• 한국방사선학회논문지
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• 제10권7호
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• pp.503-510
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• 2016

소아는 방사선 감수성이 어른에 비해 높고 몸의 크기가 작아 어른과 같은 양의 방사선에 노출 되더라도 유효선량은 어른에 비해 더 높기 때문에 불필요한 피폭 방사선량을 줄이는 것이 매우 중요하다. 따라서 본 연구에서는 소아 두부 CT 검사에 있어서 피폭 방사선량을 경감할 수 있는 방법을 모색하고자 부산지역 병원들에서 시행된 년 간 소아 두부 CT 검사에 대한 CT 선량지표(CTDI)를 국내 진단참고준위와 비교하여 분석함으로써 제안점을 도출하고자 하였다. 이를 위하여 부산시내에 설치된 CT 장비 중 소아 두부 CT 검사를 시행하며, 선량보고서를 PACS로 전송하는 24개 병원 28대 CT 장비를 대상으로 하여 소아 두부 CT 검사를 의뢰받은 10세 미만의 소아 2,043명을 후향적으로 조사하였다. 결과적으로 전체병원의 소아 두부 CT의 선량지표 CTDIvol의 평균값은 31.18 mGy, DLP는 $444.73mGy{\cdot}cm$로 나타나 진단참고준위를 초과하는 것으로 나타났다. 연령이 낮을수록 방사선에 대한 관리가 더욱 필요하다고 할 수 있는데 연구결과 6-10세 이하의 연령에 비해 더 낮은 다른 두 연령별에서 진단참고준위를 초과하는 환자수와 초과되는 비율이 높게 나타났다. 따라서 불필요한 방사선 노출을 줄이고 선량관리를 위한 노력들이 필요하다. 이를 위해 본 연구에서는 진단참고준위를 벗어나는 선량의 정도를 파악하고 초과되는 선량지표의 원인을 분석하여 선량감소를 위한 방안을 마련하고자 한다.

• 대한디지털의료영상학회논문지
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• 제13권2호
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• pp.63-69
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• 2011

Table strapis patient fixture for securing the patient movements and falls. if it designed to measure the abdominal circumference and used as an indicator of dose selection at CT scan. it will prevent the overexposure of dose without degradation of image quality and efficiently manage dose of each type of body to technician to deal with CT. First, in order to compare the dose used in CT image and qualitative characteristics. reference image is obtained by examining the abdominal phantom in same conditions with the hospital 120 kVp, 200 mAs, D-Dom (Dynamic Dose Of Modulation). SNR, PSNR, RMSE, MAE, CTDIvol of CT images are compared with reference image. for comparing with reference image, the image that Umbilicus level image of Abdomen CT is stored in the PACS were used. For comparison, the top 12 o'clock portion of the air drawn from the same ROI was measured. CTDIvol, mAs, etc. In order to analyze the characteristics of the image, by measuring the length of the umbilicus circumference, pattern of the dose was analyzed. by using the analyzed perimeter and dose information, To be identified visually, fixed band that scale marked were produced. Use them, If the length of circumference of less than 60 cm 100 mAs, Case of 61~80 cm 120 mAs, Case of 80~100 cm 150 mAs, more than 100 cm 200 mAs, dose selection based on the perimeter, the image was applied. by compare analyzed with the Reference Image, image quality was assessed. by compare with existing tests that equally 200 mAs applied, How much was confirmed that the dose reduction. 1. Depending on the Abdominal circumference, the average PSNR(dB) of the image that differently dose applied was 45.794. 2. Comparing with existing test. the dose of scan that adjusted the mAs depending on the circumference was decreased about 40%. SNR and PSNR of the image that obtained by adjusting the standard mAs based on dose modulation were not much different. Therefore, By choosing a low mAs. dose reduction can be obtained. and the dose selection method that measured Abdominal circumference using a fixed band can protect the overexposure and uniformly apply dose of each type of body to technician to deal with CT.

