Intensity modulated radiation therapy versus three‐dimensional conformal radiation therapy for the treatment of high grade glioma: a dosimetric comparison

The present study compared the dosimetry of intensity‐modulated radiation therapy (IMRT) and three‐dimensional conformal radiation therapy (3D‐CRT) techniques in patients treated for high‐grade glioma. A total of 20 patients underwent computed tomography treatment planning in conjunction with magnetic resonance imaging fusion. Prescription dose and normal‐tissue constraints were identical for the 3D‐CRT and IMRT plans. The prescribed dose was 59.4 Gy delivered at 1.8 Gy per fraction using 4 – 10 MV photons. Normal‐tissue dose constraints were 50 – 54 Gy for the optic chiasm and nerves, and 55 – 60 Gy for the brainstem. The IMRT plan yielded superior target coverage as compared with the 3D‐CRT plan. Specifically, minimum and mean planning target volume cone down doses were 54.52 Gy and 61.74 Gy for IMRT and 50.56 Gy and 60.06 Gy for 3D‐CRT [Formula: see text]. The IMRT plan reduced the percent volume of brainstem receiving a dose greater than 45 Gy by 31% [Formula: see text] and the percent volume of brain receiving a dose greater than 18 Gy, 24 Gy, and 45 Gy by 10% [Formula: see text] , 14% [Formula: see text] , and 40% [Formula: see text] respectively. With IMRT, the percent volume of optic chiasm receiving more than 45 Gy was also reduced by 30.40% [Formula: see text]. As compared with 3D‐CRT, IMRT significantly increased the tumor control probability [Formula: see text] and lowered the normal‐tissue complication probability for brain and brainstem [Formula: see text]. Intensity‐modulated radiation therapy improved target coverage and reduced radiation dose to the brain, brainstem, and optic chiasm. With the availability of new cancer imaging tools and more effective systemic agents, IMRT may be used to intensify tumor doses while minimizing toxicity, therefore potentially improving outcomes in patients with high‐grade glioma. PACs number: 87.53 Tf