Oncology Publications

Title

A method of large irregular field compensation.

Document Type

Article

Publication Date

11-1-1974

Journal

The British journal of radiology

Volume

47

Issue

563

First Page

805

Last Page

810

URL with Digital Object Identifier

http://dx.doi.org/10.1259/0007-1285-47-563-805

Abstract

For large irregular field radiation treatments, the dose distribution is affected by the surface contour, the change in SSD at points away from the central ray of the beam, and the change in scatter conditions due to the irregular shape of the field. These combined effects could produce a dose variation within the irradiated volume up to 30%. A method of compensating for all these effects is described with special consideration being given to a simple method of producing a missing tissue compensator. This method incorporates a simple mechanical device for marking out thin lead sheets to show lines of equal air gap distance.