Ergonomic Water Bolus Design

Abstract

Hyperthermia is a clinical cancer treatment method that relies on the principle of selectively heating tumour tissue with temperatures between 40 - 44 °C. For most head- and neck tumours deep hyperthermia treatment (DHT) is applied, in which electromagnetic energy is emitted to tumour tissue located ≥ 4cm below the skin surface. At the Erasmus MC Cancer Institute in Rotterdam, The Netherlands, electromagnetic energy is applied from a circular shaped applicator that is placed around the patient’s head or neck. A water bolus is placed between the applicator and the patient’s skin to act as a cooling agent to prevent skin burns and as a transferring agent to conduct the electromagnetic energy to the internal tumour tissue.

The goal of this master thesis was to redesign the water bolus that is currently applied in DHT at the Erasmus MC to increase patient- and operator comfort. For this purpose two main design challenges were addressed:

i) Design of an ergonomic fit for the water bolus
ii) Development of a method for uniform skin cooling and pressure control

For an optimal ergonomic fit of the water bolus, a 4D anthropometric model of head and neck was developed based on the 3D images of head and neck cancer patients that are treated at the Erasmus MC. Additionally, to secure appropriate cooling and pressure a honeycomb grid was developed. The pattern of the cavities in the grid guides circulating water through the entire volume to uniformly cool the skin. Furthermore, the grid itself provides shape stability to the water bolus, whereas the sides of the grid that are in contact with the patient’s skin provide flexibility. In addition, the water bolus was designed in a manner to enable an easy attachment to the deep DHT equipment by a sliding mechanism.