• Journal of radiological science and technology
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• v.15 no.1
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• pp.65-78
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• 1992

Routine chest radiography is generally imaged by high voltage technique but some radiological technologists use low voltage for imaging. High voltage is usually said between $120\;kV{\sim}140\;kV$. Some RTs like using heavy filtration but others seldom like using it. However which is better for use calcium tungustate film screen system or ortho system and high contrast film or wide latitude c-type film for the exculusive use of chest radiography. We could not make a decision which is ideal method for use. In my opinion any method is not always exellent for chest radiography. In my experiments that I had at Kaken hospital in Japan last year I expect to keep the balance between image quality and diagnostic range and to reduce radiation dose for patients. My experiments are as follows. 1. We have looked into system characteristics(speed and contrast) in accordance with kVp($80{\sim}140$) and added filter($no{\sim}1/16\;VL$) in three screen film systems(BX3+CRONEX4, SRO750+MGH, SRO750+MGL). 2. We have looked into skin dose and film dose with same D=1.8 lung field density in accordance with kVp($80{\sim}140$) and added filter($no{\sim}1/16\;VL$) in three screen film systems. 3. We have compared with the evaluation between correlation of physical image quality(MTF) and optical diagnostic capability. Result are follows. 1. Speed of BX3+CRONEX4 became higher in accodance with kVp and thickness of filter but speed of ortho system was not as like regular system. Thicker filter diminished the speed over 100 kV range in SRO750+MGL. In case of SRO750+MGH speed of 1/16VL filter was looked into lower than speed of 1/4VL filter. Sensitivity of ortho system depends on tube voltage and added filter. 2. Skin dose has been detected $225\;{\mu}Gy{\sim}66\;{\mu}Gy$ in BX3+CRONEX4 from 80 kV, no filter to 140 kV, 1/16VL filter. SRO750+MGH could reduce the patient dose $1/2{\sim}1/3$ level in comparison to that of BX3+CRONEX4. 3. The higher kV was the worse MTF became the thicker filter was the worse MTF became too. MTF of BX3+CRONEX4 was detected better than MTF of SRO750+MGH but SRO750+MGH's optical detectability of small lesion in lung field came out better than that of BX3+CRONEX4. Conclusion Recently routine chest radiography is generally imaged by high voltage but it seems to be there are some questions in using of film screen combination. In high voltage chest radiography the subject contrast will come down that means latitude become wider. In this case if we select the low contrast film screen system(C or L type) the film contrast will fall down extremly and detectability of small lesion will be deteriorated. Wide latitude C, L type film has a merit of high detectability on mediastinum. Furthermore high contrast film screen system has the advantage to keep the high contrast in low density region as like mediastinum and heart shadow. Therefore in low subject contrast high voltage chest radiography we would rather choose the high contrast film screen system(H type) I think. From a view point of patient dose detectability of mediastinum and lung field. The optimum technical facter was found out 120 kV, 1/16VL filter : BX3+CRONEX4, 140 kV, 1/4VL filter : SRO750+MGH, 100 kV, 1/4VL filter : SRO750+MGL.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.247-255
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• 2010

Purpose: Developing a roofed Pechan prism type scope with long eye relief. Methods: To reduce the overall length and to lengthen the eye relief of scope, the objective part was designed by adopting the roofed Pechan prism and also the eyepiece part was designed by adopting the field lens with minus refractive power in front of reticle, respectively. Finally, by integrating above two parts, the roofed Pechan prism type scope with 90 mm eye relief was developed. Results: The characteristics of the developed and fabricated scope with 90 mm eye relief by integrating the objective part with the roofed Pechan prism and the eyepiece part with minus refractive power had the magnification of $+3.0{\times}$, the length from the 1st lens to the last lens of about 121 mm, the barrel diameter of 28 mm, and the effective objective-diameter of 17 mm. Also it was found that the line width of resolution was about 900 cycles/rad at the 50% MTF value criterion. Conclusions: We could design and manufacture the roofed Pechan prism type scope with 90 mm eye relief, the characteristics of which had the magnification of $3.0{\times}$, the MTF above 50% at 900 cycles/rad, and the length from the 1st lens to the last lens of about 121 mm.

