Method for selecting minimum width of leaf in multileaf adjustable collimator while inhibiting passage of particle beams of radiation through sawtooth joints between collimator leaves

Patent · Sun Jan 01 00:00:00 EST 1995

OSTI ID:870012

Ludewigt, Bernhard ^[1]; Bercovitz, John ^[2]; Nyman, Mark ^[1]; Chu, William ^[3]

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1. Berkeley, CA
2. Hayward, CA
3. Lafayette, CA

A method is disclosed for selecting the minimum width of individual leaves of a multileaf adjustable collimator having sawtooth top and bottom surfaces between adjacent leaves of a first stack of leaves and sawtooth end edges which are capable of intermeshing with the corresponding sawtooth end edges of leaves in a second stack of leaves of the collimator. The minimum width of individual leaves in the collimator, each having a sawtooth configuration in the surface facing another leaf in the same stack and a sawtooth end edge, is selected to comprise the sum of the penetration depth or range of the particular type of radiation comprising the beam in the particular material used for forming the leaf; plus the total path length across all the air gaps in the area of the joint at the edges between two leaves defined between lines drawn across the peaks of adjacent sawtooth edges; plus at least one half of the length or period of a single sawtooth. To accomplish this, in accordance with the method of the invention, the penetration depth of the particular type of radiation in the particular material to be used for the collimator leaf is first measured. Then the distance or gap between adjoining or abutting leaves is selected, and the ratio of this distance to the height of the sawteeth is selected. Finally the number of air gaps through which the radiation will pass between sawteeth is determined by selecting the number of sawteeth to be formed in the joint. The measurement and/or selection of these parameters will permit one to determine the minimum width of the leaf which is required to prevent passage of the beam through the sawtooth joint.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Assignee: Regents, University of California (Berkeley, CA)
• Patent Number(s): US 5438454
• OSTI ID: 870012
• Country of Publication: United States
• Language: English

Related Subjects

method
selecting
minimum
width
leaf
multileaf
adjustable
collimator
inhibiting
passage
particle
beams
radiation
sawtooth
joints
leaves
disclosed
individual
top
bottom
surfaces
adjacent
stack
edges
capable
intermeshing
corresponding
configuration
surface
facing
edge
selected
comprise
penetration
depth
range
particular
type
comprising
beam
material
forming
plus
total
path
length
air
gaps
joint
defined
lines
drawn
peaks
half
period
single
accomplish
accordance
measured
distance
gap
adjoining
abutting
ratio
height
sawteeth
finally
pass
determined
formed
measurement
selection
parameters
permit
determine
required
prevent
bottom surfaces
air gap
path length
particle beam
bottom surface
particle beams
radiation comprising
surface facing
particular type
particular material
penetration depth
minimum width
air gaps
/359/250/378/