No abstract available.
Cobalt* ; Copper* ; Dental Alloys* ; Nickel*

Electron contamination due to the interaction between radiation beam and material was analyzed for the factors such as source-skin distance(SSD), field size, tray characteristics and position of filter, which can affect the surface dose in Cobalt teletherapy. Surface dose in open beam was more influenced by SSD with increasing field size. Relative surface charge(RSC) increased with the use of tray(solid, circular hole, slotted), compared with open beam, which is thought to be doe to increased electron contamination of the tray. To reduce the surface dose, 0.4mm thick Lipowitz metal filter was used. Compared with open beam, RSC decreased by 8.8%, 11.3%, 13.3%, 16.6%, 19.3% and 21.7% for the field size of 5x5, 10x10, 15x15, 20x20, 25x25 and 30x30 cm2, respectively. On the contrary, use of Lipowitz metal filter increased RSC at 60cm or less SSD. Suface dose was effectively reduced with Lpowitz metal filter placed right below solid tray in Cobalt teletherapy.
Cobalt ; Gamma Rays* ; Silver Sulfadiazine

PURPOSE: This study evaluated the effect of span length on the adaptation of implant-supported cobalt chromium frameworks fabricated by three techniques. MATERIALS AND METHODS: Models with two solid abutment analogs at different inter-abutment distances were digitized using a laboratory scanner. Frameworks of two-, three-, and four-unit fixed prostheses were designed by a computer. Six dots with a diameter of 0.2 mm were preset on the surface of each framework. A total of 54 implant-supported cobalt chromium frameworks were fabricated by milling, selective laser melting (SLM), and cast techniques. The frameworks were scanned and exported as Stereolithography files. Distances between two dots in X, Y, and Z coordinates were measured in both the designed and fabricated frameworks. Marginal gaps between the framework and the abutments were also evaluated by impression replica method. RESULTS: In terms of distance measurement, significant differences were found between three- and four-unit frameworks, as well as between two- and four-unit frameworks prepared by milling technique (P<.05). Significant differences were also noted between two- and three-unit frameworks, as well as between two- and four-unit frameworks prepared by cast technique (P<.05). The milling technique presented smaller differences than the SLM technique, and the SLM technique showed smaller differences than the cast technique at any unit prostheses (P<.05). Evaluation with the impression replica method indicated significant differences among the span lengths for any fabrication method (P<.05), as well as among the fabrication methods at any unit prostheses (P<.05). CONCLUSION: The adaptation of implant-supported cobalt chromium frameworks was affected by the span length and fabrication method.
Chromium* ; Cobalt* ; Freezing ; Methods ; Prostheses and Implants

A case of malignant melanoma occures in the palpebral conjuntiva is presented. A 60 years old female had dark brownish. strowbery-like peduncleated mass in her right upper conjuntiva. The tumor mass was excised radically and confirmed as malignant melanoma histopathologically and she received cobalt 60 irradiation. No recurrence was seen for 4 months since the excision of the mass.
Cobalt ; Female ; Humans ; Melanoma* ; Middle Aged ; Recurrence

OBJECTIVES: At present, removable partial denture is still one of the main restoration methods for dentition defects. However, the trend for digital partial denture is becoming more and more obvious in the field of oral repair. However, there are relatively few studies on digital removable partial denture. The aim of this study is to investigate the effects of 3 processing technologies (precision casting, digital cutting, and 3D printing) on the fitness for the clasps of cobalt chromium alloy and pure titanium removable partial denture, and to provide a theoretical basis for the clinical application of digital removable partial denture. METHODS: Clasps of Co-Cr alloy and pure titanium were produced by 3 different processing technologies (precision casting, digital cutting, and 3D printing). There are 6 groups, including a casting pure titanium group, a casting cobalt chromium group, a cutting pure titanium group, a cutting cobalt chromium group, a printing pure titanium group, and a printing cobalt chromium group ( RESULTS: There was no statistical difference in fitness between the casting pure titanium group and the casting cobalt chromium group ( CONCLUSIONS The cobalt chromium alloy and pure titanium clasps made by precision casting, digital cutting, and 3D printing have good fitness. Under the same process, there is no significant difference between cobalt chromium alloy and pure titanium clasps. The 3D printing pure titanium clasps have better fitness than casting pure titanium and cutting pure titanium clasps, which meet the needs of clinical application.
Chromium Alloys ; Cobalt ; Denture, Partial, Removable ; Titanium

Liposarcoma is extremely rare malignant tumor which develops primary in the orbit. Here, we report a case of primary orbital liposarcoma in 17 year old female patient. She visited our hospital due to decreased visual acuity and protrusion of Rt. eyeball. Malignant tumor was suspected by many examination. So exenteration was performed and tumor mass was confirmed as liposarcoma by pathologic examination. She was received cobalt 60 radiation therapy, but recurrent tumor mass appeared at the orbital apex 1 year after operation.
Adolescent ; Cobalt ; Female ; Humans ; Liposarcoma* ; Orbit* ; Visual Acuity

