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Stereotactic Radiosurgery for Gynecologic Cancer
Published on: April 17, 2012
Stereotactic radiosurgery using a self-shielded gyroscopic radiosurgery system for meningiomas: technical aspects and
Yongsook C Lee1,2, Rupesh Kotecha3,4,5, Robert H Press3,4
1Department of Radiation Oncology, Herbert Wertheim Cancer Institute, Baptist Health South Florida, Miami, FL, USA. dr.cecilialee@hotmail.com.
Background:
The ZAP-X® Gyroscopic Radiosurgery® platform (ZAP Surgical Systems, Inc., San Carlos, CA, USA) is a novel self-shielded image-guided radiotherapy device developed for frameless stereotactic radiosurgery (SRS) and fractionated SRS (FSRS) of intracranial and cervical spine lesions. This article presents technical aspects and dosimetric results for SRS and FSRS using the ZAP-X system for meningioma patients.
Methods:
Unique technical aspects of our treatment workflow using the ZAP-X system encompassing computed tomography simulation, treatment planning, independent dose calculations, patient-specific quality assurance (PSQA) and treatment delivery were described. Eighteen single-lesion meningioma patients, who were treated following this workflow, were selected and divided into two groups (Group A [thirteen patients]: 25 Gy in five fractions, FSRS); Group B [five patients]: 15 Gy in a single fraction, SRS). Plan quality metrics, independent dose calculations and PSQA for each group were reviewed and analyzed.
Results:
For Group A, mean age (range) was 60 years (35 years - 80 years) and mean planning target volume (PTV) (range) was 4.78 cc (2.10 cc - 9.38 cc). Mean (range) PTV coverage, prescribed isodose line, Paddick conformity index, gradient index, number of isocenters, number of beams, delivery time estimate per fraction and PSQA gamma passing rate were 99.5% (99.5% - 99.6%), 53.5% (50.1% - 61.3%), 0.89 (0.83-0.93), 2.64 (2.54-2.88), 11.8 (5-19), 208.5 (91-332), 43.6 min (24.5 -61.0 min) and 95.0% (91.5% - 98.4%), respectively. For Group B, corresponding values were 70 years (62 years - 75 years), 1.12 cc (0.77 cc - 1.99 cc), 99.5% (99.5% - 99.5%), 56.4% (50.6% - 62.8%), 0.89 (0.85-0.93), 2.95 (2.63-3.22), 7.2 (5-9), 102.4 (81-132), 33.9 min (27.3 -38.9 min) and 95.3% (91.1% - 100.0%). For all beams in both groups, independent dose calculations were < ± 0.02% of treatment planning system dose calculations.
Conclusions:
Our experience with SRS and FSRS using the ZAP-X system for meningioma patients demonstrated that a typical external beam radiotherapy workflow was applicable with unique technical aspects, and treatment plans met our institutional planning goals and were concordant with independent dose calculations and PSQA.
