Mobile X-Rays deployed to Improve TB Detection

Mobile X-ray project aims to find those people who do not present at health facilities and who may have TB but are asymptomatic.

Professor Martie van der Walt, director of the Tuberculosis Platform at the South African Medical Research Council, says the mobile X-ray equipment can be fitted in mobile vans or trucks and have the same performance as floor-mounted models.

She says the X-ray needs to be read by a trained medical officer, and a mobile unit requires a mobile truck, a driver, and a radiographer, so a certain level of resources is required.

Among the biggest advantages of the mobile X-ray units, is that more people can be screened and diagnosed because it can be moved to where the services are most needed, such as workplaces or for community outreach activities or campaigns.

“During such a community outreach activity those with current symptoms of TB but who were still planning to seek care, those with asymptomatic TB and those that had not known about TB signs and symptoms will all be diagnosed,” says van der Walt. “Mobile trucks bring one of the most sensitive methods to diagnose TB right to the communities where people live, and it gives an immediate result. The image of TB on a chest X-ray is very typical and gives an immediate result,” she explains.

“The speed of undergoing a CXR and the immediacy of the result makes CXR a method that can be used to screen large numbers of people in a short time, and those with presumptive TB symptoms can then be issued with a referral letter. CXR screening can be done without prior knowledge of signs and symptoms.”

Benefits and challenges

Van der Walt says that while the image of TB on a chest X-ray is very typical of TB, the disadvantage is that the image does not show if it is a current/active disease or scars from an old/already cured disease.

“Therefore, a diagnosis by chest X-ray does not mean a person should be treated and seen as infectious. When a diagnosis by chest X-ray is made, the person will still have to undergo other investigations (typically Gene Xpert or culture testing) to determine if it is active disease.

The investigations are to look for TB organisms in sputum. If found in sputum it is an indication of current disease,” she says. “In a high prevalence country, there are many people who had TB long ago and therefore when screening a population at community level a lot of old or healed TB is seen on chest X-rays.”

There are other concerns.

Best says X-ray technology is difficult to transport and relatively expensive. “These can be limiting factors in terms of the large-scale roll-out of the technology. In addition, if stigma around TB is rife, people are unwilling to screen and this can result in a limited uptake of the service,” she says.

“The cost of the chest X-rays is almost negligible as they take digital images, however, funding is needed for more trucks and radiographers,” says van der Walt. “The medical doctors do not have to be on-site as the digital chest X-ray image can be uploaded to where the reader is, as long as there is an internet connection. Reading of a chest X-ray takes only a couple of minutes and the result can almost immediately be sent back to the truck,” she says.

“The limitation of X-rays is that it cannot diagnose other types of TB like TB of bones, spine, TB meningitis among others,” says Kekana. She also notes other challenges including budget availability to buy the X-ray machines and other equipment and material resources, the sustainability and maintenance of the machine and employing the necessary staff, especially the radiographers, and providing the required skills and training to all relevant personnel for the service.