OBJECTIVES: Amid the spread of coronavirus disease 2019 (COVID-19), with its high infectivity, we have relied on mathematical models to predict the temporal evolution of the disease. This paper aims to show that, due to active behavioral changes of individuals and the inherent nature of infectious diseases, it is complicated and challenging to predict the temporal evolution of epidemics. METHODS: A modified susceptible-exposed-infectious-hospitalized-removed (SEIHR) compartment model with a discrete feedback-controlled transmission rate was proposed to incorporate individuals’ behavioral changes into the model. To figure out relative uncertainties in the infection peak time and the fraction of the infected population at the peak, a deterministic method and 2 stochastic methods were applied. RESULTS: A relatively small behavioral change of individuals with a feedback constant of 0.02 in the modified SEIHR model resulted in a peak time delay of up to 50% using the deterministic method. Incorporating stochastic methods into the modified model with a feedback constant of 0.04 suggested that the relative random uncertainty of the maximum fraction of infections and that of the peak time for a population of 1 million reached 29% and 9%, respectively. Even without feedback, the relative uncertainty of the peak time increased by up to 20% for a population of 100,000. CONCLUSIONS It is shown that uncertainty originates from stochastic properties of infections. Without a proper selection of the evolution scenario, active behavioral changes of individuals could serve as an additional source of uncertainty.

OBJECTIVES: Amid the spread of coronavirus disease 2019 (COVID-19), with its high infectivity, we have relied on mathematical models to predict the temporal evolution of the disease. This paper aims to show that, due to active behavioral changes of individuals and the inherent nature of infectious diseases, it is complicated and challenging to predict the temporal evolution of epidemics. METHODS: A modified susceptible-exposed-infectious-hospitalized-removed (SEIHR) compartment model with a discrete feedback-controlled transmission rate was proposed to incorporate individuals’ behavioral changes into the model. To figure out relative uncertainties in the infection peak time and the fraction of the infected population at the peak, a deterministic method and 2 stochastic methods were applied. RESULTS: A relatively small behavioral change of individuals with a feedback constant of 0.02 in the modified SEIHR model resulted in a peak time delay of up to 50% using the deterministic method. Incorporating stochastic methods into the modified model with a feedback constant of 0.04 suggested that the relative random uncertainty of the maximum fraction of infections and that of the peak time for a population of 1 million reached 29% and 9%, respectively. Even without feedback, the relative uncertainty of the peak time increased by up to 20% for a population of 100,000. CONCLUSIONS It is shown that uncertainty originates from stochastic properties of infections. Without a proper selection of the evolution scenario, active behavioral changes of individuals could serve as an additional source of uncertainty.

To evaluate the role of postoperative pelvic radiation therapy in rectal cancer, a retrospective analysis was done on 189 patients with modified Astler-Coller stages B2+3, C1, and C2+3 who were treated from February 1979 to June 1986. Forty-seven patients were staged as B2+3, 17 as C1, and 125 as C2+3. As a curative resection, 41 received low anterior resection, 143 received abdomino-perineal resection, and five received pelvic exenteration. The survival and disease-free survival rates of the total patients at five year were 45.3% and 44.1%, respectively. The stage was an important prognostic factor for survival and disease-free survival: the survival rates at five year were 55.7% in B2+3, 65.7% in C1, and 36.4% in C2+3, respectively (p<0.01). The liver was the most frequently involved organ of recurrence followed by the lung and the perineum. The patients who received low anterior resection achieved better disease-free survival but were more prone to late radiation bowel morbidities than those who received abdominoperineal resection. Postoperative pelvic radiation therapy proved to be effective in locoregional disease control but did not prevent the appearance of distant metastasis, which was of major concern in advanced stages. Patterns of treatment failure, and factors relating to radiation morbidity are discussed, and therapeutic options for better results are proposed.
Disease-Free Survival ; Humans ; Liver ; Lung ; Neoplasm Metastasis ; Pelvic Exenteration ; Perineum ; Rectal Neoplasms* ; Recurrence ; Retrospective Studies ; Survival Rate ; Treatment Failure