• 대한방사선기술학회지:방사선기술과학
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• 제39권1호
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• pp.71-79
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• 2016

본 연구는 전산화단층검사(computed tomography; CT)에서 저농도 조영제와 저관전압 기법이 선량과 영상에 미치는 유용성을 팬텀으로 평가하였다. 조영제 농도별로 희석정도를 달리하여 실험팬텀에 삽입 후 관전압과 관전류를 단계적으로 변화하여 촬영하였고, 획득된 팬텀영상을 통해 선량과 HU를 평가하였다. 그 결과 표준조건(350 mgI/ml, 120 kV)보다 저농도 조영제와 저관전압 조건(300 mgI/ml, 100 kV)설정이 체적 선량평가(CTDIvol; computed tomography dose $index_{vol}$)에서 평균 21% 감소하였다. SNR은 저농도 조영제와 저관전압 조건이 팬텀에서 측정한 모든 깊이(center, 4.5cm, 2.25cm)의 조영제와 생리식염수를 1:10, 1:20으로 희석한 실험에서 각각 12.2(26%), 6.2(17%) 증가하였다. CNR은 각각 11.5(32%), 6.3(26%) 증가하였다. CT 검사에서 조영제 부작용 감소를 위한 저농도 조영제의 사용과 피폭선량 감소를 위한 저관전압 사용으로 영상에서 높은 감약계수를 통한 다양한 연구가 필요할 것으로 사료된다.

• 방사선산업학회지
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• 제11권3호
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• pp.131-137
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• 2017

To compare the radiation dose and image noise of low dose computed tomography (CT) and high resolution CT using the fixed tube current technique and automatic tube current modulation (CARE Dose 4D). Chest CT and human anthropomorphic phantom were used the RPL (radiophotoluminescence) dosimeters. For image evaluation, standard deviation of mean CT attenuation coefficient and CT attenuation coefficient was measured using ROI analysis function. The effective dose was calculated using CTDIvol and DLP. CARE Dose 4D was reduced by 74.7% and HRCT by 64.4% compared to the fixed tube current technique in low dose CT of chest phantom. In CTDIvol and DLP, the dose of CARE Dose 4D was reduced by fixed tube current technique. For effective dose, CARE Dose 4D was reduced by 47% and HRCT by 46.9% compared to the fixed tube current method, and the dose of CARE Dose 4D was significantly different (p<.05). Noise in the image was higher than that in the fixed tube current technique. Noise difference in the image of CARE Dose 4D in low dose CT was significant (p<.05). The low radiation dose and the noise difference of the CARE Dose 4D were compared with the fixed tube current technique in low dose CT and HRCT using chest phantom. The radiation doses using CARE Dose 4D were in accordance with the national and international dose standards. CARE Dose 4D should be applied to low dose CT and HRCT for clinical examination.

• 한국융합학회논문지
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• 제9권12호
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• pp.107-113
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• 2018

본 연구는 복부 전산화단층촬영 검사에서 X-축 방향의 회전에 따른 선량, 영상의 화질을 평가하여 피폭선량의 감소 방안을 평가 하였다. 인체 모형 팬텀을 이용해 0도, 5도, 10도, 15도로 5도씩 X-축 방향으로 회전하여 scan을 하였다. 각각의 회전에서 CTDIvol 값, HU, 노이즈, 그리고 신호대잡음비를 측정하였다. SPSSWIN(ver 19.0) 프로그램을 사용하여 ANOVA 분석을 하였다. 회전에 따른 선량은 0도, 5도, 10도, 15도 회전에서 각각 5.44mGy, 5.70mGy, 5.98mGy, 6.38mGy 측정되었다. 회전에 따른 HU, 노이즈, 그리고 신호대잡음비는 통계적으로 유의한 차이가 없었다. 전산화단층촬영 검사에서 환자가 gantry aperture의 isocenter에 위치함과 동시에 X-축 방향으로 회전이 없다면 피폭 선량이 감소되어진다.

