Automating Radioactive Patient Discharge Using Wireless Radiation Monitors and a Mobile Phone

Radioactive iodine therapy (RAI) using a high dose of I-131 (3 or 5.5 GBq) is an effective regime to eradicate or ablate any remnant cancerous thyroid tissues after surgery or thyroid cancer which has metastasized. Hong Kong radiation regulations mandate that a patient with radioactivity of higher than 0.4 GBq of I-131 has to be hospitalized. In practice, these radioactive patients are isolated individually in radiation-shielded isolation rooms in a cancer ward until their remaining radioactivity falls below 0.4 GBq. Normally, for a dose of say, 3 GBq, it may take a couple of days for the body to excrete the excess iodine to below the quarantine level. A physicist is usually called to the ward and perform an external dose rate measurement to try to ensure the residual radioactivity to be below discharge level using a handheld radiation monitor, measuring at 1 meter from the patient. This procedure may need to be repeated if the current measured radiation level exceeded the patient discharge threshold. In this project, the cumbersome manual approach was replaced with an in-house developed automated method by mounting a wireless radiation monitor on a wall and ask the patient to stand on a footmark on the floor at 1 meter and radiation data acquired automatically with a WiFi-connected mobile phone (with an in-house app installed). A print-to-discharge button will only be enabled when the measured radioactivity is below 20 micro-sieverts per hour, which approximately equates to 0.4 GBq of I-131 in an average patient. Radiation exposure to the physicist is minimized since he/she no longer needs to enter the isolation room when the measurement can be obtained outside through Wi-Fi. This system started to go clinical in Queen Mary Hospital??s clinical oncology ward in September 2015. The advantages of this new system of radioactive patient discharge can be enhanced if ward nurses use it to discharge patients in non-office hours including weekends and bank holidays when physicists are not available on site.