Radiation therapy systems and methods

1. A system comprising:

a diagnostic-quality CT scanner for imaging a patient, the diagnostic-quality CT scanner having an imaging isocenter;

a radiation therapy device positioned adjacent the diagnostic-quality CT scanner, the radiation therapy device including a gantry carrying a radiation therapy beam source and having a radiation therapy isocenter separate from the imaging isocenter of the diagnostic-quality CT scanner; and

a couch configured to position the patient for imaging and for radiation therapy by translating the patient between the diagnostic quality CT scanner and the radiation therapy device;

wherein the system is configured to deliver only co-planar radiation therapy to the patient.

2. The system of claim 1 wherein the radiation therapy device is not cantilevered.

3. The system of claim 1 wherein the gantry is a ring gantry.

4. The system of claim 1 wherein the gantry is configured to move the source only to different positions within a plane.

5. The system of claim 1 wherein the couch is not configured to rotate.

6. The system of claim 1 wherein the radiation therapy beam source is a linear accelerator and the linear accelerator is divided into components spaced around the gantry and utilizes at least one RF waveguide between the linear accelerator components.

7. The system of claim 1 wherein the diagnostic-quality CT scanner is designed for RT simulation.

8. The system of claim 1 wherein the diagnostic quality CT scanner is a PET/CT scanner.

9. The system of claim 1 wherein the system further comprises a control system configured to utilize diagnostic-quality CT images to reoptimize a treatment plan.

10. The system of claim 9 wherein reoptimization is performed just prior to treatment, while the patient is on the couch.

11. The system of claim 1 wherein the gantry is configured to be translated orthogonally to couch motion.

12. The system of claim 11 wherein the gantry is configured to be translated over a range of at least 8 cm to facilitate the positioning of the radiation therapy isocenter in the patient before treatment.

13. The system of claim 1 further comprising radiation shielding between the radiation therapy device and the diagnostic-quality CT scanner.

14. The system of claim 13 wherein the radiation shielding comprises a high atomic number material covering or replacing a portion of an outer shroud of the diagnostic quality CT scanner facing the radiation therapy device.

15. The system of claim 1 wherein the radiation therapy device is a linac and the system further comprises RF shielding for at least one component of the linac.

16. The system of claim 1 further comprising at least one versatile baseplate configured to mount at least one system selected from a group comprising a radiation therapy device, a CT scanner, an MRI, a CT couch, a PET/CT couch, and an MRI couch.

17. The system of claim 16 wherein the at least one versatile baseplate allows the system to be converted between CT guidance and MRI guidance without removing the radiation therapy device.

18. The system of claim 1 further comprising a collimating system for collimating the radiation beam, the collimating system comprising:

a first multileaf collimator having a plurality of leaves; and

a second multileaf collimator having a plurality of leaves and configured such that the radiation beam will pass through the first multileaf collimator before passing through the second multileaf collimator, and pass through the second multileaf collimator before hitting the target;

wherein the leaves of the first multileaf collimator and the leaves of the second multileaf collimator are configured to move independently of one another; and

wherein at least one of the first multileaf collimator and the second multileaf collimator is double focused.