Characteristics relevant to portal dosimetry of a cooled CCD camera-based EPID.
Our EPIDs have recently been equipped with Peltier-cooled CCD cameras. The CCD cooling dramatically reduced deteriorating effects of radiation damage on image quality. Over more than 600 days of clinical operation, the radiation induced noise contribution has remained stable at a very low level (1 SD < or = 0.15% of the camera dynamic range), in marked contrast with the previously used noncooled cameras. The camera response (output signal versus incident EPID radiation exposure) can be accurately described with a quadratic function. This response reproduced well, both in short and long term (variation < 0.2% respectively < 0.4% (1 SD)), rendering the cooled camera well-suited for EPID dosimetry applications.
Franken
E M
EM
Department of Radiation Oncology, Division of Medical Physics, Erasmus MC/Daniel den Hoed Cancer Center, Groene Hilledijk 301, 3075 EA Rotterdam, The Netherlands. efranken@erasmusmc.nl
de Boer
J C J
JC
Barnhoorn
J C
JC
Heijmen
B J M
BJ
D003080:Cold Temperature; D019544:Equipment Failure Analysis; D011856:Radiographic Image Enhancement / Q000295:instrumentation* / Q000379:methods; D011874:Radiometry / Q000295:instrumentation*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000295:instrumentation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014741:Video Recording / Q000295:instrumentation*