TITLE:
Dosimetric Comparison of Intensity-Modulated Radiotherapy versus Three-Dimensional Conformal Radiotherapy for Patients with Brain Tumors
AUTHORS:
Doaa M. Al Zayat, Ehab M. Attalla, Hassan S. Abouelenein, Yasser M. Elkem, Wafaa Khalil
KEYWORDS:
Brain Cancer; 3DCRT; IMRT
JOURNAL NAME:
Open Journal of Radiology,
Vol.4 No.1,
March
5,
2014
ABSTRACT:
Purpose: To compare target dose distribution and dose to normal tissue
for brain tumors using intensity-modulated and three-dimensional conformal
radiotherapy. Methods and Materials: Twelve patients selected in the present
study compared the dosimetry of intensity-modulated radiation therapy (IMRT)
and three-dimensional conformal radiation therapy (3DCRT) techniques in
patients treated with different diagnosis brain tumor. All patients underwent
computed tomography planning in conjunction with magnetic resonance imaging
fusion. Prescription dose and normal-tissue constraints were identical for both
plans. The tolerance level for maximum dose was 6.0 Gy for lenses and 54.0 Gy
for brain stem, and optical nerves. Target coverage was evaluated with the
D98%, D95% and D2%. Normal tissue dose was evaluated with the maximum dose to
lenses, brain stem, and optical nerves. Results: Mean and standard deviation values of
PTV 98%, PTV 95% and PTV 2% in IMRT these values were 94.6 ± 2.3, 96.56 ± 1.67 and 106.5 ± 1.87 respectively; for 3DCRT were 92.7 ± 3.09, 95.58 ± 1.24 and 104.45 ± 2.73 respectively. IMRT plan provided reduced
dose to brainstem (72.17 ± 29.967) and lenses (2.43 ± 2.39) relative to the 3DCRT plans for
brainstem (73.05 ± 34.59) and lenses (7.65 ± 23.24). But optic nerves with IMRT
significantly received higher doses (38.86 ± 32.15) than 3D-CRT (27.57 ± 31.45). Conclusion: Dose coverage of the planning
target volume (PTV) and organ at risk (OAR) was better with IMRT. If PTV is
distant to optical nerves and brainstem 3DCRT technique can be applied, and if the
PTV is nearby OAR intensity-modulated treatment technique should be used.