The purpose of this study was to estimate the computed tomography (CT) examination frequency, patient radiation exposure, effective doses and national diagnostic reference levels (NDRLs) associated with CT examinations in clinical practice. A structured questionnaire-type form was developed for recording examination frequency, scanning protocols and patient radiation exposure during CT procedures in fully equipped medical facilities across the country. The national annual number of CT examinations per 1000 people was estimated to be 3 procedures. The volume-weighted CT dose index, dose length product, effective dose and NDRLs were determined for 20 types of adult and paediatric CT examinations. Additionally, the CT annual collective effective dose and effective dose per capita were approximated. The radiation exposure during CT examinations was broadly distributed between the facilities that took part in the study. This calls for a need to develop and implement diagnostic reference levels as a standardisation and optimisation tool for the radiological protection of patients at all the CT facilities nationwide.
The aim of this study was to estimate radiation doses patients and staff are exposed to during interventional procedures (IPs), compare them with the international diagnostic reference levels and to develop initial National Diagnostic Reference Levels. The IP survey was undertaken as the initial task of which, retrospective data were collected from the only four Kenyan hospitals carrying out interventional radiology and cardiology procedures at the time of the study. Real-time measurement of radiation dose to patients and staff during these procedures was done. To the patients, kerma-area product (KAP) and fluoroscopy time measurements were done using an in-built KAP meter, while peak skin dose (PSD) was measured using slow Extended Dose Range (EDR2(®)) radiographic films. The staff occupational doses were measured using individual thermoluminescence dosemeters. The maximum and minimum KAP values were found to be 137.1 and 4.2 Gy cm(2), while the measured PSD values were 740 and 52 mGy, respectively. The fluoroscopic time range was between 3.3 and 70 min. The staff doses per procedure ranged between 0.05 and 1.41 mSv for medical doctors, 0.03 and 1.16 mSv for nurses, 0.04 and 0.78 mSv for radiographers and 0.04 and 0.88 mSv for clinical staff. The measured patient PSDs were within the threshold limit for skin injuries. However, with the current few IP specialists, an annual increase in workload as determined in the study will result in the International Commission on Radiation Protection annual eye lens dose limit being exceeded by 10 %. A concerted effort is required to contain these dose levels through use of protective gear, optimisation of practice and justification.
This study details the distribution and trends of doses from occupational radiation exposure among radiation workers from participating medical institutions in Kenya, where monthly dose measurements were collected for a period of one year (January to December 2007) using thermoluminescent dosimeters. A total of 367 medical radiation workers were monitored, comprising 27% radiologists, 2% oncologists, 4% dentists, 5% physicists, 45% technologists, 4% nurses, 3% film processor technicians, 4% auxiliary staff, and 5% radiology office staff. The average annual effective dose for all subjects ranged from 1.19 to 2.52 mSv. Among these workers, technologists received the largest annual effective dose. The study forms the initiation stage of wider, comprehensive and more frequent monitoring of occupational radiation exposures and long-term investigations into its accumulation patterns, which could form the basis of future records on the detrimental effects of radiation, characteristic of workers in the medical sector, and other co-factors in a developing country such as Kenya.
Assessment of patient dose attributed to multislice computed tomography (CT) examination. A questionnaire method was developed and used in recording the patient dose and scanning parameters for the head, chest, abdomen and lumbar spine examinations. The patient doses due to brain, chest and abdomen examination were above the international diagnostic reference levels (DRLs) by factors of between one and four. The study demonstrated that the use of multislice CT elevates patient radiation dose, justifying the need for local optimised scanning protocols and the use of institutional DRL for dose management without affecting diagnostic image quality.
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