Physical characteristics of anti-scatter grids according to old and new JIS standards

JIS Z 4910 (anti-scatter grids) of the JIS standards was revised in 2000. Major points of revision were the provision of general-purpose and mammographic anti-scatter grids and changes in the diameter of the measuring field and difference in the manufacturing allowance. We measured the physical characteristics (grid selectivity, contrast improvement ratio, and grid exposure factor) of [general-purpose anti-scatter grids] referring to the methods of measurement [JIS Z 4910:2000] and [JIS Z 4910:1983] using an inverter-type high-voltage generator. Physical characteristics indicated a lower value for [JIS Z 4910:2000] than for [JIS Z 4910:1983]. [JIS Z 4910:2000] was able to measure primary radiation and scattered radiation more accurately than [JIS Z 4910:1983] because of the diameter of the measuring field and the measurement arrangement. Moreover, the physical characteristic values were influenced by radiation quality, e.g., differences in high-voltage generators. In the method of measuring stipulated by JIS, strict conditions regarding the arrangement of the measurement tools and the stability and other factors of the power output of the X-ray generator are provided for the type approval test conducted by the manufacturer.     

Use of grids in mammography

The authors report their experience in grid mammography in 265 patients. Image quality of grid mammograms was compared with conventional film-screen combination mammograms. The superior image quality of grid mammography, especially in large size breasts, was demonstrated. On the other hand the images obtained using grid fixed and Potter resulted almost alike.     

Effectiveness of antiscatter grids in digital subtraction angiography

An analysis of the potential value of antiscatter grids for digital subtraction angiography (DSA) is presented. Using the Rose criterion for signal detection, and assuming quantum limited statistical noise, it is shown that grid selectivity and primary transmission are the two most important parameters of grid performance for DSA. In comparison with conventional grids commonly in current use in radiology departments, a grid having a higher level of primary transmission, (approximately 90%) and a moderate level of selectivity (approximately 6) could provide comparable imaging signal-to-noise ratios, but with 20% to 45% smaller patient dose. Implications of these results are discussed.     

Characterization of the rotating display

The rotating display is a useful method for reviewing single photon emission computed tomography (SPECT) data. This study evaluated the requirements for a subjectively pleasing and useful implementation of this technique. Twelve SPECT data sets were modified and viewed by several observers who recorded the minimum framing rates for apparent smooth rotation, 3D effect, effects of image size, and other parameters. The results showed that a minimum of 16 frames was needed for a useful display. Smaller image sizes and more frames were preferred. The recommended minimal framing rate for a 64-frame study is 16-17 frames per second and for a 32-frame study, 12-13 frames per second. Other enhancements also were useful.     

旋转式生物反应器培养细胞因子诱导的杀伤细胞研究

目的采用旋转式生物反应器（rotating wall-vessel bioreactor,RWV）与传统的T-Flask培养瓶培养人外周血细胞因子诱导的杀伤（cytokine-induced killer,CIK）细胞,比较CIK细胞的增殖能力、细胞因子分泌情况、细胞杀伤力。方法提取健康志愿者的外周血,分离出外周单个核细胞（peripheral blood mononuclear cell,PBMC）,体外诱导成CIK细胞,分别接种到T-Flask培养瓶及RWV中培养。采用台酚蓝染色法检测细胞活率并绘制其生长曲线;ELISA法检测各组CIK细胞的IL-2,IFN-γ,TNF-α分泌情况;乳酸脱氢酶测定法检测CIK细胞对靶细胞的杀伤力。结果与传统的T-Flask培养瓶培养CIK细胞比较,RWV培养CIK细胞增殖数量明显多且生长力旺盛;使用RWV培养CIK细胞能使其分泌更多的IL-2,IFN-γ,TNF-α细胞因子;RWV组培养的CIK细胞对肿瘤细胞的杀伤力更强。结论RWV培养CIK细胞更能提高其增殖能力、细胞因子分泌能力及肿瘤杀伤活力,同时可解决传统细胞培养数量少、稳定性差、易污染、工作量大及周期长等问题,有效地降低临床治疗成本。