Chu J C, Bloch P
Med Phys. 1987 Mar-Apr;14(2):289-90. doi: 10.1118/1.596084.
This paper describes a multileaf collimator, designed to obtain irregularly shaped neutron fields, that fits into an existing fixed field-size collimator system. The shape of the desired portal field is obtained by appropriately setting the position of each leaf of the collimator. The collimator consists of 40 polyethylene leaves to produce fields of irregular shape of up to 400 cm2. The leaves are interlaced with grooves to prevent neutron leakage. The measured penumbra defined by the multileaf collimator is similar to that defined by the same length fixed field-size water extended polyester (WEP) collimator. The multileaf collimator has a lower neutron transmission due to its higher hydrogen concentration.
本文描述了一种多叶准直器，其设计目的是获得不规则形状的中子场，该多叶准直器可适配现有的固定射野大小的准直器系统。通过适当设置准直器各叶片的位置可得到所需的射野形状。该准直器由40片聚乙烯叶片组成，可产生面积达400平方厘米的不规则形状射野。叶片上设有交错的凹槽以防止中子泄漏。多叶准直器所定义的测量半值层与相同长度的固定射野大小的水扩展聚酯（WEP）准直器所定义的相似。由于多叶准直器的氢浓度较高，其具有较低的中子透射率。
