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Detector for monitoring Multi leaf Collimator positions (P100037)


In present treatments of some types of cancers a method called IMRT (Intensely Modulated Radiation Therapy) is used where Linear Accelerator machines are programmed to send precise doses of radiation to cancerous tissues. To develop an intricate IMRT plan, a doctor will work with a medical physicist who uses complex mathematical formulas to determine the doses of radiation required and where they need to go. The machine produces a stream of electrons that are accelerated and converted into high energy X-rays. The X-rays are shaped and adjusted to destroy cancerous tissues using multi leaf collimators (MLC), moving metal leaves that determine the shape and intensity of the radiation that will enter the patient during IMRT. MLC are controlled by preprogramed computer software to shape the X-ray beams during treatment, to protect healthy tissues and target cancerous tissue.

Computers delivering the doses of radiation to patients during treatments can malfunction; if a patient receives too high a dose of radiation it can be extremely detrimental to their recovery from radiotherapy and has even resulted in fatality (e.g. Scott Jerome-Parks received a fatal radiation overdose during treatment with IMRT).

The Technology

Scientists at Swansea University in collaboration with Bristol University and Bristol Hospital have invented an ultra-thin camera system, based on a Monolithic Active Pixel Sensor (MAPS), which can be used for monitoring radiation field shapes during IMRT. The detector is connected to the computer system which delivers controlled doses of radiation to a patient during IMRT and can detect and indicate when the X-rays are correctly aligned. Small numbers of X-rays in the radiation beam interact with the MAPS detector monitor the delivery of a beam of radiation in real-time, and so allow for the timely intervention during a possible mistreatment. If there is an error during IMRT the MAPS detector can stop the treatment or signal to an operator for urgent assistant within seconds.


Producers of dosimetry devices and verification systems.

Patents have been filed in the US and Europe: EP 2654895 & US 2014010352.


Information PDF