Voltage, current, target and filter in X-ray tubes define the X-ray spectrum; in turn, any dosimetric quantity depends on the spectrum. In the operation of an X-ray generator the dose is evaluated considering the contribution of leakage, scattered and direct beam contribution. For one X-ray unit using a voltage is important to know dose to 1 m per unit current (mA) and time (min); this feature is the Gamma factor (Γ). Using analog Monte Carlo methods, using the MCNP5 code, the objective of this work was to calculate the X-ray spectra and the Gamma factors for the ambient dose equivalent and air Kerma for X-units with two targets: Molybdenum and Rhodium and Aluminum filter. The X-rays are in the diagnostic energy range (70, 80, 90, 100, and 120 kV). Calculations were carried out in four positions (a, b, c and d) along the useful beam, and to account the radiation leakage calculations include two positions (L1 and L2) around the shielding. The spectra average energy and the Gamma factors for air Kerma and ambient dose equivalent were calculated. Low energy photons are eliminated by the glass enclosure and the filter. To 1 m from the focal spot (positions d, L1 and L2) the larger photon fluence and the Gamma factors for air Kerma and ambient dose equivalent are larger when the target in the tube is Rh in comparison to those having a target of Mo. In position d all Γ factors are described by a third degree polynomial.

X 射线管中的电压、电流、靶和滤光片定义了 X 射线光谱；反过来，任何剂量测量都取决于光谱。在 X 射线发生器的操作中，剂量的评估考虑了泄漏、散射和直接射束的贡献。对于一个使用电压的 X 射线装置，了解每单位电流 (mA) 和时间 (min) 到 1 m 的剂量很重要；这个特征就是伽玛因子（Γ）。使用模拟蒙特卡罗方法，使用 MCNP5 代码，这项工作的目的是计算 X 射线光谱和 Gamma 因子，用于具有两个目标的 X 单元的环境剂量当量和空气 Kerma：钼和铑以及铝过滤器. X 射线在诊断能量范围内（70、80、90、100 和 120 kV）。计算在四个位置（a，b，c和d）沿有用光束，并考虑辐射泄漏计算包括屏蔽周围的两个位置（ L1和L2 ）。计算了空气比释动能和环境剂量当量的光谱平均能量和伽马因子。玻璃外壳和过滤器消除了低能光子。距焦点 1 m 处（位置d、L1和L2），与具有 Mo 目标的管中的目标相比，当管中的目标是 Rh 时，更大的光子注量和空气 Kerma 和环境剂量当量的 Gamma 因子更大。在位置d，所有 Γ 因子都由三次多项式描述。