1 CHARACTERISATION OF A FAST, REGIONAL READOUT CMOS ACTIVE PIXEL SENSOR FOR APPLICATION IN IMAGE GUIDED RADIOTHERAPY

Advanced radiotherapy techniques such as intensity modulated radiation therapy (IMRT) and intensity modulated arc therapy (IMAT) requires verification of complex treatments and tracking of moving tumours in real time. Current techniques using electronic portal imaging devices (EPID) and fluoroscopic based imaging have several limitations such as low image contrast and unnecessary skin dose. Novel complementary metal oxide semiconductor active pixel sensor (CMOS APS) may have the potential to overcome these limitations by utilising on pixel intelligence such as an on pixel analog-to-digital converter (ADC) and region of interest (ROI) functionality. This work evaluated the performance of a novel APS using optical and their ROI read out. Characterisation of the sensor is presented and full performance parameters have been calculated. The APS has a good dynamic range of 66 dB with gain of 20 e-/DN. The sensor exhibits over 100 fps digital frame rate and over 20 kHz ROI acquisition speed which is superior to less than 30 fps using standard EPIDs or fluoroscopy. The sensor also exhibit low spatial dark noise namely read noise which can be eliminated through dark image calibration. Future work will be carried on to exploit the sensor for radiotherap