• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.138-142
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• 2016

Dual-energy digital radiography (DEDR) has been used for detecting lesions within the body using energy subtraction methods. The purpose of this study was to acquire optimal bone and tissue image by changing physical factors such as Tube voltage (kVp) and add filters, and then we compared with the predicted values using SRS-78 program and experimental results. For that purpose, we acquired images according to changes in physical parameters of various materials since we had to acquire the optimal bone and tissue image using energy subtraction. Used phantom consists of aluminum and polymethyl methacrylate (PMMA) and a comparison of image optimization was measured by contrast-to-noise ratio (CNR). In results, first of all, we confirmed that a subtraction image from 50 kVp image and 120 kVp image is optimal bone and tissue image. Also when we added a 10 mm Aluminum add filter, we expected it is a result of the optimal bone and tissue image. Besides, we confirmed these results are consistent with the predicted optimized condition by SRS-78 program.. In conclusion, we indicated that we can acquire optimal bone and tissue image by controling physical factors such as kVp, add filters through this study. Also we expected that DEDR will contribute to the field of medical imaging technology.

• Clinical and Experimental Pediatrics
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• v.51 no.3
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• pp.237-242
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• 2008

To investigate the trends in the survival rate (SR) for very low birth weight infants (VLBW) and extremely low birth weight infants (ELBWI) in Korea, a total of 43 articles pertaining to SR were analyzed, covering the years from 1967 to 2007. The changes in SR were compared using 5 year periods. The SR for VLBWI has increased remarkably, from 31.8% in early 1960 to 65.8% in early 1990 and 78.8% in early 2000. The SR for ELBWI has increased from 8.2% in early 1960 to 37.4% in early 1990 and 62.4% in early 2000. The SR has improved steeply since early 1990. When the SRs for VLBWI in Korea were compared with those in the U.S.A. and Japan, the figures were 40%, 72%, and 79% in 1985; 65.8%, 82%, and 86% in 1990; 71.3%, 86%, and 88% in 1995; 78.8%, 86%, and 89% in 2000, respectively. Although the recent SRs for VLBWI and ELBWI in Korea has improved rapidly, they have not yet reached the levels in these highly developed countries. To obtain accurate statistics that could be represented as an SR for premature infants in Korea, we have to develop a nationwide network database project.

• Journal of Korean Neurosurgical Society
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• v.58 no.4
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• pp.334-340
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• 2015

Objective : Pineal parenchymal tumors (PPTs) in adults are rare, and knowledge regarding their optimal management and treatment outcome is limited. Herein, we present the clinical results of our series of PPTs other than pineoblastomas managed by stereotactic radiosurgery (SRS) at upfront setting. Methods : Between 1997 and 2014, nine consecutive adult patients with the diagnosis of PPTs, either pineocytoma or pineal parenchymal tumor of intermediate differentiation, were treated with SRS. There were 6 men and 3 women. The median age was 39 years (range, 31-53 years). All of the patients presented with symptoms of hydrocephalus. Endoscopic third ventriculostomy and biopsy was done for initial management. After histologic diagnosis, patients were treated with Gamma Knife with the mean dose of 13.3 Gy (n=3) or fractionated Cyberknife with 32 Gy (n=6). Results : After a mean follow-up of 78.6 months (range, 14-223 months), all patients were alive and all of their tumors were locally controlled except for one instance of cerebrospinal fluid seeding metastasis. On magnetic resonance images, tumor size decreased in all patients, resulting in complete response in 3 patients and partial response in 6. One patient had experienced temporary memory impairment after SRS, which improved spontaneously. Conclusion : SRS is effective and safe for PPTs in adults and can be considered as a useful alternative to surgical resection at upfront setting.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.78-79
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• 2000