• Journal of Radiation Protection and Research
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• v.34 no.1
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• pp.25-30
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• 2009

Micro-columnar CsI(Tl) is the most popular scintillator material which is used for many indirect digital X-ray imaging detectors. The light scattering at the surface of micro-columnar CsI(Tl) scintillator was studied to find the correlation between the surface roughness and the resultant image resolution of indirect X-ray imaging detectors. Using a commercially available optical simulation program, Light Tools, MTF (Modulation Transfer Function) curves of the CsI(Tl) film thermally evaporated on glass substrate with different thickness were calculated and compared with the experimental estimation of MTF values by the edge X-ray image method and CCD camera. It was found that the standard deviation value of Gaussian scattering model which is determined by the surface roughness of micro-columns could certainly change the MTF value of image sensors. This model and calculation methodology will be beneficial to estimate the overall performance of indirect X-ray imaging system with CsI(Tl) scintillator film for optimum design depending on its application.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.1
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• pp.11-17
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• 2004

We tried to design and manufacture a night scope which is used in the leisure sports field. The whole system consists of an IR light source part, an objective lens part, an intensifier tube part and an eye_piece lens part. We designed an objective lens part to the infinite object imaging optical-system with 80mm focal-length, 40mm effective-aperture and 14mm image-field-size of which the chromatic aberration is reduced by using materials of BK7 and FD4. The resolution of this system is about 25lines/mm at the 40% MTF value criterion. The eye_piece lens is adopted goods to be used commercially to save cost of production. The design technique which gets in this development will be utilized greatly in good developments of the dot, the sight and the day/night riflescope system at the hereafter.

• Journal of the Korean Society of Radiology
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• v.16 no.4
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• pp.395-403
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• 2022

Flat-panel detector (FPD) used in digital radiographic imaging systems was used to perform a quantitative power spectrum evaluation as a result of the thickness change of polymethyl methacrylate (PMMA), a tissue equivalent. As the PMMA thickness increases with the resolution-chart phantom image, the effect of the scattering line increases, indicating that the modulation characteristics decrease, and the image is bright. The results show that the noise of the image increases, and noise-power spectral images are obtained by Fourier transform to confirm by spatial frequency. Thus, it can be verified that the PMMA thickness and noise are proportional through the result of evaluating the change of resolution characteristics and representing the 2D noise-power spectrum as one-dimensional values by evaluating the change of scattering line with MTF as the PMMA thickness increases in the image.

• Journal of radiological science and technology
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• v.26 no.4
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• pp.39-46
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• 2003

Digital radiographic systems based on solid-state detectors, commonly referred to as flat-panel detectors, are gaining popularity in clinical practice. Large area, flat panel solid state detectors are being investigated for digital radiography. The purpose of this work was to evaluate the active matrix flat panel digital x-ray detectors in terms of their modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). In this paper, development and evaluation of a selenium-based flat-panel digital x-ray detector are described. The prototype detector has a pixel pitch of $139\;{\mu}m$ and a total active imaging area of $14{\times}8.5\;inch^2$, giving a total 3.9 million pixels. This detector include a x-ray imaging layer of amorphous selenium as a photoconductor which is evaporated in vacuum state on a TFT flat panel, to make signals in proportion to incident x-ray. The film thickness was about $500\;{\mu}m$. To evaluate the imaging performance of the digital radiography(DR) system developed in our group, sensitivity, linearity, the modulation transfer function(MTF), noise power spectrum (NPS) and detective quantum efficiency(DQE) of detector was measured. The measured sensitivity was $4.16{\times}10^6\;ehp/pixel{\cdot}mR$ at the bias field of $10\;V/{\mu}m$ : The beam condition was 41.9\;KeV. Measured MTF at 2.5\;lp/mm was 52%, and the DQE at 1.5\;lp/mm was 75%. And the excellent linearity was showed where the coefficient of determination ($r^2$) is 0.9693.

