Mitigating Errors in External Respiratory Surrogate-Based Models of Tumor Position

Energy Technology Data Exchange (ETDEWEB)

Malinowski, Kathleen T. [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Fischell Department of Bioengineering, University of Maryland, College Park, MD (United States); McAvoy, Thomas J. [Fischell Department of Bioengineering, University of Maryland, College Park, MD (United States); Department of Chemical and Biomolecular Engineering and Institute of Systems Research, University of Maryland, College Park, MD (United States); George, Rohini [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Dieterich, Sonja [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA (United States); D' Souza, Warren D., E-mail: wdsou001@umaryland.edu [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Fischell Department of Bioengineering, University of Maryland, College Park, MD (United States)

2012-04-01

Purpose: To investigate the effect of tumor site, measurement precision, tumor-surrogate correlation, training data selection, model design, and interpatient and interfraction variations on the accuracy of external marker-based models of tumor position. Methods and Materials: Cyberknife Synchrony system log files comprising synchronously acquired positions of external markers and the tumor from 167 treatment fractions were analyzed. The accuracy of Synchrony, ordinary-least-squares regression, and partial-least-squares regression models for predicting the tumor position from the external markers was evaluated. The quantity and timing of the data used to build the predictive model were varied. The effects of tumor-surrogate correlation and the precision in both the tumor and the external surrogate position measurements were explored by adding noise to the data. Results: The tumor position prediction errors increased during the duration of a fraction. Increasing the training data quantities did not always lead to more accurate models. Adding uncorrelated noise to the external marker-based inputs degraded the tumor-surrogate correlation models by 16% for partial-least-squares and 57% for ordinary-least-squares. External marker and tumor position measurement errors led to tumor position prediction changes 0.3-3.6 times the magnitude of the measurement errors, varying widely with model algorithm. The tumor position prediction errors were significantly associated with the patient index but not with the fraction index or tumor site. Partial-least-squares was as accurate as Synchrony and more accurate than ordinary-least-squares. Conclusions: The accuracy of surrogate-based inferential models of tumor position was affected by all the investigated factors, except for the tumor site and fraction index.

Approaches to relativistic positioning around Earth and error estimations

Science.gov (United States)

Puchades, Neus; Sáez, Diego

2016-01-01

In the context of relativistic positioning, the coordinates of a given user may be calculated by using suitable information broadcast by a 4-tuple of satellites. Our 4-tuples belong to the Galileo constellation. Recently, we estimated the positioning errors due to uncertainties in the satellite world lines (U-errors). A distribution of U-errors was obtained, at various times, in a set of points covering a large region surrounding Earth. Here, the positioning errors associated to the simplifying assumption that photons move in Minkowski space-time (S-errors) are estimated and compared with the U-errors. Both errors have been calculated for the same points and times to make comparisons possible. For a certain realistic modeling of the world line uncertainties, the estimated S-errors have proved to be smaller than the U-errors, which shows that the approach based on the assumption that the Earth's gravitational field produces negligible effects on photons may be used in a large region surrounding Earth. The applicability of this approach - which simplifies numerical calculations - to positioning problems, and the usefulness of our S-error maps, are pointed out. A better approach, based on the assumption that photons move in the Schwarzschild space-time governed by an idealized Earth, is also analyzed. More accurate descriptions of photon propagation involving non symmetric space-time structures are not necessary for ordinary positioning and spacecraft navigation around Earth.

SU-E-T-261: Development of An Automated System to Detect Patient Identification and Positioning Errors Prior to Radiotherapy Treatment

Energy Technology Data Exchange (ETDEWEB)

Jani, S; Low, D; Lamb, J [UCLA, Los Angeles, CA (United States)

2015-06-15

Purpose: To develop a system that can automatically detect patient identification and positioning errors using 3D computed tomography (CT) setup images and kilovoltage CT (kVCT) planning images. Methods: Planning kVCT images were collected for head-and-neck (H&N), pelvis, and spine treatments with corresponding 3D cone-beam CT (CBCT) and megavoltage CT (MVCT) setup images from TrueBeam and TomoTherapy units, respectively. Patient identification errors were simulated by registering setup and planning images from different patients. Positioning errors were simulated by misaligning the setup image by 1cm to 5cm in the six anatomical directions for H&N and pelvis patients. Misalignments for spine treatments were simulated by registering the setup image to adjacent vertebral bodies on the planning kVCT. A body contour of the setup image was used as an initial mask for image comparison. Images were pre-processed by image filtering and air voxel thresholding, and image pairs were assessed using commonly-used image similarity metrics as well as custom -designed metrics. A linear discriminant analysis classifier was trained and tested on the datasets, and misclassification error (MCE), sensitivity, and specificity estimates were generated using 10-fold cross validation. Results: Our workflow produced MCE estimates of 0.7%, 1.7%, and 0% for H&N, pelvis, and spine TomoTherapy images, respectively. Sensitivities and specificities ranged from 98.0% to 100%. MCEs of 3.5%, 2.3%, and 2.1% were obtained for TrueBeam images of the above sites, respectively, with sensitivity and specificity estimates between 96.2% and 98.4%. MCEs for 1cm H&N/pelvis misalignments were 1.3/5.1% and 9.1/8.6% for TomoTherapy and TrueBeam images, respectively. 2cm MCE estimates were 0.4%/1.6% and 3.1/3.2%, respectively. Vertebral misalignment MCEs were 4.8% and 4.9% for TomoTherapy and TrueBeam images, respectively. Conclusion: Patient identification and gross misalignment errors can be robustly and

SU-E-T-261: Development of An Automated System to Detect Patient Identification and Positioning Errors Prior to Radiotherapy Treatment

International Nuclear Information System (INIS)

Jani, S; Low, D; Lamb, J

2015-01-01

Purpose: To develop a system that can automatically detect patient identification and positioning errors using 3D computed tomography (CT) setup images and kilovoltage CT (kVCT) planning images. Methods: Planning kVCT images were collected for head-and-neck (H&N), pelvis, and spine treatments with corresponding 3D cone-beam CT (CBCT) and megavoltage CT (MVCT) setup images from TrueBeam and TomoTherapy units, respectively. Patient identification errors were simulated by registering setup and planning images from different patients. Positioning errors were simulated by misaligning the setup image by 1cm to 5cm in the six anatomical directions for H&N and pelvis patients. Misalignments for spine treatments were simulated by registering the setup image to adjacent vertebral bodies on the planning kVCT. A body contour of the setup image was used as an initial mask for image comparison. Images were pre-processed by image filtering and air voxel thresholding, and image pairs were assessed using commonly-used image similarity metrics as well as custom -designed metrics. A linear discriminant analysis classifier was trained and tested on the datasets, and misclassification error (MCE), sensitivity, and specificity estimates were generated using 10-fold cross validation. Results: Our workflow produced MCE estimates of 0.7%, 1.7%, and 0% for H&N, pelvis, and spine TomoTherapy images, respectively. Sensitivities and specificities ranged from 98.0% to 100%. MCEs of 3.5%, 2.3%, and 2.1% were obtained for TrueBeam images of the above sites, respectively, with sensitivity and specificity estimates between 96.2% and 98.4%. MCEs for 1cm H&N/pelvis misalignments were 1.3/5.1% and 9.1/8.6% for TomoTherapy and TrueBeam images, respectively. 2cm MCE estimates were 0.4%/1.6% and 3.1/3.2%, respectively. Vertebral misalignment MCEs were 4.8% and 4.9% for TomoTherapy and TrueBeam images, respectively. Conclusion: Patient identification and gross misalignment errors can be robustly and

Impact of MLC leaf position errors on simple and complex IMRT plans for head and neck cancer

International Nuclear Information System (INIS)

Mu, G; Ludlum, E; Xia, P

2008-01-01

The dosimetric impact of random and systematic multi-leaf collimator (MLC) leaf position errors is relatively unknown for head and neck intensity-modulated radiotherapy (IMRT) patients. In this report we studied 17 head and neck IMRT patients, including 12 treated with simple plans ( 100 segments). Random errors (-2 to +2 mm) and systematic errors (±0.5 mm and ±1 mm) in MLC leaf positions were introduced into the clinical plans and the resultant dose distributions were analyzed based on defined endpoint doses. The dosimetric effect was insignificant for random MLC leaf position errors up to 2 mm for both simple and complex plans. However, for systematic MLC leaf position errors, we found significant dosimetric differences between the simple and complex IMRT plans. For 1 mm systematic error, the average changes in D 95% were 4% in simple plans versus 8% in complex plans. The average changes in D 0.1cc of the spinal cord and brain stem were 4% in simple plans versus 12% in complex plans. The average changes in parotid glands were 9% in simple plans versus 13% for the complex plans. Overall, simple IMRT plans are less sensitive to leaf position errors than complex IMRT plans

Error Analysis of Determining Airplane Location by Global Positioning System

OpenAIRE

Hajiyev, Chingiz; Burat, Alper

1999-01-01

This paper studies the error analysis of determining airplane location by global positioning system (GPS) using statistical testing method. The Newton Rhapson method positions the airplane at the intersection point of four spheres. Absolute errors, relative errors and standard deviation have been calculated The results show that the positioning error of the airplane varies with the coordinates of GPS satellite and the airplane.

SU-E-J-94: Positioning Errors Resulting From Using Bony Anatomy Alignment for Treating SBRT Lung Tumor

International Nuclear Information System (INIS)

Frame, C; Ding, G

2014-01-01

Purpose: To quantify patient setups errors based on bony anatomy registration rather than 3D tumor alignment for SBRT lung treatments. Method: A retrospective study was performed for patients treated with lung SBRT and imaged with kV cone beam computed tomography (kV-CBCT) image-guidance. Daily CBCT images were registered to treatment planning CTs based on bony anatomy alignment and then inter-fraction tumor movement was evaluated by comparing shift in the tumor center in the medial-lateral, anterior-posterior, and superior-inferior directions. The PTV V100% was evaluated for each patient based on the average daily tumor displacement to assess the impact of the positioning error on the target coverage when the registrations were based on bony anatomy. Of the 35 patients studied, 15 were free-breathing treatments, 10 used abdominal compression with a stereotactic body frame, and the remaining 10 were performed with BodyFIX vacuum bags. Results: For free-breathing treatments, the range of tumor displacement error is between 1–6 mm in the medial-lateral, 1–13 mm in the anterior-posterior, and 1–7 mm in the superior-inferior directions. These positioning errors lead to 6–22% underdose coverage for PTV - V100% . Patients treated with abdominal compression immobilization showed positional errors of 0–4mm mediallaterally, 0–3mm anterior-posteriorly, and 0–2 mm inferior-superiorly with PTV - V100% underdose ranging between 6–17%. For patients immobilized with the vacuum bags, the positional errors were found to be 0–1 mm medial-laterally, 0–1mm anterior-posteriorly, and 0–2 mm inferior-superiorly with PTV - V100% under dose ranging between 5–6% only. Conclusion: It is necessary to align the tumor target by using 3D image guidance to ensure adequate tumor coverage before performing SBRT lung treatments. The BodyFIX vacuum bag immobilization method has the least positioning errors among the three methods studied when bony anatomy is used for

Investigations on uncertainties in patient positioning for prostate treatment with EPID

International Nuclear Information System (INIS)

Bakai, A.; Nuesslin, F.; Paulsen, F.; Plasswilm, L.; Bamberg, M.

2002-01-01

Background: Conformal radiotherapy techniques as used in prostate treatment allow to spare normal tissue by conforming the radiation fields to the shape of the planning target volume (PTV). To be able to fully utilize the advantages of these techniques correct patient positioning is an important prerequisite. This study employing an electronic portal imaging device (EPID) investigated the positioning uncertainties that occur in the pelvic region for different patient positioning devices. Patients and Methods: 15 patients with prostate cancer were irradiated with or without rectal balloon/pelvic mask at a linear accelerator with multileaf collimator (MLC). For each patient multiple portal images were taken from different directions and compared to the digitally reconstructed radiographs (DRRs) of the treatment planning system and to simulation films (Table 1, Figure 1). Results: In spite of different positioning devices, all patients showed comparable total positioning uncertainties of 4.0 mm (lateral), 4.5 mm (cranio-caudal) and 1.7 mm (dorso-ventral). The lateral positioning error was reduced for the pelvic mask patients while the cranio-caudal error increased (Table 2, Figure 2). A systematic and a random component sum up to the total positioning error, and a good estimate of the magnitudes of the two is possible from six to eight portal images (Figure 3). Conclusions: With a small number of portal images it is possible to find out the systematic and random positioning error of a patient. Knowledge of the random error can be used to resize the treatment margin which is clinically relevant since this error differs greatly for different patients (Figure 4). Image analysis with EPID is convenient, yet has some problems. For example, one only gets indirect information on the movement of the ventral rectum wall. The successful operation of positioning devices, although, needs further improvement - especially if one focuses on IMRT. (orig.) [de

Laboratory errors and patient safety.

Science.gov (United States)

Miligy, Dawlat A

2015-01-01

Laboratory data are extensively used in medical practice; consequently, laboratory errors have a tremendous impact on patient safety. Therefore, programs designed to identify and reduce laboratory errors, as well as, setting specific strategies are required to minimize these errors and improve patient safety. The purpose of this paper is to identify part of the commonly encountered laboratory errors throughout our practice in laboratory work, their hazards on patient health care and some measures and recommendations to minimize or to eliminate these errors. Recording the encountered laboratory errors during May 2008 and their statistical evaluation (using simple percent distribution) have been done in the department of laboratory of one of the private hospitals in Egypt. Errors have been classified according to the laboratory phases and according to their implication on patient health. Data obtained out of 1,600 testing procedure revealed that the total number of encountered errors is 14 tests (0.87 percent of total testing procedures). Most of the encountered errors lay in the pre- and post-analytic phases of testing cycle (representing 35.7 and 50 percent, respectively, of total errors). While the number of test errors encountered in the analytic phase represented only 14.3 percent of total errors. About 85.7 percent of total errors were of non-significant implication on patients health being detected before test reports have been submitted to the patients. On the other hand, the number of test errors that have been already submitted to patients and reach the physician represented 14.3 percent of total errors. Only 7.1 percent of the errors could have an impact on patient diagnosis. The findings of this study were concomitant with those published from the USA and other countries. This proves that laboratory problems are universal and need general standardization and bench marking measures. Original being the first data published from Arabic countries that

Predicting positional error of MLC using volumetric analysis

International Nuclear Information System (INIS)

Hareram, E.S.

2008-01-01

IMRT normally using multiple beamlets (small width of the beam) for a particular field to deliver so that it is imperative to maintain the positional accuracy of the MLC in order to deliver integrated computed dose accurately. Different manufacturers have reported high precession on MLC devices with leaf positional accuracy nearing 0.1 mm but measuring and rectifying the error in this accuracy is very difficult. Various methods are used to check MLC position and among this volumetric analysis is one of the technique. Volumetric approach was adapted in our method using primus machine and 0.6cc chamber at 5 cm depth In perspex. MLC of 1 mm error introduces an error of 20%, more sensitive to other methods

Influence of Ephemeris Error on GPS Single Point Positioning Accuracy

Science.gov (United States)

Lihua, Ma; Wang, Meng

2013-09-01

The Global Positioning System (GPS) user makes use of the navigation message transmitted from GPS satellites to achieve its location. Because the receiver uses the satellite's location in position calculations, an ephemeris error, a difference between the expected and actual orbital position of a GPS satellite, reduces user accuracy. The influence extent is decided by the precision of broadcast ephemeris from the control station upload. Simulation analysis with the Yuma almanac show that maximum positioning error exists in the case where the ephemeris error is along the line-of-sight (LOS) direction. Meanwhile, the error is dependent on the relationship between the observer and spatial constellation at some time period.

Dependence of fluence errors in dynamic IMRT on leaf-positional errors varying with time and leaf number

International Nuclear Information System (INIS)

Zygmanski, Piotr; Kung, Jong H.; Jiang, Steve B.; Chin, Lee

2003-01-01

In d-MLC based IMRT, leaves move along a trajectory that lies within a user-defined tolerance (TOL) about the ideal trajectory specified in a d-MLC sequence file. The MLC controller measures leaf positions multiple times per second and corrects them if they deviate from ideal positions by a value greater than TOL. The magnitude of leaf-positional errors resulting from finite mechanical precision depends on the performance of the MLC motors executing leaf motions and is generally larger if leaves are forced to move at higher speeds. The maximum value of leaf-positional errors can be limited by decreasing TOL. However, due to the inherent time delay in the MLC controller, this may not happen at all times. Furthermore, decreasing the leaf tolerance results in a larger number of beam hold-offs, which, in turn leads, to a longer delivery time and, paradoxically, to higher chances of leaf-positional errors (≤TOL). On the other end, the magnitude of leaf-positional errors depends on the complexity of the fluence map to be delivered. Recently, it has been shown that it is possible to determine the actual distribution of leaf-positional errors either by the imaging of moving MLC apertures with a digital imager or by analysis of a MLC log file saved by a MLC controller. This leads next to an important question: What is the relation between the distribution of leaf-positional errors and fluence errors. In this work, we introduce an analytical method to determine this relation in dynamic IMRT delivery. We model MLC errors as Random-Leaf Positional (RLP) errors described by a truncated normal distribution defined by two characteristic parameters: a standard deviation σ and a cut-off value Δx 0 (Δx 0 ∼TOL). We quantify fluence errors for two cases: (i) Δx 0 >>σ (unrestricted normal distribution) and (ii) Δx 0 0 --limited normal distribution). We show that an average fluence error of an IMRT field is proportional to (i) σ/ALPO and (ii) Δx 0 /ALPO, respectively, where

Verification of the Patient Positioning in the Bellyboard Pelvic Radiotherapy

International Nuclear Information System (INIS)

Kasabasic, M.; Faj, D.; Smilovic Radojcic, D.; Svabic, M.; Ivkovic, A.; Jurkovic, S.

2008-01-01

The size and shape of the treatment fields applied in radiotherapy account for uncertainties in the daily set-up of the patients during the treatment. We investigated the accuracy of daily patient positioning in the bellyboard pelvic radiotherapy in order to find out the magnitude of the patients movement during the treatment. Translational as well as rotational movements of the patients are explored. Film portal imaging is used in order to find patient positioning error during the treatment of the pelvic region. Patients are treated in the prone position using the bellyboard positioning device. Thirty six patients are included in the study; 15 patients were followed during the whole treatment and 21 during the first 5 consecutive treatment days. The image acquisition was completed in 85 percent and systematic and random positioning errors in 453 images are analyzed. (author)

The error model and experiment of measuring angular position error based on laser collimation

Science.gov (United States)

Cai, Yangyang; Yang, Jing; Li, Jiakun; Feng, Qibo

2018-01-01

Rotary axis is the reference component of rotation motion. Angular position error is the most critical factor which impair the machining precision among the six degree-of-freedom (DOF) geometric errors of rotary axis. In this paper, the measuring method of angular position error of rotary axis based on laser collimation is thoroughly researched, the error model is established and 360 ° full range measurement is realized by using the high precision servo turntable. The change of space attitude of each moving part is described accurately by the 3×3 transformation matrices and the influences of various factors on the measurement results is analyzed in detail. Experiments results show that the measurement method can achieve high measurement accuracy and large measurement range.

Effects of Target Positioning Error on Motion Compensation for Airborne Interferometric SAR

Directory of Open Access Journals (Sweden)

Li Yin-wei

2013-12-01

Full Text Available The measurement inaccuracies of Inertial Measurement Unit/Global Positioning System (IMU/GPS as well as the positioning error of the target may contribute to the residual uncompensated motion errors in the MOtion COmpensation (MOCO approach based on the measurement of IMU/GPS. Aiming at the effects of target positioning error on MOCO for airborne interferometric SAR, the paper firstly deduces a mathematical model of residual motion error bring out by target positioning error under the condition of squint. And the paper analyzes the effects on the residual motion error caused by system sampling delay error, the Doppler center frequency error and reference DEM error which result in target positioning error based on the model. Then, the paper discusses the effects of the reference DEM error on the interferometric SAR image quality, the interferometric phase and the coherent coefficient. The research provides theoretical bases for the MOCO precision in signal processing of airborne high precision SAR and airborne repeat-pass interferometric SAR.