PURPOSE: We undertook this study to evaluate the usefullness of radiologic placement of subcutaneous infusion ports (SIP). MATERIALS AND METHODS: Between August 1999 and May 2000 we performed 45 implantations of SIP in radiologic suite. Both sonography and fluoroscopy were used for venipuncture and to guide port insertion. We prospectively evaluated 45 systems in 45 patients with solid tumors. RESULTS: Median follow-up time was 189 days (61~352 days). Technical success rate is 100% without any venipuncture-related complications. Early complication rate within 30 days of procedure was 4.4%, including wound dehiscence (n=1) and pocket hematoma and local infection (n=1). Catheter-related infection rate was 6.7% and catheter-related venous thrombosis rate was 4.4%. Mean duration of catheter use was 208 96 days (total, 9,381 days). Overall port survival rate was 38.5%, and four systems (8.9%) were prematurely removed because of catheter tunnel infection (n=1), pocket infection (n=1), and central venous thrombosis (n=2). CONCLUSION: Radiologic placement of SIP had higher success rate and equal or lower complication rate compared with reported conventional surgical technique using anatomical landmarks. Moreover, clinical convenience, resulting from ease of scheduling could make it replace surgical method.
Catheter-Related Infections ; Catheters ; Fluoroscopy ; Follow-Up Studies ; Hematoma ; Humans ; Infusions, Subcutaneous* ; Phlebotomy ; Prospective Studies ; Survival Rate ; Venous Thrombosis ; Wounds and Injuries

Radiotherapy result of 162 patients with stage I, II Intermediate Grade Non-Hodgkin's lymphoma was analyzed to clarify the role and limit of radiotherapy. Of 68 initial failures, 38.2% stageI was 30.0% and 70.0%, respectively with involved field treatment and was 43.8% and 56.2% with extended field treatment, respectively; in stageII, was 16.7% and 83.3%, 41.7% and 58.3% and 40.4% for patients with stage I and II, respectively. The survival was significantly different by stage. Bulky tumors (> or =10 cm) and B symptoms didn't influence prognosis significantly. The 5 year disease free survival with extended or wide field was better than that with involved field especially in stage I. Overall survival rates for all patients, patients with stageI, and II disease were 57.7%, 65.3% and 52.2%, respectively, after survival gain of the salvage chemotherapy was combined. But the overall survival of stageI disease was not better than that of stageII disease. Thus, extended field was required to achieve better disease free survival and relapsed cases might gain with chemotherapy.
Disease-Free Survival ; Drug Therapy ; Humans ; Lymphoma, Non-Hodgkin* ; Prognosis ; Radiotherapy* ; Survival Rate

BACKGROUND: The contribution of the private sector to the treatment of tuberculosis (TB) is getting larger, and the private sector pays more attention to individualized, intensive care than patient monitoring or education, which would improve the microbiological cure rate or at least completion of treatment. We aim in this paper to assess the impact of the improved monitoring of patient on the treatment outcome in the private tertiary healthcare center. MATERIALS AND METHODS: We compared the data of the positive sputum cultures for TB from March 1, 2003 to March 31, 2006 (37 months) with that data from July 1, 2007 to August 31, 2008 (14 months) in single private tertiary healthcare center in the Republic of Korea (ROK). In the latter period, we notified physicians of the new culture-confirmed cases via a cellular phone short-massage-service (SMS) to prevent delayed recognition of positive cultures and we gave calls to patients to encourage treatment adherence and to complete the whole schedule of medication. RESULTS: After the intervention, initiation of anti-TB medication increased from 86.3% to 94.5% (P<0.05), the interval to medication from the first culture results was shortened from 22.9 days to 5.6 days (P=0.19) and the rate of treatment complication increased from 57.4% to 68.1% (P<0.01). CONCLUSION: Our results showed a possible strategy to improve the completion of treatment in a university hospital. Health care providers in the private sector should to improve success by better notification and monitoring in addition to their existing advanced medical resources.
Appointments and Schedules ; Cellular Phone ; Critical Care ; Health Personnel ; Humans ; Monitoring, Physiologic ; Mycobacterium tuberculosis ; Nontuberculous Mycobacteria ; Private Sector ; Public-Private Sector Partnerships ; Republic of Korea ; Sputum ; Tertiary Healthcare ; Treatment Outcome ; Tuberculosis

