Oakley Paul A, Harrison Deed E
Private Practice, Newmarket, Ontario, Canada.
CBP NonProfit, Inc., Eagle, ID, USA.
Dose Response. 2021 Feb 22;19(1):1559325821995653. doi: 10.1177/1559325821995653. eCollection 2021 Jan-Mar.
There are pressures to avoid use of radiological imaging throughout all healthcare due to the notion that all radiation is carcinogenic. This perception stems from the long-standing use of the linear no-threshold (LNT) assumption of risk associated with radiation exposures. This societal perception has led to relentless efforts to avoid and reduce radiation exposures to patients at great costs. Many radiation reduction campaigns have been launched to dissuade doctors from using radiation imaging. Lower-dose imaging techniques and practices are being advocated. Alternate imaging procedures are encouraged. Are these efforts warranted? Based on recent evidence, LNT ideology is shown to be defunct for risk assessment at low-dose exposure ranges which includes X-rays and CT scans. In fact, the best evidence that was once used to support LNT ideology, including the Life Span Study data, now indicates thresholds for cancer induction are high; therefore, low-dose X-rays cannot cause harm. Current practices are safe as exposures currently encountered are orders of magnitude below threshold levels shown to be harmful. As long as imaging is medically warranted, it is shown that efforts to reduce exposures that are within background radiation levels and that are also shown to enhance health by upregulating natural adaptive protection systems are definitively wasted resources.
由于认为所有辐射都具有致癌性,整个医疗行业都面临着避免使用放射成像的压力。这种观念源于长期以来对辐射暴露风险采用的线性无阈(LNT)假设。这种社会认知导致人们不惜成本,不懈努力地避免和减少患者的辐射暴露。许多减少辐射的运动已经展开,以劝阻医生使用放射成像。人们提倡采用低剂量成像技术和做法。鼓励采用替代成像程序。这些努力是否合理?基于最近的证据,LNT理论在包括X射线和CT扫描在内的低剂量暴露范围内进行风险评估时已被证明是无效的。事实上,曾经用来支持LNT理论的最佳证据,包括寿命研究数据,现在表明诱发癌症的阈值很高;因此,低剂量X射线不会造成伤害。由于目前所遇到的辐射暴露比已证明有害的阈值水平低几个数量级,所以当前的做法是安全的。只要成像在医学上是必要的,那么在背景辐射水平内且已证明通过上调自然适应性保护系统可促进健康的情况下,减少辐射暴露的努力无疑是浪费资源。