Analysis of an Abdominal Compression Device to Reduce Respiratory Motion of Lower Thorax and Abdominal Tumours

Stereotactic ablative body radiotherapy (SABR) offers the ability to deliver a high dose of radiotherapy accurately to small tumours. It is an established, effective, non-invasive treatment option for early lung cancers as an alternative to surgery and in the treatment of limited spread of cancer (called oligo-metastatic disease) in the context of clinical trials (CORE, SARON, ABC-07 etc.). In order to deliver a high dose of radiation without damaging the surrounding structures, an accurate map of the tumour and the surrounding organs and their relationship to each other when moving (for e.g. during breathing) is important. This is usually achieved by getting a radiotherapy treatment planning 4 dimensional CT scan (4D-CT). When either the tumour or organ around them (like the lung) are moving excessively it becomes difficult to target the radiation beams and often the only solution is to treat a larger volume which covers the extent of the movement. Treating larger volumes often leads to more toxicity to the surrounding tissues.Therefore managing motion is critical to increasing tumour control probability (TCP) and reducing normal tissue complication probability (NTCP). In this context, the question of reducing the movement caused by breathing, of tumours in the lower lung and upper abdomen (like the liver, adrenals, kidney etc) is an area of intense interest. Various technical and physical methods exist to help improve motion management in patients under going radiotherapy. By limiting the movement, the target volume is smaller and this enables treatment of the tumour to high doses with lesser toxicity as some of the toxicity of radiotherapy is proportionate to the volume treated i.e. lower the volume of treatment lesser the risk of toxicity.

Abdominal compression is one such method and is well accepted to be beneficial in reducing tumour motion.

However, many of the previous studies require expensive and resource intensive immobilisation devices, costing, in many cases in excess of £10,000. This study will investigate the use of an independent compression device which can be used with any existing immobilisation system and costs in the region of £1,500. If proven to be beneficial this will allow many smaller centres or centres with budget limitations to also achieve the benefits of abdominal compression without extensive resource and cost requirements.