Quality Assurance of a Two-Dimensional CCD Detector System Applied in Dosimetry

Nowadays, charge-coupled devices (CCDs) are applied for many technological purposes, including areas as astronomy, medical diagnosis and the ones related to light detecting sensors. One of the main advantages of a digital detector is its ability to store and rapidly transfer information to digital equipments, where data can be computed (post-processing). In fact, this is a relevant feature for medical applications, specially for imaging fields, in which the radiation exposure time is highly controlled when different image quality adjustments are necessary. The main goal of this article is to demonstrate a CCD application for optical density-based dosimeters, where high accuracy and spatial resolution are required. An optical prototype was developed considering a visible light source and a CCD camera, allied with a computational processing routine. The system resolution was inferred through two different methodologies, which support a spatial resolution better than 0.5 mm: 1) a radiological test system (line pair gauge) and 2) the modulation transfer function (MTF). Results also indicate that, due to CCD suitable resolution, one and two dimension responses can be acquired. Considering the easiness and fastness of the process, the developed system exhibits potential applicability for radiotherapy dosimetry.