Feasibility of using a transmission ion chamber for QA tests of medical linear accelerators.

Purpose: To study the feasibility of using the Integral Quality Monitoring (IQM) system for routine quality assurance (QA) of photon beams.

Methods: The IQM system is a commercially available dose delivery verification tool, which consists of a spatially sensitive large area transmission ion chamber, mounted on the Linac collimator, and a calculation algorithm to predict the signals in response to radiation beams. By comparing the measured and predicted signals the system verifies the accuracy of beam delivery.

AAPM task group report 275.S: Survey strategy and results on plan review and chart check practices in US and Canada.

Background: AAPM Task Group (TG) 275 was charged with developing practical, evidence-based recommendations for physics plan and chart review clinical processes for radiation therapy. As part of this charge, and to characterize practices and clinical processes, a survey of the medical physics community was developed and conducted. Detailed analyses and trends based on the survey that exceeded TG report length constraints are presented herein.

Medical physics practice guideline 4.b: Development, implementation, use and maintenance of safety checklists.

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education, and professional practice of medical physics. The AAPM has more than 8000 members and is the principal organization of medical physicists in the US. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the US.

Assessment of dose-volume histogram precision for five clinical systems.

Purpose: To investigate the dependency of dose-volume histogram (DVH) behavior and precision on underlying discretization using shapes and dose distributions with known analytical DVHs for five commercial DVH calculators.

Methods: DVHs and summary metrics were extracted from all five systems using synthetic cone and cylinder objects for which the true volume and DVH curves were known. Trends in the curves and metrics were explored by varying the underlying voxelization of the CT image, structure set, and dose grid as well by varying the geometry of the structure and direction of a linear dose gradient.

Phantom Verification of AAA and Acuros Dose Calculations for Lung Cancer: Do Tumor Size and Regression Matter?

Purpose: This study aimed to evaluate dose calculation accuracy for the Eclipse Analytical Anisotropic Algorithm (AAA) and Acuros XB algorithm for various lung tumor sizes and to investigate dosimetric changes associated with treatment of regressing tumors.

Methods And Materials: A water phantom with cylindrical cork inserts (lung surrogates) was fabricated. Large (202 cm), medium (54 cm), and small (3 cm) solid water tumors were implanted within cork inserts.

Design and clinical use of a rotational phantom for dosimetric verification of IMRT/VMAT treatments.

Purpose: To describe the design and clinical use of a rotational phantom for dosimetric verification of IMRT/VMAT treatment plans using radiochromic film.

Methods: A solid water cylindrical phantom was designed with separable upper and lower halves and rests on plastic bearings allowing for 360° rotation about its central axis. The phantom accommodates a half sheet of radiochromic film, and by rotating the cylinder, the film can be placed in any plane between coronal and sagittal.

Image-guided radiotherapy quality control: Statistical process control using image similarity metrics.

Purpose: The purpose of this study was to demonstrate an objective quality control framework for the image review process.

Methods And Materials: A total of 927 cone-beam computed tomography (CBCT) registrations were retrospectively analyzed for 33 bilateral head and neck cancer patients who received definitive radiotherapy. Two registration tracking volumes (RTVs) - cervical spine (C-spine) and mandible - were defined, within which a similarity metric was calculated and used as a registration quality tracking metric over the course of treatment.

Patient safety is improved with an incident learning system-Clinical evidence in brachytherapy.

Background And Purpose: Health leaders have advocated for incident learning systems (ILSs) to prevent errors, but there is limited evidence demonstrating that ILSs improve cancer patient safety. Herein, we report a long-term retrospective review of ILS reports for the brachytherapy practice at a large academic institution.

Material And Methods: Over a nine-year period, the brachytherapy practice was encouraged to report all standard operating procedure deviations, including low risk deviations.

Cadaveric verification of the Eclipse AAA algorithm for spine SBRT treatments with titanium hardware.

Purpose: To assess the accuracy of the Eclipse Analytical Anisotropic Algorithm when calculating dose for spine stereotactic body radiation therapy treatments involving surgically implanted titanium hardware.

