The study-specific objectives.

IntroductionTuberculosis remains one of the top ten causes of mortality globally. Children accounted for 12% of all TB cases and 18% of all TB deaths in 2022. Paediatric TB is difficult to diagnose with conventional laboratory tests, and chest radiographs remain crucial. However, in low-and middle-income countries with high TB burden, the capacity for radiological diagnosis of paediatric TB is rarely documented and data on the associated radiation exposure limited.MethodsA multicentre, mixed-methods study is proposed in three countries, Mozambique, South Africa and Spain. At the national level, official registry databases will be utilised to retrospectively compile an inventory of licensed imaging resources (mainly X-ray and Computed Tomography (CT) scan equipment) for the year 2021. At the selected health facility level, three descriptive cross-sectional standardised surveys will be conducted to assess radiology capacity, radiological imaging diagnostic use for paediatric TB diagnosis, and radiation protection optimization: a site survey, a clinician-targeted survey, and a radiology staff-targeted survey, respectively. At the patient level, potential dose optimisation will be assessed for children under 16 years of age who were diagnosed and treated for TB in selected sites in each country. For this component, a retrospective analysis of dosimetry will be performed on TB and radiology data routinely collected at the respective sites. National inventory data will be presented as the number of units per million people by modality, region and country. Descriptive analyses will be conducted on survey data, including the demographic, clinical and programmatic characteristics of children treated for TB who had imaging examinations (chest X-ray (CXR) and/or CT scan). Dose exposure analysis will be performed by children’s age, gender and disease spectrum.DiscussionAs far as we know, this is the first multicentre and multi-national study to compare radiological capacity, radiation protection optimization and practices between high and low TB burden settings in the context of childhood TB management. The planned comparative analyses will inform policy-makers of existing radiological capacity and deficiencies, allowing better resource prioritisation. It will inform clinicians and radiologists on best practices and means to optimise the use of radiological technology in paediatric TB management.</div

Dosimetry chart.

In this figure, we describe the procedures for obtaining the dosimetry data in each country and the calculation of the cumulative organ dose to the lungs (PACS: Picture Archiving and Communications System; TB: tuberculosis; CXR: chest x-ray; CT: computed tomography scan; kVp: kilovoltage peak; mA: milliamperes; CTDI: computed tomography dose index; HVL: half-value layer; DAP: dose area product; SA: South Africa; NCIRF: National Cancer Institute dosimetry system for Radiography and Fluoroscopy; NCICT: National Cancer Institute dosimetry system for Computed Tomography; mGy: milligray).</p

Study components and methodologies.

In the figure, we describe the different study methodologies applied to answer each study objective (CT: computed tomography scan; TB: tuberculosis; PACS: Picture Archiving and Communications System; CXR: chest x-ray).</p