It is well known that high energy X and r-ray have high penetration power in tussue, but have lower survacedose which is called the “skin sparing effect”. However, the surface dose can be increased significantly by excessive electron contamination and it is an important factor intreatment planning in the presence of a blocktray, especially in isocentric set-up. So relaltive surface doses for 10MV-X-ray and Co-60 r-ray were measuredwith various field sizes and SSD with or withoug 1/4" lucite shadow tray, present in the beams, using pancakechamber and polystylene phantom. The results obtained are as follows. 1. A rapid increase in surface dose isapparant with increasing field size in 10MV X-ray and Co-60 r-ray. 2. high surface dose is evident for smallerdistance from the tray, so at least 25cm of skin shadow tray distance for 10MV X-ray and 20cm for Co-60 are desirable. 3. Utilization of either bolus for treatment field or electron boost should be considered in treatmentof superificial nodal disease. 4. A tray using an intermediate or high z No. filter can be reduced the surfacedose significantly.
Polymethyl Methacrylate ; Silver Sulfadiazine ; Skin

BACKGROUND/AIMS: This study was designed to evaluate normal Korean pancreaticobiliary ducts and to assess the prevalence and pattern of variations and anomalies of theses structures. METHODS: We performed this multicenter study in which 7 university hospitals in Korea participated from March 1997 until June 1999. Total 10,243 ERCP cases were reviewed during this study period. RESULTS: 1) Maximal and midportion diameters of common bile ducts were 6.4+/-1.8 mm and 5.5+/-1.7 mm, respectively. Maximal and midportion diameters of pancreas head were 3.2+/-1.1 mm and 2.7+/-1.0 mm, respectively. Pancreaticobiliary duct diameters of subjects above the age of 40 were greater than those of subjects below the age of 40 (p<0.05). 2) The prevalence of choledochal cyst was 0.32%. The prevalence of gallbladder anomalies and anomalous union of pancreaticobiliary duct was 4.2% and 4.1%, respectively. The prevalence of pancreas divisum and annular pancreas was 0.49% and 0.05%, respectively. The most common type of pancreaticobiliary duct union was V shape (60.2%), followed by U shape (23.7%) and Y shape (16.1%). CONCLUSIONS: Understanding normal pancreaticobiliary structures and being aware of the prevalence and pattern of variations and anomalies of pancreaticobiliary structures will be helpful to diagnose and treat patients with pancreaticobiliary problems.
Cholangiopancreatography, Endoscopic Retrograde ; Choledochal Cyst ; Common Bile Duct ; Gallbladder ; Head ; Hospitals, University ; Humans ; Korea ; Pancreas ; Prevalence