• Journal of radiological science and technology
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• v.28 no.4
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• pp.293-299
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• 2005

In the present investigation, we analyzed the data of 1,318 patients (2,636 images) who underwent mammographic examinations and obtained the distribution of the patient age and compressed breast thickness. We measured also average glandular doses (AGD) as function of compressed breast thickness. In order to obtain the values of AGD, we measured half value layer (HVL) and tube output (mR/mAs) for each kVp and target/filter combination. Entrance surface air kerma (ESAK) was calculated from the tube output as measured for each voltage used under clinical conditions and from the tube loading (mAs). AGD per exposure were calculated by multiplying the ESAK values by the conversion factors tabulated by Dance. We obtained in this study the following conclusions. The mean value of compressed breast thickness for cranio-caudal (CC) view was 35.8mm and that for medio-lateral oblique (MLO) view was 43.3 mm. The mean value of AGD for CC view was 1.55 mGy and that for MLO view was 1.70 mGy. The AGD for MLO view was 0.15 mGy (10%) higher than that for CC view because the thickness for MLO view was on average 4.8 mm higher than that for CC view. The values of AGD increased with increasing compressed brest thickness. The increased AGD value was on average 0.34 mGy per 10 mm in the thickness ranges $10{\sim}80\;mm$, therefore differences between the AGD values of each thickness were relative large. Thus, it is considered to need limited doses for mammography with the upper end of exposure range at several different compressed brest thickness.

• Journal of the Korean Society of Radiology
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• v.12 no.5
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• pp.659-667
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• 2018

The purpose of this study was to determine the effect of body mass index (BMI) on entrance surface air kerma (ESAK) in abdominal X-ray radiography using automatic exposure control (AEC). This study included 321 patients who underwent abdominal X-ray using AEC, and we correlated ESAK with height, weight, BMI and compared mean ESAK according to BMI grades (Underweight, Normal, Overweight, Obese 1, Obese 2). As a result, Weight ($R^2=0.777$, p<.001) and BMI ($R^2=0.835$, p<.001) were positively associated with ESAK, but no significant association was found between height ($R^2=0.075$, p<.001) and ESAK. The mean ESAK with respect to BMI grades showed statistically significant difference and in the post-hoc analysis, the existence of 5 subgroups at the significance level of 0.05 indicated that there were differences in the ESAK in all BMI grades. Also, as the increment of ESAK between two neighboring BMI grades increases from Underweight to Obese 2, the exposure dose dramatically increased as the BMI increased. Thus, an excessive exposure dose due to increasing BMI when using AEC should be acknowledged and Efforts to reduce dose should be taken, such as: by fixing the exposure conditions.

• Journal of the Korean Society of Radiology
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• v.8 no.4
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• pp.203-210
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• 2014

Chest radiography has been typically performed at SID of 180 cm. Image quality and patient dose were investigated between 180 cm and 340 cm by 20 cm intervals at 120 kVp and 320 mAs with the AEC. VGA was performed for qualitative assessment and SNR was analysed for quantitative assessment on the image of the chest phantom. Patients dose was measured by ESAK and PCXMC was used for effective dose. As a result, when using the standard of SID of 180 cm which is typically used in the clinical practice, in the case of ESAK, 240 cm, 280 cm, and 320 cm were 8.7%, 11.47%, and 13.56% respectively therefore significant reduction was confirmed. In the case of effective dose, 2.89%, 4.67%, and 6.41% in the body and 5.08%, 6.09%, and 9.6% in lung were reduced. In the case of SNR, 9.04%, 8.24%, and 11.46% were respectively decreased especially, by 8.03% between SID of 260 cm and 300 cm, but SNR was 5.24 up to 340 cm. There were no significant differences in VGA thus the image is valuable in diagnosis. It is predicted that increasing SID up to 300 cm in digital chest radiography can reduce patient dose without decreasing image quality.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.535-541
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• 2016

This study aimed to identify dose reduction measures by retrospectively analyzing the entrance surface dose at computed tomography and angiography in cardiovascular examination and to contribute the patients with renal impairmend and a high probability of side effects to determine the inspection's direction by measuring the contrast usages actually to active actions for the dose by actually measuring the contrast medium dose. The CTDIvol value and air kerma value, which are the entrance surface doses of the two examinations, and the contrast medium dose depending on the number of slides were compared and analyzed. This study was conducted in 21 subjects (11 males; 10 females) who underwent Cardiac Computed Tomographic Angiography (CCTA) and Coronary Angiography (CAG) in this hospital during the period from May 2014 to May 2016. The subject's age was 48~85 years old (mean $65{\pm}10$ years old), and the weight was 37.6~83.3 kg (mean $63{\pm}6kg$). Dose reduction could be expected in the cardiovascular examination using CCTA rather than in the examination using CAG. In terms of contrast medium dose, CAG used a smaller dose than CCTA. In particular, as the number of slides increases at CAG, the contrast medium dose increases. Therefore, in order to reduce the contrast medium dose, the number of slides suitable for the scan range must be selected.