Estimate of reference effective dose and renal dose during abdominal ct scan for dose optimization procedures in Ghana

Abstract

The study is to estimate renal and effective dose during abdominal MDCT scan, using image data for dose optimization for purposes of radiation protection in Ghana. In addition dose influencing parameters including: CTDIVOL, DLP and MSAD were recorded and compared with ICRP/ICRU, AAPM, EU and IAEA dose optimization recommendations. All the measurements were done during abdominal MDCT examination. The measured parameters were part of image data on the MeVisLab (DICOM) application software platform. The total photon fluence (mAs per area) and the photon energy fluence (kVp per area) on the abdominal and renal surface were also determined. Renal and effective dose were estimated using ICRP publication 103 recommendations. The results of the measured parameters based on the average renal surface area of 29.52cm2 and 30.67cm 2 for the right and left kidney respectively, shows that: The mean dose parameters were; 6.33mGy, 7.78mGy, 936.25mGy cm, 5.76mGy, 10.99mSv and 14.09mSv for CTDIV, CTDIW, DLP, MSAD, RD and E respectively. The average values were lower than the general recommended average critical values, but this seems misleading, based on the fact that 37% of the individual dose and exposure parameters exceeded the recommended critical values. A tradeoff between patient radiation dose and image quality in abdominal CT has been established. Where at a mean SNR of 6.6 decibels an adequate images were produce to answer all the clinical questions, with an average effective dose of 14.09mSv and renal dose of 10.99mSv. Radiation dose during x-ray CT imaging is an important patient safety concern. Reducing radiation dose result in a reduction of the risk to patient; however, reducing dose also reduces the signal strength and thereby reduces the signal to noise ratio in the resulting CT image, hence, the image quality is affected. It is recommended that the established reference values be used as clinical advisory mechanism to protect patience and clinicians. It is also recommended that the studies should be carry out periodical to estimates the abdominal effective dose in all the centers