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1.
Respirology ; 24(2): 171-178, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30187976

RESUMO

BACKGROUND AND OBJECTIVE: Pleural infection is a clinical challenge; its microbiology can be complex. Epidemiological and outcome data of pleural infection in adult Australians are lacking. We describe the bacteriology and clinical outcomes of Australian adults with culture-positive pleural infection (CPPI) over a 6-year period. METHODS: Cases with CPPI were identified through Western Australian public hospitals electronic record. Culture isolates, admission dates, vital status, co-morbidities, radiology, blood and pleural fluid tests were extracted. RESULTS: In total, 601 cases (71.4% males; median age: 63 years (IQR: 50-74); median hospital stay 13 days) involving 894 bacterial isolates were identified. Hospital-acquired (HA)-CPPI was defined in 398 (66.2%) cases, community-acquired (CA)-CPPI in 164 (27.3%) cases and the remaining classified as oesophageal rupture/leak. Co-morbidities, most frequently cancer, were common (65.2%). Radiological evidence of pneumonia was present in only 43.8% of CA-CPPI and 27.3% of HA-CPPI. Of the 153 different bacterial strains cultured, Streptococcus species (32.9%) especially viridans streptococci group were most common in CA-CPPI, whereas HA-CPPI was most often associated with Staphylococcus aureus (11.6%) and Gram-negative (31.9%) infections. Mortality was high during hospitalization (CA-CPPI 13.4% vs HA-CPPI 16.6%; P = 0.417) and at 1 year (CA-CPPI 32.4% vs HA-CPPI 45.5%; P = 0.006). CONCLUSION: This is the first large multicentre epidemiological study of pleural infection in Australian adults and includes the largest cohort of HA-CPPI published to date. CPPI is caused by a diverse range of organisms which vary between CA and HA sources. CPPI is a poor prognostic indicator both in the short term and in the subsequent 12 months.


Assuntos
Doenças Pleurais , Infecções Estafilocócicas , Infecções Estreptocócicas , Bactérias/classificação , Bactérias/isolamento & purificação , Técnicas Bacteriológicas , Estudos de Coortes , Empiema Pleural/diagnóstico , Empiema Pleural/microbiologia , Feminino , Hospitalização/estatística & dados numéricos , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Pleurais/diagnóstico , Doenças Pleurais/epidemiologia , Doenças Pleurais/microbiologia , Doenças Pleurais/terapia , Derrame Pleural/diagnóstico , Derrame Pleural/microbiologia , Fatores de Risco , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/terapia , Infecções Estreptocócicas/epidemiologia , Infecções Estreptocócicas/microbiologia , Infecções Estreptocócicas/terapia , Austrália Ocidental/epidemiologia
2.
Respirology ; 20(3): 507-9, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25677866

RESUMO

We report on 19 patients from Western Australia of pleural empyema with Klebsiella oxytoca, an organism never before reported in association with this condition. Median age was 65 years, 14/17 (83%) had been in hospital within 30 days prior to diagnosis, 12/18 (67%) had active cancer, 9/17 (53%) had been in intensive care and 7/17 (41%) had prior surgery. Nine patients died at the time of censure, five within 90 days of infection.


Assuntos
Empiema Pleural/microbiologia , Infecções por Klebsiella/microbiologia , Klebsiella oxytoca/isolamento & purificação , Idoso , Empiema Pleural/epidemiologia , Feminino , Humanos , Incidência , Infecções por Klebsiella/epidemiologia , Masculino , Pessoa de Meia-Idade , Austrália Ocidental/epidemiologia
3.
J Clin Microbiol ; 52(8): 2829-33, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24871216

