HUMAN CHEST PHANTOM SETUP FOR THE EVALUATION OF THE IMAGE QUALITY OF RADIOLOGICAL EQUIPMENT

摘要

he Human Chest Phantom (HCP) setup for the assessment of the imaging quality of a radiological machine, as it appearss in Diagram 1, comprises a shell of clear Perspex with a total thickness of about 2-3 cm. Its dimensions are such that is fits on a small cassette. It contains a high purity copper sheet, of suitable dimensions and thickness so that its absorbance of x-rays is equivalent to that of an average human body. It also contains, glued on its centre, a second high purity copper sheet of suitablle thickness and dimensions, with holes on the circumference of an inscribed circle. The holes have various diameters, the smaller being 0,5, 0,25 or 0.1 mm according to the machine (fluoroscopy, radiography or mammography) it will be used for. In parallel with the large side of the HCP, a high puurity aluminium sheet scale is embedded of suitable size and thickness. The sheets are placeddd so that they create a scale of comparable length to the length of the HCP, with sufficient width for each step. It is characterized by the fact that the assessment procedure comprises the exposure (in radiography or fluoroscopy) of the HCP and by the fact that the maximum visible number of holes and steps on film or on screen is recorded to be cmpared to the corresponding numbers which will be found in the future, daily assessment of the imaging system. The imaging of the HCP is done with the same parameter settings and geometry on the x-ray machine.