Giarratano J C, Duerkes R J, Almond P R
Med Phys. 1975 Nov-Dec;2(6):336-7. doi: 10.1118/1.594205.
The relative percent dose reduction by lead of 7- to 18-MeV electrons with a Siemens betatron and of 19- to 28-MeV electrons with a Sagittaire linear accelerator has been measured with a thin-wall buildup chamber for 6.3 X 6.3- and 10.5 X 10.5-cm field sizes at the chamber position for the normal treatment source-to-skin distance (SSD) of each machine. The thickness of lead necessary to attenuate the open beam by 95-98% was then determined of 7- to 28-MeV electrons. The required thickness of lead to attenuate 95% of the 7- to 28-MeV electron beam ranged from 2.3 to 18 mm for the 6.3 X 6.3-cm field and from 2.4 to 23 mm for the 10.5 X 10.5-cm field, respectively. For 98% attenuation, thicknesses from 2.6 to 25.0 mm for the 6.3 X 6.3-cm field and from 2.8 to 27.5 mm of lead for the 10.5 X 10.5-cm field were necessary.
使用薄壁积累电离室，在每台机器正常治疗源皮距（SSD）下，对西门子电子感应加速器产生的7至18兆电子伏特电子以及萨吉塔勒直线加速器产生的19至28兆电子伏特电子，在6.3×6.3厘米和10.5×10.5厘米射野尺寸的电离室位置，测量了铅对剂量的相对百分降低率。然后确定了使7至28兆电子伏特电子的开放射束衰减95%至98%所需的铅厚度。对于6.3×6.3厘米射野，使7至28兆电子伏特电子束衰减95%所需的铅厚度范围分别为2.3至18毫米，对于10.5×10.5厘米射野则为2.4至23毫米。对于98%的衰减，6.3×6.3厘米射野需要2.6至25.0毫米厚的铅，10.5×10.5厘米射野需要2.8至27.5毫米厚的铅。
