• Radiation Oncology Journal
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• v.8 no.1
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• pp.115-124
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• 1990

The characteristics of 23 MV photon beam have been presented with respect to clinical parameters of central axis depth dose, tissue-maxi mum ratios, scatter-maximum ratios, surface dose and scatter correction factors. The nominal accelerating potential was found to be $18.5\pm0.5$ MV on the central axis. The half-value layer (HVL) of this photon beam was measured with narrow beam geometry from central axis, and it has been showed the thickness of $24.5\;g/cm^2$. The tissue-maximum ratio values have been determined from measured percentage depth dose data. In our experimental dosimetry, the surface dose of maximum showed only $9.6\%$ of maximum dose at $10\times10\;cm^2$, 100 cm SSD, without blocking tray in. The TMR'S of $0\times0$ field size have been determined to get average $2.3\%$ uncertainties from three different methodis; are zero effective attenuation coefficient, non-ilnear least square fit of TMR's data and effective linear attenuation coefficient from the HVL of 23 MV photon beams of dual energy linear accelerator.

• Radiation Oncology Journal
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• v.8 no.1
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• pp.65-71
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• 1990

Between January,1974 and December 1980, fifty eight patients with locoregional recurrent breast carcinoma who did not have evidence of distant metastasis after initial treatment of surgery with or without adjuvant chemotherapy were treated with radiation therapy. Among them, five patients were excluded from this study because of incomplete record or incomplete treatment. The 5-year overall survival and disease free survival from the time of locoregional recurrence was $27\%\;and\;15\%$ respectively. In univariate analysis of prognostic variables, the clinical stage at initial diagnosis, recur duration, number of recurrence sites, size of recurrences, response to the treatment, remission duration were all found to have no significant effect on survival or disease free survival. On the other hand, menopausal status at initial diagnosis, number of positive node at initial surgery, whether or not the use of adjuvant chemotherapy after initial mastectomy had definite prognositc significance. In multivariate analysis of prognostic variables, remission duration, menopausal status at diagnosis, number of axillary node at mastectomy had definite prognostic significance. On the other hand, remission duration more than 12 months, premenopaus at initial mastectomy, less than four positive axillary lymph nodes at mastectomy predicted a good prognosis.

• Radiation Oncology Journal
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• v.12 no.1
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• pp.109-115
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• 1994

The purpose of this paper is to develop an efficient method for the quick determination of multiple isocenters plans to provide optimal dose distribution in sterotactic radiosurgery. A Spherical dose model was developed through the use of fit to the exact dose data calculated in a 18cm diameter of spherical head phantom. It computes dose quickly for each spherical part and is useful to estimate dose distribution for multiple isocenters. An automatic computer search algorithm was developed using the relationship between the isocenter move and the change of dose shape, and adapted with a spherical dose model to determine isocenter separation and cellimator sizes quickly and automatically. A spheric81 dose model shows a comparable isodose distribution with exact dose data and permits rapid calculations of 3-D isodoses. the computer search can provide reasonable isocenter settings more quickly than trial and error types of plans, while producing steep dose gradient around target boundary. A spherical dose model can be used for the quick determination of the multiple isocenter plans with 3 computer automatic search. Our guideline is useful to determine the initial multiple isocenter plans.

• Radiation Oncology Journal
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• v.14 no.1
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• pp.33-39
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• 1996

Purpose : This study was done to analyze survivals, patterns of failure, and complications of early uterine cervix cancer after curative radiotherapy. Materials and Methods : Eighty patients with uterine cervix cancer FIGO Stage IB (48 cases) and Stage IIA (32 cases) treated with radiotherapy were analyzed retrospectively. Patients were treated from November 1985 to May 1993, and minimum follow up period was 24 months and 6 cases were lost to follow up. All of them were treated with external radiotherapy and different fractions of high dose rate intracavitary radiotherapy, Survival rates, failure patterns, complication rates and degrees of severity were analyzed according to several factors. Results : Overall 5 year survival rate and relapse free survival rate were $72.3\%$, and $72.8\%$ respectively. Prognostic factors were stage, size, pathology, RT response and there was no significant survival difference among the reasons of radiotherapy choice. There were 19 cases of treatment failure, another 3 cases were not tumor related death, and most of treatment related failure occurred within 24 months Late complication rate of bladder and rectum were $8.8\%,\;15\%$ respectively, frequency and severity of complication were correlated with ICR fractionation dose and total dose. Conclusion : These results showed that survival rates of early stage radiation treated cervix cancer patients were comparable to surgical series, but more aggressive treatment methods needed for stage IIA poor prognostic patients. To decrease late complication, choice of proper ICR dose and meticulous vaginal packing is needed.

