Design and study of in-house automatic cancer patient movement monitor for radiotherapy using a micro switch controlled circuit

Accurate patient positioning and monitoring play a vital role in radiotherapy to achieve maximum tumour control and minimal normal tissue complications. The main aim of the present investigation was to fabricate indigenously micro-switch controlled circuit based Automatic Patient’s Movement Monitoring Device (APMMD) used with the radiotherapy machine that immediately halts the teletherapy treatment if patient moves claiming accurate field treatment. This device prevents unnecessary radiation exposure to a patient's normal tissue in situations where immobilization devices are not utilized. The APMMD consists of two micro switches, two LED’s, two buzzers and two AA batteries and two sensor devices. Patients were placed in between the two sensor devices which are near the treatment area. The movable rod of the sensor should touch the patient’s body on both sides. If the patient moves left lateral side, the left inner rod moves inward to the outer rod, and the micro switch is activated, so that the alarm is activated and the LED goes to OFF position automatically. Furthermore, the treatment halts automatically and repositioning of the patient is necessary to continue the treatment. This equipment is utilized for observing the movement of 130 patients with different types of cancer. Our preliminary clinical results indicate that 77 patients were moved from their position during the treatment, whereas the rest received the radiation without movements. This low cost electronic compact device and alarm system can detect patient movements with a sensitivity of about 0.5cm.