Nelms B.E.,Canis Lupus LLC |
Chan M.F.,Sloan Kettering Cancer Center |
Jarry G.,Hopital Maisonneuve Rosemont |
Lemire M.,Hopital Maisonneuve Rosemont |
And 3 more authors.
Medical Physics | Year: 2013
Purpose: This study (1) examines a variety of real-world cases where systematic errors were not detected by widely accepted methods for IMRT/VMAT dosimetric accuracy evaluation, and (2) drills-down to identify failure modes and their corresponding means for detection, diagnosis, and mitigation. The primary goal of detailing these case studies is to explore different, more sensitive methods and metrics that could be used more effectively for evaluating accuracy of dose algorithms, delivery systems, and QA devices. Methods: The authors present seven real-world case studies representing a variety of combinations of the treatment planning system (TPS), linac, delivery modality, and systematic error type. These case studies are typical to what might be used as part of an IMRT or VMAT commissioning test suite, varying in complexity. Each case study is analyzed according to TG-119 instructions for gamma passing rates and action levels for per-beam and/or composite plan dosimetric QA. Then, each case study is analyzed in-depth with advanced diagnostic methods (dose profile examination, EPID-based measurements, dose difference pattern analysis, 3D measurement-guided dose reconstruction, and dose grid inspection) and more sensitive metrics (2% local normalization/2 mm DTA and estimated DVH comparisons). Results: For these case studies, the conventional 3%/3 mm gamma passing rates exceeded 99% for IMRT per-beam analyses and ranged from 93.9% to 100% for composite plan dose analysis, well above the TG-119 action levels of 90% and 88%, respectively. However, all cases had systematic errors that were detected only by using advanced diagnostic techniques and more sensitive metrics. The systematic errors caused variable but noteworthy impact, including estimated target dose coverage loss of up to 5.5% and local dose deviations up to 31.5%. Types of errors included TPS model settings, algorithm limitations, and modeling and alignment of QA phantoms in the TPS. Most of the errors were correctable after detection and diagnosis, and the uncorrectable errors provided useful information about system limitations, which is another key element of system commissioning. Conclusions: Many forms of relevant systematic errors can go undetected when the currently prevalent metrics for IMRT/VMAT commissioning are used. If alternative methods and metrics are used instead of (or in addition to) the conventional metrics, these errors are more likely to be detected, and only once they are detected can they be properly diagnosed and rooted out of the system. Removing systematic errors should be a goal not only of commissioning by the end users but also product validation by the manufacturers. For any systematic errors that cannot be removed, detecting and quantifying them is important as it will help the physicist understand the limits of the system and work with the manufacturer on improvements. In summary, IMRT and VMAT commissioning, along with product validation, would benefit from the retirement of the 3%/3 mm passing rates as a primary metric of performance, and the adoption instead of tighter tolerances, more diligent diagnostics, and more thorough analysis. © 2013 American Association of Physicists in Medicine.
Loubert C.,Hopital Maisonneuve Rosemont
Canadian Journal of Anesthesia | Year: 2012
Purpose The purpose of this Continuing Professional Development module is to review the physiology of maternal hypotension induced by spinal anesthesia in pregnant women, and the effects of fluids and vasopressors. Principal findings Maternal hypotension induced by spinal anesthesia is caused mainly by peripheral vasodilatation and is not usually associated with a decrease in cardiac output. Although the intravenous administration of fluids helps to increase cardiac output, it does not always prevent maternal hypotension. Three strategies of fluid administrations are equivalent for the prevention of maternal hypotension and a reduced need for vasopressors: (1) colloid preload; (2) colloid coload; and (3) crystalloid coload. Crystalloid preload is not as effective as any of those three strategies. Unlike phenylephrine, ephedrine can cause fetal acidosis. Therefore, phenylephrine is recommended as first line treatment of maternal hypotension. A phenylephrine infusion (25-50 μg·min -1) appears to be more effective than phenylephrine boluses to prevent hypotension, and nausea and vomiting. In preeclamptic patients, spinal anesthesia produces less hypotension than in normal pregnant women and fluid volumes up to 1,000 mL are usually well tolerated. Therefore mild to moderate intravascular volume loading is recommended, keeping in mind the increased risk for pulmonary edema in this population. In pre-eclamptic patients, hypotension can be treated either with ephedrine or phenylephrine, and phenylephrine infusions are not recommended. Conclusion A volume loading regimen other than crystalloid preload should be adopted. A phenylephrine infusion during elective Cesarean delivery is beneficial for the mother and safe for the newborn. © 2011 Springer-Verlag.
