• Journal of Radiation Protection and Research
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• v.24 no.4
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• pp.195-203
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• 1999

It is difficult to determine dosimetric characteristics for small field photon beams since such small fields do not achieve complete lateral electronic equilibrium and have steep dose gradients. Dosimetric characteristics of small field 4, 6, and 10 MeV photon beams have been measured in water with a diamond detector and compared to measurements using small volume cylindrical and plane parallel ionization chambers. Percent depth dose (PDD) and beam profiles for 6 and 10 MeV photon beams were measured with diamond detector and cylindrical ion chamber for small fields ranging from $1{\times}1\;to\;4{\times}4cm^2$. Total scatter factors($S_{c,p}$) for 4, 6, and 10 MeV photon beams were measured with diamond detector, cylindrical and plane parallel ion chambers for small fields ranging from $1{\times}1\;to\;4{\times}4cm^2$. The $S_{c,p}$ factors obtained with three detectors for 4, 6, and 10 MeV photon beams agreed well ($\pm1.2%$) for field sizes greater than $2{\times}2,\;2.5{\times}2.5,\;and\;3{\times}3\;cm^2$, respectively. For smaller field sizes, the cylindrical and plane parallel ionization chambers measure a smaller $S_{c,p}$ factor, as a result of the steep dose gradients across their sensitive volumes. The PDD values obtained with diamond detector and cylindrical ionization chamber for 6 and 10MeV photon beams agreed well ($\pm1.5%$) for field sizes greater than $4{\times}4\;cm^2$. For smaller field sizes, diamond detector produced a depth-dose curve which had a significantly shallower falloff than that obtained from the measurements of relative depth-dose with a cylindrical ionization chamber. For the measurements of beam profiles, a distortion in terms of broadened penumbra was observed with a cylindrical ionization chamber since diamond detector exhibited higher spatial resolution. The diamond detector with small sensitive volume, near water equivalent, and high spatial resolution is suitable detector compared to ionization chambers for the measurements of small field photon beams.

• Journal of Radiation Protection and Research
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• v.36 no.2
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• pp.93-98
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• 2011

We induced the activation of melanocytes in the epidermis of C57BL/6 mice by ultraviolet-B (UV-B) irradiation, and observed the effect of an herbal preparation (HemoHIM, HH) on the formation, and decrease of UV-B-induced epidermal melanocytes. C57BL/6 mice were irradiated by UV-B $80\;mJ{\cdot}cm^{-2}$ ($0.5\;mW{\cdot}sec^{-1}$) daily for 7 days, and HH was intraperitoneally, orally or topically applied pre- or post-irradiation. For the estimation of change of epidermal melanocytes, light microscopic observation with dihydroxyphenylalanine (DOPA) stain was performed. Split epidermal sheets prepared from the ear of untreated mice exhibited 13~15 melanocytes${\cdot}mm^{-2}$, and one week after UV irradiation, the applied areas showed an increased number of strongly DOPA-positive melanocytes with stout dendrites. But intraperitoneal, oral or topical treatment with HH before each irradiation interrupted UV-B-induced pigmentation and resulted in a marked reduction in the number of epidermal melanocytes as compared to the number found in UV-B-irradiated, untreated control skin. The number and size of DOPA-positive epidermal melanocytes were also significantly decreased in intraperitoneally injected or topically applicated group after irradiation with HH at 3rd and 6th weeks after irradiation. The present study suggests the HH as inhibitor of UV-B-induced pigmentation, and depigmenting agent.

