title: Four years experience with a mercury shielded irregular field system (MSIFS).
abstract: A mercury shielded irregular field system (MSIFS) has been in use in our department since January 1979. The system is described and illustrated. Experience in treating 225 patients demonstrated that the system is accurate and reproducible. The system offers a choice of shielding efficiency in a transmission range from 100 to 3.5% for 18 MV photons. Routine measurements of mercury vapor concentration in the treatment room showed values below 0.02 mg Hg/m3 air. (The maximum acceptable concentration in The Netherlands is 0.05 mg Hg/m3 air.) It is concluded that the system is cost-effective, easy to use, and flexible and safe.
mesh_terms: D006801:Humans; D008628:Mercury; D009369:Neoplasms / Q000532:radiotherapy*; D011482:Protective Devices; D011835:Radiation Protection / Q000295:instrumentation / Q000379:methods*; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000379:methods*
chemical_list: D008628:Mercury