Needle insertion simulator for effective RF hyperthermia treatment

Hyperthermia treatment is a kind of cancer thermal treatment based on that tumor are weak at a temperature of 42–43 degrees Celsius. A radio frequency (RF) interstitial hyperthermia treatment is operated with needle electrodes. In clinics, when a doctor performs surgery with this thermal treatment, it is needed to precisely recognize the needle insertion positon and angle inside the human body. Accordingly, medical doctors are operating with an X-ray CT. In this study, we developed a virtual insertion simulator with hand tracking sensors for planning and training effective heating before the operation. This virtual reality system measures the operator's hand position precisely, using two hand-tracking sensors arranged orthogonal to each other to cover blind spots. We experimented with ager phantom and compared the accuracy between one and two sensor systems. From the measurement results, it was found that when using two tracking sensors, the positioning accuracy improved in every direction. The differences between actual measurement data and that of the VR simulator were less than 2mm in every direction. By using the developed VR insertion simulator, medical doctors can plan and train more easily and precisely for effective RF interstitial hyperthermia surgery.

I. Introduction

Hyperthermia is a physical low-invasive treatment for cancer by heating the tumor tissues to 42-43°C [1], [2]. In clinics, medical doctors use needle electrodes to heat the tumor by insertion. Figure 1 shows the illustration of an RF (Radio Frequency) interstitial needle applicator. The electromagnetic current flows between a needle electrode inserted to the tumor and a discoid electrode pasted on the patient's skin. The electromagnetic energy is concentrated to the tip of the needle electrode to heat the tumor over 43°C. Therefore, doctors need to insert the needle applicator precisely to the target region in a CT imaging room with radiation exposure [3], [4]. In addition, the heating region will be changed greatly by the angle and the position of the needle electrode. Accordingly, it is difficult to insert the needle into the target without CT imaging. For successful treatment, medical doctors need to train for critical insertion before the surgery, including simulation practice [5]–[9]. Fig. 1

RF interstitial needle applicator.