X-ray field compensation with multileaf collimators

Abstract

Purpose: It has been proposed that conformal therapy can be carried out with static ports that are each individually compensated to deliver an optimal total dose distribution. If this proposal is to be implemented, one must have a means of compensating or modulating the fluence distributions within the boundaries of individual treatment fields. A theory was developed and implemented to achieve this goal.

Methods and materials: The theory allowed creation of a leaf-setting sequence for a desired level of field-modulation precision. This method of beam modulation was experimentally verified using radiographic film to integrate the dose delivered by the sequence of discrete static multileaf collimator-defined subfields.

Results: Beam profiles were generated that matched the planned beam profiles to within the specified degree of precision.

Conclusion: This methodology is a candidate for implementation of inverse planning for conformal therapy.