Clinical outcomes of multileaf collimator-based CyberKnife for spine stereotactic body radiation therapy.

OBJECTIVE: Stereotactic body radiotherapy (SBRT) for spinal metastases is becoming a prevalent therapeutic option. We aimed to evaluate the clinical feasibility and outcomes of the recently developed multileaf collimator (MLC)-based CyberKnife (CK-M) for spine SBRT. METHODS: We reviewed 119 patients of 144 cases with 229 lesions treated with CK between November 2014 and March 2016. The lesion features, dosimetric parameters and clinical outcomes were compared between fixed cone collimator based CK (CK-F) and CK-M. RESULTS: Of 144 cases, 78 and 66 were treated with CK-F and CK-M, respectively. CK-M achieved an adequate target volume coverage that was comparable with CK-F (median 92 vs 90%; p = 0.03) even in larger targets (median 64.2 vs 46.7 cm3; p = 0.01), respectively. CK-M showed an improvement in the gradient index (p < 0.001) and no difference in conformity (p = 0.16). With CK-M, the median beam delivery time was significantly reduced by 30% (to 34 vs 48 min; p < 0.001). CK-M showed 1 year local control rates that were comparable to CK-F (77 vs 78%, respectively; p = 0.83). CONCLUSION: CK-M exhibits dosimetric data and local control that are comparable with CK-F, but with significant treatment time reduction. CK-M could be widely used in spine SBRT. Advances in knowledge: Given the recently developed MLC in CK, we aimed to evaluate the clinical feasibility and outcomes of MLC compared with fixed cone-based CK. MLC showed equivalent plan quality and significant treatment time reduction with comparable radiological control. We report here MLC as an effective and tolerable treatment option in CK.

Hippocampus-Sparing Whole-Brain Radiotherapy and Simultaneous Integrated Boost for Multiple Brain Metastases From Lung Adenocarcinoma: Early Response and Dosimetric Evaluation.

In this study, the volume response and treatment outcome after hippocampus-sparing whole-brain radiotherapy (HS-WBRT) with simultaneous integrated boost (SIB) using tomotherapy were evaluated. Patients with primary lung adenocarcinoma and multiple brain metastases who had a Karnofsky performance status ≥ 70 and exhibited well-controlled extracranial disease were treated. The prescribed dose was administered in 10 to 14 fractions as 25 to 28 Gy to whole-brain parenchyma, as 40 to 48 Gy to the gross metastatic lesion, and as 30 to 42 Gy to a 5-mm margin to the metastatic lesion. Double-dose gadolinium contrast-enhanced magnetic resonance imaging at 1-mm slice thickness was performed before treatment and at 1, 4, and 7 months post-treatment. The tumor volume reduction ratio was calculated for each follow-up. Between July 2011 and September 2012, 11 patients with 70 lesions were included in this analysis. The median number of lesions per patient was 4 (range, 2-15). The median initial tumor volume was 0.235 cm(3) (range, 0.020-10.140 cm(3)). The treatment plans were evaluated regarding conformation number (CN), target coverage (TC), and homogeneity index (HI). The median follow-up duration was 14 months (range, 3-25 months) and the 1-year intracranial control rate was 67%. The tumor volume reduction was most prominent during the first month with a median reduction rate of 0.717 (range, -0.190 to 1.000). Complete remission was seen in 22 (33%) lesions, and 45 (64%) lesions showed more than 65% reduction in tumor volume. The CN, TC, and HI values were comparable to that of previous studies, and the mean hippocampal dose was 13.65 Gy. No treatment breaks or ≥ G3 acute toxicities were observed during or after treatment. The HS-WBRT with SIB in patients with multiple brain metastases was effective and feasible for volume reduction and showed excellent intracranial control.