Azoulay L.,Sir Mortimer B Davis Jewish General Hospital |
Azoulay L.,McGill University |
Yin H.,Sir Mortimer B Davis Jewish General Hospital |
Benayoun S.,Hopital Maisonneuve Rosemont |
And 5 more authors.
European Urology | Year: 2011
Background: Some evidence indicates that androgen-deprivation therapy (ADT) increases the risk of diabetes and cardiovascular disease. To date, few studies have investigated whether this therapy also increases the risk of cerebrovascular events. Objective: To determine whether different types of ADT increase the risk of stroke/transient ischaemic attacks (TIAs) in patients with prostate cancer. Design, setting, and participants: We conducted a population-based cohort study using a nested case-control analysis within the United Kingdom's General Practice Research Database population. The cohort included all patients at least 40 yr of age newly diagnosed with prostate cancer between January 1, 1988, and December 31, 2008, and followed until December 31, 2009. Cases consisted of those who experienced a first-ever stroke/TIA during follow-up. Up to 10 controls were matched to each case on age, year of cohort entry, and duration of follow-up. Measurements: Adjusted rate ratios (RRs) of stroke/TIA associated with the use of different ADTs (gonadotropin-releasing hormone [GnRH] agonists, oral antiandrogens, combined androgen blockade, bilateral orchiectomy, and others) were estimated using conditional logistic regression. Results and limitations: The cohort included 22 310 patients with prostate cancer, followed for a mean of 3.9 yr, where 938 patients experienced a first-ever stroke/TIA (rate: 10.7 per 1000/yr). Compared with nonusers of ADT, current users of GnRH agonists (adjusted RR: 1.18; 95% confidence interval [CI], 1.00-1.39), oral antiandrogens (adjusted RR: 1.47; 95% CI, 1.08-2.01), and those who underwent bilateral orchiectomy (adjusted RR: 1.77; 95% CI, 1.25-2.39) were at an increased risk of stroke/TIA. No statistically significant increased risks were observed for patients on combined androgen blockade and other ADTs, but the small numbers do not rule out a possible association. Conclusions: The results of this large population-based study provide additional evidence that different forms of ADT may increase the risk of stroke/TIA. © 2011 European Association of Urology.
Vendittoli P-A.,Hopital Maisonneuve Rosemont |
Riviere C.,Hopital Pellegrin |
Roy A.G.,Hopital Maisonneuve Rosemont |
Barry J.,Hopital Maisonneuve Rosemont |
And 2 more authors.
Bone and Joint Journal | Year: 2013
A total of 219 hips in 192 patients aged between 18 and 65 years were randomised to 28-mm metal-on-metal uncemented total hip replacements (THRs, 107 hips) or hybrid hip resurfacing (HR, 112 hips). At a mean follow-up of eight years (6.6 to 9.3) there was no significant difference between the THR and HR groups regarding rate of revision (4.0% (4 of 99) vs 5.8% (6 of 104), p = 0.569) or re-operation rates without revision (5.1% (5 of 99) vs 2.9% (3 of 104), p = 0.428). In the THR group one recurrent dislocation, two late deep infections and one peri-prosthetic fracture required revision, whereas in the HR group five patients underwent revision for femoral head loosening and one for adverse reaction to metal debris. The mean University of California, Los Angeles activity scores were significantly higher in HR (7.5 (SD 1.7) vs 6.9 (SD 1.7), p = 0.035), but similar mean Western Ontario and McMaster Universities Osteoarthritis Index scores were obtained (5.8 (SD 9.5) in HR vs 5.1 (SD 8.9) in THR, p = 0.615) at the last follow-up. Osteolysis was found in 30 of 81 THR patients (37.4%), mostly in the proximal femur, compared with two of 83 HR patients (2.4%) (p < 0.001). At five years the mean metal ion levels were < 2.5 μg/l for cobalt and chromium in both groups; only titanium was significantly higher in the HR group (p = 0.001). Although revision rates and functional scores were similar in both groups at mid-term, longterm survival analysis is necessary to determine whether one procedure is more advantageous than the other. © 2013 The British Editorial Society of Bone & Joint Surgery.