• Radiation Oncology Journal
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• v.17 no.3
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• pp.256-260
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• 1999

Purpose : An investigation has been carried out on the factors which affect the response reading of thermoluminescent dosimeters (TLD-100) loaded with thin material in high energy Photon. The aim of the study was to assess the energy response of TLD-100 to the therapeutic ranges of photon beam. Materials and Methods : In this technique, TLD-100 (abbreviated as TLD) chips and three different thin material (Tin, Gold, and Tissue equivalent plastic plate) which mounted on the TLD chip were used in the clinical photon beam. The thickness of each metal plates was 0.1 mm and TE plastic plate was 1 mm thick. These compared with the photon energy dependence of the sensitivities of TLD (normal chip), TLD loaded with Tin or Gold plate, for the photon energy range 6 MV to 15 MV, which was of interest in radiotherapy. Results : The enhancement of surface dose in the TLD with metal plate was clearly detected. The TLD chips with a Gold plate was found to larger response by a factor of 1.83 in 10 MV photon beam with respect to normal chip. The sensitivity of TLD loaded with Tin was less than that for normal TLD and TLD loaded with Gold. The relative sensitivity of TLD loaded with metal has little energy dependence. Conclusion : The good stability and linearity with respect to monitor units of TLD loaded with metal were demonstrated by relative measurements in high energy Photon ($6\~15$ MV) beams. The TLD laminated with metals embedded system in solid water phantom is a suitable detector for relative dose measurements in a small beam size and surface dose.

• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.173-182
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• 1999

Contrast-enhanced CT has an important role in assessing liver lesions, the optimal protocol to get most effective result is not clear. The mein goal when deciding injention protocol is to optimize lesion detectability with rapid scanning when lesion to liver contrast is maximum. For this purpose, we developed a physiological model of the contrast medium enhancement based on the compartment modeling and pharmacokinetics. Blood supply to liver is achieved in two paths. This dual supply characteristic distinguishes the CT enhancement of liver from that of the other organs. The first path is by hepatic artery and to second, by portal vein. However, it is assumed that only gepatic artery can supply blood to hepatocellular carcinoma(HCC) compartment, thus, the difference of contrast enhancement is resulted between normal liver tissue and hepatic tumor. By solving differential equations for each compartment simultaneously using the computer program Matlab, CT contrast-enhancement curves were simulated. The simulated enhancement curves for aortic, hepatic, portal vein, and HCC compartments were compared with the mean enhancement curves from 24 patients exposed to the same protocols as the simulation. These enhancement curves showed a good agreement. Furthermore, we simulated lesion-to-liver curves for various injection protocols, and the effects were analyzed. The variables to be considered in the injection protocol were injection rate, dose, and concentration of contrast material. These data may help to optimize scanning protocols for better diagnosis.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.2
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• pp.200-206
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• 2005

Cemento-ossifying fibroma of the jaws is well circumscribed, generally slow-growing, benign lesions which enlarge in an expansile manner. Clinically it presents as a slowly enlarging lesion commonly in the premolar-molar area of the mandible and only occasionally in the maxilla and other locations. It occurs twice as often in females and primarily in the 20 to 30 year age group. Differential diagnosis should be peformed, preferably with other fibro-osseous lesions such as fibrous dysplasia. A faster growing and more destructive variant of cemento-ossifying fibroma sometimes occurs in patients under age 15 and is termed juvenile (aggressive) ossifying fibroma. Treatment is surgical removal with the extent depending on the size and location of the individual lesion. Recurrence is considered rare. A case involving a 12-year-old male patient with delayed eruption of right mandibular canine is discussed. Following an incisional biopsy, the histopathologic diagnosis established was cemento-ossifying fibroma. After the surgical enucleation of the lesion, no sign of recurrence was detected.

