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Total body irradiation (TBI) is used prior to bone marrow transplantation as part of the conditioning regimen in selected patients. A linear accelerator-based technique was used at our treatment centre between June, 2004 and August, 2015. Patients were treated supine with extended source-to-surface distance (SSD) lateral fields, and prescription dose was 12 Gy delivered in six fractions, two fractions per day. Dose was prescribed to midplane at the level of the umbilicus and monitor units were calculated manually based on measured beam data. Dose variation within 10% of the prescribed midplane dose is considered acceptable for TBI treatment. This was achieved in our clinic by using compensators to account for missing tissue in the head and neck and lower leg regions. Lung attenuators were routinely used to correct for internal inhomogeneity, which resulted from low density lung tissue. The purpose of this study was to determine whether dose variation was within acceptable limits for these patients as part of a quality assurance process. Following chart review, 129 patients who received six-fraction TBI from 2004 to 2015 were included in this study. Patients receiving single fraction treatment were excluded. Metal oxide semiconductor field effect transistors (MOSFET) dosimetry was used to measure surface dose at four or five locations during patients' first fraction of TBI. Dosimetry was repeated during the second fraction for any site with variation greater than 10%. Statistical analysis was carried out on patient data, diagnosis and dosimetry measurements. Of the 129 patients who met the inclusion criteria, 50 were diagnosed with acute myelogenous leukemia, 30 with acute lymphoblastic leukemia and 11 with chronic myelogenous leukemia. The rest of the patients were diagnosed with lymphoma or myelodysplastic syndromes. The mean percent variation in dosimetry measurements taken at the specific locations ranged between 3.5% and 8.3%. The highest variation was found in measurements performed on the cheek. A high percentage of all dosimetry readings (85.5%) was within the acceptable range of +10% from the expected value. The highest number of individual readings taken at a specific location that fell outside this range were found at the cheek. We conclude that the linear accelerator delivered TBI at our centre meets the acceptable limits of dose variation over an 11-year period.

A close partnership between the Canadian Partnership for Quality Radiotherapy (CPQR) and the Canadian Organization of Medical Physicist's (COMP) Quality Assurance and Radiation Safety Advisory Committee (QARSAC) has resulted in the development of a suite of Technical Quality Control (TQC) guidelines for radiation treatment equipment; they outline specific performance objectives and criteria that equipment should meet in order to assure an acceptable level of radiation treatment quality. The adopted framework for the development and maintenance of the TQCs ensures the guidelines incorporate input from the medical physics community during development, measures the workload required to perform the QC tests outlined in each TQC, and remain relevant (i.e., “living documents”) through subsequent planned reviews and updates. The framework includes consolidation of existing guidelines and/or literature by expert reviewers, structured stages of public review, external field‐testing, and ratification by COMP. This TQC development framework is a cross‐country initiative that allows for rapid development of robust, community‐driven living guideline documents that are owned by the community and reviewed to keep relevant in a rapidly evolving technical environment. Community engagement and uptake survey data shows 70% of Canadian centers are part of this process and that the data in the guideline documents reflect, and are influencing, the way Canadian radiation treatment centers run their technical quality control programs. For a medium‐sized center comprising six linear accelerators and a comprehensive brachytherapy program, we evaluate the physics workload to 1.5 full‐time equivalent physicists per year to complete all QC tests listed in this suite. PACS number(s): 87.55.Qr, 87.56.Fc, 87.56.‐v

This work describes a rapid and objective method of determining repositioning error during the course of precision radiation therapy using off‐line CT imaging and automated mutual‐information image fusion. The technique eliminates the variability associated with manual identification of anatomical landmarks by observers. A phantom study was conducted to quantify the accuracy of the image co‐registration‐based analysis itself. For CT voxel dimensions of 0.65×0.65×1.0mm3, the method is shown to detect translations with an accuracy of 0.5 mm in the anterior‐posterior and lateral dimensions and 0.8 mm in the superior‐inferior dimension. Phantom rotation in the coronal plane was detected to within 0.5° of expected values. The analysis has been applied to eight radiotherapy patients at two independent clinics, each immobilized by the same system for cranial stereotactic radiotherapy and CT‐imaged once per week over the five‐ to six‐week course of treatment. Among all patients, the ranges of translation in the anterior‐posterior, lateral, and superior‐inferior dimensions were −0.91mmto0.77mm,−0.66mm to1.02mm, and −2.24mm to3.47mm, respectively. Considering all patients and CT scans, the standard deviations of translation were 0.42 mm, 0.47 mm, and 1.36 mm in the anterior‐posterior, lateral, and superior‐inferior dimensions, respectively. The ranges of patient rotation about the superior‐inferior, left‐right, and anterior‐posterior axes were −2.84to2.62°,−1.74°to1.96°, and −1.78°to1.42°, respectively. PACS numbers: 87.53.‐j, 87.53.Kn, 87.53.Ly, 87.53.Xd

