共查询到20条相似文献,搜索用时 31 毫秒
1.
Rajesh Thiyagarajan Arunai Nambiraj Sujit Nath Sinha Girigesh Yadav Ashok Kumar Vikraman Subramani Kothandaraman 《Reports of Practical Oncology and Radiotherapy》2016,21(1):50-56
Aim
The aim of this study is to evaluate performance of ArcCHECK diode array detector for the volumetric modulated arc therapy (VMAT) patient specific quality assurance (QA). VMAT patient specific QA results were correlated with ion chamber measurement. Dose response of the ArcCHECK detector was studied.Background
VMAT delivery technique improves the dose distribution. It is complex in nature and requires proper QA before its clinical implementation. ArcCHECK is a novel three dimensional dosimetry system.Materials and methods
Twelve retrospective VMAT plans were calculated on ArcCHECK phantom. Point dose and dose map were measured simultaneously with ion chamber (IC-15) and ArcCHECK diode array detector, respectively. These measurements were compared with their respective TPS calculated values.Results
The ion chamber measurements are in good agreement with TPS calculated doses. Mean difference between them is 0.50% with standard deviation of 0.51%. Concordance correlation coefficient (CCC) obtained for ion chamber measurements is 0.9996. These results demonstrate a strong correlation between the absolute dose predicted by our TPS and the measured dose. The CCC between ArcCHECK doses and TPS predictions on the CAX was found to be 0.9978. In gamma analysis of dose map, the mean passing rate was 98.53% for 3% dose difference and 3 mm distance to agreement.Conclusions
The VMAT patient specific QA with an ion chamber and ArcCHECK phantom are consistent with the TPS calculated dose. Statistically good agreement was observed between ArcCHECK measured and TPS calculated. Hence, it can be used for routine VMAT QA. 相似文献2.
Agustina Mariana Portu Andrés Eugenio Rossini Mario Alberto Gadan Omar Alberto Bernaola Silvia Inés Thorp Paula Curotto Emiliano César Cayetano Pozzi Rómulo Luis Cabrini Gisela Saint Martin 《Reports of Practical Oncology and Radiotherapy》2016,21(2):129-134
Aim
In this work we present a methodology to produce an “imprint” of cells cultivated on a polycarbonate detector by exposure of the detector to UV C radiation.Background
The distribution and concentration of 10B atoms in tissue samples coming from BNCT (Boron Neutron Capture Therapy) protocols can be determined through the quantification and analysis of the tracks forming its autoradiography image on a nuclear track detector. The location of boron atoms in the cell structure could be known more accurately by the simultaneous observation of the nuclear tracks and the sample image on the detector.Materials and Methods
A UV C irradiator was constructed. The irradiance was measured along the lamp direction and at different distances. Melanoma cells were cultured on polycarbonate foils, incubated with borophenylalanine, irradiated with thermal neutrons and exposed to UV C radiation. The samples were chemically attacked with a KOH solution.Results
A uniform irradiation field was established to expose the detector foils to UV C light. Cells could be seeded on the polycarbonate surface. Both imprints from cells and nuclear tracks were obtained after chemical etching.Conclusions
It is possible to yield cellular imprints in polycarbonate. The nuclear tracks were mostly present inside the cells, indicating a preferential boron uptake. 相似文献3.
Objective
Although awareness of sleep disorders is increasing, limited information is available on whole night detection of snoring. Our study aimed to develop and validate a robust, high performance, and sensitive whole-night snore detector based on non-contact technology.Design
Sounds during polysomnography (PSG) were recorded using a directional condenser microphone placed 1 m above the bed. An AdaBoost classifier was trained and validated on manually labeled snoring and non-snoring acoustic events.Patients
Sixty-seven subjects (age 52.5±13.5 years, BMI 30.8±4.7 kg/m2, m/f 40/27) referred for PSG for obstructive sleep apnea diagnoses were prospectively and consecutively recruited. Twenty-five subjects were used for the design study; the validation study was blindly performed on the remaining forty-two subjects.Measurements and Results
To train the proposed sound detector, >76,600 acoustic episodes collected in the design study were manually classified by three scorers into snore and non-snore episodes (e.g., bedding noise, coughing, environmental). A feature selection process was applied to select the most discriminative features extracted from time and spectral domains. The average snore/non-snore detection rate (accuracy) for the design group was 98.4% based on a ten-fold cross-validation technique. When tested on the validation group, the average detection rate was 98.2% with sensitivity of 98.0% (snore as a snore) and specificity of 98.3% (noise as noise).Conclusions
Audio-based features extracted from time and spectral domains can accurately discriminate between snore and non-snore acoustic events. This audio analysis approach enables detection and analysis of snoring sounds from a full night in order to produce quantified measures for objective follow-up of patients. 相似文献4.