• Radiation Oncology Journal
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• v.22 no.1
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• pp.69-75
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• 2004

Purpose : A new fiduciary plate and orientation marker have been devised to assist the quality assurance (QA) procedures for port films in radiation therapy department. The plate is used in conjunction with the film/cassette combination during weekly QA procedures, at Seoul National University Hospital (SNUH), in order to verify treatment fields in high radiation therapy. Materials and Methods : A new fiduciary plate was fabricated using an acrylic plate, cerrobend, standard blocking tray and mercury. The acrylic plate had the dimension of $1{\times}25{\times}25$ cm, with two fiduciary markers. The plate was rigidly attached onto the standard blocking tray, thus making it easier to set the fiduciary plate to the center on the radiation field on the linear accelerator. The plate had two 2-mm vertical and horizontal lines, with the minor scales in 2-cm steps. The orientation marker was a small mercury filled disk, which was inserted into the plate. Results : The geometrical structure of the lines in the plate makes it easier to correlate two different images between the simulation and port films. The marker clearly indicated the orientation of the film, for example, the anterior, posterior, left, right and various oblique orientations, without the placement of a conventional orientation marker. Also, the new orientation marker could easily be applied to the simulator by placing the small orientation marker onto the image intensifier or in front of the film/cassette holder. Conclusions : The new fiduciary plate appears to be useful in verifying the treatment fields, and the new orientation marker makes the film orientation simple, which is expected to lower the block fabrication errors.

• Journal of Veterinary Clinics
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• v.28 no.3
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• pp.314-317
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• 2011

A 16-year-old, spayed female, Maltese dog weighing 4.3 kg was presented with a 2-week history of yellowish nose-and oral-discharge, anorexia and lethargy. In physical examination, indefinite ulcerative mass about $3{\times}3$ cm in size in the left sublingual region, severe gingivoperiodontitis, halitosis, moderate dental calculus, fever and swelling of mandible soft tissue were noted. In radiographic view, periodontitis and bone lysis findings on the left rostral part of maxilla and mandible were observed. In complete blood count and blood chemistry test, thrombocytosis, increased levels of serum $NH_3$, AST and ALP were obtained. Urinalysis revealed hematuria and proteinuria. In histological examination, squamous cell carcinoma was diagnosed. No surgery was performed, but combined treatment with carboplatin and piroxicam was initiated. Five days after initiation of medication, because of insistent vomiting, piroxicam was substituted to meloxicam. Although the therapeutic efficacy of meloxicam could not be known; administration of meloxicam might be less potential to gastrointestinal side-effects than piroxicam. The dog totally received 3 times of carboplatin infusion. Five days after third infusion of carboplatin, the dog was hospitalized with severe lethargy, vomiting and bloody diarrhea. In examination, severe renal failure signs were noted, and the dog was euthanized.

• Polymer(Korea)
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• v.38 no.3
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• pp.351-357
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• 2014

In membrane covered stent, occlusion and fracture from membrane degradation by gastric acid sometimes occurred. Therefore, we investigated the physical properties of membrane covered stent according to its ingredient and concentration in gastric acid environment. Membrane covered stents consisted of silicone and polyurethane with 15%, 18%, 20% concentrations were used. After incubating stents in a condition of pH 1.2, we checked any changes at every 3 weeks for 18 weeks. The changes of membrane surface, radial expansion and recovery force of stent were investigated. Coating thickness increased proportionally to an increase in ingredient concentration. Surface was evenly coated with silicone compared to the case with polyurethane and its homogeneity was excellent in a high concentration. Degradation was much severe in the case of polyurethane. The radial force of silicone was higher than polyurethane, and the decrease of radial and recovery force was higher in the case of polyurethane. In conclusion, high concentration of silicone membrane was more stable than polyurethane in acid environment of in vitro study.