You're right @vp3.
"Cyberknife is a treatment using external beam radiation. It is the brand name of a machine that delivers stereotactic radiation therapy or "radiosurgery" (SRS) and stereotactic body radiation therapy (SBRT). Despite the name, Cyberknife does not involve a knife, cutting, surgery, or anesthesia for treatment. It uses a linear accelerator (a machine that makes radiation) on a robotic arm that allows the radiation beam to be delivered from thousands of directions. Cyberknife uses real-time image-guided radiotherapy (IGRT) to treat tumors in different parts of the body, including the prostate. What this means is that the motion of the tumor is tracked, and the radiation can be directed and delivered accurately based on the motion of the tumor." Read more here: https://www.oncolink.org/cancers/prostate/treatments/cyberknife-for-prostate-cancer

@harrabus, you may also be interested in these related discussions:
- Photon Stereotactic Body Radiation Therapy (SBRT)
https://connect.mayoclinic.org/discussion/photon-sbrt/
- 2 vs 5 treatment for Viewray/SBRT
https://connect.mayoclinic.org/discussion/2-vs-5-treatment-for-viewraysbrt/
How many treatments will you be getting?