Clinical history and dermatological examinations were performed in 51 patients with contact dermatitis due to metal working fluid who were working at the metal industry. Patch tests were also performed with standard series and oil cooling fluid series. Chronic lichenified eczema such as lichenified and fissured was the most common clinical type(45.1%). 19 patients had positive reaction to either one or more of the standard series and oil & cooling fluid series. We found ammoniated mercury chloride was the most common sensitizer in standard series, followed by potassium dichromate, 4-phenylendiamine dihydrochloride, cobalt chloride, nickel sulfate, quinoline mix and cabra mix. Microbiocide was the most common allergen(4 of 6 positive result in oil & cooling fluid series.
Cobalt ; Dermatitis, Contact* ; Eczema ; Humans ; Nickel ; Patch Tests ; Potassium Dichromate

This study was carried out in order to find out the valuable measure to kill the parasite eggs in night soil. The fresh eggs of Ascaris put into human stool were irradiated with Cobalt 60 of 200,000 to 1,000,000 rad and cultured in test tubes at 25-30 C, washing with 2 percent formalin solution every 24 hours. The continuous development of those eggs were observed under microscope and the proprotions of developed eggs were compared with those of control groups. The major result can be summarized as follows: In general, The eggs in stool developed poorly than the eggs in saline. If the eggs were irradiated with the larger dose of Cobalt 60, the proportion of developed eggs were reduced subsequently. The eggs irradiated with the dose of 1,000,000 rad in saline developed in the proportion of 15.5 percent, whereas irradiated with 200,000 rad 94 percent developed in 4 weeks. The 44.5 percent of eggs in stool irradiated with 200,000 rad developed after 4 weeks, 30.5 percent with 300,000 rad, 25 percent with 500,000 rad and 3.5 percent with 1,000,000 rad respectively. The effective minimum dose of Cobalt 60 irradiation to kill the Ascaris eggs in stool was estimated 1,000,000 rad. Further examination will be required to observe the infectivity of irradiated Ascaris eggs to animals and to evaluate the effect from the standpoint of sanitary engineerings.
parasitology-nematode-Ascaris lumbricoides ; Cobalt 60 ; radiology ; prevention ; egg ; infectivity

BACKGROUND: Among metals, nickel and cobalt are very important contact allergens. They are widely used in products that have direct and prolonged contact with the skin. A frequent cause for nickel-induced allergic contact dermatitis is a nickel-containing belt buckle. The belt buckle showed a relatively high positive rate in the cobalt spot test in our previous study. Studies regarding nickel and cobalt release from belt buckles in Korea have been scarce. OBJECTIVE: We attempted to assess nickel and cobalt release from belt buckles purchased in Korea by conducting spot tests. METHODS: Belt buckles of various brands and prices were randomly purchased in Korea. They were tested using the dimethylglyoxime (DMG) test and cobalt spot test for detection of nickel and cobalt release. RESULTS: A total of 97 belts including 61 brand-name and 36 non–brand-name belts were sampled. Of 91 belt buckles tested using the DMG test, 45 (49.5%) demonstrated a positive reaction. There were statistical differences among the positive rates according to brand/non-brand and price. All belt buckles tested negative for the cobalt spot test. But in the EN1811 test, some belt buckles with a positive reaction in the DMG test showed a low nickel release rate. CONCLUSION: Although cobalt was not leached, nickel showed a relatively high positive rate in the belt buckles purchased in Korea. Therefore, we suggest that belt buckles purchased in Korea could be a common source of nickel-induced allergic contact dermatitis.
Allergens ; Cobalt* ; Dermatitis, Allergic Contact ; Korea* ; Metals ; Nickel* ; Skin

In order to find out a valuable control measure for soil-transmitted parasties, the infectivity in mice of Ascaris eggs irradiated with Cobalt(60) were examined. The results were summarised as follows. In vitro, Ascaris eggs irradiated with larger doses of Cobalt(60) developed poorly, and no difference was found between fresh eggs and those cultured for a few days. Ascaris eggs irradiated with doses of 200,000 rad. developed at the rate of 90 percent after 4 weeks, whereas those irradiated with 1,000,000 rad. developed 28 percent. Ascaris eggs irradiated with Cobalt(60) after 2 weeks of culture were poor in development compared with those of 4 week culture. Eggs cultured for 5 weeks showed weaker infectivity in mice than those cultured for 8 weeks. In the control groups, the infectivity in mice of Ascaris eggs was remained the same between 5 and 8 weeks. The minimum dose of Cobalt(60) irradiation effective for preventing infectivity in mice was estimated to be 200,000 rad.
parasiotology ; radiology ; prevention ; Ascaris suum ; nematode ; Cobalt(60) ; irradiation