Around 1950s Mass miniature radiography or MMR was a cornerstone of public health screening for Tuberculosis. It was a mobile X-ray unit that roamed villages, towns and cities, photographing the chests of millions of men women and children. It was a new technology, that was fast, scalable, and visually compelling. Yet by 1980s, MMR programs faded away from the public health landscape in many countries.
What Was Mass Miniature Radiography or MMR ?
Mass miniature radiography was a method of producing small-format chest radiographs. The equipment used a fluoroscopic screen photographed onto film (often 35–70 mm). Fluoroscopy is a method of continuous X-ray imaging via a glowing screen. Photofluorography was the next step, photographing of that screen onto small film. The miniature film format dramatically reduced cost and allowed mobile units to process large numbers of participants quickly. Trained readers could identify pulmonary lesions, especially those suggestive of active TB. The idea was to screen broadly, detect early, and intervene to break chains of transmission.
Beginnings of a technology
The technology began in 1930s in Europe, and during World War II, several nations used MMR to maintain military fitness. In the postwar years, MMR spread widely across high-income countries. TB control programs embraced it as a means to find infectious cases early, reduce community burden, and monitor high-risk settings. The technology from high income countries penetrated to TB endemic low income countries by 1960s. This field screening was used along with other screenings, such as clinical examination and tuberculin test.
MMR was not alone
TB burden was high enough to make broad screening yield meaningful numbers of cases. Further, it was a medical “progress,” that was backed by governments. Medicines for TB had just become available in 1950s, so MMR made a perfect sense. The X-ray beam passed through the chest to a screen, converting X-rays to visible light. Radiologists or trained readers used magnifiers or dedicated viewers; suspicious films prompted a call-back for a full-size chest radiograph and sputum microbiology.
Pitfalls
It was good for large lesions, but subtle early disease and small nodules could be missed due to image size and resolution limits. Further, entire population was exposed to X-rays, and as prevalence of TB waned, positive yield became low. Further, as more and more people were treated for TB, abnormal MMR films did not have active TB. Healed lesions would also lead to abnormal films, and hence another round of diagnosis.
Beginning of a decline
By 1970s MMR began to sunset. Public health strategy shifted from blanket screening to targeted approaches (contacts of known cases, migrants from high-burden settings, people living with HIV in later years, residents of shelters or correctional facilities). Symptom screening and bacteriological testing (sputum smear, later culture and molecular tests) became central pillars. Thus maintaining fleets of vans, specialized cameras, film processing, and reading centers became expensive relative to targeted strategies.
In the digital Renaissance, it seems to be making a comeback. Ultra-portable Digital X-ray, and AI-Aided Reading suggest that it may be a good idea, especially in high TB burden settings. However the problem of false positive radiography is likely to remain. MMR made TB visible, medically as well as socially. It invoked citizens to “Get your chest X-rayed,” often linking TB control with civic duty and modernity.