• Journal of the Korean Society of Radiology
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• v.10 no.5
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• pp.327-335
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• 2016

The study is enforce to study image quality evaluation of condition provide the IEC and combination of clinical conditions each quality of radiation that image quality to assess the conditions provided to IEC in the clinical environment to conduct image quality assessment of the digital radiography system in the detector have environmental limits. First, image quality evaluation was evaluated by measuring the MTF, NPS using four quality of radiation and Using MCNPX simulation lastly DQE make a image quality evaluation after calculating the particle fluence to analyze spectrum quality of radiation. Second, Using MCNPX simulation of four quality of radiation was evaluated absorbed dose rate about electronic 1 per unit air, water, muscle, bone by using Radiation flux density and energy, mass-energy absorption coefficient of matter. Results of evaluation of image quality, MTF of four quality of radiation was satisfied diagnosis frequency domain 1.0 ~ 3.0 lp/mm of general X-ray that indicated 1.13 ~ 2.91 lp/mm spatial frequency. The NPS has added filter, spatial frequency 0.5 lp/mm at standard NPS showed a tendency to decrease after increase. Unused added filter, spatial frequency 0.5 lp/mm at standard NPS showed a certain NPS result value after decrease. DQE in 70 kVp / unuesd added filter(21 mm Al) / SID 150 cm that patial frequency 1.5 lp/mm at standard showed a tendency to decrease after certain value showed. Patial frequency in the rest quality of radiation was showed a tendency to decrease after increase. Results of evaluation of absorbed dose, air < water < muscle < bone in the order showed a tendency to increase. Based on the results of this study provide to basic data that present for the image quality evaluation method of a digital radiation imaging system in various the clinical condition.

• Journal of the Optical Society of Korea
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• v.18 no.2
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• pp.110-117
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• 2014

In this study, we objectively determined whether the ReSTOR as a multifocal IOL (intraocular lens) has a multifocal function compared to the IQ as a monofocal IOL in vivo by OQAS (Optical Quality Analysis System). Eighteen patients who had cataract surgery with implantation of ReSTOR (27 eyes) and 15 patients with IQ (21 eyes), were included inthis study. Uncorrected distance visual acuity (UCDVA), corrected distance visual acuity (CDVA), uncorrected near visual acuity (UCNVA)and distance corrected near visual acuity (DCNVA) were measured. After setting the artificial pupil size to 3 mm, we performed 'Optical quality'. We inputted defocus diopters of (objective spherical refraction)(far), (objective spherical refraction-1.25 D)(intermediate),(objective spherical refraction-2.5 D)(near), and (objective spherical refraction-3.5 D)(very near) into 'selected spherical refraction' simulating the optical quality at far, intermediate, and near distance. We changed the pupil size to 5 mm and repeated the same measurements. The UCDVA and CDVA did not show significant differences between the 2 groups. But, the UCNVA and DCNVA of the ReSTOR group were better than those of the IQ group (p=0.000, p=0.000). For 3 mm pupil, at far distance, modulation transfer function (MTF) cut off and point spread function (PSF) width at 50% of ReSTOR were worse than those of IQ (p=0.039, p=0.020). At intermediate distance, MTF cut off, Strehl ratio and PSF width at 50% of ReSTOR were worse than those of IQ (p=0.001, p=0.001, p=0.000). At near distance, MTF cut off of ReSTOR was worse than that of IQ (p=0.033). At very near distance, MTF cut off and Strehl ratio of ReSTOR were worse than those of IQ (p=0.002, p=0.002), but PSF width at 50% of ReSTOR was better than that of IQ. For 5 mm pupil, most parameters at each distance, there was no significant difference between the 2 groups. Only PSF width at 50% of ReSTOR were worse than those of IQ at intermediate distance (p=0.013). It was impossible to show the multifocal function of ReSTOR compared to the IQ byOQAS.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.110-110
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• 2010