소형 루비듐 원자시계를 만들기 위해 원자에서의 CPT(coherent population trapping) 현상, 유도 라만 산란(SRS: Stimulated Raman Scattering), 루비듐 메이저 등 다양한 방법들이 소개되고 있다$^{(1, 3)}$ . 본 연구에서는 루비듐 원자 주파수 표준기를 위해 루비듐 셀을 이용한 마이크로파 주파수 표준기(즉, 원자시계)에 관한 연구를 수행하였다. 루비듐 셀을 이용한 원자시계는 가격이 저렴하고 부피가 작아 휴대용으로 적합하다. 따라서 정보통신 분야에서 동기 신호 발생기에 사용되는 등 다양한 응용분야를 갖고 있다. (중략)

• Korean Journal of Psychosomatic Medicine
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• v.10 no.2
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• pp.78-91
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• 2002

Objective : The purpose of this study was to develop the somatization rating scale (SRS), and then to use the scale in clinical pracitice. Methods: First, a preliminary survey was conducted for 109 healthy adults to obtain 40 response items. Second, a preliminary questionnaire was completed by 215 healthy subjects. Third, a comparison was made regarding somatization responses among 242 patients (71 with anxiety disorder. 73 with depressive disorder, 47 with somatoform disorder, and 51 with psychosomatic disorder) and 215 healthy subjects. Results : Factor analysis yielded 5 subscales : cardiorespiratory and nervous responses, somatic sensitivity, gastrointestinal responses, general somatic responses, genitourinary, eye and muscular responses. Reliability was computed by administering the SRS to 62 healthy subjects during a 2-week interval. Test-retest reliability for 5 subscales and the total score was significantly high, ranging between .86-.94. Internal consistency was computed, and Cronbach's ${\alpha}$ for 5 subscales ranged between .72-.92, and .95 for the total score. Convergent validity was computed by correlating the 5 subscales and the total score with the total score of the global assessment of recent stress (GARS) scale, the perceived stress questionnaire (PSQ), and the symptom checklist-90-revised (SCL-90-R). The correlations were all at significant levels. Discriminant validity was computed by comparing the total score and the 5 subscale scores of the patient and control groups. Significant differences were found for 5 subscales and the total score. Only the depressive disorder group was siginificantly higher than control group in all the subscale scores and total scores of SRS among 4 patient groups. In somatic sensitivity, only depressive disorder patients were significantly higher than the normal controls, whereas in general somatic subscale, depressive disorder and somatoform disorder groups were significantly higher than the normal controls. In total scores of the SRS, female subjects were significantly higher than males. Conclusion : These results indicate that the SRS is highly reliable and valid, and that it can be utilized as an effective measure for research in stress- and somatization-related fields. The depressive disorder and somatoform disorder groups showed more widespread somatization than the anxiety and psychosomatic disorder groups.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.595-600
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• 2016

The diagnostic multileaf collimator(MLC) was designed for patient dose reduction in diagnostic radiography We used monte carlo simulation code (MCNPX, LANL, USA) to evaluate efficiency of shielding material for making diagnostic MLC as preliminary study. The diagnostic radiography unit was designed using SRS-78 program according to tube voltage (80,100,120 kVp) and acquired energy spectrums. The shielding material was SKD11 alloy tool steel that is composed of 1.6% carbon(C), 0.4% silicon(Si), 0.6% manganese (Mn), 5% chromium (Cr), 1% molybdenum(Mo) and vanadium(V). The density of it was $7.89g/cm^3$.Using tally card 6, we calculated the shielding efficiency of MLC according to tube voltage. The results was that 98.3% (80 kVp), 95.7 %(100 kVp), 93.6% (120 kVp). We certified efficiency of diagnostic MLC fabricated from SKD11 alloy steel by monte calro simulation. Based on the results, we designed the diagnostic MLC and will develop the diagnostic MLC for reduction of patient dose in diagnostic radiography.

