CXR

A standard method of reading and recording chest radiographs for tuberculosis

The Background

While the majority of TB patients can have their diagnosis confirmed by bacteriology, such confirmation is not possible for a significant proportion. This proportion is increasing with the extension of TB/HIV coinfection. The current diagnostic algorithm calls for the use of chest radiography as part of the diagnosis. Previously, although widely used, this diagnostic procedure was neither standardized nor reliable. Recent collaborative work in which The Union has been involved has attempted to address this problem. A collaborative group led by the Japan Antituberculosis Association, funded by USAID and including experts from The Union has prepared a publication to improve the situation. Additionally, building on the work of the late Prof Neil White from Cape Town, experts from The Union have demonstrated the reliability of a standard reading and recording system in surveillance of tuberculosis and its use in a large international collaborative clinical trial funded by USAID. As part of this project, several experts in The Union have outlined the methods needed to arrive at excellent concordance in reading chest radiographs that can be used in any setting.
This work has led to the offering of an international course for chest x-ray reading and recording, offered in collaboration with The Union and the Desmond Tutu TB Centre by the University of Cape Town. Moreover, this group is working in collaboration with the Delft Corporation (a large international firm providing x-ray equipment) to evaluate and promote the use of digital technology for this examination. Following on these first steps, the TB Research Program will support further work to improve the quality of chest radiograph readings in a variety of settings and to extend this standardization to digital technology. With these improvements, the quality of diagnosis of that significant (and increasing) proportion of patients who are not bacteriologically confirmed will be enhanced and general diagnostic facilities (extending beyond the needs of TB) will be improved in low-income countries.

The Challenge

Despite discouragement concerning the reliability of reading chest radiographs for diagnosis of tuberculosis, recent reports have confirmed that it is possible, using an approach similar to that recommended by the International Labour Office for the reading of films for pneumoconiosis, to achieve acceptable levels of agreement. This has been achieved through a method of standardization of definitions and methods for reading and reporting which are now the basis of an international training course in Cape Town, South Africa.
Up until the present moment, digital equipment has not been available for radiographic examination for tuberculosis where the disease is more frequent – in low-income countries. This, however, is likely to change very rapidly. The avoidance of supply requirements for traditional film-based radiography and the ability to easily transport images through electronic networks promises to radically change the situation. Moreover, the recent interest in using chest radiography as a tool in prevalence surveys of tuberculosis, accompanied by the support of the Global Fund for AIDS, tuberculosis and malaria to undertake such services now creates the possibility that this technology will become widespread throughout low-income countries.
Similar work on standardization of reading and recording of chest radiographs has not yet been carried out for digital radiographs of the chest and this needs to be done.