RESUMO

Active surveillance is part of a multifaceted approach used to prevent the spread of vancomycin-resistant enterococci (VRE). The impact of fecal density, the vancomycin MIC of the isolate, and the vancomycin concentration in liquid medium on test performance are uncertain. Using fecal specimens spiked with a collection of 18 VRE (predominantly vanB) with a wide vancomycin MIC range, we compared the performances of commercial chromogenic agars (CHROMagar VRE, chromID VRE, Brilliance VRE, and VRE Select) and 1 liquid medium (Enterococcosel enrichment broth) for VRE detection. The specificity of solid media was excellent; however, the sensitivity at 48 h varied from 78 to 94%. Screening using liquid medium was less sensitive than screening with solid media, particularly as the vancomycin content increased. Sensitivity declined (i) as the fecal VRE density decreased, (ii) when the media were assessed at 24 h (versus 48 h), and (iii) for isolates with a low vancomycin MIC (sensitivity, 25 to 75% versus 100% for isolates with vancomycin MIC of <16 mg/liter versus >32 mg/liter on solid medium using 10(6) CFU/ml of feces). Depending on local epidemiology and in particular VRE vancomycin MICs, the sensitivity of culture-based methods for VRE screening of stool or rectal specimens may be suboptimal, potentially facilitating secondary transmission.


Assuntos
Antibacterianos/farmacologia , Enterococcus/efeitos dos fármacos , Fezes/microbiologia , Resistência a Vancomicina , Vancomicina/farmacologia , Meios de Cultura/química , Enterococcus/isolamento & purificação , Infecções por Bactérias Gram-Positivas/microbiologia , Humanos , Testes de Sensibilidade Microbiana/métodos , Sensibilidade e Especificidade
4.
Microbiol Spectr ; 10(4): e0135822, 2022 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-35950846

RESUMO

High-throughput diagnostic assays are required for large-scale population testing for severe acute respiratory coronavirus 2 (SARS-CoV-2). The gold standard technique for SARS-CoV-2 detection in nasopharyngeal swab specimens is nucleic acid extraction followed by real-time reverse transcription-PCR. Two high-throughput commercial extraction and detection systems are used routinely in our laboratory: the Roche cobas SARS-CoV-2 assay (cobas) and the Roche MagNA Pure 96 system combined with the SpeeDx PlexPCR SARS-CoV-2 assay (Plex). As an alternative to more costly instrumentation, or tedious sample pooling to increase throughput, we developed a high-throughput extraction-free sample preparation method for naso-oropharyngeal swabs using the PlexPCR SARS-CoV-2 assay (Direct). A collection of SARS-CoV-2-positive (n = 185) and -negative (n = 354) naso-oropharyngeal swabs in transport medium were tested in parallel to compare Plex to Direct. The overall agreement comparing the qualitative outcomes was 99.3%. The mean cycle of quantification (Cq) increase and corresponding mean reduction in viral load for Direct ORF1ab and RdRp compared to Plex was 3.11 Cq (-0.91 log10 IU/mL) and 4.78 Cq (-1.35 log10 IU/mL), respectively. We also compared Direct to a four-sample pool by combining each positive sample (n = 185) with three SARS-CoV-2-negative samples extracted with MagNA Pure 96 and tested with the PlexPCR SARS-CoV-2 assay (Pool). Although less sensitive than Plex or Pool, the Direct method is a sufficiently sensitive and viable approach to increase our throughput by 12,032 results per day. Combining cobas, Plex, and Direct, an overall throughput of 19,364 results can be achieved in a 24-h period. IMPORTANCE Laboratories have experienced extraordinary demand globally for reagents, consumables, and instrumentation, while facing unprecedented testing demand needed for the diagnosis of SARS-CoV-2 infection. A major bottleneck in testing throughput is the purification of viral RNA. Extraction-based methods provide the greatest yield and purity of RNA for downstream PCR. However, these techniques are expensive, time-consuming, and depend on commercial availability of consumables. Extraction-free methods offer an accessible and cost-effective alternative for sample preparation. However, extraction-free methods often lack sensitivity compared to extraction-based methods. We describe a sensitive extraction-free protocol based on a simple purification step using a chelating resin, combined with proteinase K and thermal treatment. We compare the sensitivity qualitatively and quantitatively to a well-known commercial extraction-based system, using a PCR assay calibrated to the 1st WHO international standard for SARS-CoV-2 RNA. This method entails high throughput and is suitable for all laboratories, particularly in jurisdictions where access to instrumentation and reagents is problematic.


