Both systems have a very good ability to create highly conformal volumetric dose distributions. Median HI of PTV for IMRT and CK plans were 1.08 and 1.33, respectively (p < 0.001).

IMRT significantly improved conformity and homogeneity index for plans. Heart and lung volumes receiving high doses were decreased, but OAR receiving low doses was increased.

Aim: The purpose of this study was to compare 6 treatment planning methods (5-beam coplanar intensity-modulated radiotherapy (IMRT), 7-beam coplanar IMRT, 7-beam noncoplanar IMRT, 2 full arc coplanar volumetric modulated arc therapy (VMAT), 2 half partial arc coplanar VMAT, and 2 half partial arc noncoplanar VMAT) for high-grade gliomas with planning target volumes (PTVs) overlapping the optic pathway and/or brainstem. Patients and Methods: 27 previously-treated patients with high-grade gliomas were replanned for treatment with IMRT₅, IMRT₇, IMRT_7-non, VMAT_2f, VMAT_2h, and VMAT_2h-non. In order to perform a comparative study of the treatment outcomes, 3 tumor localizations (right-sided, left-sided, and central tumors) were selected. Patients were administered a PTV dose of 60 Gy in 30 fractions with a maximum permitted dose of 110%. Results: Comparison of the 3 IMRT plans and 3 VMAT plans was performed for all 27 patients. The median conformity index was significantly higher (p < 0.05) in all IMRT plans compared to all VMAT plans in the case of right sided tumors. Significant differences were also observed between coplanar and noncoplanar plans in IMRT and VMAT in right-sided tumors (p < 0.05). Differences in brainstem mean doses were only found to be significant between coplanar and noncoplanar plans in centrally-located tumors. In right- and left-sided tumors, the VMAT_2f plans demonstrated higher values than all IMRT plans in their mean values for radiation doses to the ipsilateral optic nerves, contralateral optic nerves, ipsilateral lens, ipsilateral eye, contralateral lens, contralateral eye, and contralateral optic nerves, as well in the maximums for the optic chiasm and contralateral optic nerves. Significantly faster treatment times were achieved with all VMAT plans compared to IMRT plans. Conclusion: IMRT techniques provided better target coverage than VMAT plans. However, VMAT techniques reduced treatment delivery time more than IMRT techniques. Technique selection for tumors located in 3 different localizations should be individualized in accordance with patients' specific parameters.

Background: We evaluated the efficacy, toxicity, and dose responses of re-irradiation with stereotactic body radiotherapy (SBRT) in patients with recurrent non- small cell lung cancer (NSCLC) after previous irradiation. Patients and Methods: 28 patients were included. Previous median radiation doses were 54 and 66 Gy. The median interval time between previous radiotherapy and SBRT was 14 months. The median follow-up time after SBRT was 9 months (range 3-93 months). To evaluate the effectiveness of SBRT, local control, overall survival, and treatment-related toxicity were reported. Results: SBRT doses and fractionation ranged from 60 to 30 Gy and from 3 to 8, respectively, according to previous doses, location of the recurrence, and interval time. 65% of tumor recurrences overlapped with previous treatment, while 35% of tumors recurred outside of the previous treatment. 4 patients had local progression after SBRT at their first follow-up. The Kaplan-Meier estimates of the 1- and 2-year actuarial overall survival were 71 and 42%, respectively. The mean survival following SBRT was 32.8 months, and the median survival was 21 months. No grade 3 or higher toxicities were observed. Conclusion: Robotic SBRT is a tolerable treatment option with manageable toxicity which can be used with radical or palliative intent in carefully selected patients with locally recurrent tumors after previous irradiation.

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