A novel Hemi-Body Irradiation technique using electron beams (HBIe - ).

PURPOSE: Certain radiation responsive skin diseases may develop symptoms on the upper or the lower half of the body. The concept of a novel Hemi-Body Electron Irradiation (HBIe- ) technique, described in this work, provides a low cost, LINAC based, intermediate treatment option in between extremely localized and Total Skin irradiation techniques.

MATERIALS AND METHODS: The HBIe- technique, developed in our department, incorporates a custom crafted treatment chamber equipped with adjustable Pb shielding and a single electron beam in extended Source-Skin Distance (SSD) setup. The patient is positioned in 'Stanford' technique positions. The geometrical setup provides both optimal dose homogeneity and dose deposition up to a depth of 2 cm. To confirm this, the following characteristics were measured and evaluated: a) percentage depth dose (PDD) on the treatment plane produced by a single electron beam at perpendicular incidence for six fields at 'Stanford' angles, b) 2D profile of the entrance dose on the treatment plane produced by a single field and c) the total surface dose on an anthropomorphic phantom delivered by all 6 fields.

RESULTS: The resulting homogeneity of the surface dose in the treatment plane for an average patient was 5-6%, while surface dose homogeneity on the anthropomorphic phantom was 7% for both the upper and the lower HBIe- variants. The total PDD exhibits an almost linear decrease to a practical range of 2 g/cm2 .

CONCLUSION: In conclusion, HBIe- was proven effective in delivering the prescribed dose to the target area, while protecting the healthy skin.