• 대한방사선기술학회지:방사선기술과학
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• 제21권2호
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• pp.5-10
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• 1998

In the mammography, X-ray beam quality is one of the most important factors. Using X-ray mammography unit model GE/CGR Senography 600T Senix H.F, Authors studied four subjects. 1. The aluminum attenuation rate in 30 kVp when used with or without compression plate. 2. HVLs at 5 different area of the X-ray field of $26{\sim}32kVp$. 3. HVLs to know the influence of corrected measurement or parallel measurement. 4. Film density with microdensitometer along and cross to the long axis of X-ray tube, in terms of the Heel effect in the X-ray field. The following results were obtained. 1. Beam quality of anode area was harder than cathode area. 2. The dose reduction rate of compression plate was approximately $65.5%{\sim}88.1%$ and the beam quality with compression plate was hardened up to 4kVp accordingly. 3. If the X-ray beam enters the attenuation plate obliquely, HVL was $2.6{\sim}2.9%$ harder than perpendicular to it. 4. Because of heel effect, the film density of cathode area is higher than anode area to film density of 0.5.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.206-207
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• 2002

The effective dose due to the X-Ray radiography in the patient positioning for the heavy ion radiotherapy was measured on three regions, chest, upper-abdomen and pelvis. All the radiographic systems and the conditions used in the measurements were same as the clinical trial being performed in National Institute of Radiological Sciences, Japan. The organ or tissue for measurements was selected by following ICRP60$^1$ and the effective dose was calculated from measured organ doses and the surface dose.

• 대한방사선기술학회지:방사선기술과학
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• 제18권1호
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• pp.55-62
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• 1995

This study was performed to find out dose distribution, pdd, surface dose and off center ratio. A few articles is analysis of dose data in radiotherapy field, there is no standardized measure of an assessment of exposure dose at diagnostic radiology, yet. And authors demonstrated a new assessment measure by ion chamber, TLD and film dosimetry system. We assurance that our data is useful to quantiative analysis of exposure dose and clinical fields for reduction of radiation dose.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.260-262
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• 2002

An accurate measurement of dose distribution is indispensable to perform radiation therapy planning. A measurement technique using a radiographic film, which is called a film dosimetry, is widely used because it is easy to obtain a dose distribution with a good special resolution. In this study, we tried to develop an analyzing system for the film dosimetry using usual office automation equipments such as a personal computer and an image scanner. A film was sandwiched between two solid water phantom blocks (30 ${\times}$ 30 ${\times}$ 15cm). The film was exposed with Cobalt-60 ${\gamma}$-ray whose beam axis was parallel to the film surface. The density distribution on the exposed film was stored in a personal computer through an image scanner (8bits) and the film density was shown as the digital value with NIH-image software. Isodose curves were obtained from the relationship between the digital value and the absorbed dose calculated from percentage depth dose and absorbed dose at the reference point. The isodose curves were also obtained using an Isodose plotter, for reference. The measurements were carried out for 31cGy (exposure time: 120seconds) and 80cGy (exposure time: 300seconds) at the reference point. While the isodose curves obtained with our system were drawn up to 60% dose range for the case of 80cGy, the isodose curves could be drawn up to 80% dose range for the case of 31cGy. Furthermore, the isodose curves almost agreed with that obtained with the isodose plotter in low dose range. However, further improvement of our system is necessary in high dose range.

• 한국의학물리학회지:의학물리
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• 제24권3호
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• pp.140-144
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• 2013

본 연구에서는 방사선생물 분야에서는 사용하는 세슘-137 조사기에 대한 기준 흡수선량을 측정하고 시료의 방사선량 평가에 활용하기 위하여 유리선량계를 교정하였다. 세슘-137 감마선에 대하여 IAEA TRS-277 프로토콜을 적용하여 정밀하게 물흡수선량을 결정하였다. 기준 흡수선량 측정에는 PTW-TM300013 전리함과 PTW-TM41023 물팬텀을 사용하였으며, 유리선량계는 DoseAce사의 GD-302M 모델을 사용하였다. 교정된 유리선량계의 불확도(1 SD)는 약 2.7%로 평가되며, 본 결과는 연구용 시료의 방사선량 측정에 이용될 예정이다.

• 대한방사선기술학회지:방사선기술과학
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• 제24권2호
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• pp.29-33
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• 2001

The accurate measurement for a long bone have taken an important part in orthopedics surgical diseases when the length of extremities is different each other. However, it is true that various kinds of methods to search for the accurate measurement on used in medical centers. In this study, we measured the real length of long bone for CT Scanogram and F.F.D by 100cm and 200cm in the angle of inclination $0^{\circ},\;3^{\circ}$ and $7^{\circ}$. This method will be useful to diagnose and treat patients more accurately.

• 한국의학물리학회지:의학물리
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• 제22권4호
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• pp.198-205
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• 2011

감마선조사장치는 세포실험, 동물실험, 혈액방사선 조사, 선량측정 실험 및 교육 등에 널리 사용되고 있다. 한국원자력의 학원에서 보유하고 있는 Biobeam8000 (STS Steuerungstechnik &. Strahlenschutz GmbH, Braunschweig, Germany, Cs-137, 81.4 TBq) 감마선 조사장치는 7.5 L의 대용량과 넓은 영역에 사용이 가능한 감마선 조사장치이다. 비커 내부에 균일한 방사선조사를 위해 Cs-137 선원이 위아래 24 cm 범위를 일정한 주기로 왕복 이동하며, 기존의 다른 감마선 조사기와 같이 시료를 넣는 비커는 방사선 조사동안 360도 회전한다. 기존의 감마선 조사기와 달리 비교적 균일한 선량이 조사되는 반면에 방사선원이 이동하므로 위치에 따른 구체적인 선량정보도 필요로 하게 된다. 본 연구에서는 유리 선량계를 이용하여 Biobeam8000 감마선 조사장치의 비커 내부 선량을 측정하였고, 측정결과를 바탕으로 선량선형성과 선량재현성에 대한 평가 및 선량분포의 정보를 도출하였다. 이 결과를 바탕으로 실험 및 방사선 조사 시 효율적인 조사장치 사용을 위한 가이드라인을 제시하고자 한다.

