Funke M, Hermann K P, Breiter N, Moritz J, Müller D, Grabbe E
Abteilung Röntgendiagnostik I, Georg-August-Universität Göttingen.
Rofo. 1995 Nov;163(5):388-94. doi: 10.1055/s-2007-1016014.
The impact of different anode materials (tungsten and rhodium) on spatial resolution, image contrast and radiation exposure was studied.
Two mammographic systems providing bimetal x-ray tubes (Mo/W and Mo/Rh) were compared by imaging a breast radiography phantom with additional acrylic plates from 3 to 8 cm thickness. Spatial resolution was evaluated using a line bar pattern. Image contrast was assessed by measuring the ratio of optical densities in a acrylic step-wedge. The entrance dose was measured with a low energy ionisation chamber.
The spatial resolution was about 13 lp/mm regardless of the beam quality. The image contrast depended substantially on the thickness. A similar image contrast was found with Mo/Mo, Mo/Rh and Rh/Rh for simulated breast thicknesses of 4 to 6 cm and with Rh/Rh and W/Rh for 7 cm. In comparison to Mo/Mo the dose reduction was significant for Mo/Rh (35%), Rh/Rh (50%) and W/Rh (60%).
Bimetal x-ray tubes provide optimal conditions for screen film mammography of both normal and dense breasts, allowing good contrast and dose reduction by using the adequate anode/filter-combination.
研究不同阳极材料（钨和铑）对空间分辨率、图像对比度和辐射剂量的影响。
通过对一个乳腺摄影体模及额外厚度从3厘米至8厘米的丙烯酸板进行成像，比较两个配备双金属X射线管（钼/钨和钼/铑）的乳腺摄影系统。使用线对卡评估空间分辨率。通过测量丙烯酸阶梯楔形板中的光学密度比值来评估图像对比度。用低能电离室测量入射剂量。
无论射线质如何，空间分辨率约为13线对/毫米。图像对比度很大程度上取决于厚度。对于模拟乳腺厚度为4至6厘米的情况，钼/钼、钼/铑和铑/铑组合呈现相似的图像对比度；对于7厘米的情况，铑/铑和钨/铑组合呈现相似的图像对比度。与钼/钼相比，钼/铑（35%）、铑/铑（50%）和钨/铑（60%）的剂量降低显著。
双金属X射线管为正常乳腺和致密乳腺的屏-片乳腺摄影提供了最佳条件，通过使用合适的阳极/滤过组合可实现良好的对比度并降低剂量。
