Geographic Diffusion of Digital Mammography in the United States

Background: Examining temporal and spatial diffusion of a new technology, such as digital mammography, can provide important insights into potential disparities associated with access to new medical technologies and how quickly these technologies are adopted. Although digital mammography is currently a standard technology in the United States for breast cancer screening, its adoption and geographic diffusion, as medical facilities transitioned from film to digital units, has not been explored well. Methods: This study evaluated the geographic diffusion of digital mammography facilities from 2001 to 2014 in the contiguous United States (excluding Alaska and Hawaii) and estimated the geographic accessibility to this new technology for women aged ≥45 years at the census tract level within a 20-minute drivetime by population density, rural/urban residence, and race/ethnicity. The number of mammography units by technology type (film or digital) and density per 10,000 women were also summarized. Results: The adoption of digital mammography advanced first in densely populated regions and last in remote rural areas. Overall, proportion of digital mammography units increased from 1.4% in 2001 to 94.6% in 2014, but since 2008, there was a decline in density of units from 2.31 per 10,000 women aged ≥45 years to 1.97 in 2014. In 2014, approximately 87% of women aged ≥45 years in the contiguous United States had accessibility to digital mammography, but this proportion was substantially lower for Native American women (67%) and rural residents (32%). Conclusion: Understanding the diffusion of and accessibility to digital mammography may help predict future medical technology diffusion and assess its role in geographic differences in cancer diagnosis and treatment.