• Journal of the Korean Society of Radiology
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• v.16 no.1
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• pp.15-23
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• 2022

3D printing technology is being used in various fields such as medicine and biotechnology, and materials containing metal powder are being commercialized through recent material development. Therefore, this study intends to analyze the photon spectrum during added filtration using 3D printing material during diagnostic X-ray examination through simulation. Among the Monte Carlo techniques, MCNPX (ver. 2.5.0) was used. First, the appropriateness of the photon spectrum generated in the simulation was evaluated through SRS-78 and SpekCalc, which are X-ray spectrum generation programs in the diagnostic field. Second, photon spectrum the same thickness of Al and Cu filters were obtained for characterization of 3D printing materials containing metal powder. In addition, the total photon fluence and average energy according to changes in tube voltage were compared and analyzed. As a result, it was analyzed that PLA-Al required about 1.2 ~ 1.4 times the thickness of the existing Al filter, and PLA-Cu required about 1.4 ~ 1.7 times the thickness of the Cu filter to show the same degree of filtration. Based on this study in the future, it is judged that it can be utilized as basic data for manufacturing 3D printing additional filters in medical fields.

• Journal of radiological science and technology
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• v.41 no.3
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• pp.215-221
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• 2018

Cone beam Computed Tomography(CBCT) is an increasing trend in clinical applications due to its ability to increase the accuracy of radiation therapy. However, this leaded to an increase in exposure dose. In this study, the simulation using Monte Carlo method is performed and the absorbed dose of CBCT is analyzed and standardized data is presented. First, after simulating the CBCT, the photon spectrum was analyzed to secure the reliability and the absorbed dose of the tissue in the human body was evaluated using the MIRD phantom. Compared with SRS-78, the photon spectrum of CBCT showed similar tendency, and the average absorbed dose of MIRD phantom was 8.12 ~ 25.88 mGy depending on the body site. This is about 1% of prescription dose, but dose management will be needed to minimize patient side effects and normal tissue damage.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.389-392
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• 2002

Digital radiography (DR) is being developed for numerous applications in medical imaging. For understanding DR image, it is necessary to comprehend DR responses to X-ray in terms of absorbed energy. This study reports on the relationship of absorbed energy in the scintillator vs. pixel value of detector. Pixel value and exposure were measured from 50 kVp to 120 kVp until the detector was saturated. For representing radiation produced at the X-ray tube, we used program Srs-78 and compared experimental exposure with calculated exposure. Absorbed energy was acquired using spectrum and we got the relation between the two values.

• Journal of Korean Neurosurgical Society
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• v.29 no.3
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• pp.317-323
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• 2000

Objective : To evaluate the role of stereotactic LINAC radiosurgery in treatment of meningiomas, the authors retrospectively analyzed the result of radiosurgery in our institute. Method: During last ten years, twenty patients underwent stereotactic LINAC radiosurgery(LINAC SRS) for meningiomas. The mean age of the patients was 51 years(22-78 years). The most common tumor location for radiosurgery was parasagittal, sphenoid wing and tentorial area. With regards to indications of radiosurgery for meningiomas, LINAC radiosurgery was done for primary treatment in six patients, for postoperative residual tumors in eleven patients, for postoperative regrowth in three patients. Mean tumor volume was $5.14cm^3$($0.28-15.1cm^3$), mean field diameter was 2.01cm(1.2-3cm). The mean marginal dose was 20.55Gy(13-30Gy). The follow-up evaluation was done annually with radiologic findings and clinical status. The mean follow-up period was 46.8(24-120) months. Result : In the radiologic response, the tumor volume was reduced in five(25%) of twenty patients, fourteen showed arrested growth(70%), but one patient showed increased growth(5%). In the clinical response, nine patients improved clinically(45%), ten patients was stable(50%) and one patient worsened during follow-up period. With regards to correlation with radiologic and clinical response, in nineteen patients who showed radiologic response to radiosurgery(decreased and arrested growth after radiosurgery), nine patients(47.4%) improved and ten patients (52.6%) showed no change, one patient(5%) had symptomatic radiation necrosis at four years after SRS, which needed craniotomy. Conclusion : The overall control rate of meningiomas with LINAC radiosurgery was 95% in radiologic follow up and 95% clinically. The radiation complication rate was 5%. These results indicate that LINAC radiosurgery can be considered as safe and effective method for meningiomas.