Biomaterial Database

Quality assurance system to correct for errors arising from couch rotation in linac-based stereotactic radiosurgery. 1997

I A Brezovich, and P N Pareek, and W E Plott, and R L Jennelle

Department of Radiation Oncology, University of Alabama at Birmingham, 35233, USA.

OBJECTIVE The purpose of this project was the development of a quality assurance (QA) system that would provide geographically accurate targeting for linac-based stereotactic radiosurgery (LBSR). METHODS The key component of our QA system is a novel device (Alignment Tool) for expedient measurement of gantry and treatment table excursions (wobble) during rotation. The Alignment Tool replaces the familiar pencil-shaped pointers with a ball pointer that is used with the field light of the accelerator to indicate alignment of beam and target. Wobble is measured prior to each patient treatment and analyzed together with the BRW coordinates of the target by a spreadsheet. The corrections required to compensate for any imprecisions are identified, and a printout generated indicating the floor stand coordinates for each couch angle used to place the target at isocenter. RESULTS The Alignment Tool has an inherent accuracy of measurement better than 0.1 mm. The overall targeting error of our QA method, found by evaluating 177 target simulator films of 55 foci in 40 randomly selected patients, was 0.47 +/- 0.23 mm. The Alignment Tool was also valuable during installation of the floor stand and a supplemental collimator for the accelerator. CONCLUSIONS The QA procedure described allows accurate targeting in LBSR, even when couch rotation is imprecise. The Alignment Tool can facilitate the installation of any stereotactic irradiation system, and can be useful for annual QA checks as well as in the installation and commissioning of new accelerators.

UI	MeSH Term	Description	Entries
D011785	Quality Assurance, Health Care	Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps.	Quality Assessment, Health Care,Health Care Quality Assessment,Health Care Quality Assurance,Healthcare Quality Assessment,Healthcare Quality Assurance,Quality Assessment, Healthcare,Quality Assurance, Healthcare,Assessment, Healthcare Quality,Assessments, Healthcare Quality,Assurance, Healthcare Quality,Assurances, Healthcare Quality,Healthcare Quality Assessments,Healthcare Quality Assurances,Quality Assessments, Healthcare,Quality Assurances, Healthcare
D002138	Calibration	Determination, by measurement or comparison with a standard, of the correct value of each scale reading on a meter or other measuring instrument; or determination of the settings of a control device that correspond to particular values of voltage, current, frequency or other output.	Calibrations
D004867	Equipment Design	Methods and patterns of fabricating machines and related hardware.	Design, Equipment,Device Design,Medical Device Design,Design, Medical Device,Designs, Medical Device,Device Design, Medical,Device Designs, Medical,Medical Device Designs,Design, Device,Designs, Device,Designs, Equipment,Device Designs,Equipment Designs
D012399	Rotation	Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Clinorotation,Clinorotations,Rotations
D016634	Radiosurgery	A radiological stereotactic technique developed for cutting or destroying tissue by high doses of radiation in place of surgical incisions. It was originally developed for neurosurgery on structures in the brain and its use gradually spread to radiation surgery on extracranial structures as well. The usual rigid needles or probes of stereotactic surgery are replaced with beams of ionizing radiation directed toward a target so as to achieve local tissue destruction.	Gamma Knife Radiosurgery,Linear Accelerator Radiosurgery,Stereotactic Body Radiotherapy,Stereotactic Radiosurgery,CyberKnife Radiosurgery,LINAC Radiosurgery,Radiosurgery, Gamma Knife,Radiosurgery, Linear Accelerator,Radiosurgery, Stereotactic,Stereotactic Radiation,Stereotactic Radiation Therapy,CyberKnife Radiosurgeries,Gamma Knife Radiosurgeries,LINAC Radiosurgeries,Linear Accelerator Radiosurgeries,Radiation Therapy, Stereotactic,Radiation, Stereotactic,Radiosurgery, CyberKnife,Radiosurgery, LINAC,Radiotherapy, Stereotactic Body,Stereotactic Body Radiotherapies,Stereotactic Radiation Therapies,Stereotactic Radiations,Stereotactic Radiosurgeries,Therapy, Stereotactic Radiation