17 - Quality Assurance - Quality Assurance(QA Tarun K...

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Unformatted text preview: Quality Assurance (QA) Tarun K. Podder, PhD, DABR Department of Radiation Oncology Brody School of Medicine Leo Jenkins Cancer Center East Carolina University March 17, 2011 Lecture # 17 (Ch. 17) 2 uality Assurance in Radiation Therapy ¡ All procedures that ensure consistency of the medical prescription, and safe fulfillment of that radiotherapy related prescription. ¡ QA program Æ fulfill the objects by systematic monitoring of the quality and appropriateness of patient care. 3 Work flow in radiation therapy 4 Radiation therapy equipments ¡ External beam units: ¢ Cobalt machine ¢ Linear accelerator ¡ Brachytherapy sources ¡ Simulator 5 Overview Linear accelerator ¡ Acceptance testing ¡ Commissioning ¡ Periodic QA 6 Instruments needed in the acceptance, commissioning and QA ¡ 3-D water phantom scanner with computer interface ¡ Ion chambers, electrometers ¡ X-ray films, laser film scanner ¡ Precision level 7 3-D water phantom scanner 8 Ion chamber and electrometer 9 Film and film scanner 10 Acceptance testing 11 Linear accelerator 12 12 Mechanical check ¡ Collimator Rotation : Rotate the collimator with a pointer at isoc. Use graph paper. Ensure run out <1mm radius. ¡ Gantry Rotation : Attach pointer onto couch. Rotate gantry and ensure run out <1mm. ¡ Table Rotation : Rotate the table with a pointer at isoc. And graph paper. Ensure run out <1mm radius. Cross-hair centering < 2mm diameter Collimator mechanical isocenter < 2mm diameter Gantry mechanical isocenter < 2mm diameter Couch mechanical isocenter < 2mm diameter 13 13 Collimator rotation and gantry rotation Collimator rotation Gantry rotation 14 14 Light field alignment and calibration ¡ Verify cross-hair intersect mechanical isocenter and cross hairs are parallel with jaw projections ( ± 1mm) ¡ For symmetric and independent jaw settings, confirm digital display is with 1mm of light projection for range of FS. Ensure room is dark and graph paper is accurate Field size indicators ± 2mm or ± 1% Collimator symmetry ± 2mm 15 15 Angle Readouts ¡ Collimator: Set Gantry to 0º. Rotate the collimator CW and CCW 90º, marking cross-hair projection onto graph paper. Ensure digital and mechanical readouts are within 0.5º and 1.0º, respectively. ¡ Gantry: Using spirit level, find the “cardinal” angles (0, 90, 180, 270). Ensure digital and mechanical readouts are within 0.5º and 1.0º, respectively. 16 16 Couch motion ¡ Rotation: Check Mechanical and Digital Readouts at “cardinal” couch angles. Ensure digital and mechanical readouts are within 0.5º and 1.0º, respectively. ¡ Vertical: Check with couch at isoc. And at lowest position. Use ruler to record table increments. Ensure readouts are within 2mm....
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This note was uploaded on 01/21/2012 for the course PHYS 6720 taught by Professor Hu during the Spring '10 term at East Carolina University .

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17 - Quality Assurance - Quality Assurance(QA Tarun K...

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