Purpose: Craniospinal
axis irradiation (CSI) is a method of treating various central nervous system
malignancies. The large target volume typically includes entire spinal cord and
whole brain. Dosimetric comparison was performed between tomotherapy, volumetric modulated arc therapy
(VMAT), and 3D conformal radiation therapy (3D-CRT) for CSI. Methods and Materials: Five (n=5) CSI patients were planned using 3D-CRT, VMAT, and
tomotherapy (normalized such that 95% of PTV received at least 23.4 Gy in 13
fractions). Plans were compared using PTV conformity number (CN) and
homogeneity index (HI), normal tissue (NT) dose statistics, integral dose, and
treatment time. Results: On average,
tomotherapy plans showed higher CN (0.932 vs. 0.860 and 0.672 for SmartArc and
3D-CRT). In terms of HI, VMAT plans consistently showed better dose homogeneity
(1.07 vs. 1.15 and 1.13 for tomotherapy and 3D-CRT). SmartArc delivered lower
maximum dose for majority of NT, but higher mean dose. 3D-CRT plans delivered
higher maximum dose but lower mean dose to NT. Conclusions: SmartArc treatments achieved better PTV homogeneity
and reduced maximum dose to NT. Tomotherapy showed better target conformity,
but 3D-CRT was shown to reduce mean dose to NT. Integral doses were similar
between treatment modalities, but tomotherapy treatment times were much longer.
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