Lu Yin Jiaan Zhu Qin Xue Niansong Wang Zhenlong Hu Yunxia Huang Fang Liu Bing Hu 《PloS one》2014,9(5)
Objective
To assess the value of MicroPure, a new ultrasound image processing technique, in identifying microcalcifications (formed by monosodium urate crystals) in the first metatarsophalangeal joints attacked by gout compared to gray-scale ultrasound images.Materials and Methods
Thirty-six patients who fulfilled the study inclusion criteria underwent gray-scale ultrasound and MicroPure examinations of the first metatarsophalangeal joints attacked by gout. Static images of the target areas were acquired using gray-scale ultrasound and MicroPure. Two independent and blinded investigators analyzed the images to determine the number of microcalcifications and to score for image quality and artifacts.Results
The two investigators observed significantly more microcalcifications with MicroPure compared to gray-scale ultrasound (ρ<0.001). The level of agreement between the investigators consistently increased from gray-scale ultrasound to MicroPure imaging (gray-scale interclass correlation coefficient of 0.69 vs. MicroPure interclass correlation coefficient of 0.81). One investigator preferred the MicroPure image quality over gray-scale ultrasound (ρ<0.001), but the other investigator disagreed (ρ<0.001). Both investigators observed fewer artifacts with MicroPure than with gray-scale ultrasound (ρ<0.009).Conclusion
MicroPure imaging identified significantly more microcalcifications than gray-scale ultrasound. 相似文献5.
Purpose
The aim of this study was to develop a robust post-processing workflow for motion-corrupted datasets in diffusion kurtosis imaging (DKI).Materials and methods
The proposed workflow consisted of brain extraction, rigid registration, distortion correction, artifacts rejection, spatial smoothing and tensor estimation. Rigid registration was utilized to correct misalignments. Motion artifacts were rejected by using local Pearson correlation coefficient (LPCC). The performance of LPCC in characterizing relative differences between artifacts and artifact-free images was compared with that of the conventional correlation coefficient in 10 randomly selected DKI datasets. The influence of rejected artifacts with information of gradient directions and b values for the parameter estimation was investigated by using mean square error (MSE). The variance of noise was used as the criterion for MSEs. The clinical practicality of the proposed workflow was evaluated by the image quality and measurements in regions of interest on 36 DKI datasets, including 18 artifact-free (18 pediatric subjects) and 18 motion-corrupted datasets (15 pediatric subjects and 3 essential tremor patients).Results
The relative difference between artifacts and artifact-free images calculated by LPCC was larger than that of the conventional correlation coefficient (p<0.05). It indicated that LPCC was more sensitive in detecting motion artifacts. MSEs of all derived parameters from the reserved data after the artifacts rejection were smaller than the variance of the noise. It suggested that influence of rejected artifacts was less than influence of noise on the precision of derived parameters. The proposed workflow improved the image quality and reduced the measurement biases significantly on motion-corrupted datasets (p<0.05).Conclusion
The proposed post-processing workflow was reliable to improve the image quality and the measurement precision of the derived parameters on motion-corrupted DKI datasets. The workflow provided an effective post-processing method for clinical applications of DKI in subjects with involuntary movements. 相似文献6.
