Stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT) have settled down in the center of modern palliative and recently curative intent treatments in the last two decades. Being special, technology-driven, direct knowledge and experience based clinical procedures, both SRS and SBRT require high precision, accuracy and reproducibility to be safely and effectively delivered, which delineates the importance of quality assurance (QA) procedures from head to toe. In this review, we focused on summary of the comprehensive QA program covering clinical, technical and patient-specific treatment aspects, which need to be individualized per department based on several current recommendation guidelines.
BACKGROUND:The management of craniopharyngiomas is challenging, usually requiring multidisciplinary care. Gamma Knife radiosurgery (GKRS) is an essential technique for residual/recurrent craniopharyngiomas. OBJECTIVE: To evaluate the efficacy of frameless hypofractionated GKRS (hfGKRS) for craniopharyngioma and factors which affect tumor control and complications. METHODS: This retrospective study involved 24 patients managed with hfGKRS. Clinical and radiological data, tumor characteristics, and procedural details were analyzed. RESULTS: There were 15 (62.5%) female patients. The median age was 38.5 years (range, 3-66 years). The mean tumor volume was 2.4 (1.93) cm 3 , with a mean solid volume of 1.6 (1.75) cm 3 . The median marginal dose was 20 Gy (range, 18-25 Gy) delivered in a median of 5 fractions (range, 3-5). During a median radiological follow-up of 23.5 months (range, 12-50 months), tumor progression was noted in 5 (20.8%) patients. The 2-year and 4-year progression-free survival were 81.8% and 61.4%, respectively. No deaths were identified at a median clinical follow-up of 31.3 months (range, 12-54 months). Visual deficits attributable to progression were noted in 3 (12.5%) patients with pre-GKRS visual field defects. An additional 4 (16.7%) patients with pre-GKRS visual deficit developed new minor visual field defects. Four (16.7%) patients showed improvement of vision after GKRS. There were no new-onset post-GKRS hormonal deficits. CONCLUSION: The management of craniopharyngioma requires a multidisciplinary approach, and irradiation represents effective treatment option for residual/recurrent tumors after surgery. To the best of our knowledge, this is the first study that addresses the efficacy of frameless hfGKRS in managing craniopharyngiomas over sufficient follow-up.
Purpose
To evaluate the feasibility of shortening the duration of liver stereotactic radiotherapy (SBRT) without jeopardizing dosimetry or conformity by utilizing weight-optimized dynamic conformal arcs (WO-DCA) as opposed to volumetric modulated arc therapy (VMAT) for tumors away from critical structures.
Methods
Nineteen patients with liver metastasis were included, previously treated with 50 Gy in 4 fractions with VMAT technique using two partial coplanar arcs of 6 MV beams delivered in high-definition multi-leaf collimator (HD-MLC). Two coplanar partial WO-DCA were generated on Pinnacle treatment planning system (TPS) for each patient; and MLC aperture around the planning target volume (PTV) was automatically generated at different margins for both arcs and maintained dynamically around the target during arc rotation. Weight of the two arcs using optimization method was adjusted between the arcs to maximize tumor coverage and protect organs at risk (OAR) based on the RTOG‐0438 protocol.
Results
The WO-DCA plans successfully “agreed” with the standard VMAT for OAR (liver, spinal cord, stomach, duodenum, small bowel, and heart) and PTV (D
mean
, D
98%
, D
2%
, CI, and GI), with superior mean quality assurance (QA) pass rate (97.06 vs 93.00 for VMAT; P < 0.001 and t = 8.87). Similarly, the WO-DCA technique additionally reduced the beam‐on time (3.26 vs 4.43; P < 0.001) and monitor unit (1860 vs 2705 for VMAT; P < 0.001) values significantly.
Conclusion
The WO‐DCA plans might minimize small‐field dosimetry errors and defeat patient‐specific VMAT QA requirements due to the omission of MLC beam modulation through the target volume. The WO‐DCA plans may additionally enable faster treatment delivery times and lower OAR without sacrificing target doses in SBRT of liver tumors away from critical structures.
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