Millin A E, Smith C W
Radiotherapy Physics Service, Velindre Hospital, Whitchurch, Cardiff, UK.
Phys Med Biol. 1994 Jan;39(1):63-73. doi: 10.1088/0031-9155/39/1/004.
A method is presented to predict beam profiles and outputs for wedged asymmetric fields defined by independent collimator jaws allowing fast generation of beam profiles whilst requiring very little additional data to that already used by most treatment planning systems in generating symmetric field isodoses. Symmetric field data are modified by the use of wedged primary off-centre ratios (POCRS) which are obtained from in air measurements of the largest possible wedged field. Beam hardening occurring within the flattening filter and wedge is taken into account by the use of attenuation coefficients measured under each wedge and used to generate the wedged POCR at depth. A full investigation into the comparison between measured and calculated profiles was performed which demonstrates favourable agreement across the whole of the asymmetric field including the penumbra.
本文提出了一种方法，用于预测由独立准直器钳口定义的楔形非对称野的射束轮廓和输出，能够快速生成射束轮廓，同时与大多数治疗计划系统在生成对称野等剂量线时所使用的数据相比，只需极少的额外数据。通过使用楔形原射线偏心比（POCRS）对对称野数据进行修正，该比值是从尽可能大的楔形野的空气中测量获得的。通过使用在每个楔形下测量的衰减系数并用于生成深度处的楔形POCR，来考虑在均整器和楔形滤过器内发生的射束硬化。对测量轮廓和计算轮廓之间的比较进行了全面研究，结果表明在包括半影在内的整个非对称野中两者具有良好的一致性。
