The standard general purpose of anti-scatter girds: JIS Z 4910: 2015 (IEC 60627: 2013) has been revised, with the new addition of an image improvement factor (Q) to the physical characteristic. Using aluminum (Al) and fiber-interspaced anti-scatter grids; we studied the meaning of Q by calculating each of the physical characteristics and assessing the image. The experimental method was based on JIS Z 4910: 2015. The two anti-scatter grids had a grid ratio of 12: 1 and a strip frequency of 40 cm⁻¹. Assessment items consisted of grid exposure factor (B), grid selectivity (Σ), contrast improvement ratio (K), and Q. In addition, the contrast to noise ratio (CNR) and contrast-detail curve (CD-curve) were determined from the contrast-detail phantom image, and the inverse image quality figure (IQF) was then calculated from the CD-curve. Compared to the Al-interspaced anti-scatter grid, the fiber-interspaced anti-scatter grid had B at 0.87, Σ at 0.95, K at 0.99, and Q at 1.14. In the assessment of the contrast-detail phantom image, the fiber-interspaced anti-scatter grid had an IQF of 1.02 times and a CNR of approximately 1.24 times when compared to the Al interspaced anti-scatter grid. The fiber-interspaced anti-scatter grid was superior with respect to the B and Q of the physical characteristics and to the CNR of image quality assessment.