Njeh C F, Apple K, Temperton D H, Boivin C M
Medical Physics Department, University Hospital Birmingham NHS Trust, Edgbaston, UK.
Br J Radiol. 1996 Apr;69(820):335-40. doi: 10.1259/0007-1285-69-820-335.
Dual energy X-ray absorptiometry (DXA) is one of the most widely used techniques in the management of osteoporosis and other skeletal diseases. Although patient doses from DXA are generally low, it is still necessary to measure them to assess the risk of radiation injury. We report on a study to estimate the effective dose (ED) to patients and staff from a new DXA scanner--the Lunar EXPERT, and make a comparison with a similar study carried out on a Lunar DPX-L. The entrance surface doses were measured to be 895 microGy and 10.25 microGy for the EXPERT and DPX-L, respectively. The EXPERT maximum EDs were calculated to be 74.7 microSv and 44.9 microSv for the anteroposterior (AP) lumbar spine and the proximal femur, respectively. More than 50% reduction in ED could be achieved by using a smaller scanning width. The maximum EDs for the DPX-L were calculated to be 0.21 microSv and 0.15 microSv for the AP lumbar spine and the proximal femur, respectively. The scattered dose rates (ambient dose equivalent) were measured to be less than 2 and less than 1 microSv h-1 at 50 cm and 100 cm, respectively, for the DPX-L, and the equivalent values for the EXPERT were 240 and 64 microSv h-1. Although both the patient dose and scattered dose rates are quite low relative to other radiological examinations, good practice aimed at dose reduction should still be implemented. Whilst protection for the operator is not needed for the DPX-L system, it may be (depending on the size of the room) for the EXPERT system.
双能X线吸收法（DXA）是骨质疏松症和其他骨骼疾病管理中使用最广泛的技术之一。尽管DXA给患者的剂量通常较低，但仍有必要对其进行测量以评估辐射损伤风险。我们报告了一项研究，旨在估计新型DXA扫描仪——Lunar EXPERT给患者和工作人员带来的有效剂量（ED），并与在Lunar DPX-L上进行的类似研究进行比较。EXPERT和DPX-L的体表入射剂量分别测量为895微戈瑞和10.25微戈瑞。EXPERT前后位（AP）腰椎和近端股骨的最大有效剂量经计算分别为74.7微希沃特和44.9微希沃特。通过使用较小的扫描宽度可使有效剂量降低50%以上。DPX-L的AP腰椎和近端股骨的最大有效剂量经计算分别为0.21微希沃特和0.15微希沃特。DPX-L在50厘米和100厘米处的散射剂量率（环境剂量当量）测量值分别小于2微希沃特/小时和小于1微希沃特/小时，EXPERT的等效值为240微希沃特/小时和64微希沃特/小时。尽管相对于其他放射学检查，患者剂量和散射剂量率都相当低，但仍应实施旨在降低剂量的良好做法。对于DPX-L系统，虽然不需要对操作人员进行防护，但对于EXPERT系统可能需要（取决于房间大小）。
