Patent Number: 060977876
Section: claims

1. A method for calculating scatter radiation, the method comprising: providing a collimator leaf position;  determining a subset of collimator leaves; and  calculating fluence, wherein the fluence calculation is related to the subset of collimator leaves.  means for providing a collimator leaf position;  means for determining a subset of collimator leaves; and  means for calculating fluence, wherein the fluence calculation is related to the subset of collimator leaves.  a memory configured to provide a collimator leaf position;  a processor coupled to the memory, the processor being configured to determine a subset of collimator leaves and also configured to calculate fluence, wherein the fluence calculation is related to the subset of collimator leaves.  computer code providing a collimator leaf position;  computer code determining a subset of collimator leaves;  computer code calculating fluence, wherein the fluence calculation is related to the subset of collimator leaves; and  a computer readable medium that stores the computer codes. 2. The method of claim 1, wherein the collimator leaf position includes the identity of a leaf that is farthest out in a radiation field. 3. The method of claim 1, wherein the subset is associated with a calculation point. 4. The method of claim 3, wherein, when the calculation point is in a first position relative to a first leaf, the subset includes collimator leaves starting from the first leaf to a second leaf, wherein the first leaf is furthest out in a radiation field and the second leaf would be a last leaf traversed by a ray from a calculation point to a scattering plane. 5. The method of claim 3, wherein, when the calculation point is in a second position relative to a first leaf, the subset includes collimator leaves starting from a third leaf to the first leaf, wherein the first leaf is furthest out in a radiation field and the third leaf would be traversed first by a ray from a calculation point to a scattering plane. 6. The method of claim 1, further comprising determining a scatter strip on a scattering plane. 7. The method of claim 6, wherein a predetermined value associated with the scatter strip may be looked up. 8. The method of claim 6, wherein the predetermined value is a cumulative value. 9. The method of claim 6, further comprising determining whether a ray traced from a calculation point to the scatter strip intersects a first portion of a collimator leaf that is closer to the calculation point or a second portion of the collimator leaf that is farther from the calculation point. 10. A system for calculating scatter radiation, the system comprising: 11. The system of claim 10, wherein the subset is associated with a calculation point. 12. The system of claim 11, wherein, when the calculation point is in a first position relative to a first leaf, the subset includes collimator leaves starting from the first leaf to a second leaf, wherein the first leaf is furthest out in a radiation field and the second leaf would be a last leaf traversed by a ray from a calculation point to a scattering plane. 13. The system of claim 11, wherein, when the calculation point is in a second position relative to a first leaf, the subset includes collimator leaves starting from a third leaf to the first leaf, wherein the first leaf is furthest out in a radiation field and the third leaf would be traversed first by a ray from a calculation point to a scattering plane. 14. A system for calculating scatter radiation comprising: 15. The system of claim 14, wherein the subset is associated with a calculation point. 16. The system of claim 15, wherein, when the calculation point is in a first position relative to a first leaf, the subset includes collimator leaves starting from the first leaf to a second leaf, wherein the first leaf is furthest out in a radiation field and the second leaf would be a last leaf traversed by a ray from a calculation point to a scattering plane. 17. The system of claim 15, wherein, when the calculation point is in a second position relative to a first leaf, the subset includes collimator leaves starting from a third leaf to the first leaf, wherein the first leaf is furthest out in a radiation field and the third leaf would be traversed first by a ray from a calculation point to a scattering plane. 18. A computer program product for calculating scatter radiation, comprising: 19. The computer program product of claim 18, wherein the computer readable medium is selected from the group consisting of CD-ROM, floppy disk, tape, flash memory, system memory, hard drive, and data signal embodied in a carrier wave.