2nd Department of Radiology, Radiotherapy Unit, ATTIKON Hospital, University of Athens School of Medicine, Greece; Space Radiobiology Research, Physics Department, Strathclyde University, Glasgow, UK.
2nd Department of Radiology, Radiotherapy Unit, ATTIKON Hospital, University of Athens School of Medicine, Greece.
Phys Med. 2018 Feb;46:16-24. doi: 10.1016/j.ejmp.2017.12.022.
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.
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.
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/cm.
In conclusion, HBIe was proven effective in delivering the prescribed dose to the target area, while protecting the healthy skin.
某些辐射敏感的皮肤病可能在上半身或下半身出现症状。本研究中描述的新型半身电子照射（Hemi-Body Electron Irradiation，HBIe）技术提供了一种低成本的 LINAC 治疗选择，介于极度局部和全身皮肤照射技术之间。
HBIe 技术由我们部门开发，采用定制的治疗室，配备可调节的铅屏蔽和在扩展源皮距（Source-Skin Distance，SSD）设置下的单电子束。患者采用“斯坦福”体位定位。该几何结构提供了最佳的剂量均匀性和剂量沉积深度可达 2cm。为了证实这一点，我们测量和评估了以下特性：a）在垂直入射时，对于六个“斯坦福”角度的照射野，用单电子束在治疗平面上的百分深度剂量（percentage depth dose，PDD），b）单照射野在治疗平面上的入口剂量二维分布，以及 c）所有六个照射野在人体模型上的总表面剂量。
对于平均体型的患者，治疗平面上的表面剂量均匀度为 5-6%，而在上半身和下半身 HBIe 变体中，人体模型上的表面剂量均匀度均为 7%。总 PDD 呈现出几乎线性的下降，达到实际范围的 2g/cm。
总之，HBIe 被证明可以有效地将规定剂量输送到目标区域，同时保护健康皮肤。