Awissi D.-K.,Hopital Maisonneuve Rosemont |
Lebrun G.,Hopital Maisonneuve Rosemont |
Fagnan M.,Hopital Maisonneuve Rosemont |
Skrobik Y.,University of Montréal
Critical Care Medicine | Year: 2013
Objectives: The neurophysiology, risk factors, and screening tools associated with alcohol withdrawal syndrome in the ICU are reviewed. Alcohol withdrawal syndrome assessment and its treatment options are discussed. Description of nicotine withdrawal and related publications specific to the critically ill are also reviewed. A brief comment as to sedative and opiate withdrawal follows. Data and Summary: The role of currently published alcohol withdrawal syndrome pharmacologic strategies (benzodiazepines, ethanol, clomethiazole, antipsychotics, barbiturates, propofol, and dexmedetomidine) is detailed. Studies on nicotine withdrawal management in the ICU focus mainly on the safety (mortality) of nicotine replacement therapy. Study characteristics and methodological limitations are presented. Conclusion: We recommend a pharmacologic regimen titrated to withdrawal symptoms in ICU patients with alcohol withdrawal syndrome. Benzodiazepines are a reasonable option; phenobarbital appears to confer some advantages in combination with benzodiazepines. Propofol and dexmedetomidine have not been rigorously tested in comparative studies of drug withdrawal treatment; their use as additional or alternative strategies for managing withdrawal syndromes in ICU patients should therefore be individualized to each patient. Insufficient data preclude recommendations as to nicotine replacement therapy and management of iatrogenic drug withdrawal in ICU patients. © 2013 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins.
Hutt J.R.B.,Hopital Maisonneuve Rosemont |
Farhadnia P.,Hopital Maisonneuve Rosemont |
Masse V.,Hopital Maisonneuve Rosemont |
Lavigne M.,Hopital Maisonneuve Rosemont |
Vendittoli P.-A.,Hopital Maisonneuve Rosemont
Bone and Joint Journal | Year: 2015
This randomised trial evaluated the outcome of a single design of unicompartmental arthroplasty of the knee (UKA) with either a cemented all-polyethylene or a metal-backed modular tibial component. A total of 63 knees in 45 patients (17 male, 28 female) were included, 27 in the all-polyethylene group and 36 in the metal-backed group. The mean age was 57.9 years (39.6 to 76.9). At a mean follow-up of 6.4 years (5 to 9.9), 11 all-polyethylene components (41%) were revised (at a mean of 5.8 years; 1.4 to 8.0) post-operatively and two metal-backed components were revised (at one and five years). One revision in both groups was for unexplained pain, one in the metal-backed group was for progression of osteoarthritis. The others in the all-polyethylene group were for aseptic loosening. The survivorship at seven years calculated by the Kaplan-Meier method for the all-polyethylene group was 56.5% (95% CI 31.9 to 75.2, number at risk 7) and for the metal-backed group was 93.8% (95% CI 77.3 to 98.4, number at risk 16) This difference was statistically significant (p < 0.001). At the most recent follow-up, significantly better mean Western Ontario and McMaster Universities Arthritis Index Scores were found in the all-polyethylene group (13.4 vs 23.0, p = 0.03) but there was no difference in the mean Knee injury and Osteoarthritis Outcome scores (68.8; 41.4 to 99.0 vs 62.6; 24.0 to 100.0), p = 0.36). There were no significant differences for range of movement (p = 0.36) or satisfaction (p = 0.23). This randomised study demonstrates that all-polyethylene components in this design of fixed bearing UKA had unsatisfactory results with significantly higher rates of failure before ten years compared with the metal-back components. ©2015 The British Editorial Society of Bone & Joint Surgery.
Hetu P.-O.,Center Hospitalier Of Luniversite Of Montreal |
Robitaille R.,Hopital Maisonneuve Rosemont |
Vinet B.,Center Hospitalier Of Luniversite Of Montreal
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2012
The purpose of this paper is to describe the implantation of mass spectrometry in replacement of immunoassays for the measurement of immunosuppressant drugs in the clinical setting, from scientific and financial perspectives. A straightforward, rapid, and economical method was developed for the simultaneous quantification of tacrolimus, sirolimus, and cyclosporine. Following a simple protein precipitation step, supernatants are injected on a small C 18 guard cartridge and gradient elution of the immunosuppressants is performed in a total chromatographic run time of 2.25min. Sodium adducts of the compounds and internal standards are quantified by electrospray tandem mass spectrometry. The method shows inter-assay impression of less than 10-15% for all compounds with good extraction efficiency (89-104%) and minimal matrix effects, except for sirolimus where ion suppression is more pronounced. The method correlates well with chemiluminescent microparticle immunoassays (on the Abbott Architect analyzer), although the immunoassay results are significantly higher than those obtained by HPLC-MS/MS. The transition from immunoassays to mass spectrometry was well received by the laboratory staff, and significant reductions in reagent costs have been realized (>$250,000 CAD per year). With these savings, the purchase and installation of two complete HPLC-MS/MS systems was completely financed in less than three years. © 2011 Elsevier B.V..