Positional error in automated geocoding of residential addresses

Directory of Open Access Journals (Sweden)

Talbot Thomas O

2003-12-01

Full Text Available Abstract Background Public health applications using geographic information system (GIS technology are steadily increasing. Many of these rely on the ability to locate where people live with respect to areas of exposure from environmental contaminants. Automated geocoding is a method used to assign geographic coordinates to an individual based on their street address. This method often relies on street centerline files as a geographic reference. Such a process introduces positional error in the geocoded point. Our study evaluated the positional error caused during automated geocoding of residential addresses and how this error varies between population densities. We also evaluated an alternative method of geocoding using residential property parcel data. Results Positional error was determined for 3,000 residential addresses using the distance between each geocoded point and its true location as determined with aerial imagery. Error was found to increase as population density decreased. In rural areas of an upstate New York study area, 95 percent of the addresses geocoded to within 2,872 m of their true location. Suburban areas revealed less error where 95 percent of the addresses geocoded to within 421 m. Urban areas demonstrated the least error where 95 percent of the addresses geocoded to within 152 m of their true location. As an alternative to using street centerline files for geocoding, we used residential property parcel points to locate the addresses. In the rural areas, 95 percent of the parcel points were within 195 m of the true location. In suburban areas, this distance was 39 m while in urban areas 95 percent of the parcel points were within 21 m of the true location. Conclusion Researchers need to determine if the level of error caused by a chosen method of geocoding may affect the results of their project. As an alternative method, property data can be used for geocoding addresses if the error caused by traditional methods is

Performance monitoring and error significance in patients with obsessive-compulsive disorder.

Science.gov (United States)

Endrass, Tanja; Schuermann, Beate; Kaufmann, Christan; Spielberg, Rüdiger; Kniesche, Rainer; Kathmann, Norbert

2010-05-01

Performance monitoring has been consistently found to be overactive in obsessive-compulsive disorder (OCD). The present study examines whether performance monitoring in OCD is adjusted with error significance. Therefore, errors in a flanker task were followed by neutral (standard condition) or punishment feedbacks (punishment condition). In the standard condition patients had significantly larger error-related negativity (ERN) and correct-related negativity (CRN) ampliudes than controls. But, in the punishment condition groups did not differ in ERN and CRN amplitudes. While healthy controls showed an amplitude enhancement between standard and punishment condition, OCD patients showed no variation. In contrast, group differences were not found for the error positivity (Pe): both groups had larger Pe amplitudes in the punishment condition. Results confirm earlier findings of overactive error monitoring in OCD. The absence of a variation with error significance might indicate that OCD patients are unable to down-regulate their monitoring activity according to external requirements. Copyright 2010 Elsevier B.V. All rights reserved.

SU-E-T-195: Gantry Angle Dependency of MLC Leaf Position Error

Energy Technology Data Exchange (ETDEWEB)

Ju, S; Hong, C; Kim, M; Chung, K; Kim, J; Han, Y; Ahn, S; Chung, S; Shin, E; Shin, J; Kim, H; Kim, D; Choi, D [Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

2014-06-01

Purpose: The aim of this study was to investigate the gantry angle dependency of the multileaf collimator (MLC) leaf position error. Methods: An automatic MLC quality assurance system (AutoMLCQA) was developed to evaluate the gantry angle dependency of the MLC leaf position error using an electronic portal imaging device (EPID). To eliminate the EPID position error due to gantry rotation, we designed a reference maker (RM) that could be inserted into the wedge mount. After setting up the EPID, a reference image was taken of the RM using an open field. Next, an EPID-based picket-fence test (PFT) was performed without the RM. These procedures were repeated at every 45° intervals of the gantry angle. A total of eight reference images and PFT image sets were analyzed using in-house software. The average MLC leaf position error was calculated at five pickets (-10, -5, 0, 5, and 10 cm) in accordance with general PFT guidelines using in-house software. This test was carried out for four linear accelerators. Results: The average MLC leaf position errors were within the set criterion of <1 mm (actual errors ranged from -0.7 to 0.8 mm) for all gantry angles, but significant gantry angle dependency was observed in all machines. The error was smaller at a gantry angle of 0° but increased toward the positive direction with gantry angle increments in the clockwise direction. The error reached a maximum value at a gantry angle of 90° and then gradually decreased until 180°. In the counter-clockwise rotation of the gantry, the same pattern of error was observed but the error increased in the negative direction. Conclusion: The AutoMLCQA system was useful to evaluate the MLC leaf position error for various gantry angles without the EPID position error. The Gantry angle dependency should be considered during MLC leaf position error analysis.

Perceptual learning eases crowding by reducing recognition errors but not position errors.

Science.gov (United States)

Xiong, Ying-Zi; Yu, Cong; Zhang, Jun-Yun

2015-08-01

When an observer reports a letter flanked by additional letters in the visual periphery, the response errors (the crowding effect) may result from failure to recognize the target letter (recognition errors), from mislocating a correctly recognized target letter at a flanker location (target misplacement errors), or from reporting a flanker as the target letter (flanker substitution errors). Crowding can be reduced through perceptual learning. However, it is not known how perceptual learning operates to reduce crowding. In this study we trained observers with a partial-report task (Experiment 1), in which they reported the central target letter of a three-letter string presented in the visual periphery, or a whole-report task (Experiment 2), in which they reported all three letters in order. We then assessed the impact of training on recognition of both unflanked and flanked targets, with particular attention to how perceptual learning affected the types of errors. Our results show that training improved target recognition but not single-letter recognition, indicating that training indeed affected crowding. However, training did not reduce target misplacement errors or flanker substitution errors. This dissociation between target recognition and flanker substitution errors supports the view that flanker substitution may be more likely a by-product (due to response bias), rather than a cause, of crowding. Moreover, the dissociation is not consistent with hypothesized mechanisms of crowding that would predict reduced positional errors.

Verification of patient position and delivery of IMRT by electronic portal imaging

International Nuclear Information System (INIS)

Fielding, Andrew L.; Evans, Philip M.; Clark, Catharine H.

2004-01-01

Background and purpose: The purpose of the work presented in this paper was to determine whether patient positioning and delivery errors could be detected using electronic portal images of intensity modulated radiotherapy (IMRT). Patients and methods: We carried out a series of controlled experiments delivering an IMRT beam to a humanoid phantom using both the dynamic and multiple static field method of delivery. The beams were imaged, the images calibrated to remove the IMRT fluence variation and then compared with calibrated images of the reference beams without any delivery or position errors. The first set of experiments involved translating the position of the phantom both laterally and in a superior/inferior direction a distance of 1, 2, 5 and 10 mm. The phantom was also rotated 1 and 2 deg. For the second set of measurements the phantom position was kept fixed and delivery errors were introduced to the beam. The delivery errors took the form of leaf position and segment intensity errors. Results: The method was able to detect shifts in the phantom position of 1 mm, leaf position errors of 2 mm, and dosimetry errors of 10% on a single segment of a 15 segment IMRT step and shoot delivery (significantly less than 1% of the total dose). Conclusions: The results of this work have shown that the method of imaging the IMRT beam and calibrating the images to remove the intensity modulations could be a useful tool in verifying both the patient position and the delivery of the beam

Modeling the probability distribution of positional errors incurred by residential address geocoding

Directory of Open Access Journals (Sweden)

Mazumdar Soumya

2007-01-01

Full Text Available Abstract Background The assignment of a point-level geocode to subjects' residences is an important data assimilation component of many geographic public health studies. Often, these assignments are made by a method known as automated geocoding, which attempts to match each subject's address to an address-ranged street segment georeferenced within a streetline database and then interpolate the position of the address along that segment. Unfortunately, this process results in positional errors. Our study sought to model the probability distribution of positional errors associated with automated geocoding and E911 geocoding. Results Positional errors were determined for 1423 rural addresses in Carroll County, Iowa as the vector difference between each 100%-matched automated geocode and its true location as determined by orthophoto and parcel information. Errors were also determined for 1449 60%-matched geocodes and 2354 E911 geocodes. Huge (> 15 km outliers occurred among the 60%-matched geocoding errors; outliers occurred for the other two types of geocoding errors also but were much smaller. E911 geocoding was more accurate (median error length = 44 m than 100%-matched automated geocoding (median error length = 168 m. The empirical distributions of positional errors associated with 100%-matched automated geocoding and E911 geocoding exhibited a distinctive Greek-cross shape and had many other interesting features that were not capable of being fitted adequately by a single bivariate normal or t distribution. However, mixtures of t distributions with two or three components fit the errors very well. Conclusion Mixtures of bivariate t distributions with few components appear to be flexible enough to fit many positional error datasets associated with geocoding, yet parsimonious enough to be feasible for nascent applications of measurement-error methodology to spatial epidemiology.

Brain State Before Error Making in Young Patients With Mild Spastic Cerebral Palsy.

Science.gov (United States)

Hakkarainen, Elina; Pirilä, Silja; Kaartinen, Jukka; van der Meere, Jaap J

2015-10-01

In the present experiment, children with mild spastic cerebral palsy and a control group carried out a memory recognition task. The key question was if errors of the patient group are foreshadowed by attention lapses, by weak motor preparation, or by both. Reaction times together with event-related potentials associated with motor preparation (frontal late contingent negative variation), attention (parietal P300), and response evaluation (parietal error-preceding positivity) were investigated in instances where 3 subsequent correct trials preceded an error. The findings indicated that error responses of the patient group are foreshadowed by weak motor preparation in correct trials directly preceding an error. © The Author(s) 2015.

Force Reproduction Error Depends on Force Level, whereas the Position Reproduction Error Does Not

NARCIS (Netherlands)

Onneweer, B.; Mugge, W.; Schouten, Alfred Christiaan

2016-01-01

When reproducing a previously perceived force or position humans make systematic errors. This study determined the effect of force level on force and position reproduction, when both target and reproduction force are self-generated with the same hand. Subjects performed force reproduction tasks at

MATLAB implementation of satellite positioning error overbounding by generalized Pareto distribution

Science.gov (United States)

Ahmad, Khairol Amali; Ahmad, Shahril; Hashim, Fakroul Ridzuan

2018-02-01

In the satellite navigation community, error overbound has been implemented in the process of integrity monitoring. In this work, MATLAB programming is used to implement the overbounding of satellite positioning error CDF. Using a trajectory of reference, the horizontal position errors (HPE) are computed and its non-parametric distribution function is given by the empirical Cumulative Distribution Function (ECDF). According to the results, these errors have a heavy-tailed distribution. Sınce the ECDF of the HPE in urban environment is not Gaussian distributed, the ECDF is overbound with the CDF of the generalized Pareto distribution (GPD).

SU-G-JeP3-02: Comparison of Magnitude and Frequency of Patient Positioning Errors in Breast Irradiation Using AlignRT 3D Optical Surface Imaging and Skin Mark Techniques

International Nuclear Information System (INIS)

Yao, R; Chisela, W; Dorbu, G

2016-01-01

Purpose: To evaluate clinical usefulness of AlignRT (Vision RT Ltd., London, UK) in reducing patient positioning errors in breast irradiation. Methods: 60 patients undergoing whole breast irradiation were selected for this study. Patients were treated to the left or right breast lying on Qfix Access breast board (Qfix, Avondale, PA) in supine position for 28 fractions using tangential fields. 30 patients were aligned using AlignRT by aligning a breast surface region of interest (ROI) to the same area from a reference surface image extracted from planning CT. When the patient’s surface image deviated from the reference by more than 3mm on one or more translational and rotational directions, a new reference was acquired using AlignRT in-room cameras. The other 30 patients were aligned to the skin marks with room lasers. On-Board MV portal images of medial field were taken daily and matched to the DRRs. The magnitude and frequency of positioning errors were determined from measured translational shifts. Kolmogorov-Smirnov test was used to evaluate statistical differences of positional accuracy and precision between AlignRT and non-AlignRT patients. Results: The percentage of port images with no shift required was 46.5% and 27.0% in vertical, 49.8% and 25.8% in longitudinal, 47.6% and 28.5% in lateral for AlignRT and non-AlignRT patients, respectively. The percentage of port images requiring more than 3mm shifts was 18.1% and 35.1% in vertical, 28.6% and 50.8% in longitudinal, 11.3% and 24.2% in lateral for AlignRT and non-AlignRT patients, respectively. Kolmogorov-Smirnov test showed that there were significant differences between the frequency distributions of AlignRT and non-AlignRT in vertical, longitudinal, and lateral shifts. Conclusion: As confirmed by port images, AlignRT-assisted patient positioning can significantly reduce the frequency and magnitude of patient setup errors in breast irradiation compared to the use of lasers and skin marks.

Calculation errors of Set-up in patients with tumor location of prostate. Exploratory study; Calculo de errores de Set-up en pacientes con localizacion tumoral de prostata. Estudio exploratorio

Energy Technology Data Exchange (ETDEWEB)

Donis Gil, S.; Robayna Duque, B. E.; Jimenez Sosa, A.; Hernandez Armas, O.; Gonzalez Martin, A. E.; Hernandez Armas, J.

2013-07-01

The calculation of SM is done from errors in positioning (set-up). These errors are calculated from movements in 3D of the patient. This paper is an exploratory study of 20 patients with tumor location of prostate in which errors of set-up for two protocols of work are evaluated. (Author)

Determination of global positioning system (GPS) receiver clock errors: impact on positioning accuracy

International Nuclear Information System (INIS)

Yeh, Ta-Kang; Hwang, Cheinway; Xu, Guochang; Wang, Chuan-Sheng; Lee, Chien-Chih

2009-01-01

Enhancing the positioning precision is the primary pursuit of global positioning system (GPS) users. To achieve this goal, most studies have focused on the relationship between GPS receiver clock errors and GPS positioning precision. This study utilizes undifferentiated phase data to calculate GPS clock errors and to compare with the frequency of cesium clock directly, to verify estimated clock errors by the method used in this paper. The frequency stability calculated from this paper (the indirect method) and measured from the National Standard Time and Frequency Laboratory (NSTFL) of Taiwan (the direct method) match to 1.5 × 10 −12 (the value from this study was smaller than that from NSTFL), suggesting that the proposed technique has reached a certain level of quality. The built-in quartz clocks in the GPS receivers yield relative frequency offsets that are 3–4 orders higher than those of rubidium clocks. The frequency stability of the quartz clocks is on average two orders worse than that of the rubidium clock. Using the rubidium clock instead of the quartz clock, the horizontal and vertical positioning accuracies were improved by 26–78% (0.6–3.6 mm) and 20–34% (1.3–3.0 mm), respectively, for a short baseline. These improvements are 7–25% (0.3–1.7 mm) and 11% (1.7 mm) for a long baseline. Our experiments show that the frequency stability of the clock, rather than relative frequency offset, is the governing factor of positioning accuracy

Differences among Job Positions Related to Communication Errors at Construction Sites

Science.gov (United States)

Takahashi, Akiko; Ishida, Toshiro

In a previous study, we classified the communicatio n errors at construction sites as faulty intention and message pattern, inadequate channel pattern, and faulty comprehension pattern. This study seeks to evaluate the degree of risk of communication errors and to investigate differences among people in various job positions in perception of communication error risk . Questionnaires based on the previous study were a dministered to construction workers (n=811; 149 adminis trators, 208 foremen and 454 workers). Administrators evaluated all patterns of communication error risk equally. However, foremen and workers evaluated communication error risk differently in each pattern. The common contributing factors to all patterns wer e inadequate arrangements before work and inadequate confirmation. Some factors were common among patterns but other factors were particular to a specific pattern. To help prevent future accidents at construction sites, administrators should understand how people in various job positions perceive communication errors and propose human factors measures to prevent such errors.

An IMU-Aided Body-Shadowing Error Compensation Method for Indoor Bluetooth Positioning.

Science.gov (United States)

Deng, Zhongliang; Fu, Xiao; Wang, Hanhua

2018-01-20

Research on indoor positioning technologies has recently become a hotspot because of the huge social and economic potential of indoor location-based services (ILBS). Wireless positioning signals have a considerable attenuation in received signal strength (RSS) when transmitting through human bodies, which would cause significant ranging and positioning errors in RSS-based systems. This paper mainly focuses on the body-shadowing impairment of RSS-based ranging and positioning, and derives a mathematical expression of the relation between the body-shadowing effect and the positioning error. In addition, an inertial measurement unit-aided (IMU-aided) body-shadowing detection strategy is designed, and an error compensation model is established to mitigate the effect of body-shadowing. A Bluetooth positioning algorithm with body-shadowing error compensation (BP-BEC) is then proposed to improve both the positioning accuracy and the robustness in indoor body-shadowing environments. Experiments are conducted in two indoor test beds, and the performance of both the BP-BEC algorithm and the algorithms without body-shadowing error compensation (named no-BEC) is evaluated. The results show that the BP-BEC outperforms the no-BEC by about 60.1% and 73.6% in terms of positioning accuracy and robustness, respectively. Moreover, the execution time of the BP-BEC algorithm is also evaluated, and results show that the convergence speed of the proposed algorithm has an insignificant effect on real-time localization.

CALIBRATION ERRORS IN THE CAVITY BEAM POSITION MONITOR SYSTEM AT THE ATF2

CERN Document Server

Cullinan, F; Joshi, N; Lyapin, A

2011-01-01

It has been shown at the Accelerator Test Facility at KEK, that it is possible to run a system of 37 cavity beam position monitors (BPMs) and achieve high working resolution. However, stability of the calibration constants (position scale and radio frequency (RF) phase) over a three/four week running period is yet to be demonstrated. During the calibration procedure, random beam jitter gives rise to a statistical error in the position scale and slow orbit drift in position and tilt causes systematic errors in both the position scale and RF phase. These errors are dominant and have been evaluated for each BPM. The results are compared with the errors expected after a tested method of beam jitter subtraction has been applied.

An IMU-Aided Body-Shadowing Error Compensation Method for Indoor Bluetooth Positioning

Directory of Open Access Journals (Sweden)

Zhongliang Deng

2018-01-01

Full Text Available Research on indoor positioning technologies has recently become a hotspot because of the huge social and economic potential of indoor location-based services (ILBS. Wireless positioning signals have a considerable attenuation in received signal strength (RSS when transmitting through human bodies, which would cause significant ranging and positioning errors in RSS-based systems. This paper mainly focuses on the body-shadowing impairment of RSS-based ranging and positioning, and derives a mathematical expression of the relation between the body-shadowing effect and the positioning error. In addition, an inertial measurement unit-aided (IMU-aided body-shadowing detection strategy is designed, and an error compensation model is established to mitigate the effect of body-shadowing. A Bluetooth positioning algorithm with body-shadowing error compensation (BP-BEC is then proposed to improve both the positioning accuracy and the robustness in indoor body-shadowing environments. Experiments are conducted in two indoor test beds, and the performance of both the BP-BEC algorithm and the algorithms without body-shadowing error compensation (named no-BEC is evaluated. The results show that the BP-BEC outperforms the no-BEC by about 60.1% and 73.6% in terms of positioning accuracy and robustness, respectively. Moreover, the execution time of the BP-BEC algorithm is also evaluated, and results show that the convergence speed of the proposed algorithm has an insignificant effect on real-time localization.

Compensation for positioning error of industrial robot for flexible vision measuring system

Science.gov (United States)

Guo, Lei; Liang, Yajun; Song, Jincheng; Sun, Zengyu; Zhu, Jigui

2013-01-01

Positioning error of robot is a main factor of accuracy of flexible coordinate measuring system which consists of universal industrial robot and visual sensor. Present compensation methods for positioning error based on kinematic model of robot have a significant limitation that it isn't effective in the whole measuring space. A new compensation method for positioning error of robot based on vision measuring technique is presented. One approach is setting global control points in measured field and attaching an orientation camera to vision sensor. Then global control points are measured by orientation camera to calculate the transformation relation from the current position of sensor system to global coordinate system and positioning error of robot is compensated. Another approach is setting control points on vision sensor and two large field cameras behind the sensor. Then the three dimensional coordinates of control points are measured and the pose and position of sensor is calculated real-timely. Experiment result shows the RMS of spatial positioning is 3.422mm by single camera and 0.031mm by dual cameras. Conclusion is arithmetic of single camera method needs to be improved for higher accuracy and accuracy of dual cameras method is applicable.

