A new three-dimensional dose distribution reduction scheme for tubular organs

In tubular structures, spatial aspects of the dose distribution may be impo rtant in determining the normal tissue response. Conventional dose-volume-h istograms (DVHs) and dose-surface histograms (DSHs) lack spatial informatio n and may not be adequate to represent the three-dimensional (3D) dose data . A new 3D dose distribution data reduction scheme which preserves its long itudinal and circumferential character is presented. Dose distributions wer e generated at each axial level for esophagus or rectum in 123 patients wit h lung cancer or prostate cancer. Dose distribution histograms at each axia l level were independently analyzed along the esophageal or rectal circumfe rence to generate dose-circumference-histogram (DCH) sheets. Two types of p lots were then generated from the DCH sheet. The first considered the perce ntage of the circumference at each axial level receiving Various doses. The second considered the minimum dose delivered to any percentage of the circ umference at each axial level. The DCH as a treatment planning tool can be easily implemented in a 3D planing system and is potentially useful for the study of the relationship between the complication risk and the longitudin al and circumferential dose distributions. (C) 2000 American Association of Physicists in Medicine. [S0094-2405(00)01608-4].