PURPOSE: To apply a distributed circuit theory, to develop a head-size transverse electromagnetic(TEM) resonator coil for a home-built 3T whole-body MRI system and to report an efficiency of the coil. MATERIALS AND METHODS: The dimension of TEM resonator with 16 cavity element, the diameter of copper rod was 0.63cm and its length was 13.75cm. As raw materials, the purity of copper rod was 98% and the dielectric constant of teflon was 2.08. RESULTS: The TEM head-size resonator with 16cavity elements exhibiting 9-mode resonances was robust to the surrounding influences owing to the self-shielding structure. The isolation of quadrature with a human brain was 364 and the ratio of Q(unloaded/Q(loaded) was 2.9. CONCLUSION: It was successfully demonstrated that the TEM head-size resonator with high Q factor can provide high quality MR images at 3T MRI system. Also, the TEM resonator coil has an advantage for a fine tune with length adjustment of each cavity elements. Thus, it is expected that the TEM resonator at 3T, even higher field could be used in the clinical and research studies in near future.
Brain ; Copper ; Head* ; Humans ; Magnetic Resonance Imaging* ; Polytetrafluoroethylene

Malakoplakia is a rare chronic inflammatory process, most commonly affecting the urinary tract. This entity was first described by Michaelis and Gutman in 1902. As of 1995, only 85 cases of malakoplakia of the gastrointestinal tract has been reported. The common sites of colonic involvement are the rectum, sigmoid, and right colon, in descending order of frequency. The most common disease associated with malakoplakia is colorectal carcinoma. Surgical resection is the treatement of choice for cases associated with carcinoma or complications. But in other cases, medical treatment could be attempted. Antimicrobial drugs, such as trimethoprime-sufamethoxazole, rifampin, or as recently suggested, ciprofloxacin can be used. We report a case of rectal malakoplakia treated by ciprofloxacin with a review of literatures.
Anti-Bacterial Agents* ; Ciprofloxacin ; Colon ; Colon, Sigmoid ; Colorectal Neoplasms ; Gastrointestinal Tract ; Malacoplakia* ; Rectum* ; Rifampin ; Urinary Tract

Object of this study was to make comparison between acetazolamide and dipyridamole activated SPECT for measurement of cerebral vascular reserve capacity. This study was also carried out to evaluate response in acetazolamide and dipyridamole activated SPECT in relation to clinical parameters, such as Glasgow Coma Scale, Hunt & Hess grade, Fisher grade and Glasgow Outcome Scale. It is concluded from study that. Acetazolamide and dipyridamole activated SPECT study proved to be valuable for cerebral vascular reserve capacity. Dipyridamole activated SPECT study was somewhat equivocal because of systemic vascular dilatation effect, but this problem could be resolved by Gamma Count Ratio. Although there were minimal transient side effect of dipyridamole such as dizziness, no complication.
Acetazolamide* ; Dilatation ; Dipyridamole* ; Dizziness ; Glasgow Coma Scale ; Glasgow Outcome Scale ; Subarachnoid Hemorrhage ; Tomography, Emission-Computed, Single-Photon*

PURPOSE: Measurement of transmission dose is useful for in vivo dosimetry. In this study, the algorithm for estimating the transmission dose for open radiation fields was modified for application to partially blocked radiation fields. MATERIALS AND METHODS: The beam data was measured with a flat solid phantom with various blocked fields. A new correction algorithm for partially blocked radiation field was developed from the measured data. This algorithm was tested in some settings simulating clinical treatment with an irregular field shape. RESULTS: The correction algorithm for the beam block could accurately reflect the effect of the beam block, with an error within +/-1.0%, with both square fields and irregularly shaped fields. CONCLUSION: This algorithm can accurately estimate the transmission dose in most radiation treatment settings, including irregularly shaped field.