1996 Volume 52 Issue 3 Pages 364-370
Analysis of the focal-spot size is important for the quality control (QC) program concerning a clinical X-ray film system. It is especially important in magnification radiography. In this study the focal-spot size of a microfocus X-ray tube (Toshiba, DRX-89H) was studied using a slit focal spot camera (Nuclear Associates, Roeck). The focal-spot was examined visually. Its length was 0.115mm, and its width was 0.183mm, according to the measurements obtained by the slit images. That result were not sufficient for NEMA and IEC standards. The grid bias voltage affected the focal-spot size of the three-conductor terminal X-ray tube. Therefore, we measured it according to changes in the automatic control and the manual control of the grid bias voltage which improved (minimized) the focal spot. That obtained the best grid bias voltages to correspond with the tube voltages. We improved the focal-spot size, to 0.113mm in length and 0.165mm in width.