Assuntos
Teste para COVID-19 , COVID-19 , COVID-19/diagnóstico , Humanos , Nasofaringe , RNA Viral/análise , SARS-CoV-2/genética , Manejo de Espécimes/métodos
5.
Diagn Microbiol Infect Dis ; 101(4): 115519, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34571354

RESUMO

To improve laboratory safety we thermally treated naso-oropharyngeal samples before testing with the cobas SARS-CoV-2 assay. This study aimed to determine if thermal treatment significantly affects the qualitative detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the quantitative measurement of cobas SARS-CoV-2 ORF1a and E-gene target copy number using an in-house quantitative method. A collection of positive (n = 238) and negative samples (n = 196) was tested in parallel comparing thermal treatment (75 °C for 15 minutes) to room-temperature. There were no significant differences in the final qualitative outcomes for thermal treatment versus room-temperature (99.8% agreement) despite a statistically significant reduction (P < 0.05) in target copy number following thermal treatment. The median ORF1a and E-gene reduction in target copy number was -0.07 (1.6%) and -0.22 (4.2%) log10 copies/mL respectively. The standard curves for both ORF1a and E-gene targets were highly linear (r2 = 0.99). Good correlation was observed for ORF1a (r2 = 0.96) and E-gene (r2 = 0.98) comparing thermal treatment to room-temperature control.


Assuntos
Teste para COVID-19/métodos , COVID-19/diagnóstico , Nasofaringe/virologia , Orofaringe/virologia , SARS-CoV-2/isolamento & purificação , Manejo de Espécimes/métodos , Temperatura Alta , Humanos , RNA Viral/isolamento & purificação , Inativação de Vírus
6.
Diagn Microbiol Infect Dis ; 61(3): 302-8, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18378109

RESUMO

BK virus (BKV) may cause nephropathy in renal transplant patients, resulting in graft dysfunction and possible graft loss. We used a sensitive quantitative BKV assay to monitor plasma BK viral loads in 11 renal transplant patients for periods ranging from 37 to 189 weeks posttransplant. Five patients remained negative for BKV, and 6 developed viremia, including 1 patient with a transient viremia. Of the viremic patients, 2 were diagnosed with BKV nephropathy after increasing serial BK viral loads, prompting a renal biopsy that established the diagnosis. A 3rd patient had high initial BK viral load and biopsy-proven disease that resolved with reduced immunosuppression. Two patients did not develop nephropathy despite persistent viral loads of 10(4) copies/mL. Five of 6 patients experienced viral clearance from the plasma (BK viral load <500 copies/mL), which was associated with their renal function becoming stabilized, and the remaining patient experienced a downward trend in viral load and stable renal function. Thus, the BKV quantitative assay was useful in aiding the diagnosis of BKV nephropathy, monitoring the response to reductions in immunosuppression and identified that some patients can have persistent viremia and still develop stable renal function without specific antiviral therapy.


Assuntos
Vírus BK/isolamento & purificação , Transplante de Rim , Infecções por Polyomavirus/virologia , Infecções Tumorais por Vírus/virologia , Carga Viral , Adulto , Feminino , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade
7.
Diagn Microbiol Infect Dis ; 61(1): 72-5, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18221851

RESUMO

We assessed a real-time quantitative polymerase chain reaction (PCR) assay targeting the lytA and ply gene of Streptococcus pneumoniae. Both assays were applied to whole blood samples from 28 adult patients with community-acquired pneumonia. Our findings suggest the lytA PCR is more sensitive, and the quantitative aspect of the assay shows promise as an aid to clinical judgment.


Assuntos
Sangue/microbiologia , Infecções Comunitárias Adquiridas/microbiologia , Pneumonia Pneumocócica/diagnóstico , Reação em Cadeia da Polimerase/métodos , Streptococcus pneumoniae/isolamento & purificação , Proteínas de Bactérias/genética , Humanos , Pneumonia Pneumocócica/microbiologia , Sensibilidade e Especificidade , Streptococcus pneumoniae/genética , Estreptolisinas/genética
8.
Med Phys ; 35(6): 2513-8, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18649484