A Simulation Study on Patient Setup Errors in External Beam Radiotherapy Using an Anthropomorphic 4D Phantom

Directory of Open Access Journals (Sweden)

Payam Samadi Miandoab

2016-12-01

Full Text Available Introduction Patient set-up optimization is required in radiotherapy to fill the accuracy gap between personalized treatment planning and uncertainties in the irradiation set-up. In this study, we aimed to develop a new method based on neural network to estimate patient geometrical setup using 4-dimensional (4D XCAT anthropomorphic phantom. Materials and Methods To access 4D modeling of motion of dynamic organs, a phantom employs non-uniform rational B-splines (NURBS-based Cardiac-Torso method with spline-based model to generate 4D computed tomography (CT images. First, to generate all the possible roto-translation positions, the 4D CT images were imported to Medical Image Data Examiner (AMIDE. Then, for automatic, real time verification of geometrical setup, an artificial neural network (ANN was proposed to estimate patient displacement, using training sets. Moreover, three external motion markers were synchronized with a patient couch position as reference points. In addition, the technique was validated through simulated activities by using reference 4D CT data acquired from five patients. Results The results indicated that patient geometrical set-up is highly depended on the comprehensiveness of training set. By using ANN model, the average patient setup error in XCAT phantom was reduced from 17.26 mm to 0.50 mm. In addition, in the five real patients, these average errors were decreased from 18.26 mm to 1.48 mm various breathing phases ranging from inhalation to exhalation were taken into account for patient setup. Uncertainty error assessment and different setup errors were obtained from each respiration phase. Conclusion This study proposed a new method for alignment of patient setup error using ANN model. Additionally, our correlation model (ANN could estimate true patient position with less error.

Effect of MLC leaf position, collimator rotation angle, and gantry rotation angle errors on intensity-modulated radiotherapy plans for nasopharyngeal carcinoma

Energy Technology Data Exchange (ETDEWEB)

Bai, Sen; Li, Guangjun; Wang, Maojie; Jiang, Qinfeng; Zhang, Yingjie [State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan (China); Wei, Yuquan, E-mail: yuquawei@vip.sina.com [State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan (China)

2013-07-01

The purpose of this study was to investigate the effect of multileaf collimator (MLC) leaf position, collimator rotation angle, and accelerator gantry rotation angle errors on intensity-modulated radiotherapy plans for nasopharyngeal carcinoma. To compare dosimetric differences between the simulating plans and the clinical plans with evaluation parameters, 6 patients with nasopharyngeal carcinoma were selected for simulation of systematic and random MLC leaf position errors, collimator rotation angle errors, and accelerator gantry rotation angle errors. There was a high sensitivity to dose distribution for systematic MLC leaf position errors in response to field size. When the systematic MLC position errors were 0.5, 1, and 2 mm, respectively, the maximum values of the mean dose deviation, observed in parotid glands, were 4.63%, 8.69%, and 18.32%, respectively. The dosimetric effect was comparatively small for systematic MLC shift errors. For random MLC errors up to 2 mm and collimator and gantry rotation angle errors up to 0.5°, the dosimetric effect was negligible. We suggest that quality control be regularly conducted for MLC leaves, so as to ensure that systematic MLC leaf position errors are within 0.5 mm. Because the dosimetric effect of 0.5° collimator and gantry rotation angle errors is negligible, it can be concluded that setting a proper threshold for allowed errors of collimator and gantry rotation angle may increase treatment efficacy and reduce treatment time.

Slide-position errors degrade machined optical component quality

International Nuclear Information System (INIS)

Arnold, J.B.; Steger, P.J.; Burleson, R.R.

1975-01-01

An ultraprecision lathe is being developed at the Oak Ridge Y-12 Plant to fabricate optical components for use in high-energy laser systems. The lathe has the capability to produce virtually any shape mirror which is symmetrical about an axis of revolution. Two basic types of mirrors are fabricated on the lathe, namely: (1) mirrors which are machined using a single slide motion (such as flats and cylinders), and (2) mirrors which are produced by two-coordinated slide motions (such as hyperbolic reflectors; large, true-radius reflectors, and other contoured-surface reflectors). The surface-finish quality of typical mirrors machined by a single axis of motion is better than 13 nm, peak to valley, which is an order of magnitude better than the surface finishes of mirrors produced by two axes of motion. Surface finish refers to short-wavelength-figure errors that are visibly detectable. The primary cause of the inability to produce significantly better surface finishes on contoured mirrors has been determined as positional errors which exist in the slide positioning systems. The correction of these errors must be accomplished before contoured surface finishes comparable to the flat and cylinder can be machined on the lathe

A study of the positioning errors of head and neck in the process of intensity modulation radiated therapy of nasopharyngeal carcinoma

International Nuclear Information System (INIS)

Lin Chengguang; Lin Liuwen; Liu Bingti; Liu Xiaomao; Li Guowen

2011-01-01

Objective: To investigate the positioning errors of head and neck during intensity-modulated radiation therapy of nasopharyngeal carcinoma. Methods: Nineteen patients with middle-advanced nasopharyngeal carcinoma (T 2-4 N 1-3 M 0 ), treated by intensity-modulated radiation therapy, underwent repeated CT during their 6-week treatment course. All the patients were immobilized by head-neck-shoulder thermoplastic mask. We evaluated their anatomic landmark coordinated in a total of 66 repeated CT data sets and respective x, y, z shifts relative to their position in the planning CT. Results: The positioning error of the neck was 2.44 mm ± 2.24 mm, 2.05 mm ± 1.42 mm, 1.83 mm ± 1.53 mm in x, y, z respectively. And that of the head was 1.05 mm ± 0.87 mm, 1.23 mm ± 1.05 mm, 1.17 mm ± 1.55 mm respectively. The positioning error between neck and head have respectively statistical difference (t=-6.58, -5.28, -3.42, P=0.000, 0.000, 0.001). The system error of the neck was 2.33, 1.67 and 1.56 higher than that of the head, respectively in left-right, vertical and head-foot directions; and the random error of neck was 2.57, 1.34 and 0.99 higher than that of head respectively. Conclusions: In the process of the intensity-modulated radiation therapy of nasopharyngeal carcinoma, with the immobilization by head-neck-shoulder thermoplastic mask, the positioning error of neck is higher than that of head. (authors)

A vignette study to examine health care professionals' attitudes towards patient involvement in error prevention.

Science.gov (United States)

Schwappach, David L B; Frank, Olga; Davis, Rachel E

2013-10-01

Various authorities recommend the participation of patients in promoting patient safety, but little is known about health care professionals' (HCPs') attitudes towards patients' involvement in safety-related behaviours. To investigate how HCPs evaluate patients' behaviours and HCP responses to patient involvement in the behaviour, relative to different aspects of the patient, the involved HCP and the potential error. Cross-sectional fractional factorial survey with seven factors embedded in two error scenarios (missed hand hygiene, medication error). Each survey included two randomized vignettes that described the potential error, a patient's reaction to that error and the HCP response to the patient. Twelve hospitals in Switzerland. A total of 1141 HCPs (response rate 45%). Approval of patients' behaviour, HCP response to the patient, anticipated effects on the patient-HCP relationship, HCPs' support for being asked the question, affective response to the vignettes. Outcomes were measured on 7-point scales. Approval of patients' safety-related interventions was generally high and largely affected by patients' behaviour and correct identification of error. Anticipated effects on the patient-HCP relationship were much less positive, little correlated with approval of patients' behaviour and were mainly determined by the HCP response to intervening patients. HCPs expressed more favourable attitudes towards patients intervening about a medication error than about hand sanitation. This study provides the first insights into predictors of HCPs' attitudes towards patient engagement in safety. Future research is however required to assess the generalizability of the findings into practice before training can be designed to address critical issues. © 2012 John Wiley & Sons Ltd.

Putting a face on medical errors: a patient perspective.

Science.gov (United States)

Kooienga, Sarah; Stewart, Valerie T

2011-01-01

Knowledge of the patient's perspective on medical error is limited. Research efforts have centered on how best to disclose error and how patients desire to have medical error disclosed. On the basis of a qualitative descriptive component of a mixed method study, a purposive sample of 30 community members told their stories of medical error. Their experiences focused on lack of communication, missed communication, or provider's poor interpersonal style of communication, greatly contrasting with the formal definition of error as failure to follow a set standard of care. For these participants, being a patient was more important than error or how an error is disclosed. The patient's understanding of error must be a key aspect of any quality improvement strategy. © 2010 National Association for Healthcare Quality.

Reduction of digital errors of digital charge division type position-sensitive detectors

International Nuclear Information System (INIS)

Uritani, A.; Yoshimura, K.; Takenaka, Y.; Mori, C.

1994-01-01

It is well known that ''digital errors'', i.e. differential non-linearity, appear in a position profile of radiation interactions when the profile is obtained with a digital charge-division-type position-sensitive detector. Two methods are presented to reduce the digital errors. They are the methods using logarithmic amplifiers and a weighting function. The validities of these two methods have been evaluated mainly by computer simulation. These methods can considerably reduce the digital errors. The best results are obtained when both methods are applied. ((orig.))

Analysis of the effects of Eye-Tracker performance on the pulse positioning errors during refractive surgery☆

Science.gov (United States)

Arba-Mosquera, Samuel; Aslanides, Ioannis M.

2012-01-01

Purpose To analyze the effects of Eye-Tracker performance on the pulse positioning errors during refractive surgery. Methods A comprehensive model, which directly considers eye movements, including saccades, vestibular, optokinetic, vergence, and miniature, as well as, eye-tracker acquisition rate, eye-tracker latency time, scanner positioning time, laser firing rate, and laser trigger delay have been developed. Results Eye-tracker acquisition rates below 100 Hz correspond to pulse positioning errors above 1.5 mm. Eye-tracker latency times to about 15 ms correspond to pulse positioning errors of up to 3.5 mm. Scanner positioning times to about 9 ms correspond to pulse positioning errors of up to 2 mm. Laser firing rates faster than eye-tracker acquisition rates basically duplicate pulse-positioning errors. Laser trigger delays to about 300 μs have minor to no impact on pulse-positioning errors. Conclusions The proposed model can be used for comparison of laser systems used for ablation processes. Due to the pseudo-random nature of eye movements, positioning errors of single pulses are much larger than observed decentrations in the clinical settings. There is no single parameter that ‘alone’ minimizes the positioning error. It is the optimal combination of the several parameters that minimizes the error. The results of this analysis are important to understand the limitations of correcting very irregular ablation patterns.

Errors in imaging patients in the emergency setting.

Science.gov (United States)

Pinto, Antonio; Reginelli, Alfonso; Pinto, Fabio; Lo Re, Giuseppe; Midiri, Federico; Muzj, Carlo; Romano, Luigia; Brunese, Luca

2016-01-01

Emergency and trauma care produces a "perfect storm" for radiological errors: uncooperative patients, inadequate histories, time-critical decisions, concurrent tasks and often junior personnel working after hours in busy emergency departments. The main cause of diagnostic errors in the emergency department is the failure to correctly interpret radiographs, and the majority of diagnoses missed on radiographs are fractures. Missed diagnoses potentially have important consequences for patients, clinicians and radiologists. Radiologists play a pivotal role in the diagnostic assessment of polytrauma patients and of patients with non-traumatic craniothoracoabdominal emergencies, and key elements to reduce errors in the emergency setting are knowledge, experience and the correct application of imaging protocols. This article aims to highlight the definition and classification of errors in radiology, the causes of errors in emergency radiology and the spectrum of diagnostic errors in radiography, ultrasonography and CT in the emergency setting.

Reproducibility of patient positioning during routine radiotherapy, as assessed by an integrated megavoltage imaging system

International Nuclear Information System (INIS)

Gildersleve, J.; Dearnaley, D.P.; Evans, P.M.; Swindell, W.

1995-01-01

A portal imaging system has been used, in conjunction with a movie measurement technique to measure set-up errors for 15 patients treated with radiotherapy of the pelvis and for 12 patients treated with radiotherapy of the brain. The pelvic patients were treated without fixation devices and the brain patients were treated with individually-moulded plastic shells. As would be expected the brain treatments were found to be more accurate than the pelvic treatments. Results are presented in terms of five error types: random error from treatment to treatment, error between mean treatment position and simulation position, random simulation error, systematic simulator-to-treatment errors and total treatment error. For the brain patients the simulation-to-treatment error predominates and random treatment errors were small (95% ≤ 3 mm, 77% ≤ 1.5 mm). Vector components of the systematic simulation-to-treatment errors were 1-2 mm with maximal random simulation error of ± 5 mm (2 S.D.). There is much interest in the number of verification films necessary to evaluate treatment accuracy. These results indicate that one check film performed at the first treatment is likely to be sufficient for set-up evaluation. For the pelvis the random treatment error is larger (95% ≤ 4.5 mm, 87% ≤ 3 mm). The systematic simulation-to-treatment error is up to 3 mm and the maximal random simulation error is ± 6 mm (2 S.D.). Thus corrections made solely on the basis of a first day check film may not be sufficient for adequate set-up evaluation

Patient identification errors: the detective in the laboratory.

Science.gov (United States)

Salinas, Maria; López-Garrigós, Maite; Lillo, Rosa; Gutiérrez, Mercedes; Lugo, Javier; Leiva-Salinas, Carlos

2013-11-01

The eradication of errors regarding patients' identification is one of the main goals for safety improvement. As clinical laboratory intervenes in 70% of clinical decisions, laboratory safety is crucial in patient safety. We studied the number of Laboratory Information System (LIS) demographic data errors registered in our laboratory during one year. The laboratory attends a variety of inpatients and outpatients. The demographic data of outpatients is registered in the LIS, when they present to the laboratory front desk. The requests from the primary care centers (PCC) are made electronically by the general practitioner. A manual step is always done at the PCC to conciliate the patient identification number in the electronic request with the one in the LIS. Manual registration is done through hospital information system demographic data capture when patient's medical record number is registered in LIS. Laboratory report is always sent out electronically to the patient's electronic medical record. Daily, every demographic data in LIS is manually compared to the request form to detect potential errors. Fewer errors were committed when electronic order was used. There was great error variability between PCC when using the electronic order. LIS demographic data manual registration errors depended on patient origin and test requesting method. Even when using the electronic approach, errors were detected. There was a great variability between PCC even when using this electronic modality; this suggests that the number of errors is still dependent on the personnel in charge of the technology. © 2013.

Residual position errors of lymph node surrogates in breast cancer adjuvant radiotherapy: Comparison of two arm fixation devices and the effect of arm position correction

International Nuclear Information System (INIS)

Kapanen, Mika; Laaksomaa, Marko; Skyttä, Tanja; Haltamo, Mikko; Pehkonen, Jani; Lehtonen, Turkka; Kellokumpu-Lehtinen, Pirkko-Liisa; Hyödynmaa, Simo

2016-01-01

Residual position errors of the lymph node (LN) surrogates and humeral head (HH) were determined for 2 different arm fixation devices in radiotherapy (RT) of breast cancer: a standard wrist-hold (WH) and a house-made rod-hold (RH). The effect of arm position correction (APC) based on setup images was also investigated. A total of 113 consecutive patients with early-stage breast cancer with LN irradiation were retrospectively analyzed (53 and 60 using the WH and RH, respectively). Residual position errors of the LN surrogates (Th1-2 and clavicle) and the HH were investigated to compare the 2 fixation devices. The position errors and setup margins were determined before and after the APC to investigate the efficacy of the APC in the treatment situation. A threshold of 5 mm was used for the residual errors of the clavicle and Th1-2 to perform the APC, and a threshold of 7 mm was used for the HH. The setup margins were calculated with the van Herk formula. Irradiated volumes of the HH were determined from RT treatment plans. With the WH and the RH, setup margins up to 8.1 and 6.7 mm should be used for the LN surrogates, and margins up to 4.6 and 3.6 mm should be used to spare the HH, respectively, without the APC. After the APC, the margins of the LN surrogates were equal to or less than 7.5/6.0 mm with the WH/RH, but margins up to 4.2/2.9 mm were required for the HH. The APC was needed at least once with both the devices for approximately 60% of the patients. With the RH, irradiated volume of the HH was approximately 2 times more than with the WH, without any dose constraints. Use of the RH together with the APC resulted in minimal residual position errors and setup margins for all the investigated bony landmarks. Based on the obtained results, we prefer the house-made RH. However, more attention should be given to minimize the irradiation of the HH with the RH than with the WH.

A machine learning approach to the accurate prediction of multi-leaf collimator positional errors

Science.gov (United States)

Carlson, Joel N. K.; Park, Jong Min; Park, So-Yeon; In Park, Jong; Choi, Yunseok; Ye, Sung-Joon

2016-03-01

Discrepancies between planned and delivered movements of multi-leaf collimators (MLCs) are an important source of errors in dose distributions during radiotherapy. In this work we used machine learning techniques to train models to predict these discrepancies, assessed the accuracy of the model predictions, and examined the impact these errors have on quality assurance (QA) procedures and dosimetry. Predictive leaf motion parameters for the models were calculated from the plan files, such as leaf position and velocity, whether the leaf was moving towards or away from the isocenter of the MLC, and many others. Differences in positions between synchronized DICOM-RT planning files and DynaLog files reported during QA delivery were used as a target response for training of the models. The final model is capable of predicting MLC positions during delivery to a high degree of accuracy. For moving MLC leaves, predicted positions were shown to be significantly closer to delivered positions than were planned positions. By incorporating predicted positions into dose calculations in the TPS, increases were shown in gamma passing rates against measured dose distributions recorded during QA delivery. For instance, head and neck plans with 1%/2 mm gamma criteria had an average increase in passing rate of 4.17% (SD  =  1.54%). This indicates that the inclusion of predictions during dose calculation leads to a more realistic representation of plan delivery. To assess impact on the patient, dose volumetric histograms (DVH) using delivered positions were calculated for comparison with planned and predicted DVHs. In all cases, predicted dose volumetric parameters were in closer agreement to the delivered parameters than were the planned parameters, particularly for organs at risk on the periphery of the treatment area. By incorporating the predicted positions into the TPS, the treatment planner is given a more realistic view of the dose distribution as it will truly be

SU-E-T-377: Inaccurate Positioning Might Introduce Significant MapCheck Calibration Error in Flatten Filter Free Beams

International Nuclear Information System (INIS)

Wang, S; Chao, C; Chang, J

2014-01-01

Purpose: This study investigates the calibration error of detector sensitivity for MapCheck due to inaccurate positioning of the device, which is not taken into account by the current commercial iterative calibration algorithm. We hypothesize the calibration is more vulnerable to the positioning error for the flatten filter free (FFF) beams than the conventional flatten filter flattened beams. Methods: MapCheck2 was calibrated with 10MV conventional and FFF beams, with careful alignment and with 1cm positioning error during calibration, respectively. Open fields of 37cmx37cm were delivered to gauge the impact of resultant calibration errors. The local calibration error was modeled as a detector independent multiplication factor, with which propagation error was estimated with positioning error from 1mm to 1cm. The calibrated sensitivities, without positioning error, were compared between the conventional and FFF beams to evaluate the dependence on the beam type. Results: The 1cm positioning error leads to 0.39% and 5.24% local calibration error in the conventional and FFF beams respectively. After propagating to the edges of MapCheck, the calibration errors become 6.5% and 57.7%, respectively. The propagation error increases almost linearly with respect to the positioning error. The difference of sensitivities between the conventional and FFF beams was small (0.11 ± 0.49%). Conclusion: The results demonstrate that the positioning error is not handled by the current commercial calibration algorithm of MapCheck. Particularly, the calibration errors for the FFF beams are ~9 times greater than those for the conventional beams with identical positioning error, and a small 1mm positioning error might lead to up to 8% calibration error. Since the sensitivities are only slightly dependent of the beam type and the conventional beam is less affected by the positioning error, it is advisable to cross-check the sensitivities between the conventional and FFF beams to detect

Local Setup Reproducibility of the Spinal Column When Using Intensity-Modulated Radiation Therapy for Craniospinal Irradiation With Patient in Supine Position

International Nuclear Information System (INIS)

Stoiber, Eva Maria; Giske, Kristina; Schubert, Kai; Sterzing, Florian; Habl, Gregor; Uhl, Matthias; Herfarth, Klaus; Bendl, Rolf; Debus, Jürgen

2011-01-01

Purpose: To evaluate local positioning errors of the lumbar spine during fractionated intensity-modulated radiotherapy of patients treated with craniospinal irradiation and to assess the impact of rotational error correction on these uncertainties for one patient setup correction strategy. Methods and Materials: 8 patients (6 adults, 2 children) treated with helical tomotherapy for craniospinal irradiation were retrospectively chosen for this analysis. Patients were immobilized with a deep-drawn Aquaplast head mask. Additionally to daily megavoltage control computed tomography scans of the skull, once-a-week positioning of the lumbar spine was assessed. Therefore, patient setup was corrected by a target point correction, derived from a registration of the patient's skull. The residual positioning variations of the lumbar spine were evaluated applying a rigid-registration algorithm. The impact of different rotational error corrections was simulated. Results: After target point correction, residual local positioning errors of the lumbar spine varied considerably. Craniocaudal axis rotational error correction did not improve or deteriorate these translational errors, whereas simulation of a rotational error correction of the right–left and anterior–posterior axis increased these errors by a factor of 2 to 3. Conclusion: The patient fixation used allows for deformations between the patient's skull and spine. Therefore, for the setup correction strategy evaluated in this study, generous margins for the lumbar spinal target volume are needed to prevent a local geographic miss. With any applied correction strategy, it needs to be evaluated whether or not a rotational error correction is beneficial.

