ABSTRACT
Radiochromic films (RCFs) are able to provide visual information of the dose distribution on a plane and therefore they are used for quick verification of various Quality assurance (QA) procedures needed in CyberKnife (CK). The RCFs have good dynamic range for use of high stereotactic radiosurgery doses, but the green channel for external beam therapy2 (EBT2) has been shown to be more responsive above 8–10 Gy than the red channel. RCFs are routinely used to measure the geometrical characteristics of the Iris and the InCise secondary-collimation systems. During commissioning of the Iris fields, a series of measurements are performed by irradiating RCFs with 600 monitor units. During commissioning of the CK system, the dosimetric parameters of the used radiation fields are measured. The E2E test is performed during commissioning to establish the accuracy of the system for each treatment-delivery modality as well as during periodic QA. Dosimetry (QA) tests should be performed during machine commissioning, treatment-planning updates, and monthly QA.