RESUMO

Radiation therapy, along with other branches of medicine, is moving towards a firmer basis in evidence to optimally utilize resources. As new treatment technology and strategies place greater demands on quality assurance resources, the need to objectively evaluate equipment and process performance standards from the perspective of predicted clinical impact becomes more urgent. This study evaluates the appropriateness of recommended quality control tolerance and action levels for linear accelerators based on the calculated dosimetric impact of suboptimal equipment performance. A method is described to quantify the dosimetric changes, as reflected by the changes in the outcome surrogate, equivalent uniform dose (EUD), of machine performance deviations from the optimal, specifically in the range of tolerance and action levels promulgated by the Canadian Association of Provincial Cancer Agencies (CAPCA). Linear accelerator performance deviations were simulated for the treatment of prostate, breast, lung, and brain using 3D conformal techniques, and the impact evaluated in terms of the changes in the EUD of the target volumes and two principal organs at risk (OARs) per site. The eight key performance characteristics examined are: Output constancy, beam flatness, gantry angle, collimator angle, field size indicator, laser alignment (three directions) and, by inference, the optical distance indicator. Currently accepted CAPCA tolerance levels for these eight performance characteristics are shown to maintain average EUD deviations to within 2% for the targets and 2 Gy for the OARs. However, within the 2% or 2 Gy range, the recommended tolerance levels are found to have markedly different effects on the EUDs of the structures of interest.


Assuntos
Aceleradores de Partículas/normas , Radioterapia/métodos , Encéfalo/efeitos da radiação , Mama/efeitos da radiação , Humanos , Pulmão/efeitos da radiação , Masculino , Próstata/efeitos da radiação , Controle de Qualidade , Radiometria , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia Conformacional
9.
J Appl Clin Med Phys ; 9(1): 47-53, 2008 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-18449165

RESUMO

An essential component of quality assurance in radiation therapy is verifying the accuracy of monitor unit calculations. For tangential breast fields, monitor unit differences between primary calculations and second checks are usually larger than considered acceptable at other anatomical sites. A simple model to reconcile the differences between sophisticated and simple algorithms is presented, based on estimating the the volume irradiated by the field, replacing the breast contour with a rectangular block having an equal volume but a new field width which provides almost equivalent scatter to the prescription point. This analysis can also assist the treatment planning physicist in selecting a tolerance window for verifying monitor unit calculations for tangential breast fields.


Assuntos
Neoplasias da Mama/radioterapia , Imageamento Tridimensional/métodos , Modelos Biológicos , Radiometria/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Simulação por Computador , Feminino , Humanos , Dosagem Radioterapêutica , Eficiência Biológica Relativa , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
10.
PLoS One ; 13(7): e0201530, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30059559

RESUMO

Pleural infection/empyema is common and its incidence continues to rise. Streptococcus pneumoniae is the commonest bacterial cause of empyema in children and among the commonest in adults. The mesothelium represents the first line of defense against invading microorganisms, but mesothelial cell responses to common empyema pathogens, including S. pneumoniae, have seldom been studied. We assessed mesothelial cell viability in vitro following exposure to common empyema pathogens. Clinical isolates of S. pneumoniae from 25 patients with invasive pneumococcal disease and three reference strains were tested. All potently induced death of cultured mesothelial cells (MeT-5A) in a dose- and time-dependent manner (>90% at 107 CFU/mL after 24 hours). No significant mesothelial cell killing was observed when cells were co-cultured with Staphylococcus aureus, Streptococcus sanguinis and Streptococcus milleri group bacteria. S. pneumoniae induced mesothelial cell death via secretory product(s) as cytotoxicity could be: i) reproduced using conditioned media derived from S. pneumoniae and ii) in transwell studies when the bacteria and mesothelial cells were separated. No excess cell death was seen when heat-killed S. pneumoniae were used. Pneumolysin, a cytolytic S. pneumoniae toxin, induced cell death in a time- and dose-dependent manner. S. pneumoniae lacking the pneumolysin gene (D39 ΔPLY strain) failed to kill mesothelial cells compared to wild type (D39) controls, confirming the necessity of pneumolysin in D39-induced mesothelial cell death. However, pneumolysin gene mutation in other S. pneumoniae strains (TIGR4, ST3 and ST23F) only partly abolished their cytotoxic effects, suggesting different strains may induce cell death via different mechanisms.


