• Progress in Medical Physics
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• v.33 no.4
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• pp.80-87
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• 2022

Purpose: Proton therapy has different relative biological effectiveness (RBE) compared with X-ray treatment, which is the standard in radiation therapy, and the fixed RBE value of 1.1 is widely used. However, RBE depends on a charged particle's linear energy transfer (LET); therefore, measuring LET is important. We have developed a LET measurement method using the inefficiency characteristic of an EBT3 film on a proton beam's Bragg peak (BP) region. Methods: A Gafchromic EBT3 film was used to measure the proton beam LET. It measured the dose at a 10-cm pristine BP proton beam in water to determine the quenching factor of the EBT3 film as a reference beam condition. Monte Carlo (MC) calculations of dose-averaged LET (LET_d) were used to determine the quenching factor and validation. The dose-averaged LETs at the 12-, 16-, and 20-cm pristine BP proton beam in water were calculated with the quenching factor. Results: Using the passive scattering proton beam nozzle of the National Cancer Center in Korea, the LET_d was measured for each beam range. The quenching factor was determined to be 26.15 with 0.3% uncertainty under the reference beam condition. The dose-averaged LETs were measured for each test beam condition. Conclusions: We developed a method for measuring the proton beam LET using an EBT3 film. This study showed that the magnitude of the quenching effect can be estimated using only one beam range, and the quenching factor determined under the reference condition can be applied to any therapeutic proton beam range.

• Radiation Oncology Journal
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• v.35 no.3
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• pp.241-248
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• 2017

Purpose: To evaluate the efficacy and safety of extended-field radiation therapy for patients with thoracic superficial esophageal cancer (SEC). Materials and Methods: From May 2007 to October 2016, a total of 24 patients with thoracic SEC (T1a and T1b) who underwent definitive radiotherapy and were analyzed retrospectively. The median total radiotherapy dose was 64 Gy (range, 54 to 66 Gy) in conventional fractionation. All 24 patients received radiotherapy to whole thoracic esophagus and 23 patients received elective nodal irradiation. The supraclavicular lymph nodes, the celiac lymph nodes, and both of those nodal areas were included in 11, 3, and 9 patients, respectively. Results: The median follow-up duration was 28.7 months (range 7.9 to 108.0 months). The 3-year overall survival, local control, and progression-free survival rates were 95.2%, 89.7%, and 78.7%, respectively. There were 5 patients (20.8%) with progression of disease, 2 local failures (8.3%) and 3 (12.5%) regional failures. Three patients also experienced distant metastasis and had died of disease progression. There were no treatment-related toxicities of grade 3 or higher. Conclusion: Definitive extended-field radiotherapy for thoracic SEC showed durable disease control rates in medically inoperable and endoscopically unfit patients. Even extended-field radiotherapy with elective nodal irradiation was safe without grade 3 or 4 toxicities.

• Journal of Gastric Cancer
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• v.13 no.4
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• pp.255-262
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• 2013

Purpose: Robotic surgery for gastric cancer is a promising alternative to laparoscopic surgery, but the data are limited. We aimed to evaluate whether gaining experience in robotic gastrectomy could improve surgical outcomes in the treatment of gastric cancer. Materials and Methods: Two hundred and seven consecutive cases of patients with clinical stage I gastric cancer who underwent robotic surgery at the National Cancer Center of Korea between February 2009 and February 2012 were retrospectively reviewed. Surgical outcomes were analyzed and compared between the initial 100 and later 100 cases. Results: Seven patients required conversion to open surgery and were excluded from further analysis. The mean operating time for all patients was 248.8 minutes, and mean length of hospitalization was 8.0 days. Twenty patients developed postoperative complications. Thirteen were managed conservatively, while 6 had major complications requiring invasive procedures. One mortality occurred owing to myocardial infarction. Operating time was significantly shorter in the latter 100 cases than in the initial 100 cases (269.9 versus 233.5 minutes, P<0.001). The number of retrieved lymph nodes was significantly greater in the latter cases (35.9 versus 39.9, P=0.032). The hospital stay of patients with complications was significantly longer in the initial cases than in the latter cases (16 versus 7 days, P=0.005). Conclusions: Increased experience with the robotic procedure for gastric cancer was associated with improved outcomes, especially in operating time, lymph node retrieval, and shortened hospital stay of complicated patients. Further development of surgical techniques and technology might enhance the role of robotic surgery for gastric cancer.

