Purpose
To assess the effects of daily adaptive MR-guided replanning in stereotactic body radiation therapy (SBRT) of liver metastases based on a patient individual longitudinal dosimetric analysis.
Methods
Fifteen patients assigned to SBRT for oligometastatic liver metastases underwent daily MR-guided target localization and on-table treatment plan re-optimization. Gross tumor volume (GTV) and organs at risk (OARs) were adapted to the anatomy-of-the-day. A reoptimized plan (RP) and a rigidly shifted baseline plan (sBP) without re-optimization were generated for each fraction. After extraction of DVH parameters for GTV, planning target volume (PTV), and OARs (stomach, duodenum, bowel, liver, heart) plans were compared on a per-patient basis.
Results
Median pre-treatment GTV and PTV were 14.9 cc (interquartile range (IQR): 7.7–32.9) and 62.7 cc (IQR: 42.4–105.5) respectively. SBRT with RP improved PTV coverage (V100%) for 47/75 of the fractions and reduced doses to the most proximal OARs (D1cc, Dmean) in 33/75 fractions compared to sBP. RP significantly improved PTV coverage (V100%) for metastases within close proximity to an OAR by 4.0% (≤ 0.2 cm distance from the edge of the PTV to the edge of the OAR; n = 7; p = 0.01), but only by 0.2% for metastases farther away from OAR (> 2 cm distance; n = 7; p = 0.37). No acute grade 3 treatment-related toxicities were observed.
Conclusions
MR-guided online replanning SBRT improved target coverage and OAR sparing for liver metastases with a distance from the edge of the PTV to the nearest luminal OAR < 2 cm. Only marginal improvements in target coverage were observed for target distant to critical OARs, indicating that these patients do not benefit from daily adaptive replanning.
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Background:Surgical resection and stereotactic radiosurgery (SRS) are well-established treatment methods for patients with brain metastases, yet their respective roles in the management of brain metastases remain incompletely defined.Methods:To report on the role of SRS in the treatment of patients with brain metastases from malignant melanoma, a retrospective analysis of 381 intracranial melanoma metastases in 103 consecutive patients who underwent SRS between 2005 and 2011 at Beth Israel Deaconess Medical Center was conducted. The Cyberknife® SRS system was used to treat all patients. Clinical, technical, and radiographic data were recorded at presentation and on follow-up.Results:The patient cohort consisted of 40 female (39%) and 63 male (61%) patients with a median age of 57 years. The median overall survival from the time of radiosurgery for the entire patient cohort was 7.6 months. The local control rate at 1-year was 72% for the patients who received surgery followed by SRS and 55% for the entire patient population. Surgery followed by SRS was associated with significantly improved overall survival compared with SRS alone or whole-brain radiation therapy followed by salvage SRS (P < 0.0057).Conclusions:Both surgery plus SRS and SRS provide comparable local control. Despite the difference in lesion size in the subgroups who received surgery plus SRS and radiosurgery alone, similar outcomes were achieved in both groups, suggesting that surgical treatment of larger lesions can yield results that are not significantly different from small lesions treated by SRS alone.
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