Assuntos
Células Epiteliais/microbiologia , Células Epiteliais/fisiologia , Pleura/microbiologia , Pleura/patologia , Streptococcus pneumoniae/patogenicidade , Proteínas de Bactérias/farmacologia , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Criança , Empiema Pleural/metabolismo , Empiema Pleural/microbiologia , Empiema Pleural/patologia , Células Epiteliais/patologia , Epitélio/microbiologia , Epitélio/patologia , Epitélio/fisiologia , Humanos , Infecções Pneumocócicas/metabolismo , Infecções Pneumocócicas/microbiologia , Infecções Pneumocócicas/patologia , Streptococcus pneumoniae/isolamento & purificação , Streptococcus pneumoniae/fisiologia , Estreptolisinas/farmacologia
11.
Int J Radiat Oncol Biol Phys ; 67(1): 71-7, 2007 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-16997500

RESUMO

PURPOSE: The aim of this study was to demonstrate, based on clinical postplan dose distributions, that technology can be used efficiently to eliminate the learning curve associated with permanent seed implant planning and delivery. METHODS AND MATERIALS: Dose distributions evaluated 30 days after the implant of the initial 22 consecutive patients treated with permanent seed implants at two institutions were studied. Institution 1 (I1) consisted of a new team, whereas institution 2 (I2) had performed more than 740 preplanned implantations over a 9-year period before the study. Both teams had adopted similar integrated systems based on three-dimensional (3D) transrectal ultrasonography, intraoperative dosimetry, and an automated seed delivery and needle retraction system (FIRST, Nucletron). Procedure time and dose volume histogram parameters such as D90, V100, V150, V200, and others were collected in the operating room and at 30 days postplan. RESULTS: The average target coverage from the intraoperative plan (V100) was 99.4% for I1 and 99.9% for I2. D90, V150, and V200 were 191.4 Gy (196.3 Gy), 75.3% (73.0%), and 37.5% (34.1%) for I1 (I2) respectively. None of these parameters shows a significant difference between institutions. The postplan D90 was 151.2 Gy for I1 and 167.3 Gy for I2, well above the 140 Gy from the Stock et al. analysis, taking into account differences at planning, results in a p value of 0.0676. The procedure time required on average 174.4 min for I1 and 89 min for I2. The time was found to decrease with the increasing number of patients. CONCLUSION: State-of-the-art technology enables a new brachytherapy team to obtain excellent postplan dose distributions, similar to those achieved by an experienced team with proven long-term clinical results. The cost for bypassing the usual dosimetry learning curve is time, with increasing team experience resulting in shorter treatment times.


Assuntos
Braquiterapia/métodos , Prática Psicológica , Neoplasias da Próstata/radioterapia , Tecnologia Radiológica/normas , Braquiterapia/normas , Braquiterapia/estatística & dados numéricos , Competência Clínica , Humanos , Imageamento Tridimensional , Masculino , Neoplasias da Próstata/diagnóstico por imagem , Dosagem Radioterapêutica , Fatores de Tempo , Ultrassonografia
12.
Brachytherapy ; 6(4): 254-7, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17991622

RESUMO

INTRODUCTION: In 2003, the Tom Baker Cancer Centre started a prostate brachytherapy program using Iodine-125 seeds, intraoperative treatment planning, and an automated remote afterloader, the seedSelectron. Over a 3-month period in 2004-2005, technologic changes were implemented with the intent of reducing the time spent in the operating room and improving ergonomics for the radiation oncologist/surgeon. New commercial software including inverse planning was installed, concurrent needle insertion and seed train building was implemented, and additional hardware (a slave monitor) was connected to the system. PURPOSE: To demonstrate that, with these enhancements, dosimetry is not compromised, whereas efficiency is significantly improved. METHODS: Interactive inverse planning was used to create the treatment plans in the operating room. Seed-spacer trains were built concurrently with each needle's insertion guided by rotating the ultrasound probe to the correct sagittal plane using the Needle Navigator feature. Needles were built, inserted, and delivered one needle at a time. Needle coordinate and insert positions were verified on the live ultrasound image displayed on both the slave monitor positioned above the patient's pelvis and the operator console. Dosimetry parameters (D(90) and V(100)), numbers of seeds, and OR times were compared for 20 patients before and 11 patients after the implementation of the concurrent insertion and build protocol combined with inverse planning and the slave monitor. RESULTS: Operating room (OR) times (probe in to probe out) were reduced by 33 min and the number of seeds per unit volume by 3% on an average. The majority of the decrease in time is due to the concurrent building and insertion of needles. Before and after the new technique, average postplan D(90) and V(100) values at 4 weeks after the implant were the same to within 4 Gy and 0.1%, respectively. The range (max-min) of D(90) decreased by 20% of the mean dose and the V(100) range decreased by 6% with the new technique. Adding the slave monitor improved quality assurance of the delivery process and ergonomics for physicians. CONCLUSIONS: The concurrent insertion and build protocol, together with inverse planning and the slave monitor, have decreased OR times with greater consistency in the delivered dose distribution.


