• 대한방사선치료학회지
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• 제14권1호
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• pp.59-64
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• 2002

Purpose : In radiotherapy, various materials are used to located in treatment field unintentionally. It increases the dose delivered to the skin by interactions of the X-ray within the materials and occurs unwanted skin reaction.(due to the dose build-up effect) This aim of the this study is to measure the increase in skin dose when 13 materials are located in treatment field. Methods : Photon beam measurements were made using an plane-parallel chamber (Markus, PTW-Freiburg) in a polystyrene phantom. skin dose were measured using various overlaying 13 materials. a fixed geometry of a $10{\times}10cm$ field, a SSD=100cm and photon energy 4MV on Varian CLINAC 600C accelerator were used for all measurements. Results : There is an increase in skin dose for all materials($16.4{\sim}160.1\%$). As a percentage of maximum dose, the lowest skin dose were measured for the underwear with silk($43.2\%$) and the highest were measured for the 100m1 fluid-bag($96.6\%$) Conclusion : There is a significant increase in skin dose with 13 materials in the treatment field. a significant increase in skin dose can occur which could produce unwanted skin reaction. considerations for placement of 13 materials to be outside the treatment field whenever possible should be used to keep skin dose to a minimum level.

• 혜화의학회지
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• 제22권1호
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• pp.171-184
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• 2013

Single-and repeated-dose toxicities of Compound K (CK) were evaluated according to Toxicity Test Guidelines of Korea Food and Drug Administration using Sprague-Dawley rats. For single-dose toxicity study, CK was dissolved in drinking water, orally administered and examined for 14 days. As results, CK up to a dose of 5,000 mg/kg, the limited dose, neither induced death, clinical signs and necropsy findings, nor affected body weight gain and organ weights, in which 10% lethal dose could not be estimated. Based on the results of single-dose toxicity test, CK was administered at doses of 500, 1,000 or 2,000 mg/kg for 28 days for the evaluation of repeated-dose toxicity. All doses including the limited dose (2,000 mg/kg) of CK did not cause any abnormalities of rats, including mortality, clinical signs, body weight gain, feed/water consumption, necropsy findings, organ weights, hematology, blood biochemistry. Rather, high doses (1,000 - 2,000 mg/kg) of CK reduced the serum levels of alanine transaminase (ALT), aspartate transaminase (AST), creatinine phosphokinase (CPK), lactate dehydrogenase (LDH) and triglycerides, in addition to an increase in glucose, indicative of protective effects on hepatic and muscular injuries. Thus, both maximum tolerable dose (MTD) and no observed adverse effect level (NOAEL) were not determined. The results indicate that long-term intake of high-dose CK might not induce general adverse effects.

• 한국방사선학회논문지
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• 제6권1호
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• pp.27-37
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• 2012

2002년 1월 1일부터 2011년 6월 30일까지 지방의 C 대학병원 방사선 관계 종사자 의사, 간호사, 방사선사 및 기타 323명에 대한 개인피폭 선량 측정결과 4419건을 비교 분석하였다. 연도별로는 2003년도 수치가 가장 높았고, 2007년도 수치가 낮게 나타났다. 성별로는 남성이 여성에 비해 높고 연령대는 30대가 높았으며 직종별로는 의사, 간호사, 방사선사 순으로 나타났다. 근무부서별 평균피폭선량은 심혈관 센터, 인터벤션실, 영상의학과(의사), 투시촬영실 순으로 높은 수치를 나타냈다. 이상의 결과로 볼 때 ICRP에서 권고하는 허용선량 기준치(20mSv/년)를 초과하지 않는 범위의 피폭을 받고 있는 것으로 나타났다. 그러나 평균치와 달리 선량의 개인편차가 심하기 때문에 피폭의 최소화를 위해서 방사선 관련 종사자들이 개인별 피폭관리에 최선을 다해야 할 것이다.

• Clinical and Experimental Reproductive Medicine
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• 제29권4호
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• pp.259-267
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• 2002

Objective: This study was performed to compare the clinical outcomes of GnRH antagonist (Cetrorelix) single dose and multiple dose protocols for controlled ovarian hyperstimulation with GnRH agonist long protocol. Materials and Method: From September 2001 to March 2002, 48 patients (55 cycles) were performed controlled ovarian hyperstimulation for ART using by either GnRH antagonist and GnRH agonist. Single dose of 3 mg GnRH antagonist was administered in 15 patients (17 cycles, single dose group) at MCD #8 and multiple dose of 0.25 mg of GnRH antagonist was administered in 15 patients (18 cycles, multiple dose group) from MCD #7 to hCG injection day. GnRH agonist was administered in 18 patients (20 cycles, control group) by conventional GnRH agonist long protocol. We compared the implantation rate, number of embryos, and clinical pregnancy rate among three groups. Student-t test and Chi-square were used to determine statistical significance. Statistical significance was defined as p<0.05. Results: There were no significant differences in ampules of used gonadotropins, number of mature oocytes, obtained embryos between single and multiple dose group, but compared with control group, ampules of used gonadotropins, number of mature oocytes, obtained embryos were decreased significantly in both groups. Clinical pregnancy rate and implantation rate were not different in three groups. There were no premature LH surge and ovarian hyperstimulation syndrome in three groups. Multiple pregnancy were occurred 1 case in multiple dose group and 2 case in control group. Conclusions: GnRH antagonist is a safe, effective, and alternative method in the controlled ovarian hyperstimulation compared with GnRH agonist. Clinical outcomes and efficacy of both single and multiple dose protocol are similar between two groups.

