利用高能量電子束來治療頰黏膜癌時,常使用鉛或低熔點合金(如cerrobend)作為內部屏蔽,以保護目標體積(target Volume)外的正常組織,如頰黏膜內面的牙齦和牙床等。但因高能量電子束與高原子序的物質作用會產生回散電子(backs.catter electron),使得與內部屏蔽接觸的入射面組織表面劑量增加許多,造成劑量分佈的不均勻和腫瘤劑量計算的困難。自於原子序較低的物質可以吸收回散電子,所以我們選擇了四種常用來取模的牙科材料,採其可塑性高的特點(可以依病人的口型製作),從事吸收回散電子的研究,其結果令人滿意。
When we treat the malignancies of buccal mucosa, lead or low-melting alloy (Cerrobend) may be useful as a internal shielding for protecting the normal tissue beyond the target volume. However, the electrons backscattered from lead or Cerrobend enhance the dose to the tissue near the shield, and make the inhomogeneities of dose distribution and the complexities of tumor dose calculation. We know that the backscattered electron can be absorbed by the lower atomic number materials, so we select some of the dental materials which are easy to mold for this study. The result is satisfied.