Background
Little is known about colorectal cancer or colon and rectal cancer. Are they the same disease or different diseases?Objectives
The aim of this epidemiology study was to compare the features of colon and rectal cancer by using recent national cancer surveillance data.Design and setting
Data included colorectal cancer (1995–2008) from the Surveillance, Epidemiology, and End Results Program (SEER) database. Only adenocarcinoma was included for analysis.Patients
A total of 372,130 patients with a median follow-up of 32 months were analyzed.Main outcome measures
Mean survival of patients with the same stage of colon and rectal cancer was evaluated.Results
Around 35% of patients had stage information. Among them, colon cancer patients had better survival than those with rectal cancer, by a margin of 4 months in stage IIB. In stage IIIC and stage IV, rectal cancer patients had better survival than colon cancer patients, by about 3 months. Stage IIB colorectal cancer patients had a poorer prognosis than those with stage IIIA and IIIB colorectal cancer. After adjustment of age, sex and race, colon cancer patients had better survival than rectal cancer of stage IIB, but in stage IIIC and IV, rectal cancer patients had better survival than colon cancer.Limitations
The study is limited by its retrospective nature.Conclusion
This was a population-based study. The prognosis of rectal cancer was not worse than that of colon cancer. Local advanced colorectal cancer had a poorer prognosis than local regional lymph node metastasis. Stage IIB might require more aggressive chemotherapy, and no less than that for stage III. 相似文献7.
8.
Masanobu Manabe Soichiro Nakamura Isao Murata 《Reports of Practical Oncology and Radiotherapy》2016,21(2):102-107
Aim
To design the measuring device arrangement of array-type CdTe detector for BNCT-SPECT.Background
In a boron neutron capture therapy, a very serious unsolved problem exists, namely that the treatment effect for BNCT cannot be known during irradiation in real time. Therefore, we have been developing a so-called BNCT-SPECT with a CdTe detector, which can obtain a three-dimensional image for the BNCT treatment effect by measuring 478 keV gamma-rays emitted from the excited state of 7Li nucleus created by the 10B(n,α) reaction. However, no practical uses were realized at present, because BNCT-SPECT requires very severe conditions for spatial resolution, measuring time, statistical accuracy and energy resolution.Materials and methods
The design study was performed with numerical simulations carried out by a 3-dimenaional transport code, MCNP5 considering the detector assembly, irradiation room and even arrangement of arrayed CdTe crystals.Results
The estimated count rate of 478 keV gamma-rays was sufficiently large being more than the target value of over 1000 counts/h. However, the S/N ratio did not meet the target of S/N > 1. We confirmed that deterioration of the S/N ratio was caused by the influence of Compton scattering especially due to capture gamma-rays of hydrogen. Theoretical calculations were thereafter carried out to find out whether anti-Compton measurement in an array-type CdTe detector could decrease the noise due to Compton scatterings.Conclusions
The calculation result showed that the anti-coincidence would possibly increase the S/N ratio. In the next phase, an arrayed detector with two CdTe crystals will be produced to test removal possibility of the anti-coincident event. 相似文献9.
Mehmet Ak?akaya Seunghoon Nam Tamer A. Basha Keigo Kawaji Vahid Tarokh Reza Nezafat 《PloS one》2014,9(9)
Background
Non-Cartesian trajectories are used in a variety of fast imaging applications, due to the incoherent image domain artifacts they create when undersampled. While the gridding technique is commonly utilized for reconstruction, the incoherent artifacts may be further removed using compressed sensing (CS). CS reconstruction is typically done using conjugate-gradient (CG) type algorithms, which require gridding and regridding to be performed at every iteration. This leads to a large computational overhead that hinders its applicability.Methods
We sought to develop an alternative method for CS reconstruction that only requires two gridding and one regridding operation in total, irrespective of the number of iterations. This proposed technique is evaluated on phantom images and whole-heart coronary MRI acquired using 3D radial trajectories, and compared to conventional CS reconstruction using CG algorithms in terms of quantitative vessel sharpness, vessel length, computation time, and convergence rate.Results
Both CS reconstructions result in similar vessel length (P = 0.30) and vessel sharpness (P = 0.62). The per-iteration complexity of the proposed technique is approximately 3-fold lower than the conventional CS reconstruction (17.55 vs. 52.48 seconds in C++). Furthermore, for in-vivo datasets, the convergence rate of the proposed technique is faster (60±13 vs. 455±320 iterations) leading to a ∼23-fold reduction in reconstruction time.Conclusions
The proposed reconstruction provides images of similar quality to the conventional CS technique in terms of removing artifacts, but at a much lower computational complexity. 相似文献10.