• Radiation Oncology Journal
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• 제37권1호
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• pp.13-21
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• 2019

Purpose: Glioblastoma (GBM) carries a high propensity for in-field failure despite trimodality management. Past studies have failed to show outcome improvements with dose-escalation. Herein, we examined trends and outcomes associated with dose-escalation for GBM. Materials and Methods: The National Cancer Database was queried for GBM patients who underwent surgical resection and external-beam radiation with chemotherapy. Patients were excluded if doses were less than 59.4 Gy; dose-escalation referred to doses ≥66 Gy. Odds ratios identified predictors of dose-escalation. Univariable and multivariable Cox regressions determined potential predictors of overall survival (OS). Propensity-adjusted multivariable analysis better accounted for indication biases. Results: Of 33,991 patients, 1,223 patients received dose-escalation. Median dose in the escalation group was 70 Gy (range, 66 to 89.4 Gy). The use of dose-escalation decreased from 8% in 2004 to 2% in 2014. Predictors of escalated dose were African American race, lower comorbidity score, treatment at community centers, decreased income, and more remote treatment year. Median OS was 16.2 months and 15.8 months for the standard and dose-escalated cohorts, respectively (p = 0.35). On multivariable analysis, age >60 years, higher comorbidity score, treatment at community centers, decreased education, lower income, government insurance, Caucasian race, male gender, and more remote year of treatment predicted for worse OS. On propensity-adjusted multivariable analysis, age >60 years, distance from center >12 miles, decreased education, government insurance, and male gender predicted for worse outcome. Conclusion: Dose-escalated radiotherapy for GBM has decreased over time across the United States, in concordance with guidelines and the available evidence. Similarly, this large study did not discern survival improvements with dose-escalation.

• Journal of Radiation Protection and Research
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• 제46권3호
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• pp.98-105
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• 2021

Background: In recent events of the coronavirus disease 2019 (COVID-19) pandemic, computed tomography (CT) scans are being globally used as a complement to the reverse-transcription polymerase chain reaction (RT-PCR) tests. It will be important to be aware of major organ dose levels, which are more relevant quantity to derive potential long-term adverse effect, for Korean pediatric and adult patients undergoing CT for COVID-19. Materials and Methods: We calculated organ dose conversion coefficients for Korean pediatric and adult CT patients directly from Korean pediatric and adult computational phantoms combined with Monte Carlo radiation transport techniques. We then estimated major organ doses delivered to the Korean child and adult patients undergoing CT for COVID-19 combining the dose conversion coefficients and the international survey data. We also compared our Korean dose conversion coefficients with those from Caucasian reference pediatric and adult phantoms. Results and Discussion: Based on the dose conversion coefficients we established in this study and the international survey data of COVID-19-related CT scans, we found that Korean 7-year-old child and adult males may receive about 4-32 mGy and 3-21 mGy of lung dose, respectively. We learned that the lung dose conversion coefficient for the Korean child phantom was up to 1.5-fold greater than that for the Korean adult phantom. We also found no substantial difference in dose conversion coefficients between Korean and Caucasian phantoms. Conclusion: We estimated radiation dose delivered to the Korean child and adult phantoms undergoing COVID-19-related CT examinations. The dose conversion coefficients derived for different CT scan types can be also used universally for other dosimetry studies concerning Korean CT scans. We also confirmed that the Caucasian-based CT organ dose calculation tools may be used for the Korean population with reasonable accuracy.

