Three-dimensional treatment planning of astrocytomas: a dosimetric study of cerebral irradiation.
To demonstrate that 3-dimensional planning is both practical and applicable to the treatment of high-grade astrocytomas, 50 patients over a 2-year period have received cerebral irradiation delivered in focussed, non-axial techniques employing from 2 to 5 beams. Astrocytomas have been planned using rapid, practical incorporation of CT data to define appropriate tumor volumes. Tumor + 3.0 cm and tumor + 1.5 cm volumes have been treated to conventional doses of 4500 cGy and 5940 cGy, respectively, using beam orientations that maximally spared normal remaining parenchyma. Analyses of 3-dimensionally calculated plans have been performed using integral dose-volume histograms (DVH) to help select treatment techniques. Using identical CT-based volumetric data as input for generation of Beam's Eye View (BEV) designed blocks, DVH curves demonstrate dosimetric advantages of non-axial techniques over conventional parallel-opposed orientations. Assessment of the non-axial techniques in selected cases indicates that uniform target volume coverage could be maintained with a typical reduction of 30% in the total amount of brain tissue treated to high dose (95% isodose line).
Thornton
A F
AF
Dept. of Radiation Oncology, University of Michigan Medical Center, Ann Arbor 48109-0010.
Hegarty
T J
TJ
Ten Haken
R K
RK
Yanke
B R
BR
LaVigne
M L
ML
Fraass
B A
BA
McShan
D L
DL
Greenberg
H S
HS
D001254:Astrocytoma / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed