Intensity-modulated and 3D-conformal radiotherapy for whole-ventricular irradiation as compared with conventional whole-brain irradiation in the management of localized central nervous system germ cell tumors.
OBJECTIVE
To compare the sparing potential of cerebral hemispheres with intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) for whole-ventricular irradiation (WVI) and conventional whole-brain irradiation (WBI) in the management of localized central nervous system germ cell tumors (CNSGCTs).


METHODS
Ten cases of patients with localized CNSGCTs and submitted to WVI by use of IMRT with or without a "boost" to the primary lesion were selected. For comparison purposes, similar treatment plans were produced by use of 3D-CRT (WVI with or without boost) and WBI (opposed lateral fields with or without boost), and cerebral hemisphere sparing was evaluated at dose levels ranging from 2 Gy to 40 Gy.


RESULTS
The median prescription dose for WVI was 30.6 Gy (range, 25.2-37.5 Gy), and that for the boost was 16.5 Gy (range, 0-23.4 Gy). Mean irradiated cerebral hemisphere volumes were lower for WVI with IMRT than for 3D-CRT and were lower for WVI with 3D-CRT than for WBI. Intensity-modulated radiotherapy was associated with the lowest irradiated volumes, with reductions of 7.5%, 12.2%, and 9.0% at dose levels of 20, 30, and 40 Gy, respectively, compared with 3D-CRT. Intensity-modulated radiotherapy provided statistically significant reductions of median irradiated volumes at all dose levels (p = 0.002 or less). However, estimated radiation doses to peripheral areas of the body were 1.9 times higher with IMRT than with 3D-CRT.


CONCLUSIONS
Although IMRT is associated with increased radiation doses to peripheral areas of the body, its use can spare a significant amount of normal central nervous system tissue compared with 3D-CRT or WBI in the setting of CNSGCT treatment.
Chen
Michael Jenwei
MJ
Department of Radiation Oncology, Hospital Israelita Albert Einstein, São Paulo, Brazil. michaelchen@einstein.br
Santos
Adriana da Silva
Ada S
Sakuraba
Roberto Kenji
RK
Lopes
Cleverson Perceu
CP
Gonçalves
Vinícius Demanboro
VD
Weltman
Eduardo
E
Ferrigno
Robson
R
Cruz
José Carlos
JC
D000293:Adolescent; D016543:Central Nervous System Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D054022:Cerebrum / Q000528:radiation effects; D002648:Child; D016371:Cranial Irradiation; D005260:Female; D006801:Humans; D008297:Male; D009373:Neoplasms, Germ Cell and Embryonal / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D010871:Pinealoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated; D047368:Tumor Burden; D055815:Young Adult