i used to work in a rad dept for 2 1/2 years as a file clerk-most of my friends come from there-be it residents, attendings, rt's, and equip. engineers. i'm in pa school now, so although i never technically worked on any equipment i was always asking questions, technical or otherwise...if i remember correctly, the dose of radiation is derived from kV-basically how much juice the xray machine can put out-if enough power is available, than you can get better penetration (esp. with big pts), and better images(though too much is bad too-overexposed). usually portable machines (e.g. OR c-arms) are not powerful enough to penetrate, esp. on something as critical as an ercp to see where in the ducts the dye IS going...i've NEVER seen an ercp image from the OR (at this hosp all OR xrays are portable). they are always done in the imaging suites. the portable machines just don't have the juice to generate the nec. kV. usually a c-arm in the OR is reserved for ortho use (check pin alignment, etc) or maybe to find a possible missing needle, etc. nothing where great acuity is needed. There ARE OR's designed with built-in c-arms-usu for vascular/angio cases, and those would be powerful enough. again, i'm a puke, so take this info with a grain of salt...hope this helps! -jd