• 대한예방의학회:학술대회논문집
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• 2002.10a
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• pp.403-405
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• 2002

• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.208-209
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• 2011

• Natural Product Sciences
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• v.24 no.4
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• pp.266-271
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• 2018

Five new prenylated stilbenes (1 - 5), along with the known compounds cudraflavone C, trans-4-isopentenyl-3,5,2',4'-terahydroxystilbene, trans-4-(3-methyl-E-but-1-enyl)-3,5,2',4'-tetrahydroxystilbene, pannokin G, cycloartobiloxanthone, artonin P, morusin, artocarpin, artonin E, kuwanon C, artobiloxanthone, and artoindonesianin C (6 - 17) were isolated from the stem bark of the tropical tree Artocarpus communis. The structures were established by NMR spectroscopic analysis, MS studies, and comparison with spectral data reported in the literature.

• Korean Journal of Radiology
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• v.25 no.7
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• pp.684-686
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• 2024

• Progress in Medical Physics
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• v.33 no.4
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• pp.108-113
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• 2022

Purpose: Proton therapy has been used for optimal cancer treatment by adapting its Bragg-peak characteristics. Recently, a tissue-sparing effect was introduced in ultrahigh-dose-rate (FLASH) radiation; the high-energy transmission proton beam is considered in proton FLASH therapy. In measuring high-energy/ultrahigh-dose-rate proton beam, Faraday Cup is considered as a dose-rate-independent measurement device, which has been widely studied. In this paper, the feasibility of the simply designed Faraday Cup (Poor Man's Faraday Cup, PMFC) for transmission proton FLASH therapy is investigated. Methods: In general, Faraday cups were used in the measurement of charged particles. The simply designed Faraday Cup and Advanced Markus ion chamber were used for high-energy proton beam measurement in this study. Results: The PMFC shows an acceptable performance, including accuracy in general dosimetric tests. The PMFC has a linear response to the dose and dose rate. The proton fluence was decreased with the increase of depth until the depth was near the proton beam range. Regarding secondary particles backscatter from PMFC, the effect was negligible. Conclusions: In this study, we performed an experiment to investigate the feasibility of PMFC for measuring high-energy proton beams. The PMFC can be used as a beam stopper and secondary monitoring system for transmission proton beam FLASH therapy.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.7
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• pp.2945-2950
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• 2014

Background: This study compared risk factors for depression and suicidal ideas among cancer patients for comparison with the general population, and identified influencing factors. Materials and Methods: We analyzed data from 2,472 cancer patients in the National Cancer Center and nine Regional Cancer Centers and frequency-matched data for age and sex from 2,349 members of the general population who completed the National Health and Nutrition Examination Survey in 2008. Logistic regression analysis was used to identify factors affecting depression and suicidal ideas. Results: Cancer patients were not likely to have more depression (OR=0.96, 95%CI=0.79-1.18) and were less likely to have suicidal ideas (OR=0.64, 95%CI=0.53-0.79) compared to the general population. Female sex, more stress, and lower quality of life were influencing factors. The additional risk factors for suicidal ideas among cancer patients included income (OR=0.62, 95%CI=0.43-0.91), smoking (OR=1.63, 95% CI=1.06-2.50), recurrence (OR=1.50, 95%CI=1.15-1.95), and chemotherapy (OR=1.66, 95%CI=1.26-2.19). Conclusions: No differences appeared in depression rates between cancer patients and the general population, and cancer patients were less likely to have suicidal ideas. However, cancer patients were likely to have more risk factors than the general population, and those classified as being at high risk of suicide should receive distress management and social economic support, from early in the treatment process.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.3
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• pp.1295-1301
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• 2015

Background: Cancer imposes a significant economic burden on individuals, families and society. The purpose of this study was to estimate the economic burden of cancer using the healthcare claims and cancer registry data in Korea in 2009. Materials and Methods: The economic burden of cancer was estimated using the prevalence data where patients were identified in the Korean Central Cancer Registry. We estimated the medical, non-medical, morbidity and mortality cost due to lost productivity. Medical costs were calculated using the healthcare claims data obtained from the Korean National Health Insurance (KNHI) Corporation. Non-medical costs included the cost of transportation to visit health providers, costs associated with caregiving for cancer patients, and costs for complementary and alternative medicine (CAM). Data acquired from the Korean National Statistics Office and Ministry of Labor were used to calculate the life expectancy at the time of death, age- and gender-specific wages on average, adjusted for unemployment and labor force participation rate. Sensitivity analysis was performed to derive the current value of foregone future earnings due to premature death, discounted at 3% and 5%. Results: In 2009, estimated total economic cost of cancer amounted to $17.3 billion at a 3% discount rate. Medical care accounted for 28.3% of total costs, followed by non-medical (17.2%), morbidity (24.2%) and mortality (30.3%) costs. Conclusions: Given that the direct medical cost sharply increased over the last decade, we must strive to construct a sustainable health care system that provides better care while lowering the cost. In addition, a comprehensive cancer survivorship policy aimed at lower caregiving cost and higher rate of return to work has become more important than previously considered.