On using 3D γ-analysis for IMRT and VMAT pretreatment plan QA.

Purpose: To investigate using 3D γ analysis for IMRT and VMAT QA.

Methods: We explored and studied 3D γ-analysis by comparing TPS computed and EPID back-projection reconstructed doses in patient's CT images. Two 3D γ quantities, γ(PTV) and γ(10), were proposed and studied for evaluating the QA results, and compared to 2D γ (MapCheck composite: γ(MC)).

SU-E-T-164: Clinical Implementation of ASi EPID Panels for QA of IMRT/VMAT Plans.

Purpose: To investigate various issues for clinical implementation of aSi EPID panels for IMRT/VMAT QA.

Methods: Six linacs are used in our clinic for EPID-based plan QA; two Varian Truebeams, two Varian 2100 series, two Elekta Infiniti series. Multiple corrections must be accounted for in the calibration of each panel for dosimetric use.

Clinically shaped fields: relative outputs for Varian multileaf collimators and tray-mounted cerrobend blocks.

The purpose of this study was to determine the variation in relative output factors for fields shaped using a multileaf collimator (MLC) versus tray-mounted cerrobend blocks. A total of 21 different clinical fields from 16 patients were compared by casting cerrobend blocks from the same films that had generated the MLC shapes. Output measurements were made on a Varian 2300CD (26 1 cm leaves per side) in solid water for 6 and 20 MV at source-to-axis-distance (SAD = 100 cm) and at two depths, 5 cm (d5) and the clinically prescribed depth (d(clinical)).

Practical and technical considerations in establishing an intraoperative radiation therapy program in the community practice.

The Radiation Oncology Center in Sacramento, California, has developed a procedure for establishing an intraoperative radiation therapy facility in a community practice. The logistics pertaining to personnel, equipment, physical measurements, and quality assurance are presented. Particular emphasis is given to the most effective means of acquiring the large quantity of data needed to ensure a program of acceptable quality.