• Radiation Oncology Journal
• /
• v.19 no.1
• /
• pp.66-73
• /
• 2001

Purpose : For the research of Boron Neutron Capture Therapy (BNCT), fast neutrons generated from the MC-50 cyclotron with maximum energy of 34.4 MeV in Korea Cancer Center Hospital were moderated by 70 cm paraffin and then the dose characteristics were investigated. Using these results, we hope to establish the protocol about dose measurement of epi-thermal neutron, to make a basis of dose characteristic of epi-thermal neutron emitted from nuclear reactor, and to find feasibility about accelerator-based BNCT. Method and Materials : For measuring the absorbed dose and dose distribution of fast neutron beams, we used Unidos 10005 (PTW, Germany) electrometer and IC-17 (Far West, USA), IC-18, ElC-1 ion chambers manufactured by A-150 plastic and used IC-l7M ion chamber manufactured by magnesium for gamma dose. There chambers were flushed with tissue equivalent gas and argon gas and then the flow rate was S co per minute. Using Monte Carlo N-Particle (MCNP) code, transport program in mixed field with neutron, photon, electron, two dimensional dose and energy fluence distribution was calculated and there results were compared with measured results. Results : The absorbed dose of fast neutron beams was $6.47\times10^{-3}$ cGy per 1 MU at the 4 cm depth of the water phantom, which is assumed to be effective depth for BNCT. The magnitude of gamma contamination intermingled with fast neutron beams was $65.2{\pm}0.9\%$ at the same depth. In the dose distribution according to the depth of water, the neutron dose decreased linearly and the gamma dose decreased exponentially as the depth was deepened. The factor expressed energy level, $D_{20}/D_{10}$, of the total dose was 0.718. Conclusion : Through the direct measurement using the two ion chambers, which is made different wall materials, and computer calculation of isodose distribution using MCNP simulation method, we have found the dose characteristics of low fluence fast neutron beams. If the power supply and the target material, which generate high voltage and current, will be developed and gamma contamination was reduced by lead or bismuth, we think, it may be possible to accelerator-based BNCT.

• Pediatric Infection and Vaccine
• /
• v.15 no.1
• /
• pp.59-67
• /
• 2008

Purpose : According to the 2008 WHO report, incidence, prevalence, and mortality of tuberculosis are decreasing globally. The 7th National Tuberculosis Survey of 1995 in Korea showed that the prevalence of tuberculosis was also decreasing. This study was performed to review the hospitalized childhood tuberculosis in a children's hospital over a 20 year period. Methods : Medical records of children <16 years of age hospitalized with the diagnosis of tuberculosis at the Seoul National University Children's Hospital between 1988 and 2007 were reviewed retrospectively. Changes in number of patients and involved sites were also analyzed by four 5-year periods. Results : Out of the 186 hospitalized patients, 59.1% were male. Median age at diagnosis was 5.5 years old (range, 10 days-15 years). The main involved sites included the lung (n=54, 29%) or pleura (n=12, 6.5%), central nervous system (n=49, 26.3%), lymph node (n=15, 8.1 %), bone and joint (n=9, 4.8%), gastrointestinal tract (n=5, 2.7%) or peritoneum (n=5, 2.7%), pericardium (n=2, 1.1%) and others (n=3, 1.6%). Total 32 patients (17.2%) showed miliary pattern. The proportion of hospitalization with newly diagnosed tuberculosis among all cause hospitalization decreased from 0.61% to 0.09%, comparing the period of 1988-1992 and 2003-2007 (P<0.001) and the incidence of hospitalized tuberculosis of any involved organs also decreased with a statistical significance. Conclusion : The data from a single children's hospital suggest that the number of hospitalized childhood patients with tuberculosis has decreased over a 20 year period in Korea.

• Pediatric Infection and Vaccine
• /
• v.15 no.2
• /
• pp.174-179
• /
• 2008

Purpose : The purpose of this study was to investigate the clinical features of adolescent TB. Methods : We retrospectively reviewed the medical records of the adolescents aged 12 to 18 years and who are hospitalized with the diagnosis of TB at Dong Kang General Hospital between January 2003 and December 2007. Results : Of the 29 patients who were identified, 65.5% were male. The median age at diagnosis was 16.9 years (range: 12.1-18.9 years). A tuberculin skin test (TST) was performed for 6 patients (20.7%). Among them, 5 (5 of 8[62.5%]) in the 12-15 years age group (Group A) and 1 (1 of 21[4.8%]) in the 16-18 years of age group (Group B) were TST positive, which showed that the TST performing rate decreased with age (P<0.01). Twenty-five patients (86.2%) were detected by evaluating the clinical symptoms that suggested TB and 4 patients (13.8%) were detected by screening, but no cases were detected by contact tracing. Twenty patients (69.0%) had isolated pulmonary disease. Seven patients (24.1%) had pulmonary and extrapulmonary disease and 2 patients (6.9%) had exclusively extrapulmonary disease. Most patients presented with multiple symptoms, and the most common were cough (79.3%), fever (75.9%), sputum (65.8%) and chest pain (34.5%). M. tuberculosis was isolated from the sputum of 20 patients (69.0%). The culture-positive rate increased with age (range: 62.5% in Group A to 71.4% in Group B), but the difference between the groups was not significant. Cavitary lesions were found 13 patients (44.8%). The cavitary lesion rate increased with age (range: 25.0% in Group A to 52.4% in Group B), but the difference between the groups was not significant. Four patients (13.8%) were lost during follow-up. One patient (6.9%) relapsed. Conclusion : Clinicians need to be aware of the unique features of adolescent TB, and they also need awareness of the importance of TST and contact investigation for an adult suspected of having TB for making the diagnosis of TB.