The use of modern diagnostic equipment in oncology has made it possible to detect small tumor foci, as
 well as to detect distant metastases of the disease at an early stage of their formation. In these cases, it
 becomes possible to refuse surgical interventions, replacing them with stereotactic radiosurgery using
 radiation therapy devices. In this case, small irradiation fields can be used (from fields less than 1 cm to
 4 cm). In such cases, there is a problem of delivering large doses to small foci. It consists in the accuracy of determining the absorbed doses delivered to small targets. The complexity of monitoring the quality of dosimetric support of irradiation with the use of various radiotherapy devices is increasing. Increased requirements are also imposed on the detectors used for measurements.
 This work has several goals:
 1) to study the results of measurements of the output factors using five different detectors of small
 sizes;
 2) to determine the changes in the output factors when using two types of beam collimation (collimator
 shutters - JAWS and multileaf collimator - MLC) of linear electron accelerators;
 3) to study the dependence of the output factors on the source-to-surface distance (SSD), on the depth
 of measurements and on the type of detectors.
 The measurements were carried out in 6 MV photon beams with a flattening filter on a TrueBeam linear
 accelerator. Five IBA detectors were used: two diode detectors (PFD and SFD) and three ionization
 chambers (CC01, CC04 and CC13). The field sizes varied from 1010 cm to 11 cm. The studies were
 carried out for the following combinations of parameters: SSD is 100 cm and the measurement depth is
 10 cm; SSD is 95 cm and the measurement depth is 5 cm. The fields were formed by JAWS and MLC.
 The analysis of the obtained results made it possible to compare the data obtained from each detector
 in similar combinations of measurements. Based on the analysis of the output factors measured by all
 five detectors, conclusions were drawn about the parameters that affect the change in the output factors.