• Journal of Radiation Protection and Research
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• v.36 no.2
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• pp.71-78
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• 2011

Yeong-Gwang N.P.P Private Environment Supervisory Organization analyzed over 3,000 samples including 10 marine and 24 land samples from the year 2,000 to 2009. According to the results of the analysis, artificial nuclides that resulted from the effect of Yeong-Gwang Nuclear Power Plant operations were not detected in most samples. However, from the rain and seawater samples, which were taken from inside the plants such as the intake, the discharge and the observatory, $^3H$ was detected although it was below the regulation level. The $^3H$ concentration detected in the rain taken from the observatory, by the yearly average criterion, was 30.5~40.0 $Bq{\cdot}L^{-1}$, which is around 20 times the $^3H$ concentration detected in the surroundings of the power plants, but it is 0.1% of the regulation level of 40,000 $Bq{\cdot}L^{-1}$. Also, $^3H$ concentration detected in the seawater taken from the intake and the discharge, by the yearly average criterion, was 2.75~17.8$Bq{\cdot}L^{-1}$, which means the concentration detected in the discharge is about 140~280% higher than that detected in the intake except the year 2006. Based on these results, it was determined that, although lower than the regulation level, the $^3H$ in gas and liquid form detected in the rain and seawater sampled from the observatory and the discharge was released into the environment from the power plants. Therefore, regular monitoring and analysis is required on the level of $^3H$ in the observatory and the discharge.

• Journal of Radiation Protection and Research
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• v.35 no.4
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• pp.135-141
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• 2010

Purpose : The patients who visited this department for pulmonary disease and need CT scans for Follow-up to observe change of CT value, evaluation of image quality and decrease of radiation dose as change of kVp. Subjects and Methods : Subjects were the patients of 20 persons visited this department for pulmonary disease and Somatom Sensation 16(Semens, Enlarge, Germany) was used. Measurement of CT value as change of kVp was done by setting up ROI diameter of 1cm at the height of thyroid, aortic arch, right pulmonary artery in arterial phase image using 100 kVp, measuring 3 times, and recorded the average. CT value of phantom was measured by scanning phantoms which means contrast media diluted by normal saline by various ratio with tube voltage of 80 kVp, 100 kVp, 120 kVp, 140 kVp and recorded the average of 3 CT values of center of phantom image. In analysing radiation dose, CTDIVOL values of the latest arterial phase image of 120 kVp and as this research set that of 100 kVp were analyzed comparatively. 2 observers graded quality of chest images by 5 degrees (Unacceptable, Suboptimal, Adequate, Good, Excellent). Results : CT value of chest image increased at 100 kVp by 14.06%~27.26% in each ROI than 120 kVp. CT value of phantom increased as tube voltage lowered at various concentration of contrast media. CTDIVOL decreased at 100 kVp(5.00 mGy) by 36% than 120 kVp(7.80 mGy) in radiation dose analysis. here were 0 Unacceptable, 1 Suboptimal, 3 Adequate, 10 Good, 6 Excellent in totally 20 persons. Conclusion : Chest CT scanning with low kilo-voltage for patients who need CT scan repeatedly can bring images valuable for diagnose, and decrease radiation dose against patients.

• Journal of Radiation Protection and Research
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• v.32 no.3
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• pp.123-133
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• 2007

Z-axis automatic tube current modulation technique automatically adjusts tube current based on size of body region scanned. The purpose of the current study was to compare noise, and radiation dose of multi-detector row CT (MDCT) of lower extremity performed with Z-axis modulation technique of automatic tube current modulation with manual selection fixed tube current. Fifty consecutive underwent MDCT venography of lower extremity with use of a MDCT scanner fixed tube current and Z-axis automatic tube current modulation technique (10, 11 and 12 HU noise index, $70{\sim}450\;mA$). Scanning parameters included 120 kVp, 0.5 second gantry rotation time, 1.35:1 beam pitch, and 1 mm reconstructed section thickness. For each subject, images obtained with Z-axis modulation were compared with previous images obtained with fixed tube current (200, 250, 300 mA) and with other parameters identical. Images were compared for noise at five levels: iliac, femoral, popliteal, tibial, and peroneal vein of lower extremity. Tube current and gantry rotation time used for acquisitions at these levels were recorded. All CT examinations of study and control groups were diagnostically acceptable, though objective noise was significantly more with Z-axis automatic tube current modulation. Compared with fixed tube current, 2-axis modulation resulted in reduction of CTDIvol (range, $-6.5%{\sim}-35.6%$) and DLP (range, $-0.2%{\sim}-20.2%$). Compared with manually selected fixed tube current, 2-axis automatic tube current modulation resulted in reduced radiation dose at MDCT of lower extremity venography.

