3D-CRT uses imaging technologies to create three-dimensional representations of tumors and surrounding organs. The radiation beams are shaped to match the tumor from multiple angles using uniform beam intensities.
| Parameter | Typical Value | Clinical Context |
|---|---|---|
| Number of Beams | 3-7 static fields | Simple beam arrangements (box, wedge pair) |
| Beam Modulation | None (uniform fluence) | May use wedges for dose homogeneity |
| Treatment Time | 5-10 minutes | Fast delivery, minimal MU |
| Dose Conformity | Moderate | Limited by beam geometry |
| MU Efficiency | 100-300 MU typical | Direct beam delivery |
IMRT uses computer-controlled linear accelerators to deliver precise radiation doses. The beam intensity is modulated using multileaf collimators (MLCs) to create highly conformal dose distributions with steep gradients.
| Parameter | Typical Value | Clinical Context |
|---|---|---|
| Number of Beams | 5-9 static fields | Optimized angles for OAR sparing |
| Beam Modulation | Step-and-shoot or sliding window | 10-100 segments per field |
| Treatment Time | 10-20 minutes | Longer due to MLC motion |
| Dose Conformity | High | Excellent target coverage |
| MU Efficiency | 600-1500 MU typical | 2-5x higher than 3D-CRT |
VMAT delivers radiation therapy through one or more arcs with simultaneous variation of gantry speed, MLC positions, and dose rate. This creates highly conformal distributions with improved delivery efficiency.
| Parameter | Typical Value | Clinical Context |
|---|---|---|
| Number of Arcs | 1-3 full or partial arcs | Single arc often sufficient |
| Beam Modulation | Continuous (dynamic MLC) | 178-360 control points per arc |
| Treatment Time | 2-5 minutes | Fastest modulated delivery |
| Dose Conformity | Very High | Similar or better than IMRT |
| MU Efficiency | 300-800 MU typical | More efficient than static IMRT |