November 8, 2005
'IMRT Sensors' - a smart dose of medicine for cancer treatmentTopics: Medical Science News
IMRT, developed about 10-years ago, works by ‘painting’ small areas of different intensity radiation over the tumour. It involves the use of a servo-controlled device called a multi-leaf collimator, that has about eighty "moving fingers" that can "allow or stop" the radiation from the treatment machine reaching the patient. It's precise control allows a three dimensional pattern of dose to be scaled up. By painting the dose distribution in this manner, a high tumour-killing radiation dose is conformed to the tumour while an acceptably low and safe radiation dose goes to the surrounding tissues and vital organs. This is very different from conventional radiotherapy in which no such painting is done and the high dose can extend beyond the tumour and damage healthy tissue.
Intensity Modulated Radiotherapy (IMRT), is a radiation therapy for cancers that improves clinical outcomes by a providing more accurate targeting of tumours then with standard radiotherapy, and minimising the amount of radiation absorbed by healthy tissues. The good news about IMRT is that it results in patients only receiving a high radiation dose where they need it, thereby preserving healthy tissues. But like most good things in life, it doesn't come with a free lunch - there's a catch. It becomes increasingly more difficult to verify that patients are receiving the prescribed dose of radiation during the course of treatment, because of the complex computer simulations required by IMRT. There's a need to validate the simulations by verifying exactly how much radiation is reaching the patient, and where it's going, and up to now, that's been a problem.
But now INVORAD has come up with a solution by developing two sensors, a silicon diode and a p-channel metal-oxide semiconductor field-effect transistor (MOSFET), to solve the validation problem.
"Several features, such as miniature size, response to types of radiation involved in radiotherapy, compatibility with microprocessors that enables real-time read-out and low cost, make these semiconductor sensors eminently suitable for the intended application...Read more ...
The diode sensor system is arranged in a series of modules containing 1069 individual diodes that can pick up incoming radiation.
"These diodes need to be very small and while there are commercial packaged diodes out there we needed diodes in bare die form with some novel properties so we developed the diodes ourselves, here at the Tyndall Institute," ...
The arrays are extremely accurate and can track radiation at micro-Gray resolution over millimetres of spatial resolution.
Posted by Richard at November 8, 2005 6:33 PM
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