[Feasibility of a new initial check-up program for medical X-ray and computed radiography systems]

We investigated the feasibility of a simple, easy method that uses a digital radiography (DR) phantom for daily operational checks of the medical X-ray system and computed radiography (CR) system. First, we measured exposure indicator calibration (S value) from 12 seconds to 11 minutes after irradiation to examine the effect of fading of the photostimulable phosphor screen. We then examined the management width of the exposure indicator calibration ratio and limiting resolution of the CR system. Finally, we studied the exposure indicator calibration ratio, limiting the resolution and time necessary for the initial check-up by running the program 20 times for five weeks. Under the influence of the fading, the S value increased gradually, although the level of variation was small. From the mean and coefficient of variation of the exposure indicator calibration ratio, the management width was determined as +/-10%. The exposure indicator calibration ratio and limiting resolution were within +/-10% and +/-20%, respectively. It took three minutes to accomplish the initial check-up. The initial check-up using a DR phantom is simple and can perform the operational check of the medical X-ray system and the CR system with sufficient accuracy in only 3 minutes.