Dose-surface histograms as treatment planning tool for prostate conformal therapy.
Dose-surface histograms are studied and compared with dose-volume histograms, as an evaluation tool for prostate treatment planning. For thin walled hollow organs, such as the rectum and bladder, the surface area irradiated is a more appropriate measure of the biological effect than the full volume. It is also more accurate and efficient to define the surface for a hollow structure and compute the surface area histograms. Application of the dose-surface histograms provide new insights into prostate treatment planning. A simple idealized geometry model demonstrates that the percentage surface area intersected by the geometric beam edge differs from the percentage volume intersected. For a group of prostate patients, it is shown that the dose-surface histograms yield substantially different results from the dose-volume histograms in ranking four-, six-, and, eight-field treatment plans and in calculating the fraction of the rectum irradiated to high dose. The difference in terms of surface area between these plans in the high-dose region is usually less than that in terms of the volume, and a reverse of plan ranking order can consequently occur. The percentage of organ surface irradiated to high dose is typically greater than the percentage volume by 5% to 10%. The use of the dose-surface histograms in analysis of organ motion and/or patient setup uncertainty, and analysis of rectal complications, is also discussed.
Lu
Y
Y
Department of Radiation and Cellular Oncology, University of Chicago, Illinois 60637, USA.
Li
S
S
Spelbring
D
D
Song
P
P
Vijayakumar
S
S
Pelizzari
C
C
Chen
G T
GT
D055592:Biophysical Phenomena; D001703:Biophysics; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012007:Rectum / Q000293:injuries / Q000473:pathology / Q000528:radiation effects; D014057:Tomography, X-Ray Computed; D001743:Urinary Bladder / Q000473:pathology / Q000528:radiation effects