SU-E-P-21: Impact of MLC Position Errors On Simultaneous Integrated Boost Intensity-Modulated Radiotherapy for Nasopharyngeal Carcinoma

Energy Technology Data Exchange (ETDEWEB)

Chengqiang, L; Yin, Y; Chen, L [Shandong Cancer Hospital and Institute, 440 Jiyan Road, Jinan, 250117 (China)

2015-06-15

Purpose: To investigate the impact of MLC position errors on simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) for patients with nasopharyngeal carcinoma. Methods: To compare the dosimetric differences between the simulated plans and the clinical plans, ten patients with locally advanced NPC treated with SIB-IMRT were enrolled in this study. All plans were calculated with an inverse planning system (Pinnacle3, Philips Medical System{sub )}. Random errors −2mm to 2mm{sub )},shift errors{sub (} 2mm,1mm and 0.5mm) and systematic extension/ contraction errors (±2mm, ±1mm and ±0.5mm) of the MLC leaf position were introduced respectively into the original plans to create the simulated plans. Dosimetry factors were compared between the original and the simulated plans. Results: The dosimetric impact of the random and system shift errors of MLC position was insignificant within 2mm, the maximum changes in D95% of PGTV,PTV1,PTV2 were-0.92±0.51%,1.00±0.24% and 0.62±0.17%, the maximum changes in the D0.1cc of spinal cord and brainstem were 1.90±2.80% and −1.78±1.42%, the maximum changes in the Dmean of parotids were1.36±1.23% and −2.25±2.04%.However,the impact of MLC extension or contraction errors was found significant. For 2mm leaf extension errors, the average changes in D95% of PGTV,PTV1,PTV2 were 4.31±0.67%,4.29±0.65% and 4.79±0.82%, the averaged value of the D0.1cc to spinal cord and brainstem were increased by 7.39±5.25% and 6.32±2.28%,the averaged value of the mean dose to left and right parotid were increased by 12.75±2.02%,13.39±2.17% respectively. Conclusion: The dosimetric effect was insignificant for random MLC leaf position errors up to 2mm. There was a high sensitivity to dose distribution for MLC extension or contraction errors.We should pay attention to the anatomic changes in target organs and anatomical structures during the course,individual radiotherapy was recommended to ensure adaptive doses.

Medication errors: the role of the patient.

Science.gov (United States)

Britten, Nicky

2009-06-01

1. Patients and their carers will usually be the first to notice any observable problems resulting from medication errors. They will probably be unable to distinguish between medication errors, adverse drug reactions, or 'side effects'. 2. Little is known about how patients understand drug related problems or how they make attributions of adverse effects. Some research suggests that patients' cognitive models of adverse drug reactions bear a close relationship to models of illness perception. 3. Attributions of adverse drug reactions are related to people's previous experiences and to their level of education. The evidence suggests that on the whole patients' reports of adverse drug reactions are accurate. However, patients do not report all the problems they perceive and are more likely to report those that they do perceive as severe. Patients may not report problems attributed to their medications if they are fearful of doctors' reactions. Doctors may respond inappropriately to patients' concerns, for example by ignoring them. Some authors have proposed the use of a symptom checklist to elicit patients' reports of suspected adverse drug reactions. 4. Many patients want information about adverse drug effects, and the challenge for the professional is to judge how much information to provide and the best way of doing so. Professionals' inappropriate emphasis on adherence may be dangerous when a medication error has occurred. 5. Recent NICE guidelines recommend that professionals should ask patients if they have any concerns about their medicines, and this approach is likely to yield information conducive to the identification of medication errors.

Source position error influence on industry CT image quality

International Nuclear Information System (INIS)

Cong Peng; Li Zhipeng; Wu Haifeng

2004-01-01

Based on the emulational exercise, the influence of source position error on industry CT (ICT) image quality was studied and the valuable parameters were obtained for the design of ICT. The vivid container CT image was also acquired from the CT testing system. (authors)

Local Setup Reproducibility of the Spinal Column When Using Intensity-Modulated Radiation Therapy for Craniospinal Irradiation With Patient in Supine Position

Energy Technology Data Exchange (ETDEWEB)

Stoiber, Eva Maria, E-mail: eva.stoiber@med.uni-heidelberg.de [Department of Radiation Oncology, University Hospital Heidelberg, Heidelberg (Germany); Department of Medical Physics, German Cancer Research Center, Heidelberg (Germany); Giske, Kristina [Department of Medical Physics, German Cancer Research Center, Heidelberg (Germany); Schubert, Kai; Sterzing, Florian; Habl, Gregor; Uhl, Matthias; Herfarth, Klaus [Department of Radiation Oncology, University Hospital Heidelberg, Heidelberg (Germany); Bendl, Rolf [Department of Medical Physics, German Cancer Research Center, Heidelberg (Germany); Medical Informatics, Heilbronn University, Heilbronn (Germany); Debus, Juergen [Department of Radiation Oncology, University Hospital Heidelberg, Heidelberg (Germany)

2011-12-01

Purpose: To evaluate local positioning errors of the lumbar spine during fractionated intensity-modulated radiotherapy of patients treated with craniospinal irradiation and to assess the impact of rotational error correction on these uncertainties for one patient setup correction strategy. Methods and Materials: 8 patients (6 adults, 2 children) treated with helical tomotherapy for craniospinal irradiation were retrospectively chosen for this analysis. Patients were immobilized with a deep-drawn Aquaplast head mask. Additionally to daily megavoltage control computed tomography scans of the skull, once-a-week positioning of the lumbar spine was assessed. Therefore, patient setup was corrected by a target point correction, derived from a registration of the patient's skull. The residual positioning variations of the lumbar spine were evaluated applying a rigid-registration algorithm. The impact of different rotational error corrections was simulated. Results: After target point correction, residual local positioning errors of the lumbar spine varied considerably. Craniocaudal axis rotational error correction did not improve or deteriorate these translational errors, whereas simulation of a rotational error correction of the right-left and anterior-posterior axis increased these errors by a factor of 2 to 3. Conclusion: The patient fixation used allows for deformations between the patient's skull and spine. Therefore, for the setup correction strategy evaluated in this study, generous margins for the lumbar spinal target volume are needed to prevent a local geographic miss. With any applied correction strategy, it needs to be evaluated whether or not a rotational error correction is beneficial.

Local setup errors in image-guided radiotherapy for head and neck cancer patients immobilized with a custom-made device.

Science.gov (United States)

Giske, Kristina; Stoiber, Eva M; Schwarz, Michael; Stoll, Armin; Muenter, Marc W; Timke, Carmen; Roeder, Falk; Debus, Juergen; Huber, Peter E; Thieke, Christian; Bendl, Rolf

2011-06-01

To evaluate the local positioning uncertainties during fractionated radiotherapy of head-and-neck cancer patients immobilized using a custom-made fixation device and discuss the effect of possible patient correction strategies for these uncertainties. A total of 45 head-and-neck patients underwent regular control computed tomography scanning using an in-room computed tomography scanner. The local and global positioning variations of all patients were evaluated by applying a rigid registration algorithm. One bounding box around the complete target volume and nine local registration boxes containing relevant anatomic structures were introduced. The resulting uncertainties for a stereotactic setup and the deformations referenced to one anatomic local registration box were determined. Local deformations of the patients immobilized using our custom-made device were compared with previously published results. Several patient positioning correction strategies were simulated, and the residual local uncertainties were calculated. The patient anatomy in the stereotactic setup showed local systematic positioning deviations of 1-4 mm. The deformations referenced to a particular anatomic local registration box were similar to the reported deformations assessed from patients immobilized with commercially available Aquaplast masks. A global correction, including the rotational error compensation, decreased the remaining local translational errors. Depending on the chosen patient positioning strategy, the remaining local uncertainties varied considerably. Local deformations in head-and-neck patients occur even if an elaborate, custom-made patient fixation method is used. A rotational error correction decreased the required margins considerably. None of the considered correction strategies achieved perfect alignment. Therefore, weighting of anatomic subregions to obtain the optimal correction vector should be investigated in the future. Copyright © 2011 Elsevier Inc. All rights

Square-Wave Voltage Injection Algorithm for PMSM Position Sensorless Control With High Robustness to Voltage Errors

DEFF Research Database (Denmark)

Ni, Ronggang; Xu, Dianguo; Blaabjerg, Frede

2017-01-01

relationship with the magnetic field distortion. Position estimation errors caused by higher order harmonic inductances and voltage harmonics generated by the SVPWM are also discussed. Both simulations and experiments are carried out based on a commercial PMSM to verify the superiority of the proposed method......Rotor position estimated with high-frequency (HF) voltage injection methods can be distorted by voltage errors due to inverter nonlinearities, motor resistance, and rotational voltage drops, etc. This paper proposes an improved HF square-wave voltage injection algorithm, which is robust to voltage...... errors without any compensations meanwhile has less fluctuation in the position estimation error. The average position estimation error is investigated based on the analysis of phase harmonic inductances, and deduced in the form of the phase shift of the second-order harmonic inductances to derive its...

SU-E-T-114: Analysis of MLC Errors On Gamma Pass Rates for Patient-Specific and Conventional Phantoms

Energy Technology Data Exchange (ETDEWEB)

Sterling, D; Ehler, E [University of Minnesota, Minneapolis, MN (United States)

2015-06-15

Purpose: To evaluate whether a 3D patient-specific phantom is better able to detect known MLC errors in a clinically delivered treatment plan than conventional phantoms. 3D printing may make fabrication of such phantoms feasible. Methods: Two types of MLC errors were introduced into a clinically delivered, non-coplanar IMRT, partial brain treatment plan. First, uniformly distributed random errors of up to 3mm, 2mm, and 1mm were introduced into the MLC positions for each field. Second, systematic MLC-bank position errors of 5mm, 3.5mm, and 2mm due to simulated effects of gantry and MLC sag were introduced. The original plan was recalculated with these errors on the original CT dataset as well as cylindrical and planar IMRT QA phantoms. The original dataset was considered to be a perfect 3D patient-specific phantom. The phantoms were considered to be ideal 3D dosimetry systems with no resolution limitations. Results: Passing rates for Gamma Index (3%/3mm and no dose threshold) were calculated on the 3D phantom, cylindrical phantom, and both on a composite and field-by-field basis for the planar phantom. Pass rates for 5mm systematic and 3mm random error were 86.0%, 89.6%, 98% and 98.3% respectively. For 3.5mm systematic and 2mm random error the pass rates were 94.7%, 96.2%, 99.2% and 99.2% respectively. For 2mm systematic error with 1mm random error the pass rates were 99.9%, 100%, 100% and 100% respectively. Conclusion: A 3D phantom with the patient anatomy is able to discern errors, both severe and subtle, that are not seen using conventional phantoms. Therefore, 3D phantoms may be beneficial for commissioning new treatment machines and modalities, patient-specific QA and end-to-end testing.

SU-E-T-114: Analysis of MLC Errors On Gamma Pass Rates for Patient-Specific and Conventional Phantoms

International Nuclear Information System (INIS)

Sterling, D; Ehler, E

2015-01-01

Purpose: To evaluate whether a 3D patient-specific phantom is better able to detect known MLC errors in a clinically delivered treatment plan than conventional phantoms. 3D printing may make fabrication of such phantoms feasible. Methods: Two types of MLC errors were introduced into a clinically delivered, non-coplanar IMRT, partial brain treatment plan. First, uniformly distributed random errors of up to 3mm, 2mm, and 1mm were introduced into the MLC positions for each field. Second, systematic MLC-bank position errors of 5mm, 3.5mm, and 2mm due to simulated effects of gantry and MLC sag were introduced. The original plan was recalculated with these errors on the original CT dataset as well as cylindrical and planar IMRT QA phantoms. The original dataset was considered to be a perfect 3D patient-specific phantom. The phantoms were considered to be ideal 3D dosimetry systems with no resolution limitations. Results: Passing rates for Gamma Index (3%/3mm and no dose threshold) were calculated on the 3D phantom, cylindrical phantom, and both on a composite and field-by-field basis for the planar phantom. Pass rates for 5mm systematic and 3mm random error were 86.0%, 89.6%, 98% and 98.3% respectively. For 3.5mm systematic and 2mm random error the pass rates were 94.7%, 96.2%, 99.2% and 99.2% respectively. For 2mm systematic error with 1mm random error the pass rates were 99.9%, 100%, 100% and 100% respectively. Conclusion: A 3D phantom with the patient anatomy is able to discern errors, both severe and subtle, that are not seen using conventional phantoms. Therefore, 3D phantoms may be beneficial for commissioning new treatment machines and modalities, patient-specific QA and end-to-end testing

[Medical errors from positions of mutual relations of patient-lawyer-doctor].

Science.gov (United States)

Radysh, Ia F; Tsema, Ie V; Mehed', V P

2013-01-01

The basic theoretical and practical aspects of problem of malpractice in the system of health protection Ukraine are presented in the article. On specific examples the essence of the term "malpractice" is expounded. It was considered types of malpractice, conditions of beginning and kinds of responsibility to assumption of malpractice. The special attention to the legal and mental and ethical questions of problem from positions of protection of rights for a patient and medical worker is spared. The necessity of qualification malpractices on intentional and unintentional, possible and impermissible is grounded.

The frequency of diagnostic errors in radiologic reports depends on the patient's age

International Nuclear Information System (INIS)

Diaz, Sandra; Ekberg, Olle

2010-01-01

Background: Patients who undergo treatment may suffer preventable medical errors. Some of these errors are due to diagnostic imaging procedures. Purpose: To compare the frequency of diagnostic errors in different age groups in an urban European population. Material and Methods: A total of 19 129 reported radiologic examinations were included. During a 6-month period, the analyzed age groups were: children (aged 0-9 years), adults (40-49 years), and elderly (86-95 years). Results: The frequency of radiologic examinations per year was 0.3 in children, 0.6 in adults, and 1.1 in elderly. Significant errors were significantly more frequent in the elderly (1.7%) and children (1.4%) compared with adults (0.8%). There were 60 false-positive reports and 232 false-negative reports. Most errors were made by staff radiologists after hours when they reported on examinations outside their area of expertise. Conclusion: Diagnostic errors are more frequent in children and the elderly compared with middle-aged adults

Learning from errors in radiology to improve patient safety.

Science.gov (United States)

Saeed, Shaista Afzal; Masroor, Imrana; Shafqat, Gulnaz

2013-10-01

To determine the views and practices of trainees and consultant radiologists about error reporting. Cross-sectional survey. Radiology trainees and consultant radiologists in four tertiary care hospitals in Karachi approached in the second quarter of 2011. Participants were enquired as to their grade, sub-specialty interest, whether they kept a record/log of their errors (defined as a mistake that has management implications for the patient), number of errors they made in the last 12 months and the predominant type of error. They were also asked about the details of their department error meetings. All duly completed questionnaires were included in the study while the ones with incomplete information were excluded. A total of 100 radiologists participated in the survey. Of them, 34 were consultants and 66 were trainees. They had a wide range of sub-specialty interest like CT, Ultrasound, etc. Out of the 100 responders, 49 kept a personal record/log of their errors. In response to the recall of approximate errors they made in the last 12 months, 73 (73%) of participants recorded a varied response with 1 - 5 errors mentioned by majority i.e. 47 (64.5%). Most of the radiologists (97%) claimed receiving information about their errors through multiple sources like morbidity/mortality meetings, patients' follow-up, through colleagues and consultants. Perceptual error 66 (66%) were the predominant error type reported. Regular occurrence of error meetings and attending three or more error meetings in the last 12 months was reported by 35% participants. Majority among these described the atmosphere of these error meetings as informative and comfortable (n = 22, 62.8%). It is of utmost importance to develop a culture of learning from mistakes by conducting error meetings and improving the process of recording and addressing errors to enhance patient safety.

Performance of a video-image-subtraction-based patient positioning system

International Nuclear Information System (INIS)

Milliken, Barrett D.; Rubin, Steven J.; Hamilton, Russell J.; Johnson, L. Scott; Chen, George T.Y.

1997-01-01

Purpose: We have developed and tested an interactive video system that utilizes image subtraction techniques to enable high precision patient repositioning using surface features. We report quantitative measurements of system performance characteristics. Methods and Materials: Video images can provide a high precision, low cost measure of patient position. Image subtraction techniques enable one to incorporate detailed information contained in the image of a carefully verified reference position into real-time images. We have developed a system using video cameras providing orthogonal images of the treatment setup. The images are acquired, processed and viewed using an inexpensive frame grabber and a PC. The subtraction images provide the interactive guidance needed to quickly and accurately place a patient in the same position for each treatment session. We describe the design and implementation of our system, and its quantitative performance, using images both to measure changes in position, and to achieve accurate setup reproducibility. Results: Under clinical conditions (60 cm field of view, 3.6 m object distance), the position of static, high contrast objects could be measured with a resolution of 0.04 mm (rms) in each of two dimensions. The two-dimensional position could be reproduced using the real-time image display with a resolution of 0.15 mm (rms). Two-dimensional measurement resolution of the head of a patient undergoing treatment for head and neck cancer was 0.1 mm (rms), using a lateral view, measuring the variation in position of the nose and the ear over the course of a single radiation treatment. Three-dimensional repositioning accuracy of the head of a healthy volunteer using orthogonal camera views was less than 0.7 mm (systematic error) with an rms variation of 1.2 mm. Setup adjustments based on the video images were typically performed within a few minutes. The higher precision achieved using the system to measure objects than to reposition

Reducing patient identification errors related to glucose point-of-care testing

Directory of Open Access Journals (Sweden)

Gaurav Alreja

2011-01-01

Full Text Available Background: Patient identification (ID errors in point-of-care testing (POCT can cause test results to be transferred to the wrong patient′s chart or prevent results from being transmitted and reported. Despite the implementation of patient barcoding and ongoing operator training at our institution, patient ID errors still occur with glucose POCT. The aim of this study was to develop a solution to reduce identification errors with POCT. Materials and Methods: Glucose POCT was performed by approximately 2,400 clinical operators throughout our health system. Patients are identified by scanning in wristband barcodes or by manual data entry using portable glucose meters. Meters are docked to upload data to a database server which then transmits data to any medical record matching the financial number of the test result. With a new model, meters connect to an interface manager where the patient ID (a nine-digit account number is checked against patient registration data from admission, discharge, and transfer (ADT feeds and only matched results are transferred to the patient′s electronic medical record. With the new process, the patient ID is checked prior to testing, and testing is prevented until ID errors are resolved. Results: When averaged over a period of a month, ID errors were reduced to 3 errors/month (0.015% in comparison with 61.5 errors/month (0.319% before implementing the new meters. Conclusion: Patient ID errors may occur with glucose POCT despite patient barcoding. The verification of patient identification should ideally take place at the bedside before testing occurs so that the errors can be addressed in real time. The introduction of an ADT feed directly to glucose meters reduced patient ID errors in POCT.

