A survey of computed tomography imaging techniques and patient dose in Kenya

Abstract

Objectives: To assess the level of patient dose in Computed Tomography examination in Kenya, compare with the international diagnostic reference levels and establish the initial national diagnostic reference levels. Design: The patient doses for brain, chest, abdomen and pelvis examinations were assessed using typical exposure factors on head and body dosimetry phantoms. A log normal graphical method was developed and used in deriving the initial national diagnostic reference levels for the two dose quantities. Setting: Twenty one representative Computed Tomography facilities at different hospitals and clinics. Subjects: A questionnaire method was developed and used in recording the scanning parameters for head, chest, abdomen and pelvis adult examinations at each facility. Results: The radiation exposure from Computed Tomography examinations was determined to be below the weighted Computed Tomography Dose Index (CTDlw) and Dose Length Product (DLP) reference levels by 90% and 62% respectively. Conclusion: The mean CTDlw measurements for the adult patients were below Diagnostic Reference levels (DRLs). The mean DLP values for adult patients in some examination were above DRLs, with large variations of up to a factor of eleven. This indicates the need for local optimised scanning protocols and use of local diagnostic reference level in order to reduce patient doses without affecting diagnostic image quality.