Clinical commissioning and use of the Novalis Tx linear accelerator for SRS and SBRT.

摘要: The purpose of this study was to perform comprehensive measurements and testing a Novalis Tx linear accelerator, develop technical guidelines for com­missioning from the time acceptance first clinical treatment. (NTX) accelerator is equipped with, among other features, high-definition MLC (HD120 MLC) with 2.5 mm central leaves, 6D robotic couch, an optical guidance positioning system, as well X-ray-based image tools provide high accuracy radiation delivery stereotactic radiosurgery body therapy procedures. We have performed extensive tests each components, analyzed data collected in our clinic. present report focusing on methods for: (1) efficient accurate beam collection commissioning treatment planning systems, including small field output conducted using wide range de­tectors; (2) HD120 MLC; (3) baseline characteristics on-board imager (OBI) ExacTrac X-ray (ETX) systems conjunction couch; (4) end-to-end entire process. Established experience thus far, recommendations are provided use OBI ETX localization intra- extracranial sites. Four results presented. Basic measurements: Our confirmed necessity detectors fields. Total scatter factors varied significantly (30% approximately 62%) detectors. Unshielded diode (SFD) overestimated dose by ~ 2% large sizes. Ion chambers active diameters 6 suffered significant volume averaging. sharpest profile penumbra observed SFD because its diameter (0.6 mm). commissioning: Winston Lutz test, light/radiation congruence, Picket Fence were within criteria established relevant task group reports. measured mean transmission dynamic leaf gap MV SRS 1.17% 0.36 mm, respectively. Baseline ETX: isocenter errors left/right, posterior/anterior, superior/inferior directions were, respectively, -0.2 ± 0.2 -0.8 0.4 ETX, 0.5 0.7 0.6 0.0 cone-beam computed tomography. registration angular discrepancy 0.1 0.2°, maximum couch error 0.2°. End-to-end tests: differences planned values 0.8% 0.4%, respectively ion chamber film. gamma pass rate, EBT2 film, 95% (3% DD 1 DTA). Through system­atic series quantitative experiments initial experience, described report, we demonstrate that NTX robust requirements treat variety sites — particular highly SBRT-based treatments.