SU-E-T-132: Dosimetric Impact of Positioning Errors in Hypo-Fractionated Cranial Radiation Therapy Using Frameless Stereotactic BrainLAB System

International Nuclear Information System (INIS)

Keeling, V; Jin, H; Ali, I; Ahmad, S

2014-01-01

Purpose: To determine dosimetric impact of positioning errors in the stereotactic hypo-fractionated treatment of intracranial lesions using 3Dtransaltional and 3D-rotational corrections (6D) frameless BrainLAB ExacTrac X-Ray system. Methods: 20 cranial lesions, treated in 3 or 5 fractions, were selected. An infrared (IR) optical positioning system was employed for initial patient setup followed by stereoscopic kV X-ray radiographs for position verification. 6D-translational and rotational shifts were determined to correct patient position. If these shifts were above tolerance (0.7 mm translational and 1° rotational), corrections were applied and another set of X-rays was taken to verify patient position. Dosimetric impact (D95, Dmin, Dmax, and Dmean of planning target volume (PTV) compared to original plans) of positioning errors for initial IR setup (XC: Xray Correction) and post-correction (XV: X-ray Verification) was determined in a treatment planning system using a method proposed by Yue et al. (Med. Phys. 33, 21-31 (2006)) with 3D-translational errors only and 6D-translational and rotational errors. Results: Absolute mean translational errors (±standard deviation) for total 92 fractions (XC/XV) were 0.79±0.88/0.19±0.15 mm (lateral), 1.66±1.71/0.18 ±0.16 mm (longitudinal), 1.95±1.18/0.15±0.14 mm (vertical) and rotational errors were 0.61±0.47/0.17±0.15° (pitch), 0.55±0.49/0.16±0.24° (roll), and 0.68±0.73/0.16±0.15° (yaw). The average changes (loss of coverage) in D95, Dmin, Dmax, and Dmean were 4.5±7.3/0.1±0.2%, 17.8±22.5/1.1±2.5%, 0.4±1.4/0.1±0.3%, and 0.9±1.7/0.0±0.1% using 6Dshifts and 3.1±5.5/0.0±0.1%, 14.2±20.3/0.8±1.7%, 0.0±1.2/0.1±0.3%, and 0.7±1.4/0.0±0.1% using 3D-translational shifts only. The setup corrections (XC-XV) improved the PTV coverage by 4.4±7.3% (D95) and 16.7±23.5% (Dmin) using 6D adjustment. Strong correlations were observed between translation errors and deviations in dose coverage for XC. Conclusion

Evaluation of Setup Error Correction for Patients Using On Board Imager in Image Guided Radiation Therapy

International Nuclear Information System (INIS)

Kang, Soo Man

2008-01-01

To reduce side effects in image guided radiation therapy (IGRT) and to improve the quality of life of patients, also to meet accurate SETUP condition for patients, the various SETUP correction conditions were compared and evaluated by using on board imager (OBI) during the SETUP. Each 30 cases of the head, the neck, the chest, the belly, and the pelvis in 150 cases of IGRT patients was corrected after confirmation by using OBI at every 2-3 day. Also, the difference of the SETUP through the skin-marker and the anatomic SETUP through the OBI was evaluated. General SETUP errors (Transverse, Coronal, Sagittal) through the OBI at original SETUP position were Head and Neck: 1.3 mm, Brain: 2 mm, Chest: 3 mm, Abdoman: 3.7 mm, Pelvis: 4 mm. The patients with more that 3 mm in the error range were observed in the correction devices and the patient motions by confirming in treatment room. Moreover, in the case of female patients, the result came from the position of hairs during the Head and Neck, Brain tumor. Therefore, after another SETUP in each cases of over 3 mm in the error range, the treatment was carried out. Mean error values of each parts estimated after the correction were 1 mm for the head, 1.2 mm for the neck, 2.5 mm for the chest, 2.5 mm for the belly, and 2.6 mm for the pelvis. The result showed the correction of SETUP for each treatment through OBI is extremely difficult because of the importance of SETUP in radiation treatment. However, by establishing the average standard of the patients from this research result, the better patient satisfaction and treatment results could be obtained.

Evaluation of Setup Error Correction for Patients Using On Board Imager in Image Guided Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Kang, Soo Man [Dept. of Radiation Oncology, Kosin University Gospel Hospital, Busan (Korea, Republic of)

2008-09-15

To reduce side effects in image guided radiation therapy (IGRT) and to improve the quality of life of patients, also to meet accurate SETUP condition for patients, the various SETUP correction conditions were compared and evaluated by using on board imager (OBI) during the SETUP. Each 30 cases of the head, the neck, the chest, the belly, and the pelvis in 150 cases of IGRT patients was corrected after confirmation by using OBI at every 2-3 day. Also, the difference of the SETUP through the skin-marker and the anatomic SETUP through the OBI was evaluated. General SETUP errors (Transverse, Coronal, Sagittal) through the OBI at original SETUP position were Head and Neck: 1.3 mm, Brain: 2 mm, Chest: 3 mm, Abdoman: 3.7 mm, Pelvis: 4 mm. The patients with more that 3 mm in the error range were observed in the correction devices and the patient motions by confirming in treatment room. Moreover, in the case of female patients, the result came from the position of hairs during the Head and Neck, Brain tumor. Therefore, after another SETUP in each cases of over 3 mm in the error range, the treatment was carried out. Mean error values of each parts estimated after the correction were 1 mm for the head, 1.2 mm for the neck, 2.5 mm for the chest, 2.5 mm for the belly, and 2.6 mm for the pelvis. The result showed the correction of SETUP for each treatment through OBI is extremely difficult because of the importance of SETUP in radiation treatment. However, by establishing the average standard of the patients from this research result, the better patient satisfaction and treatment results could be obtained.

Negative cognitive errors and positive illusions for negative divorce events: predictors of children's psychological adjustment.

Science.gov (United States)

Mazur, E; Wolchik, S A; Sandler, I N

1992-12-01

This study examined the relations among negative cognitive errors regarding hypothetical negative divorce events, positive illusions about those same events, actual divorce events, and psychological adjustment in 38 8- to 12-year-old children whose parents had divorced within the previous 2 years. Children's scores on a scale of negative cognitive errors (catastrophizing, overgeneralizing, and personalizing) correlated significantly with self-reported symptoms of anxiety and self-esteem, and with maternal reports of behavior problems. Children's scores on a scale measuring positive illusions (high self-regard, illusion of personal control, and optimism for the future) correlated significantly with less self-reported aggression. Both appraisal types accounted for variance in some measures of symptomatology beyond that explained by actual events. There was no significant association between children's negative cognitive errors and positive illusions. The implications of these results for theories of negative cognitive errors and of positive illusions, as well as for future research, are discussed.

SU-E-J-15: Automatically Detect Patient Treatment Position and Orientation in KV Portal Images

International Nuclear Information System (INIS)

Qiu, J; Yang, D

2015-01-01

Purpose: In the course of radiation therapy, the complex information processing workflow will Result in potential errors, such as incorrect or inaccurate patient setups. With automatic image check and patient identification, such errors could be effectively reduced. For this purpose, we developed a simple and rapid image processing method, to automatically detect the patient position and orientation in 2D portal images, so to allow automatic check of positions and orientations for patient daily RT treatments. Methods: Based on the principle of portal image formation, a set of whole body DRR images were reconstructed from multiple whole body CT volume datasets, and fused together to be used as the matching template. To identify the patient setup position and orientation shown in a 2D portal image, the 2D portal image was preprocessed (contrast enhancement, down-sampling and couch table detection), then matched to the template image so to identify the laterality (left or right), position, orientation and treatment site. Results: Five day’s clinical qualified portal images were gathered randomly, then were processed by the automatic detection and matching method without any additional information. The detection results were visually checked by physicists. 182 images were correct detection in a total of 200kV portal images. The correct rate was 91%. Conclusion: The proposed method can detect patient setup and orientation quickly and automatically. It only requires the image intensity information in KV portal images. This method can be useful in the framework of Electronic Chart Check (ECCK) to reduce the potential errors in workflow of radiation therapy and so to improve patient safety. In addition, the auto-detection results, as the patient treatment site position and patient orientation, could be useful to guide the sequential image processing procedures, e.g. verification of patient daily setup accuracy. This work was partially supported by research grant from

SU-E-J-15: Automatically Detect Patient Treatment Position and Orientation in KV Portal Images

Energy Technology Data Exchange (ETDEWEB)

Qiu, J [Washington University in St Louis, Taian, Shandong (China); Yang, D [Washington University School of Medicine, St Louis, MO (United States)

2015-06-15

Purpose: In the course of radiation therapy, the complex information processing workflow will Result in potential errors, such as incorrect or inaccurate patient setups. With automatic image check and patient identification, such errors could be effectively reduced. For this purpose, we developed a simple and rapid image processing method, to automatically detect the patient position and orientation in 2D portal images, so to allow automatic check of positions and orientations for patient daily RT treatments. Methods: Based on the principle of portal image formation, a set of whole body DRR images were reconstructed from multiple whole body CT volume datasets, and fused together to be used as the matching template. To identify the patient setup position and orientation shown in a 2D portal image, the 2D portal image was preprocessed (contrast enhancement, down-sampling and couch table detection), then matched to the template image so to identify the laterality (left or right), position, orientation and treatment site. Results: Five day’s clinical qualified portal images were gathered randomly, then were processed by the automatic detection and matching method without any additional information. The detection results were visually checked by physicists. 182 images were correct detection in a total of 200kV portal images. The correct rate was 91%. Conclusion: The proposed method can detect patient setup and orientation quickly and automatically. It only requires the image intensity information in KV portal images. This method can be useful in the framework of Electronic Chart Check (ECCK) to reduce the potential errors in workflow of radiation therapy and so to improve patient safety. In addition, the auto-detection results, as the patient treatment site position and patient orientation, could be useful to guide the sequential image processing procedures, e.g. verification of patient daily setup accuracy. This work was partially supported by research grant from

Mixing of multi-modal images for conformational radiotherapy: application to patient re positioning

International Nuclear Information System (INIS)

Vassal, P.

1998-01-01

This study shows a procedure of patient re positioning by comparative evaluation between the position of the patient and the theoretical expected position of the patient; the stagger between the two information gives the error of installation in translation and rotation. A correction is calculated and applied to the treatment environment (position and orientation of the patient, position and orientation of the irradiation source). The control system allows to determine the precise position of the tumor volume. The echography allows to determine the position of an organ.The surface captor is used to localize the tumors of the face or of the brain, with the respect to the face, the acquisition and the treatment of information take only few minutes. The X rays imager is applied for the localization of bones structures. (N.C.)

Influence of chronic neck pain on cervical joint position error (JPE): Comparison between young and elderly subjects.

Science.gov (United States)

Alahmari, Khalid A; Reddy, Ravi Shankar; Silvian, Paul; Ahmad, Irshad; Nagaraj, Venkat; Mahtab, Mohammad

2017-11-06

Evaluation of cervical joint position sense in subjects with chronic neck pain has gained importance in recent times. Different authors have established increased joint position error (JPE) in subjects with acute neck pain. However, there is a paucity of studies to establish the influence of chronic neck pain on cervical JPE. The objective of the study was to understand the influence of chronic neck pain on cervical JPE, and to examine the differences in cervical JPE between young and elderly subjects with chronic neck pain. Forty-two chronic neck pain patients (mean age 47.4) were compared for cervical JPE with 42 age-matched healthy subjects (mean age 47.8), using a digital inclinometer. The cervical JPE were measured in flexion, extension, and rotation in right and left movement directions. The comparison of JPE showed significantly larger errors in subjects with chronic neck pain when compared to healthy subjects (ppain revealed no significant differences (P> 0.05) in cervical JPE. Cervical joint position sense is impaired in subjects with chronic neck pain.

Errors in laboratory medicine: practical lessons to improve patient safety.

Science.gov (United States)

Howanitz, Peter J

2005-10-01

Patient safety is influenced by the frequency and seriousness of errors that occur in the health care system. Error rates in laboratory practices are collected routinely for a variety of performance measures in all clinical pathology laboratories in the United States, but a list of critical performance measures has not yet been recommended. The most extensive databases describing error rates in pathology were developed and are maintained by the College of American Pathologists (CAP). These databases include the CAP's Q-Probes and Q-Tracks programs, which provide information on error rates from more than 130 interlaboratory studies. To define critical performance measures in laboratory medicine, describe error rates of these measures, and provide suggestions to decrease these errors, thereby ultimately improving patient safety. A review of experiences from Q-Probes and Q-Tracks studies supplemented with other studies cited in the literature. Q-Probes studies are carried out as time-limited studies lasting 1 to 4 months and have been conducted since 1989. In contrast, Q-Tracks investigations are ongoing studies performed on a yearly basis and have been conducted only since 1998. Participants from institutions throughout the world simultaneously conducted these studies according to specified scientific designs. The CAP has collected and summarized data for participants about these performance measures, including the significance of errors, the magnitude of error rates, tactics for error reduction, and willingness to implement each of these performance measures. A list of recommended performance measures, the frequency of errors when these performance measures were studied, and suggestions to improve patient safety by reducing these errors. Error rates for preanalytic and postanalytic performance measures were higher than for analytic measures. Eight performance measures were identified, including customer satisfaction, test turnaround times, patient identification

Impact of habitat-specific GPS positional error on detection of movement scales by first-passage time analysis.

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David M Williams

Full Text Available Advances in animal tracking technologies have reduced but not eliminated positional error. While aware of such inherent error, scientists often proceed with analyses that assume exact locations. The results of such analyses then represent one realization in a distribution of possible outcomes. Evaluating results within the context of that distribution can strengthen or weaken our confidence in conclusions drawn from the analysis in question. We evaluated the habitat-specific positional error of stationary GPS collars placed under a range of vegetation conditions that produced a gradient of canopy cover. We explored how variation of positional error in different vegetation cover types affects a researcher's ability to discern scales of movement in analyses of first-passage time for white-tailed deer (Odocoileus virginianus. We placed 11 GPS collars in 4 different vegetative canopy cover types classified as the proportion of cover above the collar (0-25%, 26-50%, 51-75%, and 76-100%. We simulated the effect of positional error on individual movement paths using cover-specific error distributions at each location. The different cover classes did not introduce any directional bias in positional observations (1 m≤mean≤6.51 m, 0.24≤p≤0.47, but the standard deviation of positional error of fixes increased significantly with increasing canopy cover class for the 0-25%, 26-50%, 51-75% classes (SD = 2.18 m, 3.07 m, and 4.61 m, respectively and then leveled off in the 76-100% cover class (SD = 4.43 m. We then added cover-specific positional errors to individual deer movement paths and conducted first-passage time analyses on the noisy and original paths. First-passage time analyses were robust to habitat-specific error in a forest-agriculture landscape. For deer in a fragmented forest-agriculture environment, and species that move across similar geographic extents, we suggest that first-passage time analysis is robust with regard to

Residual setup errors caused by rotation and non-rigid motion in prone-treated cervical cancer patients after online CBCT image-guidance

International Nuclear Information System (INIS)

Ahmad, Rozilawati; Hoogeman, Mischa S.; Quint, Sandra; Mens, Jan Willem; Osorio, Eliana M. Vásquez; Heijmen, Ben J.M.

2012-01-01

Purpose: To quantify the impact of uncorrected or partially corrected pelvis rotation and spine bending on region-specific residual setup errors in prone-treated cervical cancer patients. Methods and materials: Fifteen patients received an in-room CBCT scan twice a week. CBCT scans were registered to the planning CT-scan using a pelvic clip box and considering both translations and rotations. For daily correction of the detected translational pelvis setup errors by couch shifts, residual setup errors were determined for L5, L4 and seven other points of interest (POIs). The same was done for a procedure with translational corrections and limited rotational correction (±3°) by a 6D positioning device. Results: With translational correction only, residual setup errors were large especially for L5/L4 in AP direction (Σ = 5.1/5.5 mm). For the 7 POIs the residual setup errors ranged from 1.8 to 5.6 mm (AP). Using the 6D positioning device, the errors were substantially smaller (for L5/L4 in AP direction Σ = 2.7/2.2 mm). Using this device, the percentage of fractions with a residual AP displacement for L4 > 5 mm reduced from 47% to 9%. Conclusions: Setup variations caused by pelvis rotations are large and cannot be ignored in prone treatment of cervical cancer patients. Corrections with a 6D positioning device may considerably reduce resulting setup errors, but the residual setup errors should still be accounted for by appropriate CTV-to-PTV margins.

Error or "act of God"? A study of patients' and operating room team members' perceptions of error definition, reporting, and disclosure.

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Espin, Sherry; Levinson, Wendy; Regehr, Glenn; Baker, G Ross; Lingard, Lorelei

2006-01-01

Calls abound for a culture change in health care to improve patient safety. However, effective change cannot proceed without a clear understanding of perceptions and beliefs about error. In this study, we describe and compare operative team members' and patients' perceptions of error, reporting of error, and disclosure of error. Thirty-nine interviews of team members (9 surgeons, 9 nurses, 10 anesthesiologists) and patients (11) were conducted at 2 teaching hospitals using 4 scenarios as prompts. Transcribed responses to open questions were analyzed by 2 researchers for recurrent themes using the grounded-theory method. Yes/no answers were compared across groups using chi-square analyses. Team members and patients agreed on what constitutes an error. Deviation from standards and negative outcome were emphasized as definitive features. Patients and nurse professionals differed significantly in their perception of whether errors should be reported. Nurses were willing to report only events within their disciplinary scope of practice. Although most patients strongly advocated full disclosure of errors (what happened and how), team members preferred to disclose only what happened. When patients did support partial disclosure, their rationales varied from that of team members. Both operative teams and patients define error in terms of breaking the rules and the concept of "no harm no foul." These concepts pose challenges for treating errors as system failures. A strong culture of individualism pervades nurses' perception of error reporting, suggesting that interventions are needed to foster collective responsibility and a constructive approach to error identification.

Coordinated joint motion control system with position error correction

Science.gov (United States)

Danko, George L.

2016-04-05

Disclosed are an articulated hydraulic machine supporting, control system and control method for same. The articulated hydraulic machine has an end effector for performing useful work. The control system is capable of controlling the end effector for automated movement along a preselected trajectory. The control system has a position error correction system to correct discrepancies between an actual end effector trajectory and a desired end effector trajectory. The correction system can employ one or more absolute position signals provided by one or more acceleration sensors supported by one or more movable machine elements. Good trajectory positioning and repeatability can be obtained. A two joystick controller system is enabled, which can in some cases facilitate the operator's task and enhance their work quality and productivity.

Nonlinear control of ships minimizing the position tracking errors

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Svein P. Berge

1999-07-01

Full Text Available In this paper, a nonlinear tracking controller with integral action for ships is presented. The controller is based on state feedback linearization. Exponential convergence of the vessel-fixed position and velocity errors are proven by using Lyapunov stability theory. Since we only have two control devices, a rudder and a propeller, we choose to control the longship and the sideship position errors to zero while the heading is stabilized indirectly. A Virtual Reference Point (VRP is defined at the bow or ahead of the ship. The VRP is used for tracking control. It is shown that the distance from the center of rotation to the VRP will influence on the stability of the zero dynamics. By selecting the VRP at the bow or even ahead of the bow, the damping in yaw can be increased and the zero dynamics is stabilized. Hence, the heading angle will be less sensitive to wind, currents and waves. The control law is simulated by using a nonlinear model of the Japanese training ship Shiojimaru with excellent results. Wind forces are added to demonstrate the robustness and performance of the integral controller.

