Assessment of cancer incidence and mortality risks associated with effective dose of computed tomography examinations

Advances in diagnostic medical imaging in the past few decades using procedures such as computed tomography (CT), have significantly enhanced health care delivery. The effective doses and associated cancer incidence and mortality risks were estimated for adult patients undergoing the five most common types of CT examinations, namely, head, neck, chest, abdomen and pelvis, at Sweden Ghana Medical Centre (SGMC) in Accra, Ghana. The two methods employed in the study were patients’ data collection and phantom measurements to verify the patien-ts’ data. The effective doses were estimated using the dose length product (DLP) from the control console of the CT machine and the anatomic region specific conversion factors. The lifetime attributable risks of cancer inciden-ce and cancer mortality for each patient for a particular examination were both determined from the effective dose, age and sex of each patient using the standard Biological Effects of Ionizing Radiation (BEIR) VII criteria. The effective doses were all within the range of 1 - 10 mSv recommended for CT examinations. The average risk for all the examinations was observed to be very low, i.e. 1 in 10001 to 1 in 10 000. The average lifetime attributable risk (LAR) of cancer incidence was 0.049 % (1 in 2041), while for risk of cancer mortality, the average was 0.030 % (1 in 3333).Keywords: Computed tomography, Effective dose, Dose length product, Life attributable risk, Cancer incidence, Cancer mortalit

Public exposure to natural radioactivity and radon exhalation rate in construction materials used within Greater Accra Region of Ghana

The natural radioactivity of 238U, 232Th, 40K, radiological hazards and 222Rn exhalation rate in building materials used within Greater Accra Region of Ghana, have been measured using Gamma spectrometry and CR-39. The results obtained are as follows 238U (2.6–47.1 Bq/kg), 232Th (3.6–43.0 Bq/kg), 40K (62.8–1222.2 Bq/kg), radium equivalent (32.7–174.3 Bq/kg), internal hazard index (0.04–0.51), external hazard index (0.04–0.23), activity concentration index (0.10–0.63 mSv/y) absorbed dose rate (9.5–76.3 nGy/h), outdoor effective doses (11.6–93.6 μSv/y), indoor effective doses (46.5–374.1 μSv/y,) and excess lifetime cancer risk (0.04 × 10−3–0.33 × 10−3). 222Rn exhalation rate (3.1 × 10−5–11.4 × 10−5 Bq/m2 h), 222Rn activity (17.4–42.6 Bq/m3), effective radium (0.19–0.64 Bq/kg). Positive correlation was found between 238U and 222Rn. The results were discussed in terms of limits to the accepted natural radioactivity levels and compared with similar studies reported in other countries. The gneiss rocks recorded excess lifetime cancer risk values of (0.32 × 10−3 and 0.33 × 10−3) greater than the world value of 0.29 × 10−3 proposed by UNSCEAR, 2000. With exception gneiss rocks from Shai hills which recorded high value of cancer risk as compare to the world average value, all the studied building materials do not pose any radiological effects to the people of Greater Accra Region when used for construction. Keywords: HPGe, CR-39, 222Rn, NORMS, Construction material

Seasonal indoor radon studies in buildings of Accra Metropolis of Greater Accra region of Ghana

Indoor radon concentration for annual, rainy and dry season have been studied in 228 buildings which includes bedroom, kitchen, sitting room, laboratories and offices in Accra metropolis of Greater Accra of Ghana. The passive radon CR-39 SSNTD was used for this study. The cumulative frequency distribution, normalizing Q-Q plots, Kolmogorov-Smirnov and Shapiro-Wilk statistical test showed that the result of both workplaces and dwellings are not normally distributed. The strong positive correlation between the two seasons occurred at 95% confidence level with 2 tailed. The rainy season recorded highest coefficient variation of r2 = 0.982. Statistical analysis of median (39.3), AM (103.4), GM (57.9) and GSD (3.2) for rainy season were greater than that of the dry season of median (26.9), AM (88.2), GM (49.2) and GSD (2.8) respectively. Rainy season was found to contain high radon concentrations than the dry season for all the studied locations. In general, workplace had radon concentration far greater than dwellings. The results obtained from this study ranged between 13.6 to 533.7 Bq/m3, out of which 9.6%, 12.7% and 3.5% were found to be greater than action levels proposed by WHO, EC and ICRP

Knowledge levels on applications of radiation in medicine among medical practitioners in Ghana

The evaluation of medical practitioners’ knowledge levels of radiation and safety is essential for planning diagnostic procedures and treatment in radiation medicine. This study sought to identify levels of knowledge and the predictor variables influencing knowledge of medical practitioners on applications of radiation in medicine in Ghana. Online survey was conducted with Google Form consisting of 37-point questionnaire highlighting on physicians’ background information, professional experience, knowledge on radiation usage in medicine, radiation protection and safety. Evaluation of the data was performed by descriptive analysis using frequency distributions and percentages. Among 152 respondents who participated in the study, specialists and consultants made up a higher representation of 46.7%. Two-thirds (64.0%) of the respondents who had received refresher training in the application of radiation in medicine exhibited full knowledge in the field. Medical practitioners who had practiced between 21–25 years were also found to demonstrate full knowledge of the application of radiation in medicine, while 36.6% of those who had practiced for < 6 years demonstrated extensive knowledge. Majority of the medical practitioners, constituting 39.5%, exhibited full knowledge in medical radiation protection and safety. This level of knowledge was found higher than what was demonstrated for general and occupational radiation protection. With medical imaging forming a key component in the diagnosis of several medical conditions, education in the field of radiation usage and radiological protection and safety should be a subject of periodic training for medical practitioners regardless of their level of training or duration of practic

Radiation doses in cerebral perfusion computed tomography: patient and phantom study

The purpose of this study was to investigate radiation doses in cerebral perfusion computed tomography (CT) examination. As a part of routine patient monitoring, data were collected on patients in terms of the skin dose and CT dose index (CTDIvol) and dose-length product (DLP) values. For the estimation of the dose to the lens a phantom study was performed. Dose values for skin and lens were below the threshold for deterministic effects. The results were also compared with already published data. For better comparison, the effective dose was also estimated. The values collected on patients were in the ranges 230680 mGy for CTDI and 21202740 mGy cm for DLP, while the skin dose and estimated effective dose were 340800 mGy and 4.96.3 mSv, respectively. These values measured in the phantom study were similar, while the doses estimated to the lens were 53 and 51 mGy for the right and left lens, respectively