• Journal of Biomedical Engineering Research
• /
• v.25 no.5
• /
• pp.403-414
• /
• 2004

In the accompanying paper, we proposed a real. time volumetric imaging method using a cross array based on receive dynamic focusing and synthetic aperture focusing along lateral and elevational directions, respetively. But synthetic aperture methods using spherical waves are subject to beam spreading with increasing depth due to the wave diffraction phenomenon. Moreover, since the proposed method uses only one element for each transmission, it has a limited transmit power. To overcome these limitations, we propose a new real. time volumetric imaging method using cross arrays based on synthetic aperture technique with linear wave fronts. In the proposed method, linear wave fronts having different angles on the horizontal plane is transmitted successively from all transmit array elements. On receive, by employing the conventional dynamic focusing and synthetic aperture methods along lateral and elevational directions, respectively, ultrasound waves can be focused effectively at all imaging points. Mathematical analysis and computer simulation results show that the proposed method can provide uniform elevational resolution over a large depth of field. Especially, since the new method can construct a volume image with a limited number of transmit receive events using a full transmit aperture, it is suitable for real-time 3D imaging with high transmit power and volume rate.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.31 no.3
• /
• pp.391-399
• /
• 2004

The purpose of this study was to compare curing efficiency of newly developed curing units to traditional halogen curing unit by measuring thermal change and surface microhardness according to curing light system. Materials and mathods : The types of curing units were traditional low intensity halogen light(Optilux 360), plasma arc light(Flipo), low heat plasma arc light(Aurys), low intensity LED(Starlight), and high intensity LED(Freelight2). Temperature at the tip of light guide was measured by a digital thermometer using K-type thermocouple. And after resin was filled to 2, 3, 4mm teflon mold, bottom temperature measured during curing. After 24 hours, microhardness of top surface and bottom surface of each resin specimen were measured. Results : The result of this study can be summarized as follows, 1. As measuring temperature of curing unit tips, Flipo is the highest as $52.4^{\circ}C,\;Freelight2(37.86^{\circ}C),\;Optilux360(32.68^{\circ}C),\;Aurys(32.34^{\circ}C),\;and\;Starlight(26.14^{\circ}C)$ were followed. 2. Flipo and Freelight2 were the highest similarly and Optilux360 and Aurys were similarly next and Starlight was lowest in temperature of bottom surface of resin mold. 3. Microhardness of top surface were generally similar, and Aurys was relatively low. 4. Optilux 360 and Freelight2 were the highest, and Flipo, Starlight, and Aurys were followed in microhardness of bottom surface. Conclusions : The results suggest that careful use of Flipo and Freelight2 might be able to cure greater depth of resin composite and do not cause thermal problems than other curing units.

• Journal of Chest Surgery
• /
• v.37 no.8
• /
• pp.665-671
• /
• 2004

Background: Lymph node metastasis is commonly reported in thoracic esophageal cancer, even in the early esophageal cancer which may be localized only in the mucosa or within the submucosal layer. Although lymph node metastasis greatly influence long-term outcome and cure of the disease, endoscopic mucosal resection or photodynamic therapy without lymph node dissection is widely attempted. The investigation of the pattern of lymph node metastasis and results of surgical resection of superficial esophageal cancer is needed. Material and Method: Pattern of lymph node metastsis and depth of tumor invasion were studied retrospectively from 44 patients with early esophageal cancer who underwent radical resection of the tumor from December, 1995 to August, 2001. Result: Lymph node metastasis was found in 10 patients (22.7%) out of total of 44 patients. Lymph node metastasis was found in 0% (0 of 3), 0% (0 of 4), 50% (2 of 4), and 24.24% (8 of 33) of tumors that invaded the intraepitherium, lamina propria, muscularis mucosa, and submucosa respectively. Anatomically distant lymph node metastases were found more frequently in recurrent laryngeal nerve node(5 cases of 10 patients) and in intraperitoneal node (8 cases of 10). than intrathoracic node (3 cases of 10). There was no operative mortality, however, there were 1 hospital death in patient with lamina propria cancer, 1 late death in patient with submucosal cancer. Three-year survival rates (except hospital death) were 100% in mucosal cancer and 97.0% in submucosal cancer (p>0.05), and 100% in the node negative group and 90.0% in the node positive group (p>0.05). Conclusion: The survival rate of superficial esophageal cancer patient who was recieved operative resection was excellent. But, lymph node metastasis were found in superficial esophageal cancer, even in esophageal cancer limited to the muscularis mucosa. Systemic lymph node dissection which includes recurrent laryngeal nerve nodes and intraperitoneal nodes was recommended for favorable outcome in superficial esophageal cancer.

• Radiation Oncology Journal
• /
• v.21 no.1
• /
• pp.82-93
• /
• 2003

Purpose : To reduce the Irradiation dose to the lungs and heart in the case of chest wail irradiation using an oppositional electron beam, we used an Individualized custom bolus, which was precisely designed to compensate for the differences In chest wall thickness. The benefits were evaluated by comparing the normal tissue complication probablilties (NTCPS) and dose statistics both with and without boluses. Materials and Methods : Boluses were made, and their effects evaluated in ten patients treated using the reverse hockey-stick technique. The electron beam energy was determined so as to administer 80% of the irradiation prescription dose to the deepest lung-chest wall border, which was usually located at the internal mammary lymph node chain. An individualized custom bolus was prepared to compensate for a chest wall thinner than the prescription depth by meticulously measuring the chest wall thickness at 1 emf intervals on the planning CT Images. A second planning CT was obtained overlying the individuailzed custom bolus for each patient's chest wall. 3-D treatment planning was peformed using ADAC-Pinnacle$^{3}$ for all patients with and without bolus. NTCPS based on 'the Lyman-Kutcher' model were analyzed and the mean, maximum, minimum doses, V$_{50}$ and V$_{95}$ for 4he heari and lungs were computed. Results .The average NTCPS in the ipsliateral lung showed a statistically significant reduction (p<0.01), from 80.2${\pm}$3.43% to 47.7${\pm}$4.61%, with the use of the individualized custom boluses. The mean lung irradiation dose to the ipsilateral iung was also significantly reduced by about 430 cGy, Trom 2757 cGy to 2,327 cGy (p<0.01). The V$_{50}$ and V$_{95}$ in the ipsilateral lung markedly decreased from the averages of 54.5 and 17.4% to 45.3 and 11.0%, respectively. The V$_{50}$ and V$_{95}$ In the heart also decreased from the averages of 16.8 and 6.1% to 9.8% and 2.2%, respectively. The NTCP In the contralateral lung and the heart were 0%, even for the cases with no bolus because of the small effective mean radiation volume values of 4.4 and 7.1%, respectively Conclusion : The use of an Individualized custom bolus in the radiotherapy of postrnastectorny chest wall reduced the NTCP of the ipsilateral lung by about 24.5 to 40.5%, which can improve the complication free cure probability of breast cancer patients.