Patent Number: 
Section: claims

1. A system for providing a particle beam to a patient, comprising:a first device to limit horizontal application of the particle beam;a second device to provide vertical compensation for the first device relative to the patient, the second device comprising a mounting structure, and the first device being substantially aligned to the second device at the mounting structure;a stationary yoke comprising a first end and a second end, the stationary yoke attaching to the first device and the second device; anda catch arm attached pivotally secured to the first end of the yoke, the catch arm being configured to attach to the first device and the second device, and the catch arm being configured to pivot about the first end of the stationary yoke both towards, and away from, the mounting structure. 2. The system of claim 1, wherein the first device comprises a patient aperture having an area for inhibiting passage of the particle beam; andwherein the second device comprises a range compensator that affects a distance between the patient and the first device. 3. The system of claim 1, wherein the first device comprises first notch features and the mounting structure comprises second notch features, the first notch features aligning to the second notch features; andwherein the stationary yoke comprises a first structure configured to mate to the first notch features that are aligned and the catch arm comprises a second structure configured to mate to the second notch features that are aligned. 4. The system of claim 1, wherein the first device, the second device, the stationary yoke, and the catch arm form an integrated structure; andwherein the system further comprises a C-shaped inner gantry on which the integrated structure is mounted. 5. The system of claim 1, wherein the stationary yoke comprises an indicator switch to detect locked and unlocked positions of the catch arm. 6. The system of claim 1, wherein the mounting structure comprises a rim and wherein the stationary yoke and the catch arm each comprise a groove to which the rim interfaces. 7. The system of claim 1, further comprising a catch arm locking feature defined by the yoke to inhibit rotation of the catch arm, the catch arm locking feature for engaging a catch arm lock, the catch arm lock comprising a latch plate that is positionable to engage the catch arm locking feature. 8. The system of claim 7, wherein the catch arm locking feature is configured to spring bias the latch plate. 9. The system of claim 7, further comprising at least one spring biased plunger on the stationary yoke and configured to urge the first device against the locking feature. 10. A system for providing a particle beam to a patient, comprising:a structure to limit a delivery area of the particle beam to the patient, the structure comprising a rim and notches around the rim; andan arm having a shape that corresponds to a shape of at least part of a perimeter of the structure, the arm having a groove that mates to the rim and protrusions that mate to the notches, the arm comprising a first part and a second part, the first part being configured to pivot relative to the second part. 11. The system of claim 10, wherein the structure comprises a patient aperture having an area for inhibiting passage of the particle beam; andwherein the structure comprises a range compensator that affects a distance between the patient and the first device. 12. The system of claim 11, wherein the notches comprise first notches on the patient aperture and second notches on the range compensator, the first notches aligning to the second notches; andwherein the protrusions comprise a first protrusion configured to mate to the first notches that are aligned and a second protrusion configured to mate to the second notches that are aligned. 13. The system of claim 10, wherein the structure and the arm form an integrated structure; andwherein the system further comprises a C-shaped inner gantry on which the integrated structure is mounted. 14. The system of claim 10, wherein the arm comprises an indicator switch to detect locked and unlocked positions of the first part of the arm. 15. The system of claim 10, further comprising at least one spring biased plunger on the second part of the arm. 16. The system of claim 10, further comprising a catch arm locking feature defined by the arm to inhibit rotation of the first part, the catch arm locking feature for engaging a catch arm lock, the catch arm lock comprising a latch plate that is positionable to engage the catch arm locking feature. 17. The system of claim 16, wherein the catch arm locking feature is configured to spring bias the latch plate.