Assuntos
Braquiterapia/métodos , Próstata/diagnóstico por imagem , Neoplasias da Próstata/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Ergonomia , Humanos , Radioisótopos do Iodo , Masculino , Agulhas , Salas Cirúrgicas/organização & administração , Neoplasias da Próstata/diagnóstico por imagem , Ultrassonografia
13.
PLoS One ; 12(11): e0188833, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29190798

RESUMO

Empyema is defined by the presence of bacteria and/or pus in pleural effusions. However, the biology of bacteria within human pleural fluid has not been studied. Streptococcus pneumoniae is the most common cause of pediatric and frequent cause of adult empyema. We investigated whether S. pneumoniae can proliferate within human pleural fluid and if growth is affected by the cellular content of the fluid and/or characteristics of pneumococcal surface proteins. Invasive S. pneumoniae isolates (n = 24) and reference strain recovered from human blood or empyema were inoculated (1.5×106CFU/mL) into sterile human malignant pleural fluid samples (n = 11). All S. pneumoniae (n = 25) strains proliferated rapidly, increasing by a median of 3009 (IQR 1063-9846) from baseline at 24hrs in all pleural effusions tested. Proliferation was greater than in commercial pneumococcal culture media and concentrations were maintained for 48hrs without autolysis. A similar magnitude of proliferation was observed in pleural fluid before and after removal of its cellular content, p = 0.728. S. pneumoniae (D39 strain) wild-type, and derivatives (n = 12), each with mutation(s) in a different gene required for full virulence were inoculated into human pleural fluid (n = 8). S. pneumoniae with pneumococcal surface antigen A (ΔpsaA) mutation failed to grow (2207-fold lower than wild-type), p<0.001, however growth was restored with manganese supplementation. Growth of other common respiratory pathogens (n = 14) across pleural fluid samples (n = 7) was variable and inconsistent, with some strains failing to grow. We establish for the first time that pleural fluid is a potent growth medium for S. pneumoniae and proliferation is dependent on the PsaA surface protein and manganese.


Assuntos
Empiema Pleural/microbiologia , Derrame Pleural/microbiologia , Streptococcus pneumoniae/crescimento & desenvolvimento , Humanos , Streptococcus pneumoniae/patogenicidade
14.
Med Phys ; 33(9): 3213-9, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17022214

RESUMO

We have compared four computational methods for quantifying the effect of set-up error and uncertainty on delivered doses to targets and organs at risk in the intensity modulated radiation therapy treatment of head and neck cancer. These four methods were direct simulation, simple convolution, plus two modified convolution approaches. Discrepancies of up to 20% in the equivalent uniform dose (EUD) between direct simulation and simple convolution were estimated for the relatively superficial parotid gland at a systematic set-up error of 6 mm standard deviation and a random uncertainty of 2 mm standard deviation. Truncated convolution agreed with direct simulation to within 6% for all situations studied. However, of the four methods, only direct simulation can quantify the range of outcomes (EUD) associated with a finite number of courses and fractions. Our results are particularly relevant to the design of dose escalation studies in head and neck cancer.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Erros Médicos/prevenção & controle , Modelos Biológicos , Radiometria/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Conformacional/métodos , Simulação por Computador , Humanos , Lesões por Radiação/prevenção & controle , Dosagem Radioterapêutica , Eficiência Biológica Relativa , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
15.
J Appl Clin Med Phys ; 7(2): 50-7, 2006 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-17533323

RESUMO

An essential component of quality assurance in radiation therapy is verifying the accuracy of monitor unit calculations. Differences between between sophisticated algorithms using 2.5D or 3D calculations and simpler Monitor unit check algorithms assuming a flat water phantom must be expected. For many anatomical sites such differences are small and of little or no consequence in the context of monitor unit verification. However, for tangential breast fields the discrepancies are considerably larger than those that would generally be considered acceptable. A simple model to reconcile the differences between sophisticated and simple algorithms is presented based on replacing the breast contour with a triangular or elliptical contour and using this to estimate an equivalent rectangle providing equivalent scatter to the prescription point. The elliptical approximation reconciles the observed differences in calculated monitor units. The analysis we present can assist the treatment planning physicist in selecting a method and tolerance window for verifying monitor unit calculations for tangential breast fields.