Gerben ter Riet Paula Chesley Alan G. Gross Lara Siebeling Patrick Muggensturm Nadine Heller Martin Umbehr Daniela Vollenweider Tsung Yu Elie A. Akl Lizzy Brewster Olaf M. Dekkers Ingrid Mühlhauser Bernd Richter Sonal Singh Steven Goodman Milo A. Puhan 《PloS one》2013,8(11)
Background
Acknowledgment of all serious limitations to research evidence is important for patient care and scientific progress. Formal research on how biomedical authors acknowledge limitations is scarce.Objectives
To assess the extent to which limitations are acknowledged in biomedical publications explicitly, and implicitly by investigating the use of phrases that express uncertainty, so-called hedges; to assess the association between industry support and the extent of hedging.Design
We analyzed reporting of limitations and use of hedges in 300 biomedical publications published in 30 high and medium -ranked journals in 2007. Hedges were assessed using linguistic software that assigned weights between 1 and 5 to each expression of uncertainty.Results
Twenty-seven percent of publications (81/300) did not mention any limitations, while 73% acknowledged a median of 3 (range 1–8) limitations. Five percent mentioned a limitation in the abstract. After controlling for confounders, publications on industry-supported studies used significantly fewer hedges than publications not so supported (p = 0.028).Limitations
Detection and classification of limitations was – to some extent – subjective. The weighting scheme used by the hedging detection software has subjective elements.Conclusions
Reporting of limitations in biomedical publications is probably very incomplete. Transparent reporting of limitations may protect clinicians and guideline committees against overly confident beliefs and decisions and support scientific progress through better design, conduct or analysis of new studies. 相似文献11.
Background
The quality of colonoscopies performed by primary care physicians (PCPs) is unknown.Objective
To determine whether PCP colonoscopists achieve colonoscopy quality benchmarks, and patient satisfaction with having their colonoscopy performed by a primary care physician.Design
Prospective multi-center, multi-physician observational study. Colonoscopic quality data collection occurred via completion of case report forms and pathological confirmation of lesions. Patient satisfaction was captured by a telephone survey.Setting
Thirteen rural and suburban hospitals in Alberta, Canada.Measurements
Proportion of successful cecal intubations, average number of adenomas detected per colonoscopy, proportion of patients with at least one adenoma, and serious adverse event rates; patient satisfaction with their wait time and procedure, as well as willingness to have a repeat colonoscopy performed by their primary care endoscopist.Results
In the two-month study period, 10 study physicians performed 577 colonoscopies. The overall adjusted proportion of successful cecal intubations was 96.5% (95% CI 94.6–97.8), and all physicians achieved the adjusted cecal intubation target of ≥90%. The average number of ademonas detected per colonoscopy was 0.62 (95% CI 0.5–0.74). 46.4% (95% CI 38.5–54.3) of males and 30.2% (95% CI 22.3–38.2) of females ≥50 years of age having their first colonoscopy, had at least one adenoma. Four serious adverse events occurred (three post polypectomy bleeds and one perforation) and 99.3% of patients were willing to have a repeat colonoscopy performed by their primary care colonoscopist.Limitations
Two-month study length and non-universal participation by Alberta primary care endoscopists.Conclusions
Primary care physician colonoscopists can achieve quality benchmarks in colonoscopy. Training additional primary care physicians in endoscopy may improve patient access and decrease endoscopic wait times, especially in rural settings. 相似文献12.
Anja Vogel Thomas Fester Nico Eisenhauer Michael Scherer-Lorenzen Bernhard Schmid Wolfgang W. Weisser Alexandra Weigelt 《PloS one》2013,8(8)
1
Given the predictions of increased drought probabilities under various climate change scenarios, there have been numerous experimental field studies simulating drought using transparent roofs in different ecosystems and regions. Such roofs may, however, have unknown side effects, called artifacts, on the measured variables potentially confounding the experimental results. A roofed control allows the quantification of potential artifacts, which is lacking in most experiments.2
We conducted a drought experiment in experimental grasslands to study artifacts of transparent roofs and the resulting effects of artifacts on ecosystems relative to drought on three response variables (aboveground biomass, litter decomposition and plant metabolite profiles). We established three drought treatments, using (1) transparent roofs to exclude rainfall, (2) an unroofed control treatment receiving natural rainfall and (3) a roofed control, nested in the drought treatment but with rain water reapplied according to ambient conditions.3
Roofs had a slight impact on air (+0.14°C during night) and soil temperatures (−0.45°C on warm days, +0.25°C on cold nights), while photosynthetically active radiation was decreased significantly (−16%). Aboveground plant community biomass was reduced in the drought treatment (−41%), but there was no significant difference between the roofed and unroofed control, i.e., there were no measurable roof artifact effects.4
Compared to the unroofed control, litter decomposition was decreased significantly both in the drought treatment (−26%) and in the roofed control treatment (−18%), suggesting artifact effects of the transparent roofs. Moreover, aboveground metabolite profiles in the model plant species Medicago x varia were different from the unroofed control in both the drought and roofed control treatments, and roof artifact effects were of comparable magnitude as drought effects.5
Our results stress the need for roofed control treatments when using transparent roofs for studying drought effects, because roofs can cause significant side effects. 相似文献13.