Three-dimensional planning and use of patient-specific guides improve glenoid component position: an in vitro study.

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Walch, Gilles; Vezeridis, Peter S; Boileau, Pascal; Deransart, Pierric; Chaoui, Jean

2015-02-01

Glenoid component positioning is a key factor for success in total shoulder arthroplasty. Three-dimensional (3D) measurements of glenoid retroversion, inclination, and humeral head subluxation are helpful tools for preoperative planning. The purpose of this study was to assess the reliability and precision of a novel surgical method for placing the glenoid component with use of patient-specific templates created by preoperative surgical planning and 3D modeling. A preoperative computed tomography examination of cadaveric scapulae (N = 18) was performed. The glenoid implants were virtually placed, and patient-specific guides were created to direct the guide pin into the desired orientation and position in the glenoid. The 3D orientation and position of the guide pin were evaluated by performing a postoperative computed tomography scan for each scapula. The differences between the preoperative planning and the achieved result were analyzed. The mean error in 3D orientation of the guide pin was 2.39°, the mean entry point position error was 1.05 mm, and the mean inclination angle error was 1.42°. The average error in the version angle was 1.64°. There were no technical difficulties or complications related to use of patient-specific guides for guide pin placement. Quantitative analysis of guide pin positioning demonstrated a good correlation between preoperative planning and the achieved position of the guide pin. This study demonstrates the reliability and precision of preoperative planning software and patient-specific guides for glenoid component placement in total shoulder arthroplasty. Copyright © 2015. Published by Elsevier Inc.

Evaluation of rotational set-up errors in patients with thoracic neoplasms

International Nuclear Information System (INIS)

Wang Yanyang; Fu Xiaolong; Xia Bing; Fan Min; Yang Huanjun; Ren Jun; Xu Zhiyong; Jiang Guoliang

2010-01-01

Objective: To assess the rotational set-up errors in patients with thoracic neoplasms. Methods: 224 kilovoltage cone-beam computed tomography (KVCBCT) scans from 20 thoracic tumor patients were evaluated retrospectively. All these patients were involved in the research of 'Evaluation of the residual set-up error for online kilovoltage cone-beam CT guided thoracic tumor radiation'. Rotational set-up errors, including pitch, roll and yaw, were calculated by 'aligning the KVCBCT with the planning CT, using the semi-automatic alignment method. Results: The average rotational set-up errors were -0.28 degree ±1.52 degree, 0.21 degree ± 0.91 degree and 0.27 degree ± 0.78 degree in the left-fight, superior-inferior and anterior-posterior axis, respectively. The maximal rotational errors of pitch, roll and yaw were 3.5 degree, 2.7 degree and 2.2 degree, respectively. After correction for translational set-up errors, no statistically significant changes in rotational error were observed. Conclusions: The rotational set-up errors in patients with thoracic neoplasms were all small in magnitude. Rotational errors may not change after the correction for translational set-up errors alone, which should be evaluated in a larger sample future. (authors)

Patient positioning in radiotherapy based on surface imaging using time of flight cameras

Energy Technology Data Exchange (ETDEWEB)

Gilles, M., E-mail: marlene.gilles@univ-brest.fr; Fayad, H.; Clement, J. F.; Bert, J.; Visvikis, D. [INSERM, UMR 1101, LaTIM, Brest 29609 (France); Miglierini, P. [Academic Radiotherapy Department, CHRU Morvan, Brest 29200 (France); Scheib, S. [Varian Medical Systems Imaging Laboratory GmbH, Baden-Daettwil 5405 (Switzerland); Cozzi, L. [Radiotherapy and Radiosurgery Department, Instituto Clinico Humanitas, Rozzano 20089 (Italy); Boussion, N.; Schick, U.; Pradier, O. [INSERM, UMR 1101, LaTIM, Brest 29609, France and Academic Radiotherapy Department, CHRU Morvan, Brest 29200 (France)

2016-08-15

Purpose: To evaluate the patient positioning accuracy in radiotherapy using a stereo-time of flight (ToF)-camera system. Methods: A system using two ToF cameras was used to scan the surface of the patients in order to position them daily on the treatment couch. The obtained point clouds were registered to (a) detect translations applied to the table (intrafraction motion) and (b) predict the displacement to be applied in order to place the patient in its reference position (interfraction motion). The measures provided by this system were compared to the effectively applied translations. The authors analyzed 150 fractions including lung, pelvis/prostate, and head and neck cancer patients. Results: The authors obtained small absolute errors for displacement detection: 0.8 ± 0.7, 0.8 ± 0.7, and 0.7 ± 0.6 mm along the vertical, longitudinal, and lateral axes, respectively, and 0.8 ± 0.7 mm for the total norm displacement. Lung cancer patients presented the largest errors with a respective mean of 1.1 ± 0.9, 0.9 ± 0.9, and 0.8 ± 0.7 mm. Conclusions: The proposed stereo-ToF system allows for sufficient accuracy and faster patient repositioning in radiotherapy. Its capability to track the complete patient surface in real time could allow, in the future, not only for an accurate positioning but also a real time tracking of any patient intrafraction motion (translation, involuntary, and breathing).

Disclosing harmful medical errors to patients: tackling three tough cases.

Science.gov (United States)

Gallagher, Thomas H; Bell, Sigall K; Smith, Kelly M; Mello, Michelle M; McDonald, Timothy B

2009-09-01

A gap exists between recommendations to disclose errors to patients and current practice. This gap may reflect important, yet unanswered questions about implementing disclosure principles. We explore some of these unanswered questions by presenting three real cases that pose challenging disclosure dilemmas. The first case involves a pancreas transplant that failed due to the pancreas graft being discarded, an error that was not disclosed partly because the family did not ask clarifying questions. Relying on patient or family questions to determine the content of disclosure is problematic. We propose a standard of materiality that can help clinicians to decide what information to disclose. The second case involves a fatal diagnostic error that the patient's widower was unaware had happened. The error was not disclosed out of concern that disclosure would cause the widower more harm than good. This case highlights how institutions can overlook patients' and families' needs following errors and emphasizes that benevolent deception has little role in disclosure. Institutions should consider whether involving neutral third parties could make disclosures more patient centered. The third case presents an intraoperative cardiac arrest due to a large air embolism where uncertainty around the clinical event was high and complicated the disclosure. Uncertainty is common to many medical errors but should not deter open conversations with patients and families about what is and is not known about the event. Continued discussion within the medical profession about applying disclosure principles to real-world cases can help to better meet patients' and families' needs following medical errors.

Characterization of positional errors and their influence on micro four-point probe measurements on a 100 nm Ru film

DEFF Research Database (Denmark)

Kjær, Daniel; Hansen, Ole; Østerberg, Frederik Westergaard

2015-01-01

Thin-film sheet resistance measurements at high spatial resolution and on small pads are important and can be realized with micrometer-scale four-point probes. As a result of the small scale the measurements are affected by electrode position errors. We have characterized the electrode position...... errors in measurements on Ru thin film using an Au-coated 12-point probe. We show that the standard deviation of the static electrode position error is on the order of 5 nm, which significantly affects the results of single configuration measurements. Position-error-corrected dual......-configuration measurements, however, are shown to eliminate the effect of position errors to a level limited either by electrical measurement noise or dynamic position errors. We show that the probe contact points remain almost static on the surface during the measurements (measured on an atomic scale) with a standard...

Error Analysis System for Spacecraft Navigation Using the Global Positioning System (GPS)

Science.gov (United States)

Truong, S. H.; Hart, R. C.; Hartman, K. R.; Tomcsik, T. L.; Searl, J. E.; Bernstein, A.

1997-01-01

The Flight Dynamics Division (FDD) at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) is currently developing improved space-navigation filtering algorithms to use the Global Positioning System (GPS) for autonomous real-time onboard orbit determination. In connection with a GPS technology demonstration on the Small Satellite Technology Initiative (SSTI)/Lewis spacecraft, FDD analysts and programmers have teamed with the GSFC Guidance, Navigation, and Control Branch to develop the GPS Enhanced Orbit Determination Experiment (GEODE) system. The GEODE system consists of a Kalman filter operating as a navigation tool for estimating the position, velocity, and additional states required to accurately navigate the orbiting Lewis spacecraft by using astrodynamic modeling and GPS measurements from the receiver. A parallel effort at the FDD is the development of a GPS Error Analysis System (GEAS) that will be used to analyze and improve navigation filtering algorithms during development phases and during in-flight calibration. For GEAS, the Kalman filter theory is extended to estimate the errors in position, velocity, and other error states of interest. The estimation of errors in physical variables at regular intervals will allow the time, cause, and effect of navigation system weaknesses to be identified. In addition, by modeling a sufficient set of navigation system errors, a system failure that causes an observed error anomaly can be traced and accounted for. The GEAS software is formulated using Object Oriented Design (OOD) techniques implemented in the C++ programming language on a Sun SPARC workstation. The Phase 1 of this effort is the development of a basic system to be used to evaluate navigation algorithms implemented in the GEODE system. This paper presents the GEAS mathematical methodology, systems and operations concepts, and software design and implementation. Results from the use of the basic system to evaluate

Aerobic training in aquatic environment improves the position sense of stroke patients: A randomized clinical trial

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Flávia de Andrade e Souza Mazuchi

2018-03-01

Full Text Available Abstract AIMS (Stroke patients often present sensory-motor alterations and less aerobic capacity. Joint position sense, which is crucial for balance and gait control, is also affected in stroke patients. To compare the effect of two exercise training protocols (walking in deep water and on a treadmill on the knee position sense of stroke patients. METHODS This study was designed as a randomized controlled clinical trial. Twelve adults, who suffered a stroke at least one year prior to the start of the study, were randomly assigned to one of two groups: 1 pool group submitted to aerobic deep water walking training; and 2 the treadmill group which was submitted to aerobic walk on a treadmill. Measurements: The position sense, absolute error and variable error, of the knee joint was evaluated prior to and after nine weeks of aerobic training. RESULTS The pool group presented smaller absolute (13.9o versus 6.1o; p < 0.05 and variable (9.2o versus 3.9o; p < 0.05 errors after nine-weeks gait training than the treadmill group. CONCLUSIONS Nine-week aerobic exercise intervention in aquatic environment improved precision in the position sense of the knee joint of stroke patients, suggesting a possible application in a rehabilitation program.

Dosimetric implications of inter- and intrafractional prostate positioning errors during tomotherapy : Comparison of gold marker-based registrations with native MVCT.

Science.gov (United States)

Wust, Peter; Joswig, Marc; Graf, Reinhold; Böhmer, Dirk; Beck, Marcus; Barelkowski, Thomasz; Budach, Volker; Ghadjar, Pirus

2017-09-01

For high-dose radiation therapy (RT) of prostate cancer, image-guided (IGRT) and intensity-modulated RT (IMRT) approaches are standard. Less is known regarding comparisons of different IGRT techniques and the resulting residual errors, as well as regarding their influences on dose distributions. A total of 58 patients who received tomotherapy-based RT up to 84 Gy for high-risk prostate cancer underwent IGRT based either on daily megavoltage CT (MVCT) alone (n = 43) or the additional use of gold markers (n = 15) under routine conditions. Planned Adaptive (Accuray Inc., Madison, WI, USA) software was used for elaborated offline analysis to quantify residual interfractional prostate positioning errors, along with systematic and random errors and the resulting safety margins after both IGRT approaches. Dosimetric parameters for clinical target volume (CTV) coverage and exposition of organs at risk (OAR) were also analyzed and compared. Interfractional as well as intrafractional displacements were determined. Particularly in the vertical direction, residual interfractional positioning errors were reduced using the gold marker-based approach, but dosimetric differences were moderate and the clinical relevance relatively small. Intrafractional prostate motion proved to be quite high, with displacements of 1-3 mm; however, these did not result in additional dosimetric impairments. Residual interfractional positioning errors were reduced using gold marker-based IGRT; however, this resulted in only slightly different final dose distributions. Therefore, daily MVCT-based IGRT without markers might be a valid alternative.

Early math and reading achievement are associated with the error positivity

Directory of Open Access Journals (Sweden)

Matthew H. Kim

2016-12-01

Full Text Available Executive functioning (EF and motivation are associated with academic achievement and error-related ERPs. The present study explores whether early academic skills predict variability in the error-related negativity (ERN and error positivity (Pe. Data from 113 three- to seven-year-old children in a Go/No-Go task revealed that stronger early reading and math skills predicted a larger Pe. Closer examination revealed that this relation was quadratic and significant for children performing at or near grade level, but not significant for above-average achievers. Early academics did not predict the ERN. These findings suggest that the Pe – which reflects individual differences in motivational processes as well as attention – may be associated with early academic achievement.

Rotational patient setup errors in IGRT with XVI system in Elekta Synergy and their clinical relevance

International Nuclear Information System (INIS)

Madhusudhana Sresty, N.V.N.; Muralidhar, K.R.; Raju, A.K.; Sha, R.L.; Ramanjappa

2008-01-01

The goal of Image Guided Radiotherapy (IGRT) is to improve the accuracy of treatment delivery. In this technique, it is possible to get volumetric images of patient anatomy before delivery of treatment.XVI( release 3.5) system in Elekta Synergy linear accelerator (Elekta,Crawley,UK) has the potential to ensure that, the relative positions of the target volume is same as in the treatment plan. It involves acquiring planar images produced by a kilo Voltage cone beam rotating about the patient in the treatment position. After 3 dimensional match between reference and localization images, the system gives rotational errors also along with translational shifts. One can easily perform translational shifts with treatment couch. But rotational shifts cannot be performed. Most of the studies dealt with translational shifts only. Few studies reported regarding rotational errors. It is found that in the treatment of elongated targets, even small rotational errors can show difference in results. The main objectives of this study is 1) To verify the magnitude of rotational errors in different clinical sites observed and to compare with the other reports. 2) To find its clinical relevance 3) To find difference in rotational shift results with improper selection of kV collimator

Sensorless SPMSM Position Estimation Using Position Estimation Error Suppression Control and EKF in Wide Speed Range

Directory of Open Access Journals (Sweden)

Zhanshan Wang

2014-01-01

Full Text Available The control of a high performance alternative current (AC motor drive under sensorless operation needs the accurate estimation of rotor position. In this paper, one method of accurately estimating rotor position by using both motor complex number model based position estimation and position estimation error suppression proportion integral (PI controller is proposed for the sensorless control of the surface permanent magnet synchronous motor (SPMSM. In order to guarantee the accuracy of rotor position estimation in the flux-weakening region, one scheme of identifying the permanent magnet flux of SPMSM by extended Kalman filter (EKF is also proposed, which formed the effective combination method to realize the sensorless control of SPMSM with high accuracy. The simulation results demonstrated the validity and feasibility of the proposed position/speed estimation system.

Frecuencia de errores de los pacientes con su medicación Frequency of medication errors by patients

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José Joaquín Mira

2012-02-01

Full Text Available OBJETIVO: Analizar la frecuencia de errores de medicación que son cometidos e informados por los pacientes. MÉTODOS: Estudio descriptivo basado en encuestas telefónicas a una muestra aleatoria de pacientes adultos del nivel primario de salud del sistema público español. Respondieron un total de 1 247 pacientes (tasa de respuesta, 75%. El 63% eran mujeres y 29% eran mayores de 70 años. RESULTADOS: Mientras 37 pacientes (3%, IC 95%: 2-4 sufrieron complicaciones asociadas a la medicación en el curso del tratamiento, 241 (19,4%, IC 95%: 17-21 informaron haber cometido algún error con la medicación. Un menor tiempo de consulta (P OBJECTIVE: Analyze the frequency of medication errors committed and reported by patients. METHODS: Descriptive study based on a telephone survey of a random sample of adult patients from the primary care level of the Spanish public health care system. A total of 1 247 patients responded (75% response rate; 63% were women and 29% were older than 70 years. RESULTS: While 37 patients (3%, 95% CI: 2-4 experienced complications associated with medication in the course of treatment, 241 (19.4%, 95% CI: 17-21 reported having made some mistake with their medication. A shorter consultation time (P < 0.01 and a worse assessment of the information provided by the physician (P < 0.01 were associated with the fact that during pharmacy dispensing the patient was told that the prescribed treatment was not appropriate. CONCLUSIONS: In addition to the known risks of an adverse event due to a health intervention resulting from a system or practitioner error, there are risks associated with patient errors in the self-administration of medication. Patients who were unsatisfied with the information provided by the physician reported a greater number of errors.

SU-E-P-36: Evaluation of MLC Positioning Errors in Dynamic IMRT Treatments by Analyzing Dynalog Files

International Nuclear Information System (INIS)

Olasolo, J; Pellejero, S; Gracia, M; Gallardo, N; Martin, M; Lozares, S; Maneru, F; Bragado, L; Miquelez, S; Rubio, A

2015-01-01

Purpose: To assess the accuracy of MLC positioning in Varian linear accelerator, in dynamic IMRT technique, from the analysis of dynalog files generated by the MLC controller. Methods: In Clinac accelerators (pre-TrueBeam technology), control system has an approximately 50ms delay (one control cycle time). Then, the system compares the measured position to the planned position corresponding to the next control cycle. As it has been confirmed by Varian technical support, this effect causes that measured positions appear in dynalogs one cycle out of phase with respect to the planned positions. Around 9000 dynalogs have been analyzed, coming from the three linear accelerators of our center (one Trilogy and two Clinac 21EX) equipped with a Millennium 120 MLC. In order to compare our results to recent publications, leaf positioning errors (RMS and 95th percentile) are calculated with and without delay effect. Dynalogs have been analyzed using a in-house Matlab software. Results: The RMS errors were 0.341, 0.339 and 0.348mm for each Linac; being the average error 0.343 mm. The 95th percentiles of the error were 0.617, 0.607 and 0.625; with an average of 0.617mm. A recent multi-institution study carried out by Kerns et al. found a mean leaf RMS error of 0.32mm and a 95th percentile error value of 0.64mm.Without delay effect, mean leaf RMS errors obtained were 0.040, 0.042 and 0.038mm for each treatment machine; being the average 0.040mm. The 95th percentile error values obtained were 0.057, 0.058 and 0.054 mm, with an average of 0.056mm. Conclusion: Results obtained for the mean leaf RMS error and the mean 95th percentile were consistent with the multi-institution study. Calculated error statistics with delay effect are significantly larger due to the speed proportional and systematic leaf offset. Consequently it is proposed to correct this effect in dynalogs analysis to determine the MLC performance

Error identification and recovery by student nurses using human patient simulation: opportunity to improve patient safety.

Science.gov (United States)

Henneman, Elizabeth A; Roche, Joan P; Fisher, Donald L; Cunningham, Helene; Reilly, Cheryl A; Nathanson, Brian H; Henneman, Philip L

2010-02-01

This study examined types of errors that occurred or were recovered in a simulated environment by student nurses. Errors occurred in all four rule-based error categories, and all students committed at least one error. The most frequent errors occurred in the verification category. Another common error was related to physician interactions. The least common errors were related to coordinating information with the patient and family. Our finding that 100% of student subjects committed rule-based errors is cause for concern. To decrease errors and improve safe clinical practice, nurse educators must identify effective strategies that students can use to improve patient surveillance. Copyright 2010 Elsevier Inc. All rights reserved.

Robust Adaptive Beamforming with Sensor Position Errors Using Weighted Subspace Fitting-Based Covariance Matrix Reconstruction.

