Several evidences indicate that various elements including antioxidant minerals might play an important role in preeclampsia (PE). This study was carried out to investigate the relationship between serum mineral levels such as zinc, calcium, iron and selenium and the risk of preeclampsia in Korean women. Thirty women with preeclampsia and 29 normal controls were recruited for the study. Preeclampsia was defined as high blood pressure (≥ 140/90 mmHg after 20 weeks gestation) and proteinuria (≥ 300 mg/24 hours). Serum mineral content was determined by instrumental neutron activation analysis. Serum zinc (P < 0.0001) and calcium (P = 0.0188) levels were lower in women with preeclampsia than those of normal women, while serum iron was significantly higher in women with preeclampsia (P = 0.0045). The odds ratio for preeclampsia was lower in women with higher serum zinc levels than those with lower levels after adjustment for age, height, and weight before delivery (P < 0.0001). The adjusted odds ratio for preeclampsia also decreased across tertiles of serum calcium concentration (P = 0.0452). However, we found increased adjusted odds ratio for preeclampsia across tertiles of serum iron level (P = 0.0104). These results suggest that levels of serum minerals such as zinc, calcium, and iron may be associated with the risk of preeclampsia in Korean pregnant women.
For evaluating the feasibility of treating recurrent lesions in the vaginal cuff by hyperthermia, a 2-element ultrasound applicator was designed, constructed and characterized. A half-cylindrical transducer (d=1 cm, length=1 cm) was used to construct the 2-element ultrasound applicator. Each element of this applicator was operated at 1.5 MHz and characterized by measuring transducer efficiency and acoustic power distribution. Thermocouple probes were used to measure the temperature rise in the phantom. The element sizes used in this study were selected to be comparable to a high dose rate brachytherapy colpostat applicator. Each element was powered separately to achieve a desired temperature pattern in a target. The acoustic output power as a function of applied electric power of elements 1 and 2 were linear over this 1-40 W range and efficiencies were 32.2 +/- 3.4% and 46.2 +/- 0.8%, respectively. The temperature measurements in the phantom showed that a 6 degrees C temperature rise was achieved 2 cm from the applicator surface. As a conclusion, the ability of the ultrasound colpostat applicator to be used for hyperthermia was demonstrated by measuring acoustic output power, ultrasound field distribution and temperature rise in the phantom. Based on the characteristics of this applicator, it has the potential to be useful for inducing hyperthermia to the vaginal cuff in the clinic.
This study was performed to develop and evaluate a semi-automatic seed localization algorithm from magnetic resonance (MR) images for interstitial prostate brachytherapy. The computerized tomography (CT) and MR images (3 mm-slice thickness) of six patients who had received real-time MR imaging-guided interstitial prostate brachytherapy were obtained. An automatic seed localization method was performed on CT images to obtain seed coordinates, and an algorithm for seed localization from MR images of the prostate was developed and tested. The resultant seed distributions from MR images were then compared to CT-derived distribution by matching the same seeds and calculating percent volume receiving 100% of the prescribed dose and the extent of the volume in 3-dimensions. The semiautomatic seed localization method made it possible to extract more than 90% of the seeds with either less than 8% of noises or 3% of missing seeds. The mean volume difference obtained from CT and MR receiving 100% of the prescribed dose was less than 3%. The maximum extent of the volume receiving the prescribed dose were 0.3, 0.6, and 0.2 cm in x, y, and z directions, respectively. These results indicate that the algorithm is very useful in identifying seeds from MR image for post-implant dosimety.
A mathematical model, which represents the radio-chemical reactions in water, was developed to study the effect of the radio-chemical products on cell killing. The five differential equations were solved using dose rate equation and cell survival as a function of dose was computed. The known chemical rate constants were taken from the literature and unknown constants were determined by curve fitting to an experimental data. Sensitivity studies were performed by varying the rate constants and showed that the yield of H-radical had little effect whereas the change in concentration of OH-radical and direct interaction resulted in significant change on cell survival. The sensitivity studies showed good agreement with the observed effects. In conclusion, we developed a mathematical model that could be used as a means for the estimation of radiation damage.
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