• 한국방사선학회논문지
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• 제16권4호
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• pp.387-394
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• 2022

갑상샘이 포함된 인체모형 팬텀을 이용하여 임상에서 많이 적용하는 NECK CT 프로토콜 중 관전압을 변화 적용하여 스캔 후 Raw data를 이용하여 FBP, ASIR-V, DLIR 재구성기법 적용 영상 획득하여 120 kVp FBP 재구성 영상 기준 DLIR 재구성기법의 유용성을 알아보았다. 그 결과 DLIR 재구성기법 적용 시 CTDIvol 이 감소하였으며, 특히 동일 관전압에서 FBP 적용보다 ASIR-V, DLIR 재구성 시 낮은 선량에서도 기준 스캔 조건으로 획득한 화질에 도달하였다. 또한, SNR, CNR 분석결과 DLIR 재구성 영상이 SNR, CNR 값이 높게 분석되었고, SSIM분석결과 100 kVp, DLIR 재구성 영상이 SSIM 지수가 1에 근사하게 측정되어 원본 영상에 대한 재구성 영상의 유사도가 높은 것으로 분석되었다(p>0.05). 본 연구결과를 활용하여 임상 영상 평가를 시행하여 보완하고 다양한 해부학적 구조에 적용 가능한 알고리즘을 추가 개발한다면 검사 선량을 현재 보다 낮추면서 화질을 유지할 수 있어 임상 적용 시 유용할 것으로 생각된다.

• Korean Journal of Radiology
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• 제24권10호
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• pp.1006-1016
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• 2023

Objective: Computed tomography (CT) is an established method for the diagnosis, staging, and treatment of multiple myeloma. Here, we investigated the potential of photon-counting detector computed tomography (PCD-CT) in terms of image quality, diagnostic confidence, and radiation dose compared with energy-integrating detector CT (EID-CT). Materials and Methods: In this prospective study, patients with known multiple myeloma underwent clinically indicated whole-body PCD-CT. The image quality of PCD-CT was assessed qualitatively by three independent radiologists for overall image quality, edge sharpness, image noise, lesion conspicuity, and diagnostic confidence using a 5-point Likert scale (5 = excellent), and quantitatively for signal homogeneity using the coefficient of variation (CV) of Hounsfield Units (HU) values and modulation transfer function (MTF) via the full width at half maximum (FWHM) in the frequency space. The results were compared with those of the current clinical standard EID-CT protocols as controls. Additionally, the radiation dose (CTDIvol) was determined. Results: We enrolled 35 patients with multiple myeloma (mean age 69.8 ± 9.1 years; 18 [51%] males). Qualitative image analysis revealed superior scores (median [interquartile range]) for PCD-CT regarding overall image quality (4.0 [4.0-5.0] vs. 4.0 [3.0-4.0]), edge sharpness (4.0 [4.0-5.0] vs. 4.0 [3.0-4.0]), image noise (4.0 [4.0-4.0] vs. 3.0 [3.0-4.0]), lesion conspicuity (4.0 [4.0-5.0] vs. 4.0 [3.0-4.0]), and diagnostic confidence (4.0 [4.0-5.0] vs. 4.0 [3.0-4.0]) compared with EID-CT (P ≤ 0.004). In quantitative image analyses, PCD-CT compared with EID-CT revealed a substantially lower FWHM (2.89 vs. 25.68 cy/pixel) and a significantly more homogeneous signal (mean CV ± standard deviation [SD], 0.99 ± 0.65 vs. 1.66 ± 0.5; P < 0.001) at a significantly lower radiation dose (mean CTDIvol ± SD, 3.33 ± 0.82 vs. 7.19 ± 3.57 mGy; P < 0.001). Conclusion: Whole-body PCD-CT provides significantly higher subjective and objective image quality at significantly reduced radiation doses than the current clinical standard EID-CT protocols, along with readily available multi-spectral data, facilitating the potential for further advanced post-processing.