Assuntos
Neoplasias da Mama/radioterapia , Radioterapia Assistida por Computador/métodos , Algoritmos , Feminino , Humanos , Modelos Anatômicos , Garantia da Qualidade dos Cuidados de Saúde , Radioterapia Assistida por Computador/instrumentação
17.
Diagn Microbiol Infect Dis ; 51(1): 13-7, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15629224

RESUMO

A multiplex real-time polymerase chain reaction (RT-PCR) targeting the mecA and nuc genes was developed for the detection of methicillin resistance and identification of Staphylococcus aureus. Novel mecA and nuc primers and fluorescence resonance energy transfer hybridization probes specific for the mecA and nuc genes were evaluated. The assay was performed using the LightCycler system (Roche Molecular Biochemicals, Mannheim, Germany) and evaluated against the traditional gel-based multiplex PCR (PCR-gel) method currently used at Royal Perth Hospital. Clinical isolates (n = 222) and isolates from a culture collection library (n = 206) were tested by both assays in parallel. The RT-PCR assay was 100% sensitive and specific for the detection of methicillin resistance and for the identification of S. aureus when compared with the PCR-gel assay. Results from the RT-PCR assay showed 5 isolates with lower efficiency fluorescence curves for the nuc gene PCR fragment. DNA sequencing showed mutations within the region of the probe-binding sites compared with the reference strain. The results of the RT-PCR assay were available within 2 h. This rapid mecA/nuc RT-PCR assay is a suitable and practical tool for the routine detection of methicillin resistance and identification of S. aureus, which can be easily incorporated into the diagnostic molecular microbiology laboratory work flow.


Assuntos
Proteínas de Bactérias/genética , Endonucleases/genética , Resistência a Meticilina , Nuclease do Micrococo/genética , Reação em Cadeia da Polimerase/métodos , Staphylococcus aureus/isolamento & purificação , Sequência de Bases , Humanos , Dados de Sequência Molecular , Proteínas de Ligação às Penicilinas , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética
18.
J Appl Clin Med Phys ; 6(1): 22-50, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15770195

RESUMO

The Fully Integrated Real-time Seed Treatment (FIRST) system by Nucletron has been available in Europe since November 2001 and is being used more and more in Canada and the United States. Like the conventional transrectal ultrasound implant procedure, the FIRST system utilizes an ultrasound probe, needles, and brachytherapy seeds. However, this system is unique in that it (1) utilizes a low-dose-rate brachytherapy seed remote afterloader (the seedSelectron), (2) utilizes 3D image reconstruction acquired from electromechanically controlled, nonstepping rotation of the ultrasound probe, (3) integrates the control of a remote afterloader with electromechanical control of the ultrasound probe for integrating the clinical procedure into a single system, and (4) automates the transfer of planning information and seed delivery to improve quality assurance and radiation safety. This automated delivery system is specifically intended to address reproducibility and accuracy of seed positioning during implantation. The FIRST computer system includes two software environments: SPOT PRO and seedSelectron; both are used to facilitate treatment planning and brachytherapy seed implantation from beginning to completion of the entire procedure. In addition to these features, the system is reported to meet certain product specifications for seed delivery positioning accuracy and reproducibility, seed calibration accuracy and reliability, and brachytherapy dosimetry calculations. Consequently, a technical evaluation of the FIRST system was performed to determine adherence to manufacturer specifications and to the American Association of Physicists in Medicine (AAPM) Task Group Reports 43, 53, 56, 59, and 64 and recommendations of the American Brachytherapy Society (ABS). The United States Nuclear Regulatory Commission (NRC) has recently added Licensing Guidance for the seedSelectron system under 10 CFR 35.1000. Adherence to licensing guidance is made by referencing applicable AAPM Task Group recommendations. In general, results of this evaluation indicated that the system met its claimed specifications as well as the applicable recommendations outlined in the AAPM and ABS reports.