• Korean Journal of Radiology
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• 제21권4호
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• pp.450-461
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• 2020

Objective: We performed a meta-analysis to evaluate the agreement of cardiac computed tomography (CT) with cardiac magnetic resonance imaging (CMRI) in the assessment of right ventricle (RV) volume and functional parameters. Materials and Methods: PubMed, EMBASE, and Cochrane library were systematically searched for studies that compared CT with CMRI as the reference standard for measurement of the following RV parameters: end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), or ejection fraction (EF). Meta-analytic methods were utilized to determine the pooled weighted bias, limits of agreement (LOA), and correlation coefficient (r) between CT and CMRI. Heterogeneity was also assessed. Subgroup analyses were performed based on the probable factors affecting measurement of RV volume: CT contrast protocol, number of CT slices, CT reconstruction interval, CT volumetry, and segmentation methods. Results: A total of 766 patients from 20 studies were included. Pooled bias and LOA were 3.1 mL (-5.7 to 11.8 mL), 3.6 mL (-4.0 to 11.2 mL), -0.4 mL (5.7 to 5.0 mL), and -1.8% (-5.7 to 2.2%) for EDV, ESV, SV, and EF, respectively. Pooled correlation coefficients were very strong for the RV parameters (r = 0.87-0.93). Heterogeneity was observed in the studies (I² > 50%, p < 0.1). In the subgroup analysis, an RV-dedicated contrast protocol, ≥ 64 CT slices, CT volumetry with the Simpson's method, and inclusion of the papillary muscle and trabeculation had a lower pooled bias and narrower LOA. Conclusion: Cardiac CT accurately measures RV volume and function, with an acceptable range of bias and LOA and strong correlation with CMRI findings. The RV-dedicated CT contrast protocol, ≥ 64 CT slices, and use of the same CT volumetry method as CMRI can improve agreement with CMRI.

• 대한방사선기술학회지:방사선기술과학
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• 제47권3호
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• pp.183-195
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• 2024

Additional functional upgrades to the large-area compton camera (LACC) measurement device that can provide characteristics evaluation information (nuclear species and radioactivity) and two-dimensional or three-dimensional distribution imaging information of radioactive materials existing in surface or internal of concrete structures are required in terms of work stability and efficiency in order to apply to actual decommissioning sites such as nuclear power plants or medical cyclotron facilities by using this measurement device. To this purpose, the technology that allows radiation workers to intuitively and visually check the distribution of radioactive materials in advance by matching the two-dimensional distribution imaging information of radioactive materials obtained through the LACC measurement device and visual imaging of the measurement zone (10 m × 5 m) was developed. In addition, the separate system that can automatically adjust the position (height) in units of the measurement area size (0.7 m × 0.3 m × 0.8 m) of the LACC measurement device was developed and the integrated management system for characteristics evaluation information and two-dimensional or three-dimensional distribution imaging information obtained per unit of measurement for radioactive materials was developed. These functional upgrades related to LACC measurement device can improve work efficiency and safety when measuring radioactivity of concrete structures and enable the establishment of appropriate decommissioning strategies using radioactivity measurement information for decommissioning nuclear power plants or medical cyclotron facilities.

• Investigative Magnetic Resonance Imaging
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• 제20권4호
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• pp.207-214
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• 2016

Purpose: The purpose of this study was to investigate the effect of the number of measurement points on the calculation of transverse relaxation time (T2) with a focus on muscle T2. Materials and Methods: This study assumed that muscle T2 was comprised of a single component. Two phantom types were measured, 1 each for long ("phantom") and short T2 ("polyvinyl alcohol gel"). Right calf muscle T2 measurements were conducted in 9 healthy male volunteers using multiple-spin-echo magnetic resonance imaging. For phantoms and muscle (medial gastrocnemius), 5 regions of interests were selected. All region of interest values were expressed as the mean ${\pm}$ standard deviation. The T2 effective signal-ratio characteristics were used as an index to evaluate the magnetic resonance image quality for the calculation of T2 from T2-weighted images. The T2 accuracy was evaluated to determine the T2 reproducibility and the goodness-of-fit from the probability Q. Results: For the phantom and polyvinyl alcohol gel, the standard deviation of the magnetic resonance image signal at each echo time was narrow and mono-exponential, which caused large variations in the muscle T2 decay curves. The T2 effective signal-ratio change varied with T2, with the greatest decreases apparent for a short T2. There were no significant differences in T2 reproducibility when > 3 measurement points were used. There were no significant differences in goodness-of-fit when > 6 measurement points were used. Although the measurement point evaluations were stable when > 3 measurement points were used, calculation of T2 using 4 measurement points had the highest accuracy according to the goodness-of-fit. Even if the number of measurement points was increased, there was little improvement in the probability Q. Conclusion: Four measurement points gave excellent reproducibility and goodness-of-fit when muscle T2 was considered mono-exponential.