Focused ultrasound – A review

Focused ultrasound – A review

952 Abstracts / Physica Medica 32 (2016) 948–959 and MRI images. The overlapping volumes were compared for CT–MRI, CT–US (un-deformed prostate), CT–...

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Abstracts / Physica Medica 32 (2016) 948–959

and MRI images. The overlapping volumes were compared for CT–MRI, CT–US (un-deformed prostate), CT–US (deformed prostate), MRI-US (un-deformed prostate), MRI-US (deformed prostate) and US–US(un-deformed prostate and deformed prostate). Contour overlap varied from 90% to 40% for the lesion, which was approximately 1 cm3, and 96% to 78% contour overlap for the whole prostate. This study demonstrates how a tissue equivalent phantom can be used for testing and commissioning of multi-modality registration systems in brachytherapy.

Radiation protection considerations in the case death of radionuclide therapy patients Lynn Gaynor St Luke’s Radiation Oncology Network (SLRON), Ireland Radionuclide therapies have been widely used in Irish Nuclear Medicine Centres for decades. Historically, the majority of these were Iodine 131 therapies, which are typically administered across a broad range of patient ages. Palliative therapies such as Strontium 89 and Samarium 153 therapies have also been commonplace in Irish Nuclear Medicine for many years, and are clinically indicated for patient approaching their end of life. The relatively recent advent of Radium 223 therapies has meant that significantly greater numbers of patients, approaching their end of life, are now receiving radionuclide therapies. Life expectancy is a very important consideration for a prescriber in determining patient suitability for a given therapy, however difficulty in accurately estimating life expectancy is a problem among physicians, regardless of their specialty or years of experience. As such unexpected death becomes more likely in end of life care. This paper will detail radiation protection risk assessments for unexpected death of patients following administration of a variety radionuclide therapies. These will include Radium 223, Iodine 131, and also Strontium 89 and Samarium 153. One of the biggest determinants of the control measures required is the clinical pharmacology of the radionuclide in question. There will be discussion regarding radiation protection issues around for emergency surgery and in the case of death: autopsy, embalming, burial and cremation.

A case study on the use of cine MR images to create an ITV for the treatment of liver tumours with Stereotactic Ablative Radiotherapy (SABR) Cora Marshall, Luke Rock, Darina Hickey Beacon Hospital, Ireland Liver tumours are rarely visible on CT imaging without the use of contrast. In addition to the need for contrast, the CT image must be acquired at a specific phase of the contrast injection. This presents difficulties for synchronization of the contrast injection with the acquisition of a 4dCT. Liver tumours move significantly due to respiration so a reliable method of measuring motion due to respiration is required. This work describes a method to measure tumour motion using cine MR images acquired in three sagittal planes and three coronal planes at two frames per second for 30 seconds. Images were then manually binned into different breathing phases by measuring the distance between a fixed and moving anatomical point. The images were binned into five phases and imported into the Eclipse TPS. The tumour was drawn on each MR image set and a composite tumour volume was constructed to create the ITV. For treatment planning, an end-expiration breathhold CT simulation was acquired. This CT scan was registered with

each MR image set and the ITV generated from the cine MR images was transposed onto the CT scan. This work has demonstrated that the use of cine MR images of liver tumours may be used to assess motion due to respiration and represents a valuable tool in the treatment planning of SABR for such tumours.

Focused ultrasound – A review Aoife O’Brien University College Hospital Galway, Ireland ‘Focused ultrasound’ (FUS) is a term used to describe a range of techniques using high intensity ultrasound in medical treatment. It is not new – the first patient treatment was recorded in 1957 but for many years, the technology was considered unwieldy and of limited usefulness since it was difficult to track progress during treatment. However, FUS has enjoyed a resurgence of interest recently – partly due to new imaging techniques that allow FUS treatment to be accurately targeted and monitored in real time. In addition, FUS is non-ionising and non-invasive, two attractive attributes as modern healthcare continues to move towards minimally invasive treatments and shorter hospital stays. FUS can interact with tissue in many ways. High intensity thermal interactions and disruptive mechanical interactions, (such as cavitation), are well understood and widely used in surgical treatments. However, several other non-thermal interactions are possible and have interesting therapeutic applications such as sonoporation, localised vasodilation, opening of the blood-brain-barrier, and neuromodulation. Further development is still needed to improve the effectiveness, safety and applicability of FUS but a significant number of clinical trials are ongoing. Many of the early trials have recently come to a conclusion and have demonstrated promising results, clearing the way for the use of FUS treatments in the wider population. If this happens, FUS could significantly reduce the need for radiation and surgery in healthcare and change patient management in a wide variety of illnesses.

Poster Presentations A proposed process map for respiratory gated radiotherapy Amanda Barry a, Alan Pembroke a, Eimear O. Neill a, Olex Boychak b a UPMC Whitfield Cancer Centre, Ireland b St. Luke’s Radiation Oncology Network (SLRON), Ireland Aim. To propose a process map that improves the operational effectiveness and overall process performance for patients undergoing respiratory gated radiotherapy. Introduction. Respiratory motion gating in radiotherapy is performed to manage target or organ motion in the thorax and abdomen that can be influenced by breathing. In order to accurately and reproducibly account for respiratory motion, careful management of the patient before and during a respiratory gated procedure, as well as management of data acquisition methods for treatment planning and treatment delivery purposes are critical. This article integrates respiratory gating practices from the UPMC Whitfield Cancer Centre with respiratory gating methods reported in the literature to propose a process map which can optimally manage this complex technique. Discussion of results. A critical assessment of the various stages in the proposed process will be presented which will highlight improvements in overall process performance. Specific focus will