Science.gov (United States)

Chen, Peng; Yang, Yixin; Wang, Yong; Ma, Yuanliang

2018-05-08

When sensor position errors exist, the performance of recently proposed interference-plus-noise covariance matrix (INCM)-based adaptive beamformers may be severely degraded. In this paper, we propose a weighted subspace fitting-based INCM reconstruction algorithm to overcome sensor displacement for linear arrays. By estimating the rough signal directions, we construct a novel possible mismatched steering vector (SV) set. We analyze the proximity of the signal subspace from the sample covariance matrix (SCM) and the space spanned by the possible mismatched SV set. After solving an iterative optimization problem, we reconstruct the INCM using the estimated sensor position errors. Then we estimate the SV of the desired signal by solving an optimization problem with the reconstructed INCM. The main advantage of the proposed algorithm is its robustness against SV mismatches dominated by unknown sensor position errors. Numerical examples show that even if the position errors are up to half of the assumed sensor spacing, the output signal-to-interference-plus-noise ratio is only reduced by 4 dB. Beam patterns plotted using experiment data show that the interference suppression capability of the proposed beamformer outperforms other tested beamformers.

Direct focusing error correction with ring-wide TBT beam position data

International Nuclear Information System (INIS)

Yang, M.J.

2011-01-01

Turn-By-Turn (TBT) betatron oscillation data is a very powerful tool in studying machine optics. Hundreds and thousands of turns of free oscillations are taken in just few tens of milliseconds. With beam covering all positions and angles at every location TBT data can be used to diagnose focusing errors almost instantly. This paper describes a new approach that observes focusing error collectively over all available TBT data to find the optimized quadrupole strength, one location at a time. Example will be shown and other issues will be discussed. The procedure presented clearly has helped to reduce overall deviations significantly, with relative ease. Sextupoles, being a permanent feature of the ring, will need to be incorporated into the model. While cumulative effect from all sextupoles around the ring may be negligible on turn-to-turn basis it is not so in this transfer line analysis. It should be noted that this procedure is not limited to looking for quadrupole errors. By modifying the target of minimization it could in principle be used to look for skew quadrupole errors and sextupole errors as well.

Treatment delay and radiological errors in patients with bone metastases

International Nuclear Information System (INIS)

Ichinohe, K.; Takahashi, M.; Tooyama, N.

2003-01-01

During routine investigations, we are surprised to find that therapy for bone metastases is sometimes delayed for a considerable period of time. To determine the extent of this delay and its causes, we reviewed the medical records of symptomatic patients seen at our hospital who had been recently diagnosed as having bone metastases for the last four years. The treatment delay was defined as the interval between presentation with symptoms and definitive treatment for bone metastases. The diagnostic delay was defined as the interval between presentation with symptoms and diagnosis of bone metastases. The results of diagnostic radiological examinations were also reviewed for errors. The study population included 76 males and 34 females with a median age of 66 years. Most bone metastases were diagnosed radiologically. Over 75% of patients were treated with radiotherapy. The treatment delay ranged from 2 to 307 days, with a mean of 53.3 days. In 490 radiological studies reviewed, we identified 166 (33.9%) errors concerning 62 (56.4%) patients. The diagnostic delay was significantly longer for patients with radiological errors than for patients without radiological errors (P < 0.001), and much of it was due to radiological errors. In conclusion, the treatment delay in patients with symptomatic bone metastases was much longer than expected, and much of it was caused by radiological errors. Considerable efforts should therefore be made to more carefully examine the radiological studies in order to ensure prompt treatment of bone metastases. (author)

Medical errors in hospitalized pediatric trauma patients with chronic health conditions

Directory of Open Access Journals (Sweden)

Xiaotong Liu

2014-01-01

Full Text Available Objective: This study compares medical errors in pediatric trauma patients with and without chronic conditions. Methods: The 2009 Kids’ Inpatient Database, which included 123,303 trauma discharges, was analyzed. Medical errors were identified by International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes. The medical error rates per 100 discharges and per 1000 hospital days were calculated and compared between inpatients with and without chronic conditions. Results: Pediatric trauma patients with chronic conditions experienced a higher medical error rate compared with patients without chronic conditions: 4.04 (95% confidence interval: 3.75–4.33 versus 1.07 (95% confidence interval: 0.98–1.16 per 100 discharges. The rate of medical error differed by type of chronic condition. After controlling for confounding factors, the presence of a chronic condition increased the adjusted odds ratio of medical error by 37% if one chronic condition existed (adjusted odds ratio: 1.37, 95% confidence interval: 1.21–1.5, and 69% if more than one chronic condition existed (adjusted odds ratio: 1.69, 95% confidence interval: 1.48–1.53. In the adjusted model, length of stay had the strongest association with medical error, but the adjusted odds ratio for chronic conditions and medical error remained significantly elevated even when accounting for the length of stay, suggesting that medical complexity has a role in medical error. Higher adjusted odds ratios were seen in other subgroups. Conclusion: Chronic conditions are associated with significantly higher rate of medical errors in pediatric trauma patients. Future research should evaluate interventions or guidelines for reducing the risk of medical errors in pediatric trauma patients with chronic conditions.

Decreasing patient identification band errors by standardizing processes.

Science.gov (United States)

Walley, Susan Chu; Berger, Stephanie; Harris, Yolanda; Gallizzi, Gina; Hayes, Leslie

2013-04-01

Patient identification (ID) bands are an essential component in patient ID. Quality improvement methodology has been applied as a model to reduce ID band errors although previous studies have not addressed standardization of ID bands. Our specific aim was to decrease ID band errors by 50% in a 12-month period. The Six Sigma DMAIC (define, measure, analyze, improve, and control) quality improvement model was the framework for this study. ID bands at a tertiary care pediatric hospital were audited from January 2011 to January 2012 with continued audits to June 2012 to confirm the new process was in control. After analysis, the major improvement strategy implemented was standardization of styles of ID bands and labels. Additional interventions included educational initiatives regarding the new ID band processes and disseminating institutional and nursing unit data. A total of 4556 ID bands were audited with a preimprovement ID band error average rate of 9.2%. Significant variation in the ID band process was observed, including styles of ID bands. Interventions were focused on standardization of the ID band and labels. The ID band error rate improved to 5.2% in 9 months (95% confidence interval: 2.5-5.5; P error rates. This decrease in ID band error rates was maintained over the subsequent 8 months.

Action errors, error management, and learning in organizations.

Science.gov (United States)

Frese, Michael; Keith, Nina

2015-01-03

Every organization is confronted with errors. Most errors are corrected easily, but some may lead to negative consequences. Organizations often focus on error prevention as a single strategy for dealing with errors. Our review suggests that error prevention needs to be supplemented by error management--an approach directed at effectively dealing with errors after they have occurred, with the goal of minimizing negative and maximizing positive error consequences (examples of the latter are learning and innovations). After defining errors and related concepts, we review research on error-related processes affected by error management (error detection, damage control). Empirical evidence on positive effects of error management in individuals and organizations is then discussed, along with emotional, motivational, cognitive, and behavioral pathways of these effects. Learning from errors is central, but like other positive consequences, learning occurs under certain circumstances--one being the development of a mind-set of acceptance of human error.

Performance of muon reconstruction including Alignment Position Errors for 2016 Collision Data

CERN Document Server

CMS Collaboration

2016-01-01

From 2016 Run muon reconstruction is using non-zero Alignment Position Errors to account for the residual uncertainties of muon chambers' positions. Significant improvements are obtained in particular for the startup phase after opening/closing the muon detector. Performance results are presented for real data and MC simulations, related to both the offline reconstruction and the High-Level Trigger.

Analysis of the effects of Eye-Tracker performance on the pulse positioning errors during refractive surgery

Directory of Open Access Journals (Sweden)

Samuel Arba-Mosquera

2012-01-01

Conclusions: The proposed model can be used for comparison of laser systems used for ablation processes. Due to the pseudo-random nature of eye movements, positioning errors of single pulses are much larger than observed decentrations in the clinical settings. There is no single parameter that ‘alone’ minimizes the positioning error. It is the optimal combination of the several parameters that minimizes the error. The results of this analysis are important to understand the limitations of correcting very irregular ablation patterns.

[Medication error management climate and perception for system use according to construction of medication error prevention system].

Science.gov (United States)

Kim, Myoung Soo

2012-08-01

The purpose of this cross-sectional study was to examine current status of IT-based medication error prevention system construction and the relationships among system construction, medication error management climate and perception for system use. The participants were 124 patient safety chief managers working for 124 hospitals with over 300 beds in Korea. The characteristics of the participants, construction status and perception of systems (electric pharmacopoeia, electric drug dosage calculation system, computer-based patient safety reporting and bar-code system) and medication error management climate were measured in this study. The data were collected between June and August 2011. Descriptive statistics, partial Pearson correlation and MANCOVA were used for data analysis. Electric pharmacopoeia were constructed in 67.7% of participating hospitals, computer-based patient safety reporting systems were constructed in 50.8%, electric drug dosage calculation systems were in use in 32.3%. Bar-code systems showed up the lowest construction rate at 16.1% of Korean hospitals. Higher rates of construction of IT-based medication error prevention systems resulted in greater safety and a more positive error management climate prevailed. The supportive strategies for improving perception for use of IT-based systems would add to system construction, and positive error management climate would be more easily promoted.

The Impact of a Patient Safety Program on Medical Error Reporting

Science.gov (United States)

2005-05-01

307 The Impact of a Patient Safety Program on Medical Error Reporting Donald R. Woolever Abstract Background: In response to the occurrence of...a sentinel event—a medical error with serious consequences—Eglin U.S. Air Force (USAF) Regional Hospital developed and implemented a patient safety...communication, teamwork, and reporting. Objective: To determine the impact of a patient safety program on patterns of medical error reporting. Methods: This

Antiretroviral medication prescribing errors are common with hospitalization of HIV-infected patients.

Science.gov (United States)

Commers, Tessa; Swindells, Susan; Sayles, Harlan; Gross, Alan E; Devetten, Marcel; Sandkovsky, Uriel

2014-01-01

Errors in prescribing antiretroviral therapy (ART) often occur with the hospitalization of HIV-infected patients. The rapid identification and prevention of errors may reduce patient harm and healthcare-associated costs. A retrospective review of hospitalized HIV-infected patients was carried out between 1 January 2009 and 31 December 2011. Errors were documented as omission, underdose, overdose, duplicate therapy, incorrect scheduling and/or incorrect therapy. The time to error correction was recorded. Relative risks (RRs) were computed to evaluate patient characteristics and error rates. A total of 289 medication errors were identified in 146/416 admissions (35%). The most common was drug omission (69%). At an error rate of 31%, nucleoside reverse transcriptase inhibitors were associated with an increased risk of error when compared with protease inhibitors (RR 1.32; 95% CI 1.04-1.69) and co-formulated drugs (RR 1.59; 95% CI 1.19-2.09). Of the errors, 31% were corrected within the first 24 h, but over half (55%) were never remedied. Admissions with an omission error were 7.4 times more likely to have all errors corrected within 24 h than were admissions without an omission. Drug interactions with ART were detected on 51 occasions. For the study population (n = 177), an increased risk of admission error was observed for black (43%) compared with white (28%) individuals (RR 1.53; 95% CI 1.16-2.03) but no significant differences were observed between white patients and other minorities or between men and women. Errors in inpatient ART were common, and the majority were never detected. The most common errors involved omission of medication, and nucleoside reverse transcriptase inhibitors had the highest rate of prescribing error. Interventions to prevent and correct errors are urgently needed.

Medication errors : the impact of prescribing and transcribing errors on preventable harm in hospitalised patients

NARCIS (Netherlands)

van Doormaal, J.E.; van der Bemt, P.M.L.A.; Mol, P.G.M.; Egberts, A.C.G.; Haaijer-Ruskamp, F.M.; Kosterink, J.G.W.; Zaal, Rianne J.

Background: Medication errors (MEs) affect patient safety to a significant extent. Because these errors can lead to preventable adverse drug events (pADEs), it is important to know what type of ME is the most prevalent cause of these pADEs. This study determined the impact of the various types of

Patient safety in the clinical laboratory: a longitudinal analysis of specimen identification errors.

Science.gov (United States)

Wagar, Elizabeth A; Tamashiro, Lorraine; Yasin, Bushra; Hilborne, Lee; Bruckner, David A

2006-11-01

Patient safety is an increasingly visible and important mission for clinical laboratories. Attention to improving processes related to patient identification and specimen labeling is being paid by accreditation and regulatory organizations because errors in these areas that jeopardize patient safety are common and avoidable through improvement in the total testing process. To assess patient identification and specimen labeling improvement after multiple implementation projects using longitudinal statistical tools. Specimen errors were categorized by a multidisciplinary health care team. Patient identification errors were grouped into 3 categories: (1) specimen/requisition mismatch, (2) unlabeled specimens, and (3) mislabeled specimens. Specimens with these types of identification errors were compared preimplementation and postimplementation for 3 patient safety projects: (1) reorganization of phlebotomy (4 months); (2) introduction of an electronic event reporting system (10 months); and (3) activation of an automated processing system (14 months) for a 24-month period, using trend analysis and Student t test statistics. Of 16,632 total specimen errors, mislabeled specimens, requisition mismatches, and unlabeled specimens represented 1.0%, 6.3%, and 4.6% of errors, respectively. Student t test showed a significant decrease in the most serious error, mislabeled specimens (P patient safety projects. Trend analysis demonstrated decreases in all 3 error types for 26 months. Applying performance-improvement strategies that focus longitudinally on specimen labeling errors can significantly reduce errors, therefore improving patient safety. This is an important area in which laboratory professionals, working in interdisciplinary teams, can improve safety and outcomes of care.

Consonant acquisition: a first approach to the distribution of errors in four positions in the word

Directory of Open Access Journals (Sweden)

Silvia Llach

2012-12-01

Full Text Available The goal of this study is to describe the behavior of errors in two types of onsets (initial and intervocalic and two types of codas (in the middle and end of the word in order to determine if any of these positions are more prone to specific types of errors than the others.We have looked into the errors that are frequently produced in these four contexts during the acquisition of consonant sounds in the Catalan language. The data were taken from a study on the acquisition of consonants in Catalan, carried out on 90 children between the ages of 3 and 5 years from several kindergarten schools. The results do show that there are characteristic errors depending on the position within the word.

Positional accommodative intraocular lens power error induced by the estimation of the corneal power and the effective lens position

Directory of Open Access Journals (Sweden)

David P Piñero

2015-01-01

Full Text Available Purpose: To evaluate the predictability of the refractive correction achieved with a positional accommodating intraocular lenses (IOL and to develop a potential optimization of it by minimizing the error associated with the keratometric estimation of the corneal power and by developing a predictive formula for the effective lens position (ELP. Materials and Methods: Clinical data from 25 eyes of 14 patients (age range, 52-77 years and undergoing cataract surgery with implantation of the accommodating IOL Crystalens HD (Bausch and Lomb were retrospectively reviewed. In all cases, the calculation of an adjusted IOL power (P IOLadj based on Gaussian optics considering the residual refractive error was done using a variable keratometric index value (n kadj for corneal power estimation with and without using an estimation algorithm for ELP obtained by multiple regression analysis (ELP adj . P IOLadj was compared to the real IOL power implanted (P IOLReal , calculated with the SRK-T formula and also to the values estimated by the Haigis, HofferQ, and Holladay I formulas. Results: No statistically significant differences were found between P IOLReal and P IOLadj when ELP adj was used (P = 0.10, with a range of agreement between calculations of 1.23 D. In contrast, P IOLReal was significantly higher when compared to P IOLadj without using ELP adj and also compared to the values estimated by the other formulas. Conclusions: Predictable refractive outcomes can be obtained with the accommodating IOL Crystalens HD using a variable keratometric index for corneal power estimation and by estimating ELP with an algorithm dependent on anatomical factors and age.

Medication Errors in Patients with Enteral Feeding Tubes in the Intensive Care Unit.

Science.gov (United States)

Sohrevardi, Seyed Mojtaba; Jarahzadeh, Mohammad Hossein; Mirzaei, Ehsan; Mirjalili, Mahtabalsadat; Tafti, Arefeh Dehghani; Heydari, Behrooz

2017-01-01

Most patients admitted to Intensive Care Units (ICU) have problems in using oral medication or ingesting solid forms of drugs. Selecting the most suitable dosage form in such patients is a challenge. The current study was conducted to assess the frequency and types of errors of oral medication administration in patients with enteral feeding tubes or suffering swallowing problems. A cross-sectional study was performed in the ICU of Shahid Sadoughi Hospital, Yazd, Iran. Patients were assessed for the incidence and types of medication errors occurring in the process of preparation and administration of oral medicines. Ninety-four patients were involved in this study and 10,250 administrations were observed. Totally, 4753 errors occurred among the studied patients. The most commonly used drugs were pantoprazole tablet, piracetam syrup, and losartan tablet. A total of 128 different types of drugs and nine different oral pharmaceutical preparations were prescribed for the patients. Forty-one (35.34%) out of 116 different solid drugs (except effervescent tablets and powders) could be substituted by liquid or injectable forms. The most common error was the wrong time of administration. Errors of wrong dose preparation and administration accounted for 24.04% and 25.31% of all errors, respectively. In this study, at least three-fourth of the patients experienced medication errors. The occurrence of these errors can greatly impair the quality of the patients' pharmacotherapy, and more attention should be paid to this issue.

Catching errors with patient-specific pretreatment machine log file analysis.

Science.gov (United States)

Rangaraj, Dharanipathy; Zhu, Mingyao; Yang, Deshan; Palaniswaamy, Geethpriya; Yaddanapudi, Sridhar; Wooten, Omar H; Brame, Scott; Mutic, Sasa

2013-01-01

A robust, efficient, and reliable quality assurance (QA) process is highly desired for modern external beam radiation therapy treatments. Here, we report the results of a semiautomatic, pretreatment, patient-specific QA process based on dynamic machine log file analysis clinically implemented for intensity modulated radiation therapy (IMRT) treatments delivered by high energy linear accelerators (Varian 2100/2300 EX, Trilogy, iX-D, Varian Medical Systems Inc, Palo Alto, CA). The multileaf collimator machine (MLC) log files are called Dynalog by Varian. Using an in-house developed computer program called "Dynalog QA," we automatically compare the beam delivery parameters in the log files that are generated during pretreatment point dose verification measurements, with the treatment plan to determine any discrepancies in IMRT deliveries. Fluence maps are constructed and compared between the delivered and planned beams. Since clinical introduction in June 2009, 912 machine log file analyses QA were performed by the end of 2010. Among these, 14 errors causing dosimetric deviation were detected and required further investigation and intervention. These errors were the result of human operating mistakes, flawed treatment planning, and data modification during plan file transfer. Minor errors were also reported in 174 other log file analyses, some of which stemmed from false positives and unreliable results; the origins of these are discussed herein. It has been demonstrated that the machine log file analysis is a robust, efficient, and reliable QA process capable of detecting errors originating from human mistakes, flawed planning, and data transfer problems. The possibility of detecting these errors is low using point and planar dosimetric measurements. Copyright © 2013 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

Per-beam, planar IMRT QA passing rates do not predict clinically relevant patient dose errors

International Nuclear Information System (INIS)

Nelms, Benjamin E.; Zhen Heming; Tome, Wolfgang A.

2011-01-01

Purpose: The purpose of this work is to determine the statistical correlation between per-beam, planar IMRT QA passing rates and several clinically relevant, anatomy-based dose errors for per-patient IMRT QA. The intent is to assess the predictive power of a common conventional IMRT QA performance metric, the Gamma passing rate per beam. Methods: Ninety-six unique data sets were created by inducing four types of dose errors in 24 clinical head and neck IMRT plans, each planned with 6 MV Varian 120-leaf MLC linear accelerators using a commercial treatment planning system and step-and-shoot delivery. The error-free beams/plans were used as ''simulated measurements'' (for generating the IMRT QA dose planes and the anatomy dose metrics) to compare to the corresponding data calculated by the error-induced plans. The degree of the induced errors was tuned to mimic IMRT QA passing rates that are commonly achieved using conventional methods. Results: Analysis of clinical metrics (parotid mean doses, spinal cord max and D1cc, CTV D95, and larynx mean) vs IMRT QA Gamma analysis (3%/3 mm, 2/2, 1/1) showed that in all cases, there were only weak to moderate correlations (range of Pearson's r-values: -0.295 to 0.653). Moreover, the moderate correlations actually had positive Pearson's r-values (i.e., clinically relevant metric differences increased with increasing IMRT QA passing rate), indicating that some of the largest anatomy-based dose differences occurred in the cases of high IMRT QA passing rates, which may be called ''false negatives.'' The results also show numerous instances of false positives or cases where low IMRT QA passing rates do not imply large errors in anatomy dose metrics. In none of the cases was there correlation consistent with high predictive power of planar IMRT passing rates, i.e., in none of the cases did high IMRT QA Gamma passing rates predict low errors in anatomy dose metrics or vice versa. Conclusions: There is a lack of correlation between

Detection of treatment setup errors between two CT scans for patients with head and neck cancer

International Nuclear Information System (INIS)

Ezzell, Leah C.; Hansen, Eric K.; Quivey, Jeanne M.; Xia Ping

2007-01-01

methods used for verifying patient positioning may misinterpret rotational shifts as translational shifts, and our study demonstrated that rotational errors may be significant in the treatment of head and neck cancer

Medication Administration Errors Involving Paediatric In-Patients in a ...