• Journal of Yeungnam Medical Science
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• v.19 no.1
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• pp.28-38
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• 2002

Background: Chronic paranasal sinusitis is one of the most common disease in the otorhinolaryngologic field. Endoscopic sinus surgery is treatment of choice in chronic paranasal sinusitis. The aim of this study was to evaluate objective and subjective treatment outcomes of endoscopic sinus surgery in adult chronic paranasal sinusitis with or without polyp. Materials and Methods: We reviewed 84 adult patients underwent endoscopic sinus surgery by one surgeon from June 1999 to June 2000, prospectively. We analyzed preoperative and postoperative subjective symptom scores and acoustic rhinometric results. Results: Fifty cases were male and thirty four cases female. The average age was of 33 year-old (range: 17 to 66 years). There was significantly improvement of symptom scores in postoperative 3 months and 6 months compared with preoperative symptom scores. There was significantly increased postoperative total volume of nasal cavity. When we compared high score group with low score group, there was statistically significant improvement of symptom scores between preoperative stage and postoperative 3 months in radiologic grading group. Conclusions: Endoscopic sinus surgery is considered to be effective for the treatment of chronic paranasal sinusitis. It seems to be helpful to employ subjective symptom score system and objective total volume change of nasal cavity through acoustic rhinometric test to analyze effectiveness of endoscopic sinus surgery. In this study, the most important preoperative factor of sinus surgery outcomes is radiologic grading system.

• Progress in Medical Physics
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• v.17 no.4
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• pp.212-223
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• 2006

Positional accuracy of the on-board imager (OBI) isocenter with gantry rotation was presented in this paper. Three different type of automatic evaluation methods of discrepancies between therapeutic and OBI isocenter using digital image processing techniques as well as a procedure stated in the customer acceptance procedure (CAP) were applied to check OBI isocenter migration trends. Two kinds of kV x-ray image set obtained at OBI source angle of $0^{\circ},\;90^{\circ},\;180^{\circ},\;270^{\circ}$ and every $10^{\circ}$ and raw projection data for cone-beam CT reconstruction were used for each evaluation method. Efficiencies of the methods were also estimated. If a user needs to obtain an isocenter variation map with full gantry rotation, a method taking OBI image for every $10^{\circ}$ and fitting with 5th order polynomial was appropriate. However for a mere quality assurance (QA) purpose of OBI isocenter accuracy, it was adequate to use only four OBI Images taken at the OBI source angle of $0^{\circ},\;90^{\circ},\;180^{\circ}\;and\;270^{\circ}$. Maximal discrepancy was 0.44 mm which was observed between the OBI source angle of $90^{\circ}\;and\;180^{\circ}$ OBI isocenter accuracy was maintained below 0.5 mm for a year. Proposed QA program may be helpful to Implement a reasonable routine QA of the OBI isocenter accuracy without great efforts.

• The Korean Journal of Nuclear Medicine
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• v.34 no.5
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• pp.371-380
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• 2000

Purpose: Thallim-201 ($^{201}Tl$) brain SPECT, which can represent cellular activity of brain lesions, may provide more useful information in differentiating between benign and malignant brain lesions more so than CT of MRI, that merely represents anatomic changes or breakdown of blood brain barrier. We used $^{201}Tl$ brain SPECT prospectively to evaluate the utility of $^{201}Tl$-indices as an indicator of benign or malig nant lesions. Materials and Methods: We studied 28 patients. There were 13 cases of benign lesions (3: nonspecific benign lesion, 3: meningioma, 2: low grade glioma, 1: tuberculoma, central neurocytoma, hemangioblastoma, radiation necrosis, and choroid plexus papilloma) and 15 cases of malignant lesions (6: glioblastoma multiforme, 5: anaplastic glioma, 2: medulloblastoma, 1: metastasis and lymphoma). In all patients, CT and/or MRI were obtained and then $^{201}Tl$ brain SPECT was obtained with measuring mean $^{201}Tl$ index and peak $^{201}Tl$ index. An unpaired t-test was performed to compare the $^{201}Tl$-indices and pathologic diagnoses to evaluate the utility of $^{201}Tl$-indices as all indicator of benign or malignant lesions. Results: There were no statistically significant difference in $^{201}Tl$-indices between benign and malignant brain lesion (p>0.05). Conclusion: These results demonstrated that we could not use $^{201}Tl$ indices on brain SPECT alone as an indicator of benign or malignant brain lesions.