Alberto Biete Izaskun Valduvieco Angels Rovirosa Blanca Farrús Francesc Casas Carlos Conill 《Reports of Practical Oncology and Radiotherapy》2010,15(2):27-30
Objectives
The aim of the study was to evaluate the clinical outcome and toxicity after adjuvant whole abdominal radiotherapy (WART) in patients with ovarian cancer.Material and methods
Ten patients with optimal cytoreduced ovarian cancer, with a mean age of 58 years (40–70) and stage Ic: 4, stage II: 2, stage III: 4, were treated with WART and adjuvant chemotherapy (9/10). The total radiation dose was 22.5 Gy in the whole abdomen and 42–45 Gy in the pelvis.Results
The mean follow-up was 8 years. The 5-year actuarial disease-free survival (DFS) was 60%, and the overall survival (OS) was 70%. Four patients had disease recurrence. The sites of recurrence were the abdomen in 2 patients and distant metastases in the other 2 patients (liver and brain metastasis). Gastrointestinal toxicity was as follows: acute 3/10 grades I and II, and late toxicity: 2/10 grades I and II, and only 1 patient developed small bowel obstruction (SBO) that required surgery.Conclusions
Whole abdominal radiotherapy after surgery and platinum-based chemotherapy achieves high locoregional disease control with an acceptable risk of acute toxicity. 相似文献14.
Gon?alo Fernandez Susanna Marín i Borràs Valentín Navarro Pérez Ferran Guedea 《Reports of Practical Oncology and Radiotherapy》2013,18(3):153-158
Aim
The aim of this retrospective study was to investigate the clinical and histopathological characteristics of the disease and treatment outcome of patients with pure uterine sarcomas.Background
Uterine sarcomas are especially rare tumours, comprising only 3–5% of uterine cancers. They are characterized by histopathological diversity, rapid clinical progression, and poor prognosis. Optimal management consists of complete surgical removal and adjuvant radiotherapy may improve the prognosis.Materials and methods
All patients with pure uterine sarcoma histology treated at our centre, the Institut Català D’Oncologia in Barcelona Spain, between 2002 and 2010 were reviewed.Results
Records of 17 patients treated at our hospital over an 8-year period were obtained. Nine patients (53%) had leiomyosarcoma, 7 (41%) had endometrial stromal sarcoma, and 1 patient had unclassified sarcoma. All patients were treated with external beam radiation after surgical excision. Mean age was 62 years (range, 51–69 years). Of the 17 patients, 13 (76%) presented with stage I disease, 2 (12%) were stage II, and 2 (12%) stage III. The overall actuarial 2-year survival estimate was 82.5%. Two patients experienced local relapse. The 2-year local control rate was 90%. A total of 5 patients experienced either local or metastatic relapse. The 2-year progression free survival rate was 58%.Conclusion
In our experience, combined treatment (surgery and adjuvant radiation therapy) is effective with acceptable side effects. Larger and multicenter studies are needed to assess treatment outcome for pure uterine sarcoma histology. 相似文献15.
