The field of radiology has evolved considerably since the time X-rays were first used for diagnosis in the early days of radiology. The cancer risk due to high radiation doses was recognized following the experience of initial radiologists, and efforts were made to reduce the radiation dose. The average radiation dose received by the radiologists declined with time, as seen in the figure below using data from (Linet et al., 2010).
The cancer mortality rate in British radiologists has been compiled as a function of year of registration (Berrington et al., 2001), and the SMR of the radiologists when compared to male physicians is shown in the graph below:
Whereas the British radiologists who registered during 1897-1920, who had exposure to high radiation levels, had increased SMR for cancer mortality, those registered during 1955-1979, who would have exposure to low level radiation, had significantly reduced SMR for cancer mortality.
In a more recent publication (Linet et al., 2017), in a study comparing cancer mortality rate of radiologists who perform interventional procedures and so would have exposure to low level radiation and psychiatrists (who would have no radiation exposure), the SMR for male radiologists is reported to be 0.92 (0.85, 0.99).
Note: The female radiologist data also showed reduced SMR but it was not statistically significant, and so the female radiologist data has not been used here.
The above studies indicate exposure to low level radiation has a cancer preventive effect and not a carcinogenic effect, consistent with radiation hormesis and contradicting the LNT model.
Berrington A, Darby SC, Weiss HA and Doll R. 2001. 100 years of observation on British radiologists: mortality from cancer and other causes 1897-1997. Br J Radiol 74: 507-19. http://www.ncbi.nlm.nih.gov/pubmed/11459730
Linet MS, Kim KP, Miller DL, Kleinerman RA, Simon SL and Berrington de Gonzalez A. 2010. Historical review of occupational exposures and cancer risks in medical radiation workers. Radiat Res 174: 793-808. http://www.ncbi.nlm.nih.gov/pubmed/21128805
Linet MS, Kitahara CM, Ntowe E, Kleinerman RA, Gilbert ES, Naito N, Lipner RS, Miller DL, Berrington de Gonzalez A and Multi-Specialty Occupational Health G. 2017. Mortality in U.S. Physicians Likely to Perform Fluoroscopy-guided Interventional Procedures Compared with Psychiatrists, 1979 to 2008. Radiology 284: 482-494. https://www.ncbi.nlm.nih.gov/pubmed/28234559