Modulated Electro-Hyperthermia in the Treatment of Brain Cancers: A Study of Safety and Effects

Abstract

Brain cancer is one of the deadliest forms of cancer with 5 year survival rates recording around 22% with no improvements over several decades. Current treatment methods rarely deviate from surgery, radiotherapy and chemotherapy. Modulated Electro-Hyperthermia (sometimes referred to as oncothermia) is a non-invasive cancer treatment method which uses non-ionising 13.56 MHz radiofrequency radiation to induce therapeutic hyperthermia in tumours. Repeated treatment using this method has been shown to cause tumour cell apoptosis. The technology is currently being used in Europe, parts of Asia and America. Resistance to the uptake of this technology is based on lack of understanding of how to optimally use the device and concerns over safety of the patient regarding overheating. Current protocols utilise a step-wise increment of power dosage using patient discomfort as an indicator. However, discomfort is not a reliable feedback mechanism, particularly when treating brain cancer. This thesis investigates four different points. Firstly, what is the relationship between energy dose and resulting temperature? Does the clinical device accurately measure internal temperatures? Does the treatment have any side effects on healthy brain tissue? Finally, what clinical monitoring protocol could be used to ensure optimal treatment of patients? These research questions were investigated using a variety of experimental techniques. Phantom models were designed and used to study the relationship of energy dose to temperature profile and accuracy of temperature measurement. Animal models were used to study potential side effects on the brain. Lastly, image processing techniques were used to develop a clinical monitoring system. It was determined that hydration, electrolyte balance, tissue composition and location of the treatment area had important roles in determining optimal energy dosage. While no gross tissue damage occurred from optimal treatment usage, there is cellular response to the treatment. Tumour volumes and locations can be analysed from diagnostic MRI scans to aid optimisation of treatment protocol.