• 대한방사선기술학회지:방사선기술과학
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• 제42권1호
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• pp.47-51
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• 2019

This study was conducted from July 1 to September 30, 2018 using Optically Stimulated Luminescence Dosimeter(OSLD) and photoluminescent glass dosimeter(PLD) to measure the 3-month exposure dose and the cumulative dose in the active working area of the nuclear medicine worker Respectively. As a result, the cumulative dose for three months in the worker and work area was measured as 1.97 mSv and 2.02 mSv in the PLD. The mean surface dose and the mean depth dose of the OSLD were measured to be 2.04 mSv. The difference in the total surface dose measured by the PLD and the OSLD was 0.66mSv and the total mean surface dose was 0.07mSv. The difference between the total depth dose and the total depth dose was 0.1mSv and 0.02mSv, respectively. It was found that the dose value of the OSLD was higher than that of the PLD. In addition, it was found that the maximum difference of 0.01mSv was observed between the PLD and the OSLD of the worker. For the dose measurement of the two dosimetry systems, there was no significant difference between the PLD and the OSLD in the surface dose of 0.239 (p>0.05). Also, the significance of PLD and OSLD in the deep dose was 0.109, which was not statistically significant (p>0.05).

• 대한방사선기술학회지:방사선기술과학
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• 제42권4호
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• pp.271-277
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• 2019

CareDose 4D which is the Siemens's Automatic Exposure Control (AEC) can adjust the level of radiation dose distribution which is based on organ characteristic unlike other manufacturer's AEC. Currently, a wide scan range containing different organs is sometimes examined at once (defined as one scan). The purpose of this study was to figure out which organ characteristic option is suitable when one scan method is utilized. Two types of anthropomorphic phantoms were scanned in the same range which were from frontal bone to carina level according to three different organ characteristics such as Thorax, Abdomen, and Neck. All scans and image reconstruction parameters were equally applied and radiation dose were compared. Radiation dose with Thorax organ characteristic was lower than that with Neck. Also, that with Abdomen oran characteristic was lower than Thorax. There were significant differences in radiation dose according to different organ characteristics at the same parameters (P<0.05). Usage of Neck organ characteristic had a result of the highest radiation dose to all phantom. On the other hand, utilization of Abdomen organ characteristic showed the lowest radiation dose. As a result, it is desirable to set appropriate organ characteristic according to examined body part when you checkup patients. Also, when you implement one scan method, selection of Abdomen-based organ characteristic has reduced more radiation dose compared with two different organ characteristic.

• 한국의학물리학회지:의학물리
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• 제31권3호
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• pp.54-62
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• 2020

Dose calculation algorithms play an important role in radiation therapy and are even the basis for optimizing treatment plans, an important feature in the development of complex treatment technologies such as intensity-modulated radiation therapy. We reviewed the past and current status of dose calculation algorithms used in the treatment planning system for radiation therapy. The radiation-calculating dose calculation algorithm can be broadly classified into three main groups based on the mechanisms used: (1) factor-based, (2) model-based, and (3) principle-based. Factor-based algorithms are a type of empirical dose calculation that interpolates or extrapolates the dose in some basic measurements. Model-based algorithms, represented by the pencil beam convolution, analytical anisotropic, and collapse cone convolution algorithms, use a simplified physical process by using a convolution equation that convolutes the primary photon energy fluence with a kernel. Model-based algorithms allowing side scattering when beams are transmitted to the heterogeneous media provide more precise dose calculation results than correction-based algorithms. Principle-based algorithms, represented by Monte Carlo dose calculations, simulate all real physical processes involving beam particles during transportation; therefore, dose calculations are accurate but time consuming. For approximately 70 years, through the development of dose calculation algorithms and computing technology, the accuracy of dose calculation seems close to our clinical needs. Next-generation dose calculation algorithms are expected to include biologically equivalent doses or biologically effective doses, and doctors expect to be able to use them to improve the quality of treatment in the near future.

• Communications for Statistical Applications and Methods
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• 제29권4호
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• pp.421-439
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• 2022

Phase I dose-finding trials are essential in drug development. By finding the maximum tolerated dose (MTD) of a new drug or treatment, a Phase I trial establishes the recommended doses for later-phase testing. The primary toxicity endpoint of interest is often a binary variable, which describes an event of a patient who experiences dose-limiting toxicity. However, there is a growing interest in dose-finding studies regarding non-binary outcomes, defined by either the weighted sum of rates of various toxicity grades or a continuous outcome. Although several novel methods have been proposed in the literature, accessible software is still lacking to implement these methods. This study introduces a newly developed R package, UnifiedDoseFinding, which implements three phase I dose-finding methods with non-binary outcomes (Quasi- and Robust Quasi-CRM designs by Yuan et al. (2007) and Pan et al. (2014), gBOIN design by Mu et al. (2019), and by a method by Ivanova and Kim (2009)). For each of the methods, UnifiedDoseFinding provides corresponding functions that begin with next that determines the dose for the next cohort of patients, select, which selects the MTD defined by the non-binary toxicity endpoint when the trial is completed, and get oc, which obtains the operating characteristics. Three real examples are provided to help practitioners use these methods. The R package UnifiedDoseFinding, which is accessible in R CRAN, provides a user-friendly tool to facilitate the implementation of innovative dose-finding studies with nonbinary outcomes.