격자와 초점간 거리에 따른 Cut-Off 현상

Purpose : The grid in one of the most effective ways to eliminate scattered radiation is shown a specified FD (focus distance). We for FGD (focusgrid distance) grid specified regulation range of the FD widely in FGD the grid to minimize the cut-off phenomenon due to changes. In case can not keep a specified FD is displayed on grid to evaluate find best FGD to minimize cut-off phenomenon. Materials and Methods : 85 lines/inch, FD: 100 ~ 180 ㎝ <grid 1> and 103 lines/inch, FD: 100 ㎝ <grid 2> in the X-ray imaging apparatus <grid 1>, <grid 2> grid ratio (6:1, 8:1, 10:1, 12:1) and measuring the transmission while changing the dose of the FGD 7.5 ㎝ and 15 ㎝ to right and left (LㆍR) from the center of gravity and the center (0 ㎝) of grid to the grid in the center the dose was calculated to 100% and the transmission dose (%) of right and left distance. Results : 1. <grid 1> is FGD 100, 150, 180, 200 ㎝ in the dose of L transmitting to R 15 ㎝ (%) was defined for both IEC. 2. <grid 2> 50 ㎝ 10 in FGD: 1, 12:1 in the lattice portion is transmitted through the dose (%) was not appropriate to the IEC standard with more than 60%. 3. <grid 1> impact of the transmission attenuation difference between the lowest dose is 150 ㎝ when the FGD days. 4. <grid 2> impact was greater than 50 ㎝ when the transmission is in accordance with dose attenuation difference FGD change is 150 cm. 5. Even if the same distance great influence higher ratio grid. Conclusion : If the grid is in the range of regulation FD designated broadly FD of mid-point of minimum distance and maximum distance suitable and to be suitable for use remotely rather than using if not keep the specified FD of the grid has to close the FGD the feed. In addition, even the same distance, it is necessary to identify a higher grid ratio of the FD and the attenuation difference in the non-grid using the X-ray imaging apparatus to be adjusted due to the size of the recording conditions.