Robert M.-C.,Hopital Maisonneuve Rosemont |
Maleki B.,Queen Elizabeth Health science Center |
Boulos P.R.,Hopital Maisonneuve Rosemont
Ophthalmic Plastic and Reconstructive Surgery | Year: 2013
PURPOSE: To describe the technique of endocanalicular laser dacryocystorhinostomy with mucosal flap creation and to report the outcomes of this technique. METHODS: Prospective noncomparative case series of 7 patients with primary acquired nasolacrimal duct obstruction undergoing endocanalicular laser dacryocystorhinostomy with mucosal flap. The mucosal flap was created using an endoscopic endonasal approach. An endocanalicular approach was used to fashion the lacrimal sac opening and the osteotomy of the lacrimal sac fossa. RESULTS: Nine procedures were performed in 7 female patients. Average patient age was 68 ± 15 years. Intraoperative complications included bleeding during the creation of the mucosal flap in 1 patient. The procedure was associated with no pain to moderate pain in all cases. Anatomical success was achieved in 89% of procedures and symptomatic relief was achieved in 89% of surgeries for an average follow up of 10 ± 5 months. Only 1 patient required an external dacryocystorhinostomy revision because of postoperative restenosis. CONCLUSIONS: Endocanalicular laser dacryocystorhinostomy provides a minimally invasive approach to epiphora with a good success rate. The addition of a nasal mucosal flap to this technique may aid in proper fistulization and should be studied in larger prospective trials. © 2013 The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc.
Aoude A.,McGill University |
Amiot L.-P.,Hopital Maisonneuve Rosemont
Canadian Journal of Surgery | Year: 2014
Background: The prognosis of patients with spinal metastasis is not very promising and hard to predict. It is for this reason that scoring systems, such as the modified Tokuhashi and Tomita scores, have been created. We sought to determine the effect - iveness of these scores in predicting patient survival. Methods: We retrospectively reviewed the data of all patients treated for spinal metastasis between March 2003 and March 2012 in our centre. We computed the Tokuhashi and Tomita scores and compared them with documented patient survival. The 2 scores were also compared with one another. Results: We identified 128 patients with spinal metastasis. The average survival of patients with predicted poor, average and good prognosis was 5, 17 and 25 months, respectively for the modified Tokuhashi score and 3, 16 and 19 months, respectively, for the Tomita score. Poor, average and good prognosis predictions differed significantly from one another for all 3 categories for the Tokuhashi score (all p < 0.05). There was no significant difference in the moderate and good prognoses for the Tomita score (p = 0.15). When comparing both scores, we obtained a weighted ? of 0.4489 (standard deviation 0.0568, 95% confidence interval 0.3376-0.5602), demonstrating moderate agreement between scores. Conclusion: Both scores have merit for use in a clinical setting and can be used as tools to help determine treatment choice. The modified Tokuhashi score had better accuracy in determining actual survival. © 2014 Canadian Medical Association.
Hopital Maisonneuve Rosemont and University of Montréal | Date: 2013-03-29
Compositions and methods for reducing or preventing graft-versus-host disease associated with allogeneic stem cell transplantation are described. A method includes harvesting hematopoietic cells from a patient with an immunologic disorder and harvesting hematopoietic cells from a donor. The harvested hemaptopoietic cells from the patient and the donor are mixed ex vivo for a period of time sufficient to activate lymphocytes within the hematopoietic cells harvested from the donor such that an immune reaction occurs and an activated portion and an unactivated portion is produced. A rhodamine B derivative is then added to the mixture of cells and the mixture is irradiated at a suitable wavelength and intensity for the selective destruction and/or inactivation of the activated portion without substantially affecting the unactivated portion or causing systemic toxicity in said patient. The irradiated cells are then infused into the patient.