• Journal of Yeungnam Medical Science
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• v.17 no.1
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• pp.49-54
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• 2000

Background: Echocardiography is rapidly establishing itself as the primary diagnostic technique for investigation of children with heart diseases, and referrals are increasing to the pediatric cardiology clinic for investigation. However, because there is a lack of analyzed data on the patients referred to the pediatric cardiology clinics, we have proceeded to compare and analyze their characteristics to provide basic data base. Methods: From Oct. 1, 1998 to Jul. 10, 1999, total 443 cases referred to the pediatric cardiology clinic of Yeungnam University Hospital were studied retrospectively by medical records, chest X-ray, EKG and echocardiography, etc. Results: The results were as follows. 1. The proportion of male was 61.0%(261 cases) and that of female was 39.0%(67 cases). The ratio of male to female was 1.6:1. The proportion infants less than 1 year-old was 62.6% (26R cases) of all patients. 2. Cardiac murmur was present in 248 cases(57.9%), which was the most common case of referral ed to the pediatric cardiology clinic. The impression at referral was more congenital heart disease(70.6%) than acquired heart disease(17.8%) and arrhythmia01.6%). 3. The final diagnosis was as follows : congenital heart disease was present in 212 cases(49.5%), acquired heart disease, 59 cases(13.9%); arrhythmia. 13 cases(3.0%); normal heart. 144 cases(33.6%). Conclusion: Among the patients referred to pediatric cardiology clinic, 33.6%(144 cases) had normal hearts and why these patients were referred may be possibly due to more dependence on echocardiography than on auscultation instruction. Therefore, clinical and auscultatory skill should be emphasized to minimize dependence on expensive echocardiography for evaluation of pediatric heart disease.

• Journal of the Korean Arthroscopy Society
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• v.7 no.2
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• pp.169-175
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• 2003

Purpose : The purpose was to evaluate the early result of revision of failed anterior cruciate ligament (ACL) reconstruction. Materials and Methods : From August 1997 to February 2002, this report presents the findings of 18 patients who had revision surgery for failed ACL reconstruction. There was an average of 39 $(7\~120)$months from index procedure to the time of revision. Allografts were used in 14 $(78\%)$cases and autografts were used in 4 $(22\%)$cases and the revision procedures were assisted by arthroscopic technique. The majority of chief complaints were instability in 16 $(89\%)$cases. Sixteen $(89\%)$ cases had 1 previous reconstruction, 2 $(11\%)$ cases had 2. Before and after revision, patients were evaluated by Lachman test, pivot shift test, KT 2000, radiographs, Lysholm score and HSS score and subjective satisfaction. Results : Average length of followup was 27 $(12\~60)$months. Preoperatively, all cases were positive in Lachman test and pivot shift test. After revision the majority of cases were negative. Objectively improving stability was confirmed by KT 2000 and all average KT 2000 was 7.75 $(3.5\~12.5)$mm preoperatively and 2.36 $(1.0\~6.0)$mm at final followup. Lysholm score and HSS score were also improved from 72.6 $(66\~77)$ and 72.5 $(68\~78)$ preoperatively to 89.2 $(80\~92)$ and 88.2 $(81\~92)$ at final followup. Most $(89\%)$ of patients were satisfied with their results. The most common causes of failed ACL reconstruction were malposition of femoral tunnel in 11 $(61\%)$cases. Conclusion : Arthroscopic revision ACL surgery with adequate graft for failed ACL reconstruction was successful in objectively and subjectively improving stability. However, considering the most common causes of failure after ACL reconstruction were errors in surgical technique, it is important that the primary ACL reconstruction should be performed with correct surgical technique.