• 대한방사선기술학회지:방사선기술과학
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• 제38권1호
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• pp.51-61
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• 2015

모든 방사선 검사는 검사를 결정하고 실행하는 과정에서 정당성이 확보되어야하고 피폭선량과 영상의 화질에 대한 최적화가 이루어져야 할 뿐만 아니라 ALARA의 원칙에 따라 최소의 방사선을 사용하여 최적의 임상 정보를 얻을 수 있어야 한다. CT 검사는 방사선 검사 중에서 많은 피폭을 환자에게 조사하는 검사이다. 특히 방사선 민감도가 높은 소아 환자의 CT 검사 있어서는 특별한 주의가 필요하다. 임상에서 CT선량에 대한 정확한 이해와 정보는 환자에게 불필요한 방사선 피폭을 줄이고 안전한 검사를 제공하기 위해 절대적으로 필요하다. 이에 본 연구에서는 여러 선행 연구의 고찰을 통하여 CT의 피폭선량에 대한 개념을 확인하고 CT장치의 선량 저감화를 위한 각 파라미터의 이해와 American Association of Physicists in Medicine (AAPM)report 204에서 소개하고 있는 환자의 사이즈에 따른 피폭선량의 보정방법인 Size-Specific Dose Estimates(SSDE)와 XR 25의 개념을 이해하고자 한다.

• 대한방사선기술학회지:방사선기술과학
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• 제41권5호
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• pp.405-411
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• 2018

We will provide basic data on the evaluation of patient dose in terms of DECT quality control by comparing the equipment-provided dose with the measured dose according to the configuration method of the X-ray generator by the manufacturer of the dual-energy CT unit. For computed tomography (CT) equipment, Discovery 750HD, Aquilion ONE GENESIS Edition, and Somatom Definition Flash were used. The $CTDI_{vol}$ value was measured by inserting the Unfors Xi ion chamber into a 32 cm PMMA acryl Phantom. The results of estimated $CTDI_{vol}$ DECT and measured $CTDI_{vol}$ showed that the dose difference between DECT 80 + 140 kVp of G company was at least 0.51% and -1.90% max, and measured $CTDI_{vol}$ was slightly lower (p<0.05). The difference of 80 + 140 kVp of S company was the minimum of 5.84% and the maximum of 7.52% (p<0.05). The measured $CTDI_{vol}$ was less than estimated $CTDI_{vol}$. The C company's 80 + 135 kVp showed a difference of at least 7.58% and a maximum of 13.58% (P<0.05), and all of measured $CTDI_{vol}$ was less. The linearity of exposure dose for all DECT equipment was very linearly reflected with $R^2$ being 0.97 or above, and the measured dose of the ionization chamber was less than the predicted dose of the monitor.

• 대한의용생체공학회:의공학회지
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• 제39권3호
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• pp.116-123
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• 2018

This study is a model experimental study using a phantom to propose an optimized brain CT scan protocol that can reduce the radiation dose of a patient and remain quality of image. We investigate the CT scan parameters of brain CT in clinical medical institutions and to measure the important parameters that determine the quality of CT images. We used 52 multislice spiral CT (SOMATOM Definition AS+, Siemens Healthcare, Germany). The scan parameters were tube voltage (kVp), tube current (mAs), scan time, slice thickness, pitch, and scan field of view (SFOV) directly related to the patient's exposure dose. The CT dose indicators were CTDIvol and DLP. The CT images were obtained while increasing the imaging conditions constantly from the phantom limit value (Q1) to the maximum value (Q4) for AAPM CT performance evaluation. And statistics analyzed with Pearson's correlation coefficients. The result of tube voltage that the increase in tube voltage proportionally increases the variation range of the CT number. And similar results were obtained in the qualitative evaluation of the CT image compared to the tube voltage of 120 kVp, which was applied clinically at 100 kVp. Also, the scan conditions were appropriate in the tube current range of 250 mAs to 350 mAs when the tube voltage was 100 kVp. Therefore, by applying the proposed brain CT scanning parameters can be reduced the radiation dose of the patient while maintaining quality of image.