| Model | Clinac 600CD/6EX | Clinac 600C/CD | Unique | Halcyon |
| Years Manufactured | 1999 & newer | 1989 -1999 | 2012 & newer | 2017 & newer |
| Power Source | Magnetron | Magnetron | Magnetron | Magnetron |
| Photon Energy Configuration | 4 MV or 6 MV | 4 MV or 6 MV | 6 MV | 6 MV FFF |
| Electron Energies | N/A | N/A | N/A | N/A |
| Multi-Leaf Collimator (MLC)** | 80 MLC (Field size 40x40cm); 120 MLC (Field size 40x40cm, Central 20cm of field - 5mm leaf width, Outer 20cm of field - 10mm leaf width) | 52 MLC (Field size 26x40cm, Leaf widths 10mm); 80 MLC (Field size 40x40cm); 120 MLC (Field size 40x40cm, Central 20cm of field - 5mm leaf width, Outer 20cm of field - 10mm leaf width) (optional) | 120 MLC | Dual Layer MLC |
| Portal Imager(EPID)** | aS500, aS1000 (optional) | (optional) LC250, aS500, aS1000 | aS500II | NO |
| Treatment Delivery | 3D, IMRT, SRS (optional) | 2D, 3D (optional), IMRT (optional), SRS (optional) | 2D, 3D (optional), IMRT (optional), SRS/SBRT (optional) | IMRT, RapidArc |
| KV Imaging for IGRT** | N/A | N/A | N/A | YES |
| CBCT | N/A | N/A | N/A | Volumectric CMBCT, 15 sec Image Capture |
| VMAT | N/A | N/A | Yes with Software | Multi-Arc VMAT |
| Treatment Couch | Exact | ETR, Exact (optional) | Exact | Halcyon |
| Market Demand*** |  |
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| Pros | Will fit into smaller vaults than high energy systems, even Silhouette models Simpler and faster to install Easier and less expensive to service | Similar to a 6EX in performance Two versions available Can be upgraded to perform Rapid Arc | 2X quieter than other systems Accelerated treatment time 100% image guidance | |
| Cons | Only available with single photon energy (6MV or 4MV) Waveguides and magnetrons often require replacement No electron energies available | Only available with single photon energy No electrons Not sold in the U.S. as new Limited availability in the used market | Only available with single photon energy No electrons |
*Data shown here may not be accurate and is based on equipment seen in the secondary market. See manufacturers for exact data.
**Similar devices are manufactured by vendors other than the linear accelerator manufacturer.
***Five stars indicate that the resale demand for like systems is high, and used equipment will therefore command a higher price. Few stars indicate that the resale demand is lower, and prices for used equipment are lower. One star indicates very little, if any, demand currently exists.