This work describes a rapid and objective method of determining repositioning error during the course of precision radiation therapy using off-line CT imaging and automated mutual-information image fusion. The technique eliminates the variability associated with manual identification of anatomical landmarks by observers. A phantom study was conducted to quantify the accuracy of the image co-registration-based analysis itself. For CT voxel dimensions of 0.65 x 0.65 x1.0 mm3, the method is shown to detect translations with an accuracy of 0.5 mm in the anterior-posterior and lateral dimensions and 0.8 mm in the superior-inferior dimension. Phantom rotation in the coronal plane was detected to within 0.5 degrees of expected values. The analysis has been applied to eight radiotherapy patients at two independent clinics, each immobilized by the same system for cranial stereotactic radiotherapy and CT-imaged once per week over the five- to six-week course of treatment. Among all patients, the ranges of translation in the anterior-posterior, lateral, and superior-inferior dimensions were -0.91 mm to 0.77 mm, -0.66 mm to 1.02 mm, and -2.24 mm to 3.47 mm, respectively. Considering all patients and CT scans, the standard deviations of translation were 0.42 mm, 0.47 mm, and 1.36 mm in the anterior-posterior, lateral, and superior-inferior dimensions, respectively. The ranges of patient rotation about the superior-inferior, left-right, and anterior-posterior axes were -2.84 to 2.62 degrees, -1.74 degrees to 1.96 degrees, and -1.78 degrees to 1.42 degrees, respectively.

The Canadian Organization of Medical Physicists (COMP), in close partnership with the Canadian Partnership for Quality Radiotherapy (CPQR) has developed a series of Technical Quality Control (TQC) guidelines for radiation treatment equipment. These guidelines outline the performance objectives that equipment should meet in order to ensure an acceptable level of radiation treatment quality. The TQC guidelines have been rigorously reviewed and field tested in a variety of Canadian radiation treatment facilities. The development process enables rapid review and update to keep the guidelines current with changes in technology. This announcement provides an introduction to the guidelines, describing their scope and how they should be interpreted. Details of recommended tests can be found in separate, equipment specific TQC guidelines published in the JACMP (COMP Reports), or the website of the Canadian Partnership for Quality Radiotherapy (www.cpqr.ca).

The term \"radiosurgery\" implies delivery of a single large fraction of stereotactic radiation. Gamma-knife therapy does typically involve single-fraction treatment, because the patient must be positioned in a stereotactic head frame, and patient discomfort becomes a factor if more than one dose is required. However, for tumours such as pituitary adenomas, with proximity to the optic chiasm or tracts, medial temporal lobe or other important functional brain structures, it may be advantageous to use a fractionated technique (multiple treatments), with a smaller dose per fraction, to minimize injury to the adjacent normal tissues. Such treatment is properly referred to as \"stereotactic radiotherapy.\"

This thesis presents new detailed$\\sp{12}$ CO and$\\sp{13}$ CO observations, using 21\" resolution, around the two luminous infrared sources GL 490 and NGC 7538 IRS 9. Observations show strong evidence for bipolarity of the high-velocity outflows surrounding these two objects. Calculations of optical depth indicate that$\\sp{12}$ CO J = 2$\\to$1 emission is optically thick in the inner wings and optically thin in the outer wings. The total outflow masses were determined to be 9 MO for GL 490 and 50 MO for NGC 7538 IRS 9. The calculated mechanical luminosities of the outflows are much smaller than the stellar luminosities of the respective sources which is consistent with radiation pressure being the driving mechanism. The calculated force required to accelerate the molecular outflow is, however, much larger than the force that could be exerted on the gas if every photon emitted by the central object were absorbed. Mass loss rates were calculated by dividing total outflow mass by the dynamical timescale and were found to be 1.7$\\times$10 $\\sp{-3}$MO/yr for NGC 7538 IRS 9 and$\\sim$ 6$\\times$10 $\\sp{-4}$MO/yr for GL 490. Our observations imply that much of the emission arises from swept-up material which is possibly the result of the interaction of a collimated wind and the ambient molecular cloud. (Abstract shortened by UMI.)