ABSTRACT
In this chapter, small field dosimetry for two dedicated radiosurgery treatment delivery devices, the CyberKnife and the ZAP-X, are presented. After a short technical overview and introduction to the respective device, small field dosimetry beam data is discussed. For each device, the adaptation of reference dosimetry protocols for the machine-specific reference field is covered. Measurement methods to collect data for output factors, percent depth dose (PDD) or tissue-phantom ratio (TPR), and off-axis factors are presented. Suitable detectors for measuring each beam data type are listed. Sample data to visualize the specific characteristics of each beam dataset are provided. This chapter covers the difference between beam data from the fixed cones, IRIS collimator and multi-leaf collimator (M6) for the CyberKnife, including selected comparison data plots.