Assuntos
Braquiterapia/instrumentação , Braquiterapia/normas , Análise de Falha de Equipamento/normas , Guias como Assunto , Física Médica/normas , Implantação de Prótese/instrumentação , Implantação de Prótese/normas , Desenho de Equipamento , Análise de Falha de Equipamento/métodos , Garantia da Qualidade dos Cuidados de Saúde/normas , Cirurgia Assistida por Computador/instrumentação , Cirurgia Assistida por Computador/normas , Avaliação da Tecnologia Biomédica
19.
Brachytherapy ; 14(6): 809-17, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26392375

RESUMO

PURPOSE: Compression of the prostate during transrectal ultrasound-guided permanent prostate brachytherapy is not accounted for during treatment planning. Dosimetry effects are expected to be small but have not been reported. The study aims to characterize the seed movement and prostate deformation due to probe pressure and to estimate the effects on dosimetry. METHODS AND MATERIALS: C-arm fluoroscopy imaging was performed to reconstruct the implanted seed distributions (compressed and relaxed prostate) for 10 patients immediately after implantation. The compressed prostate was delineated on ultrasound and registered to the fluoroscopy-derived seed distribution via manual seed localization. Thin-plate spline mapping, generated with implanted seeds as control points, was used to characterize the deformation field and to infer the prostate contour in the absence of probe compression. Differences in TG-43 dosimetry for the compressed prostate and that on probe removal were calculated. RESULTS: Systematic seed movement patterns were observed on probe removal. Elastic decompression was characterized by expansion in the anterior-posterior direction and contraction in the superior-inferior and lateral directions up to 4 mm. Bilateral shearing in the anterior direction was up to 6 mm, resulting in contraction of the 145 Gy prescription isodose line by 2 mm with potential consequences for the posterior-lateral margin. The average whole prostate D90 increased by 2% of prescription dose (6% max; p < 0.01). CONCLUSIONS: The current investigation presents a novel study on ultrasound probe-induced deformation. Seed movements were characterized, and the associated dosimetry effects were nonnegligible, contrary to common expectation.


Assuntos
Braquiterapia , Endossonografia/métodos , Próstata , Neoplasias da Próstata/radioterapia , Implantação de Prótese , Endossonografia/instrumentação , Humanos , Masculino , Movimento (Física) , Pressão , Implantação de Prótese/métodos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Estresse Mecânico
20.
Infect Control Hosp Epidemiol ; 25(5): 384-90, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15188843

RESUMO

OBJECTIVE: To demonstrate that nosocomial transmission of vancomycin-resistant enterococci (VRE) can be terminated and endemicity prevented despite widespread dissemination of an epidemic strain in a large tertiary-care referral hospital. INTERVENTIONS: Two months after the index case was detected in the intensive care unit, 68 patients became either infected or colonized with an epidemic strain of vanB vancomycin-resistant Enterococcus faecium despite standard infection control procedures. The following additional interventions were then introduced to control the outbreak: (1) formation of a VRE executive group; (2) rapid laboratory identification (30 to 48 hours) using culture and polymerase chain reaction detection of vanA and vanB resistance genes; (3) mass screening of all hospitalized patients with isolation of carriers and cohorting of contacts; (4) environmental screening and increased cleaning; (5) electronic flagging of medical records of contacts; and (6) antibiotic restrictions (third-generation cephalosporins and vancomycin). RESULTS: A total of 19,658 patient and 24,396 environmental swabs were processed between July and December 2001. One hundred sixty-nine patients in 23 wards were colonized with a single strain of vanB vancomycin-resistant E. faecium. Introducing additional control measures rapidly brought the outbreak under control. Hospital-wide screening found 39 previously unidentified colonized patients, with only 7 more nonsegregated patients being detected in the next 2 months. The outbreak was terminated within 3 months at a cost of dollar 2.7 million (Australian dollars). CONCLUSION: Despite widespread dissemination of VRE in a large acute care facility, eradication was achievable by a well-resourced, coordinated, multifaceted approach and was in accordance with good clinical governance.


Assuntos
Enterococcus faecium/efeitos dos fármacos , Hospitais de Ensino , Resistência a Vancomicina , Estudos de Coortes , Enterococcus faecium/isolamento & purificação , Hospitais de Ensino/economia , Humanos , Austrália Ocidental
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