2009년 7월 23일-24일 양일간의 APEC MTF 컨퍼런스는 APEC 회원 경제가 아시아-태평양지역에서 광업부문의 지속가능한 발전의 주제를 토의할 기회를 제공했다. 본 컨퍼런스는 APEC의 광업부문의 지속가능한 발전이라는 프로젝트의 중요 부분이며 컨퍼런스의 활발한 참여는 프로젝트의 성공을 증진시켰다. 지속가능한 발전에 대한 안건이 수년간 APEC의 핵심부분이었으며, 특히 광업장관(MRM)회의에 상정되어 왔다. 2004년 6월 칠레 안토파가스타의 제1차 회의에서, 광업장관들은 APEC 지역에서 광업 및 금속산업의 지속가능한 발전은 부를 창출하고, 환경사업을 창출하며, 사회적으로 책임있는 발전을 도모하며 사회를 위한 향상된 가치를 만들어낸다는데 동의했다. 초기의 action item들 중에서 지속가능한 발전에 있어서 광물 및 금속의 기여를 규명하는 것도 있었다. 광업에 있어서 지속가능한 발전에 대한 안건의 토의는 2005년 10월 한국의 경주 제2차 APEC MRM 회의에서 속계되었다. 관련된 action task는 채광 후 토지운영 뿐만 아니라 에너지 효율기술, 광업 오염 통제 기술과 같은 환경친화적인 채광기술에 대한 정보교환 및 협조를 독려하는 것이었다. 2007년 호주 퍼스의 제3차 회의에서 APEC MRM 회의는 특히 지구화의 시대에 APEC 지역 광물자원의 지속가능한 발전에 대한 긴밀한 지역적 협조에 대한 필요성을 인지하고 있다. 장관들은 역시 광업부문에서 지속가능한 발전에 대한 APEC 위상을 정립하기 위한 작업을 주도하기로 했으며 APEC 경제의 공통관심사를 UNCSD에 반영키 위한 자료제공을 하기로 결정했다. APEC 광업분야의 지속 가능한 개발에 관한 APEC MTF회의는 호주, 캐나다, 칠레, 중국, 인도네시아, 일본, 말레이시아, 파푸아 뉴기니, 페루, 필리핀, 한국, 러시아, 싱가포르, 타이완, 태국, 미국, 베트남에서 자신들의 지속 가능한 개발을 위한 활동에 관한 발표나 의견을 제시하였다. 세계 은행이나 AIM에서도 발표를 하였다. 중요한 소주제들은 다음과 같다. $\cdot$ APEC MTF가 APEC 광업분야의 지속 가능한 발전을 추구하는데 있어 적절한 포럼이라는 것 $\cdot$ 기업들이 사회적 책임(CSR)을 성실히 이행할 필요가 있다는 것 $\cdot$ 수자원과 인적자원의 부족을 다룰 필요가 있다는 것 $\cdot$ 적절한 광산 복구가 필요하다는 것이다. 한국은 "광업분야의 지속가능한 발전을 위한 환경과 광업간의 균형"이라는 프로젝트 아이디어를 제안했다. 인도네시아와 말레이시아는 한국측 프로젝트 수행의 중요성을 강조했다. 러시아 연방은 "광업에 있어 투자 활성화"라는 프로젝트 아이디어를 제안했다. 이 관점에서 MTF는 APEC 투자전문가 그룹과의 협력을 지지했으며 이 포럼간 활동을 활성화시키기 위하여 APEC 사무국에 요청했다. 이 프로젝트는 세계 광업분야의 투자를 증진시키는 최적관행 분석에 따라 제안될 것이고 수행될 것이다. 말레이시아는 광업 및 광업 산업의 지속가능한 발전지시자를 위한 역량구축 프로젝트를 제안했다. 태국은 말레이시아의 제안을 지지했으며 공동프로젝트를 제안했다.

• Korean Journal of Remote Sensing
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• v.30 no.1
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• pp.137-147
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• 2014

We proposed and verified the methods to maintain data qualities as well as to reduce data volume for the Geostationary Ocean Color Imager (GOCI), the world's first ocean color sensor operated in geostationary orbit. For the GOCI level-2 data, 92.9% of data volume could be saved by only the data compression. For the GOCI level-1 data, however, just 20.7% of data volume could be saved by the data compression therefore another approach was required. First, we found the optimized number of bits per a pixel for the GOCI level-1 data from an idea that the quantization bit for the GOCI (i.e. 12 bit) was less than the number of bits per a pixel for the GOCI level-1 data (i.e. 32 bit). Experiments were conducted using the $R^2$ and the Modulation Transfer Function (MTF). It was quantitatively revealed that the data qualities were maintained although the number of bits per a pixel was reduced to 14. Also, we performed network simulations using the Network Simulator 2 (Ns2). The result showed that 57.7% of the end-toend delay for a GOCI level-1 data was saved when the number of bits per a pixel was reduced to 14 and 92.5% of the end-to-end delay for a GOCI level-2 data was saved when 92.9% of the data size was reduced due to the compression.