# K222941: Halcyon, Ethos Radiotherapy System

- Pathway: 510(k) (Traditional)
- Applicant: Varian Medical Systems, Inc.
- Decided: Jan 17, 2023 after 113 days
- Product code: IYE (Accelerator, Linear, Medical)
- Device class: 2
- Regulation: 21 CFR 892.5050
- Recalls of this device: none
- Data: FDA decisions to Oct 25, 2026; recalls to Oct 12, 2026

## Lineage
Longest line of descent: 16 generations back to K010975 (2001). 62 ancestors in all.
3 later devices descend from it; 1 cites it directly.
0 of 66 devices in its family (counting itself) have a Class I recall.

## Predicates on the family tree (from the FDA summary)
- K192377: Ethos Treatment Management, Ethos Treatment Planning, Ethos Radiotherapy System, Halcyon, Varian Medical Systems, Inc. (2020) Summary page 4.

## Most influential descendants
- K232113: Halcyon, Ethos Radiotherapy System (2023), 2 descendants of its own
- K252977: Halcyon, Ethos Radiotherapy System (5.0) (2026), 1 descendant of its own
- K261856: Halcyon, Ethos Radiotherapy System (5.0) (2026), 0 descendants of its own

## Indications for use
Halcyon and Ethos Radiotherapy System are indicated for the delivery of stereotactic radiosurgery and precision radiotherapy for lesions, tumors and conditions anywhere in the body where radiation is indicated for adults and pediatric patients. The Halcyon and Ethos Radiotherapy System produce CBCT images that can be used in Image Guided Radiation Therapy, and the simulation and planning for adaptive radiation therapy.

Source page: https://510kreport.com/device/K222941
Methodology: https://510kreport.com/methodology