Radiation dosimetry system
MedTech - ISO 13485
Of the 20 million cancer patients diagnosed each year radiation therapy is recommended for over 50%, with around 90 million treatment fractions delivered. Accurate dosage according to a treatment plan is critical to patient wellbeing, with overdosing leading to burns and tissue damage which can severely impact patient quality of life with long term implications. Acute skin toxicity is experienced by more than 70% of patients receiving radiotherapy following breast cancer. Underdosing is just as problematic, paving the way for cancer recurrence and reduced tumour control. Current systems often rely on dose estimates provided by the machines delivering the radiation, which can be inaccurate and is prone to human error. Current on-patient dosimeters to measure the actual dose received have limited accuracy and can take up to 24 hours to obtain measurements.
Electrogenics Laboratories' MOSkin system is the next generation of dosimetry technology, commercialising breakthrough technology developed by the Centre for Medical Radiation Physics at the University of Wollongong. The Centre developed a custom MOSFET semiconductor, that when properly packaged on a detector, provides an accurate and real-time measure of radiation dose. Further, the technology is completely translucent under X-ray, so it does not perturb the beam in radiotherapy and makes it uniquely suitable for diagnostic scans and interventional radiology procedures such as angiogram or spinal/vascular surgery where is it important not to obscure the surgeon's vision.
Genesys undertook the early-stage investigations of manufacturing options for the custom semiconductor and its attachment to the sensor, a search that spanned multiple continents and several technology options, before identifying a preferred option and handing over to a specialist in the field.
The system comprises three major components - the disposable radiation Sensor, a Hub for reading the dose and transmitting the data, and a mobile app Reader for displaying the data. The sensors are placed on the patient in a location set out in the patient's treatment plan. The radiation alters the properties of the oxide in the MOSFET which can be measured. Immediately after the procedure, the sensors are placed back in the Hub to read and transmit the information to the app. The Hub can accommodate four sensors at a time, which is a typical number placed on the patient.
Genesys is the lead contractor in developing the MOSkin system, undertaking all the project planning including charting a pathway to regulatory compliance. In addition to developing all the electronics and software for the system, Genesys undertook use case analysis and is leading the system level risk analysis with input from Electrogenics, medical experts and other design partners. Industrial Design and Usability was conducted by Design and Industry, with images in this case study provided by D+I as part of their concept outputs.
Design challenges in the electronics includes a conditioning circuit for reading changes in the MOSFET with very low currents in the order of microamps. A precision sampling circuit is included to ensure the measurements are undertaken to a very high accuracy. The system also includes a multiplexing circuit for measuring up to four sensor at a time.
Genesys developed the Mobile Application that manages the system, guides the user through the process and displays dose information. Key features include authentication/sign-in pages, user account management, selecting options for real-time or offline measurement of radiation, connection status, and graphical display of dose.