform making. This project will develop 3D ultrasound imaging which can measure multiple ultrasound characteristics of tumours which may be used to evaluate tumour response to therapy.

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3D ultrasound contrast imaging biomarkers for assessment of tumour response to cancer therapies

Ultrasound contrast imaging is an effective method for monitoring the response of the tumour vascular system to cancer therapies such as targeted drug therapies which target the tumour blood supply, radiotherapy and chemotherapy. One limitation of the techniques is that it is a 2D imaging technique, typically allowing only a small portion of the tumour to be evaluated. We are developing 3D ultrasound contrast imaging which will allow us to evaluate the response of the entire tumour and to look for heterogeneity in tumour response, which is believed to contribute to treatment resistance.

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Radiation treatments are planned using Computed Tomography (CT) scans of the patients. These images allow us to plan the radiation beam arrangement to target the cancer and avoid other tissues, based on the position of the anatomy at CT scanning. Changes in anatomy between CT scanning and treatment, and motion of tissues during radiation delivery means that the treatment may not be delivered exactly as planned. These changes decrease the accuracy of radiotherapy and increase the likelihood, and in some cases, the severity of treatment toxicity. By imaging the radiotherapy target, just prior to and during the treatment, we can ensure that the radiation is safely delivered as planned. Furthermore, some cancers will respond to radiotherapy and some cancers may not respond. Clinicians would like to be able to understand, as soon as possible which tumours are responding and which are not, allowing them to alter the treatment for the best chance of success, or to stop the treatment if the patient will not benefit.

Dr Harris’s group develops new image processing techniques, new implementations of established, and novel, ultrasound technologies to image soft tissues and to estimate their motion during therapy. Ultrasonic elastography and ultrasound backscatter characterisation techniques are being developed for the purpose of assessing the response of cancer and normal tissues to treatments of breast and head and neck cancers. The group, are exploring further integration of functional and molecular ultrasound imaging into the radiation treatment room techniques. Multi-parametric ultrasound imaging has potential to be an affordable and easily implantable method of monitoring tumour response to radiotherapy.

In collaboration with clinical colleagues at the Royal Marsden Hospital the group are currently testing a number of these techniques in clinical trials. These techniques enable more accurate delivery of radiation therapy that spares normal tissue from radiation damage and helps improve the efficacy of radiation therapy.

Dr Harris is a state registered clinical scientist and is a member of the NCRI Breast Clinical Studies Group.