Integral dose delivered to normal brain with conventional intensity-modulated radiotherapy (IMRT) and helical tomotherapy IMRT during partial brain radiotherapy for high-grade gliomas with and without selective sparing of the hippocampus, limbic circuit a

AbstractPurposeTo evaluate the extent to which intensity-modulated arc therapy (IMAT) for high-grade gliomas is comparable with three-dimensional conformal radiotherapy (3DCRT) in relation to the dose delivered to normal brain tissue (NBT), planning target volume (PTV) conformity and the dose delivered to brainstem and optic chiasma.MethodA total of 16 randomly selected 3DCRT treatment plans of grade 3 gliomas were re-planned using an IMAT planning technique and dose–volume histograms were compared. Primary outcomes were maximum, mean, 1/3 and 2/3 doses to NBT outside the PTV. Also the maximum, mean, D50 and D20 doses to PTV. Secondary outcomes were maximum and mean doses to the brainstem and optic chiasm. Wilcoxon signed rank test was used to compare data.ResultsIMAT led to a statistically significant increase in mean dose to NBT (34·4 versus 33·3 Gy, (p=0·047) but a statistically significant reduction in maximum dose to NBT (62·7 versus 63·8 Gy, p=0·004) compared with 3DCRT. IMAT led to statistically significant reductions in maximum, D50 and D20 doses to the PTV (63·3 versus 64·7 Gy, p=0·001; 60·0 versus 60·7 Gy, p=0·001 and 60·5 versus 61·8 Gy, p=0·002, respectively). No statistically significant differences were seen in doses to brainstem and optic chiasm.ConclusionIMAT is at least comparable with 3DCRT in relation to minimising dose to NBT and ensuring good PTV conformity. Doses delivered to organs at risk using IMAT were also comparable with 3DCRT. This study supports the continued use of IMAT for the treatment of high-grade gliomas.

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Dosimetric Comparison of Intensity-Modulated Radiosurgery and Helical Tomotherapy for the Treatment of Multiple Intracranial Metastases

Technology in Cancer Research & Treatment ◽

10.1177/153303460900800506 ◽

2009 ◽

Vol 8 (5) ◽

pp. 361-367 ◽

Cited By ~ 7

Author(s):

Lauren VanderSpek ◽

Glenn Bauman ◽

Jia-Zhu Wang ◽

Slav Yartsev ◽

Cynthia Ménard ◽

...

Keyword(s):

At Risk ◽

Helical Tomotherapy ◽

Organs At Risk ◽

Conformity Index ◽

Normal Brain ◽

Gradient Index ◽

Integral Dose ◽

Intensity Modulated ◽

Intracranial Metastases ◽

The Mean

The purpose of this study was to evaluate the dosimetry of single fraction, single-isocenter intensity-modulated radiosurgery (IMRS) plans for multiple intracranial metastases and to compare Helical Tomotherapy (HT). Ten treatment plans with 3–6 brain metastases treated with IMRS were re-planned with HT. The mean number of lesions was 5 and mean PTV 22 cm3. The prescribed dose was 16–20 Gy. The mean V100% was similar for IMRS and HT, and the mean conformity index was 1.4, mean Paddick confirmity index was 0.7, and mean MDPD was 1.1 for both. The mean gradient index was similar for both. The mean 50% isodose volume was 179.2 cm3 for IMRS and 277.0 cm3 for HT (p=0.01). The mean maximum doses to organs at risk were lower for IMRS except brainstem and right optic nerve. For brain, the integral dose was 5.1 and 6.8 Gy-kg (p<0.001) and mean dose 4.0 and 5.4 Gy (p<0.001) for IMRS and HT, respectively. The mean treatment times were 23 (IMRS) and 41 (HT) minutes. Conformity and homogeneity indices were equivalent and sparing of the organs at risk was clinically acceptable for both IMRS and HT. Though the gradient index was similar for IMRS and HT, the mean 50% isodose volume and integral dose to normal brain were lower for IMRS as was treatment time.

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