Methods And Materials: A human spine was removed from a cadaver, cut sagittally along the midline, and then separated into thoracic and lumbar sections. The thoracic section was implanted with titanium stabilization hardware; the lumbar section was not implanted.

Technical Note: Initial characterization of the new EBT-XD Gafchromic film.

Purpose: To assess the dosimetric accuracy and energy dependence of the new EBT-eXtended Dose (XD) Gafchromic film and to compare the lateral response artifact (LRA) between EBT-XD and EBT3 film.

Methods: EBT3 and EBT-XD calibration curves were created by exposing films to known doses from 0 to 3000 cGy using a 6 MV beam. To assess the accuracy and dynamic range of EBT-XD, a 60° enhanced dynamic wedge (EDW) was used to deliver a dose range of approximately 200-2900 cGy.

Medical Physics Practice Guideline 4.a: Development, implementation, use and maintenance of safety checklists.

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States.The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States.

Separating the dosimetric consequences of changing tumor anatomy from positional uncertainty for conventionally fractionated lung cancer patients.

Purpose: To separate the dosimetric consequences of changing tumor volume from positional uncertainty for patients undergoing conventionally fractionated lung radiation therapy (RT) and to quantify which factor has a larger impact on dose to target volumes and organs at risk (OAR).

Methods And Materials: Clinical treatment plans from 20 patients who had received conventionally fractionated RT were retrospectively altered by replacing tumor and atelectasis with lung equivalent tissue in the treatment planning system calculations. To simulate positional uncertainty, the isocenter was shifted in both the altered and original plans by 2 and 5 mm in 6 directions.

Influence of patient's physiologic factors and immobilization choice with stereotactic body radiotherapy for upper lung tumors.

The purpose of the present study was to compare the impact of pulmonary function, body habitus, and stereotactic body radiation therapy (SBRT) immobilization on setup and reproducibility for upper lung tumor. From 2008 through 2011, our institution's prospective SBRT database was searched for patients with upper lung tumors. Two SBRT immobilization strategies were used: full-length BodyFIX and thermoplastic S-frame.

Analysis of automatic match results for cone-beam computed tomography localization of conventionally fractionated lung tumors.

Purpose: To evaluate the dependence of an automatic match process on the size of the user-defined region of interest (ROI), the structure volume of interest (VOI), and changes in tumor volume when using cone-beam computed tomography (CBCT) for tumor localization and to compare these results with a gold standard defined by a physician's manual match.

Methods And Materials: Daily CBCT images for 11 patients with lung cancer treated with conventionally fractionated radiation therapy were retrospectively matched to a reference CT image using the Varian On Board Imager software (Varian, Palo Alto, CA) and a 3-step automatic matching protocol. Matches were performed with 3 ROI sizes (small, medium, large), with and without a structure VOI (internal target volume [ITV] or planning target volume [PTV]) used in the last step.

Radiation oncology information systems and clinical practice compatibility: Workflow evaluation and comprehensive assessment.

Purpose: To map the level of clinical practice compatibility with a radiation oncology information system (ROIS) through a workflow- and clinical process-based method aimed at optimizing the safety, efficacy, and efficiency of patient care; to improve the understanding of the critical relationship between the clinical practice and ROIS.

Methods And Materials: Clinic-specific workflow and infrastructure were classified into clinical processes, information management, and technological innovation integration. Clinical information systems-information technology infrastructure and process maps were generated by a team of experts, representing clinical constituents.

Clinical outcomes and dosimetric considerations using stereotactic body radiotherapy for abdominopelvic tumors.

Purpose/objectives: To present clinical outcomes, early toxicity, and dosimetric constraints for patients undergoing stereotactic body radiation therapy (SBRT) for abdominal or pelvic tumors.

Materials And Methods: From May 2008 to February 2010, 47 patients with 50 lesions in proximity to hollow viscous organs at risk, including stomach, duodenum, small bowel, and colon, underwent SBRT at Mayo Clinic. Treated sites included liver (21), lymph node (14), adrenal gland (6), intramuscular (4), pancreas (3), and spleen (2).