Chen X Gorlov IP Ying J Merriman KW Kimmel M Lu C Reyes-Gibby CC Gorlova OY 《PloS one》2012,7(3):e32644
Background
Detection of early stage non-small cell lung cancer (NSCLC) is commonly believed to be incidental. Understanding the reasons that caused initial detection of these patients is important for early diagnosis. However, these reasons are not well studied.Methods
We retrospectively reviewed medical records of patients diagnosed with stage I or II NSCLC between 2000 and 2009 at UT MD Anderson Cancer Center. Information on suggestive LC-symptoms or other reasons that caused detection were extracted from patients'' medical records. We applied univariate and multivariate analyses to evaluate the association of suggestive LC-symptoms with tumor size and patient survival.Results
Of the 1396 early stage LC patients, 733 (52.5%) presented with suggestive LC-symptoms as chief complaint. 347 (24.9%) and 287 (20.6%) were diagnosed because of regular check-ups and evaluations for other diseases, respectively. The proportion of suggestive LC-symptom-caused detection had a linear relationship with the tumor size (correlation 0.96; with p<.0001). After age, gender, race, smoking status, therapy, and stage adjustment, the symptom-caused detection showed no significant difference in overall and LC-specific survival when compared with the other (non-symptom-caused) detection.Conclusion
Symptoms suggestive of LC are the number one reason that led to detection in early NSCLC. They were also associated with tumor size at diagnosis, suggesting early stage LC patients are developing symptoms. Presence of symptoms in early stages did not compromise survival. A symptom-based alerting system or guidelines may be worth of further study to benefit NSCLC high risk individuals. 相似文献16.
Background
Artifacts caused by dental restorations, such as dental crowns, dental fillings and orthodontic appliances, are a common problem in MRI and CT scans of the head and neck. The aim of this in-vitro study was to identify and evaluate the artifacts produced by different dental restoration materials in CT and MRI images.Methods
Test samples of 44 materials (Metal and Non-Metal) commonly used in dental restorations were fabricated and embedded with reference specimens in gelatin moulds. MRI imaging of 1.5T and CT scan were performed on the samples and evaluated in two dimensions. Artifact size and distortions were measured using a digital image analysis software.Results
In MRI, 13 out of 44 materials produced artifacts, while in CT 41 out of 44 materials showed artifacts. Artifacts produced in both MRI and CT images were categorized according to the size of the artifact.Significance
Metal based restoration materials had strong influence on CT and less artifacts in MRI images. Rare earth elements such as Ytterbium trifluoride found in composites caused artifacts in both MRI and CT. Recognizing these findings would help dental materials manufacturers and developers to produce materials which can cause less artifacts in MRI and CT images. 相似文献17.
18.
Importance
Emergency treatment options in myocardial infarction are guided by presence or absence of ST-elevations in electrocardiography. Occurrence and factors associated with ST-presentation in different population groups are however inadequately known.Objective
To determine likelihood and patient features associated with ST-elevations in myocardial infarction.Design
Nationwide registry study including 22 hospitals with angiolaboratory during an eight year period in Finland.Setting
Hospitalized care.Participants
68,162 consecutive patients aged ≥30 with myocardial infarction.Measures
Likelihood and patient features associated with presence of ST-elevations.Results
Myocardial infarction presented with ST-elevation in 37.5% (CI 37.0–37.9%) and without in 62.5% (CI 61.9–63.1%) of patients, p<0.0001. Majority of patients aged 30–59 years with myocardial infarction had ST-elevation, but among octogenarians ST-elevations were present in only 24.7%. Presence of ST-elevations decreased with age by estimated 15.6% (CI 15.0–16.2%) per 10 year increase (p<0.0001). Men aged 40–79 years had significantly higher rate for ST-elevation myocardial infarction compared to women. Sex-based difference in presentation of myocardial infarction declined with increasing age. Overall, men had a 13% (CI 11–15%, p<0.0001) higher relative risk for ST-elevations compared to women when adjusted for age and co-morbidities. Diabetes, atrial fibrillation, peripheral or cerebral artery disease, chronic pulmonary disease, malignancy, and renal insufficiency were associated with absence of ST-elevations in myocardial infarction in multivariate analysis.Conclusions and Relevance
Myocardial infarction presents with ST-elevations more commonly in men. Presence of ST-elevations decreases with increasing age. Diabetes, atrial fibrillation, peripheral or cerebral artery disease, chronic pulmonary disease, malignancy, and renal insufficiency are associated with absence of ST-elevations in myocardial infarction. These findings may help to predict likelihood of ST-elevations in a patient with myocardial infarction. 相似文献19.
20.
Sajid Shahul Michele R. Hacker Victor Novack Ariel Mueller Shahzad Shaefi Bilal Mahmood Syed Haider Ali Daniel Talmor 《PloS one》2014,9(9)