The combination of a clinically useable neodymium iron boron rare earth mag
netic deflector with a clinically viable thin walled helium bag which could
be placed over a patients skin has shown that it could be very effective i
n reducing unwanted skin dose to radiotherapy patients by the removal of un
wanted lepton contamination from the entry beam while not affecting dose at
depth or beam symmetry. Results have shown that up to 70% of existing dose
applied to the patients skin which causes damage could be removed by the t
ested devices, The magnetic deflectors characteristics for interference wit
h linear accelerator electronic components and field strengths that a patie
nt would be exposed to are also tested. (C) 2000 Elsevier Science Ltd. All
rights reserved.