Quality control of superficial hyperthermia by treatment evaluation

Steering of multi-element heating arrays for superficial hyperthermia (SHT) can be a challenge in the clinic. This is because the technician has to deal with a multiple-input multiple-output system, varying tissue dynamics, and often sparse tissue temperature data. In addition, patient feedback needs to be taken into account. Effective management of the steering task determines the quality of heating. Systematic evaluation is an effective tool to control the quality of treatments. The purpose of this manuscript is to report on a treatment evaluation flow developed for SHT at the Erasmus MC. This flow is used to secure the quality of steering as well as to stimulate general quality awareness in the hyperthermia team. All treatments are evaluated in a multidisciplinary discussion. Tools and methods were developed to enable effective and efficient evaluations. The treatment evaluation sheet is a compact and intuitive representation of power and temperature data. Trend lines and a temperature-depth plot allow a quick analysis of the steering parameters and the heating profile within the target volume. In addition, the principal statistics of applicator power, water bolus and tissue temperature values are given. Power steering data includes the number of switch-off events, interruption time and the number of steering actions. A list of basic checks and reference values for clinical data support further the treatment evaluation. These tools and the systematic treatment evaluations they facilitate, ultimately lead to consistent performance and fine tuning of the set-up and steering strategy for each individual patient.