One role of the ADCL is to calibrate user ionization chambers against national reference standards (such as those from NIST) for clinics to calibrate the high-energy photon and electron beams of the linac.  Presently, these user chambers are calibrated in a ⁶⁰Co   beam due to its monoenergetic energy spectrum and continuous nature.  However, ⁶⁰Co irradiators are being eliminated from the clinical setting, introducing a need for a calibration service in the beams that will be used for treatment.  This type of calibration service would provide a standards lab to provide calibration factors and the beam quality conversion factor, k_Q, for the beams used in radiation therapy treatments.  This method of calibration has only been done at primary standard dosimetry labs (PSDL) and one secondary standard dosimetry laboratory (SSDL) in Germany, making the investigation of this type of service at the SSDL level significant.  The goal of this project is to determine how direct linac calibrations at SSDLs compare to those done at PSDLs while simultaneously monitoring ionization chamber stability over the duration of the project.