| Abbreviation | Definition |
|---|---|
| RV | Record and Verify |
| S-A | Spencer-Attix |
| SAAT | Subcutaneous Abdominal Adipose Tissue |
| SAD | Source-Axis Distance |
| SAR | Scatter-Air Ratio |
| SCD | Source-Collimator Distance |
| SE | Spin Echo |
| SEBI | Stereotactic External Beam Irradiation |
| SELADIN | Selective AD Indicator |
| SF | Scatter Factor |
| SHH | Sonic-HedgeHog |
| SI | Système International d'unités (International System of Units) |
| SIR | Society of Interventional Radiology |
| SME | Spectroscopy Made Easy |
| SMLC | Segmented Multi-Leaf Collimator |
| SMRE | Scanning Micro-Reference Electrode |
| SPECT | Single photon emission tomography |
| SPTA | Space Peak Time Average |
| SPTN | Sciatic/Posterior Tibial Nerve |
| SSD | Source-to-Surface Distance |