African Journals Online (AJOL)

Erah

In-Patients in a Hospital in Ethiopia. Yemisirach Feleke ... Purpose: To assess the type and frequency of medication administration errors (MAEs) in the paediatric ward of .... prescribers, does not go beyond obeying ... specialists, 43 general practitioners, 2 health officers ..... Medication Errors, International Council of Nurses.

Circular Array of Magnetic Sensors for Current Measurement: Analysis for Error Caused by Position of Conductor.

Science.gov (United States)

Yu, Hao; Qian, Zheng; Liu, Huayi; Qu, Jiaqi

2018-02-14

This paper analyzes the measurement error, caused by the position of the current-carrying conductor, of a circular array of magnetic sensors for current measurement. The circular array of magnetic sensors is an effective approach for AC or DC non-contact measurement, as it is low-cost, light-weight, has a large linear range, wide bandwidth, and low noise. Especially, it has been claimed that such structure has excellent reduction ability for errors caused by the position of the current-carrying conductor, crosstalk current interference, shape of the conduction cross-section, and the Earth's magnetic field. However, the positions of the current-carrying conductor-including un-centeredness and un-perpendicularity-have not been analyzed in detail until now. In this paper, for the purpose of having minimum measurement error, a theoretical analysis has been proposed based on vector inner and exterior product. In the presented mathematical model of relative error, the un-center offset distance, the un-perpendicular angle, the radius of the circle, and the number of magnetic sensors are expressed in one equation. The comparison of the relative error caused by the position of the current-carrying conductor between four and eight sensors is conducted. Tunnel magnetoresistance (TMR) sensors are used in the experimental prototype to verify the mathematical model. The analysis results can be the reference to design the details of the circular array of magnetic sensors for current measurement in practical situations.

Assessment of residual error for online cone-beam CT-guided treatment of prostate cancer patients

International Nuclear Information System (INIS)

Letourneau, Daniel; Martinez, Alvaro A.; Lockman, David; Yan Di; Vargas, Carlos; Ivaldi, Giovanni; Wong, John

2005-01-01

Purpose: Kilovoltage cone-beam CT (CBCT) implemented on board a medical accelerator is available for image-guidance applications in our clinic. The objective of this work was to assess the magnitude and stability of the residual setup error associated with CBCT online-guided prostate cancer patient setup. Residual error pertains to the uncertainty in image registration, the limited mechanical accuracy, and the intrafraction motion during imaging and treatment. Methods and Materials: The residual error for CBCT online-guided correction was first determined in a phantom study. After online correction, the phantom residual error was determined by comparing megavoltage portal images acquired every 90 deg. to the corresponding digitally reconstructed radiographs. In the clinical study, 8 prostate cancer patients were implanted with three radiopaque markers made of high-winding coils. After positioning the patient using the skin marks, a CBCT scan was acquired and the setup error determined by fusing the coils on the CBCT and planning CT scans. The patient setup was then corrected by moving the couch accordingly. A second CBCT scan was acquired immediately after the correction to evaluate the residual target setup error. Intrafraction motion was evaluated by tracking the coils and the bony landmarks on kilovoltage radiographs acquired every 30 s between the two CBCT scans. Corrections based on soft-tissue registration were evaluated offline by aligning the prostate contours defined on both planning CT and CBCT images. Results: For ideal rigid phantoms, CBCT image-guided treatment can usually achieve setup accuracy of 1 mm or better. For the patients, after CBCT correction, the target setup error was reduced in almost all cases and was generally within ±1.5 mm. The image guidance process took 23-35 min, dictated by the computer speed and network configuration. The contribution of the intrafraction motion to the residual setup error was small, with a standard deviation of

Relating faults in diagnostic reasoning with diagnostic errors and patient harm.

NARCIS (Netherlands)

Zwaan, L.; Thijs, A.; Wagner, C.; Wal, G. van der; Timmermans, D.R.M.

2012-01-01

Purpose: The relationship between faults in diagnostic reasoning, diagnostic errors, and patient harm has hardly been studied. This study examined suboptimal cognitive acts (SCAs; i.e., faults in diagnostic reasoning), related them to the occurrence of diagnostic errors and patient harm, and studied

[The effectiveness of error reporting promoting strategy on nurse's attitude, patient safety culture, intention to report and reporting rate].

Science.gov (United States)

Kim, Myoungsoo

2010-04-01

The purpose of this study was to examine the impact of strategies to promote reporting of errors on nurses' attitude to reporting errors, organizational culture related to patient safety, intention to report and reporting rate in hospital nurses. A nonequivalent control group non-synchronized design was used for this study. The program was developed and then administered to the experimental group for 12 weeks. Data were analyzed using descriptive analysis, X(2)-test, t-test, and ANCOVA with the SPSS 12.0 program. After the intervention, the experimental group showed significantly higher scores for nurses' attitude to reporting errors (experimental: 20.73 vs control: 20.52, F=5.483, p=.021) and reporting rate (experimental: 3.40 vs control: 1.33, F=1998.083, porganizational culture and intention to report. The study findings indicate that strategies that promote reporting of errors play an important role in producing positive attitudes to reporting errors and improving behavior of reporting. Further advanced strategies for reporting errors that can lead to improved patient safety should be developed and applied in a broad range of hospitals.

Safety coaches in radiology: decreasing human error and minimizing patient harm

Energy Technology Data Exchange (ETDEWEB)

Dickerson, Julie M.; Adams, Janet M. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, MLC 5031, Cincinnati, OH (United States); Koch, Bernadette L.; Donnelly, Lane F. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, MLC 5031, Cincinnati, OH (United States); Cincinnati Children' s Hospital Medical Center, Department of Pediatrics, Cincinnati, OH (United States); Goodfriend, Martha A. [Cincinnati Children' s Hospital Medical Center, Department of Quality Improvement, Cincinnati, OH (United States)

2010-09-15

Successful programs to improve patient safety require a component aimed at improving safety culture and environment, resulting in a reduced number of human errors that could lead to patient harm. Safety coaching provides peer accountability. It involves observing for safety behaviors and use of error prevention techniques and provides immediate feedback. For more than a decade, behavior-based safety coaching has been a successful strategy for reducing error within the context of occupational safety in industry. We describe the use of safety coaches in radiology. Safety coaches are an important component of our comprehensive patient safety program. (orig.)

Safety coaches in radiology: decreasing human error and minimizing patient harm

International Nuclear Information System (INIS)

Dickerson, Julie M.; Adams, Janet M.; Koch, Bernadette L.; Donnelly, Lane F.; Goodfriend, Martha A.

2010-01-01

Successful programs to improve patient safety require a component aimed at improving safety culture and environment, resulting in a reduced number of human errors that could lead to patient harm. Safety coaching provides peer accountability. It involves observing for safety behaviors and use of error prevention techniques and provides immediate feedback. For more than a decade, behavior-based safety coaching has been a successful strategy for reducing error within the context of occupational safety in industry. We describe the use of safety coaches in radiology. Safety coaches are an important component of our comprehensive patient safety program. (orig.)

Safety coaches in radiology: decreasing human error and minimizing patient harm.

Science.gov (United States)

Dickerson, Julie M; Koch, Bernadette L; Adams, Janet M; Goodfriend, Martha A; Donnelly, Lane F

2010-09-01

Successful programs to improve patient safety require a component aimed at improving safety culture and environment, resulting in a reduced number of human errors that could lead to patient harm. Safety coaching provides peer accountability. It involves observing for safety behaviors and use of error prevention techniques and provides immediate feedback. For more than a decade, behavior-based safety coaching has been a successful strategy for reducing error within the context of occupational safety in industry. We describe the use of safety coaches in radiology. Safety coaches are an important component of our comprehensive patient safety program.

Skull registration for prone patient position using tracked ultrasound

Science.gov (United States)

Underwood, Grace; Ungi, Tamas; Baum, Zachary; Lasso, Andras; Kronreif, Gernot; Fichtinger, Gabor

2017-03-01

PURPOSE: Tracked navigation has become prevalent in neurosurgery. Problems with registration of a patient and a preoperative image arise when the patient is in a prone position. Surfaces accessible to optical tracking on the back of the head are unreliable for registration. We investigated the accuracy of surface-based registration using points accessible through tracked ultrasound. Using ultrasound allows access to bone surfaces that are not available through optical tracking. Tracked ultrasound could eliminate the need to work (i) under the table for registration and (ii) adjust the tracker between surgery and registration. In addition, tracked ultrasound could provide a non-invasive method in comparison to an alternative method of registration involving screw implantation. METHODS: A phantom study was performed to test the feasibility of tracked ultrasound for registration. An initial registration was performed to partially align the pre-operative computer tomography data and skull phantom. The initial registration was performed by an anatomical landmark registration. Surface points accessible by tracked ultrasound were collected and used to perform an Iterative Closest Point Algorithm. RESULTS: When the surface registration was compared to a ground truth landmark registration, the average TRE was found to be 1.6+/-0.1mm and the average distance of points off the skull surface was 0.6+/-0.1mm. CONCLUSION: The use of tracked ultrasound is feasible for registration of patients in prone position and eliminates the need to perform registration under the table. The translational component of error found was minimal. Therefore, the amount of TRE in registration is due to a rotational component of error.

The Relationships Among Perceived Patients' Safety Culture, Intention to Report Errors, and Leader Coaching Behavior of Nurses in Korea: A Pilot Study.

Science.gov (United States)

Ko, YuKyung; Yu, Soyoung

2017-09-01

This study was undertaken to explore the correlations among nurses' perceptions of patient safety culture, their intention to report errors, and leader coaching behaviors. The participants (N = 289) were nurses from 5 Korean hospitals with approximately 300 to 500 beds each. Sociodemographic variables, patient safety culture, intention to report errors, and coaching behavior were measured using self-report instruments. Data were analyzed using descriptive statistics, Pearson correlation coefficient, the t test, and the Mann-Whitney U test. Nurses' perceptions of patient safety culture and their intention to report errors showed significant differences between groups of nurses who rated their leaders as high-performing or low-performing coaches. Perceived coaching behavior showed a significant, positive correlation with patient safety culture and intention to report errors, i.e., as nurses' perceptions of coaching behaviors increased, so did their ratings of patient safety culture and error reporting. There is a need in health care settings for coaching by nurse managers to provide quality nursing care and thus improve patient safety. Programs that are systematically developed and implemented to enhance the coaching behaviors of nurse managers are crucial to the improvement of patient safety and nursing care. Moreover, a systematic analysis of the causes of malpractice, as opposed to a focus on the punitive consequences of errors, could increase error reporting and therefore promote a culture in which a higher level of patient safety can thrive.

The Effect of Antenna Position Errors on Redundant-Baseline Calibration of HERA

Science.gov (United States)

Orosz, Naomi; Dillon, Joshua; Ewall-Wice, Aaron; Parsons, Aaron; HERA Collaboration

2018-01-01

HERA (the Hydrogen Epoch of Reionization Array) is a large, highly-redundant radio interferometer in South Africa currently being built out to 350 14-m dishes. Its mission is to probe large scale structure during and prior to the epoch of reionization using the 21 cm hyperfine transition of neutral hydrogen. The array is designed to be calibrated using redundant baselines of known lengths. However, the dishes can deviate from ideal positions, with errors on the order of a few centimeters. This potentially increases foreground contamination of the 21 cm power spectrum in the cleanest part of Fourier space. The calibration algorithm treats groups of baselines that should be redundant, but are not due to position errors, as if they actually are. Accurate, precise calibration is critical because the foreground signals are 100,000 times stronger than the reionization signal. We explain the origin of this effect and discuss weighting strategies to mitigate it.

Investigations on uncertainties in patient positioning for prostate treatment with EPID; Untersuchungen zur Positionierungsgenauigkeit bei Prostatakonformationsbestrahlungen mittels Portal-Imaging

Energy Technology Data Exchange (ETDEWEB)

Bakai, A.; Nuesslin, F. [Universitaetsklinik fuer Radioonkologie, Tuebingen (Germany). Abt. Medizinische Physik; Paulsen, F.; Plasswilm, L.; Bamberg, M. [Universitaetsklinik fuer Radioonkologie, Tuebingen (Germany). Abt. Strahlentherapie

2002-02-01

Background: Conformal radiotherapy techniques as used in prostate treatment allow to spare normal tissue by conforming the radiation fields to the shape of the planning target volume (PTV). To be able to fully utilize the advantages of these techniques correct patient positioning is an important prerequisite. This study employing an electronic portal imaging device (EPID) investigated the positioning uncertainties that occur in the pelvic region for different patient positioning devices. Patients and Methods: 15 patients with prostate cancer were irradiated with or without rectal balloon/pelvic mask at a linear accelerator with multileaf collimator (MLC). For each patient multiple portal images were taken from different directions and compared to the digitally reconstructed radiographs (DRRs) of the treatment planning system and to simulation films (Table 1, Figure 1). Results: In spite of different positioning devices, all patients showed comparable total positioning uncertainties of 4.0 mm (lateral), 4.5 mm (cranio-caudal) and 1.7 mm (dorso-ventral). The lateral positioning error was reduced for the pelvic mask patients while the cranio-caudal error increased (Table 2, Figure 2). A systematic and a random component sum up to the total positioning error, and a good estimate of the magnitudes of the two is possible from six to eight portal images (Figure 3). Conclusions: With a small number of portal images it is possible to find out the systematic and random positioning error of a patient. Knowledge of the random error can be used to resize the treatment margin which is clinically relevant since this error differs greatly for different patients (Figure 4). Image analysis with EPID is convenient, yet has some problems. For example, one only gets indirect information on the movement of the ventral rectum wall. The successful operation of positioning devices, although, needs further improvement - especially if one focuses on IMRT. (orig.) [German] Hintergrund

Refractive errors in presbyopic patients in Kano, Nigeria

African Journals Online (AJOL)

Annals of African Medicine, Vol. ... Information extracted includes patient's age, sex, and types of refractive error. ... All patients had basic eye examination and streak retinoscopy at two third meter working distance. ... symptoms may start earlier or later than this age .... presbyopia was associated with reduced workers'.

Nurses' Behaviors and Visual Scanning Patterns May Reduce Patient Identification Errors

Science.gov (United States)

Marquard, Jenna L.; Henneman, Philip L.; He, Ze; Jo, Junghee; Fisher, Donald L.; Henneman, Elizabeth A.

2011-01-01

Patient identification (ID) errors occurring during the medication administration process can be fatal. The aim of this study is to determine whether differences in nurses' behaviors and visual scanning patterns during the medication administration process influence their capacities to identify patient ID errors. Nurse participants (n = 20)…

SU-F-J-208: Prompt Gamma Imaging-Based Prediction of Bragg Peak Position for Realistic Treatment Error Scenarios

Energy Technology Data Exchange (ETDEWEB)

Xing, Y; Macq, B; Bondar, L [Universite catholique de Louvain, Louvain-la-Neuve (Belgium); Janssens, G [IBA, Louvain-la-Neuve (Belgium)

2016-06-15

Purpose: To quantify the accuracy in predicting the Bragg peak position using simulated in-room measurements of prompt gamma (PG) emissions for realistic treatment error scenarios that combine several sources of errors. Methods: Prompt gamma measurements by a knife-edge slit camera were simulated using an experimentally validated analytical simulation tool. Simulations were performed, for 143 treatment error scenarios, on an anthropomorphic phantom and a pencil beam scanning plan for nasal cavity. Three types of errors were considered: translation along each axis, rotation around each axis, and CT-calibration errors with magnitude ranging respectively, between −3 and 3 mm, −5 and 5 degrees, and between −5 and +5%. We investigated the correlation between the Bragg peak (BP) shift and the horizontal shift of PG profiles. The shifts were calculated between the planned (reference) position and the position by the error scenario. The prediction error for one spot was calculated as the absolute difference between the PG profile shift and the BP shift. Results: The PG shift was significantly and strongly correlated with the BP shift for 92% of the cases (p<0.0001, Pearson correlation coefficient R>0.8). Moderate but significant correlations were obtained for all cases that considered only CT-calibration errors and for 1 case that combined translation and CT-errors (p<0.0001, R ranged between 0.61 and 0.8). The average prediction errors for the simulated scenarios ranged between 0.08±0.07 and 1.67±1.3 mm (grand mean 0.66±0.76 mm). The prediction error was moderately correlated with the value of the BP shift (p=0, R=0.64). For the simulated scenarios the average BP shift ranged between −8±6.5 mm and 3±1.1 mm. Scenarios that considered combinations of the largest treatment errors were associated with large BP shifts. Conclusion: Simulations of in-room measurements demonstrate that prompt gamma profiles provide reliable estimation of the Bragg peak position for

Initial clinical experience with infrared-reflecting skin markers in the positioning of patients treated by conformal radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Soete, Guy; Steene, Jan van de; Verellen, Dirk; Vinh-Hung, Vincent; Berge, Dirk van den; Michielsen, Dirk; Keuppens, Frans; Roover, Patricia de; Storme, Guy

2002-01-01

Purpose: To evaluate an infrared (IR) marker-based positioning system in patients receiving conformal radiotherapy for prostate cancer. Methods and materials: During 553 treatments, the ability of the IR system to automatically position the isocenter was recorded. Setup errors were measured by means of orthogonal verification films and compared to conventional positioning (using skin drawings and lasers) in 184 treatments. Results: The standard deviation of anteroposterior (AP) and lateral setup errors was significantly reduced with IR marker positioning compared to conventional: 2 vs. 4.8 mm AP (p<0.01) and 1.6 vs. 3.5 mm laterally (p<0.01). Longitudinally, the difference was not significant (3.5 vs. 3.0 mm). Systematic errors were on the average smaller AP and laterally for the IR method: 4.1 vs. 7.8 mm AP (p=0.01) and 3.1 vs. 5.6 mm lateral (p=0.07). Longitudinally, the IR system resulted in somewhat larger systematic errors: 5.0 vs. 3.4 mm for conventional positioning (p=0.03). The use of an off-line correction protocol, based on the average deviation measured over the first four fractions, allowed virtual elimination of systematic errors. Inability of the IR system to correctly locate the markers, leading to an executional failure, occurred in 21% of 553 fractions. Conclusion: IR marker-assisted patient positioning significantly improves setup accuracy along the AP and lateral axes. Executional failures need to be reduced

Open table-top device positioning technique to reduce small bowel obstruction. Positioning accuracy and impact on conformal radiation therapy techniques

International Nuclear Information System (INIS)

Rudat, V.; Flentje, M.; Engenhart, R.; Metzger, M.; Wannenmacher, M.

1995-01-01

The immobilization error of patients positioned on the opern table-top device in prone prosition as well as the movement of the small bowel out of the pelvis by this positioning technique was determined. The positioning error is of special importance for the 3-dimensional treatment planning for conformal radiotherapy. The positioning error was determined by superposing 106 portal films with the corresponding simultor films from 21 patients with carcinoma of the rectum who received 3D-planned conformal radiotherapy (o-field technique with irregular blocks). The movement of the small bowel out of the pelvis was studied by comparing simulator films after barium swallow in supine and open table-top position as well with 3D-treatment plans of the same patient in both positions in 3 cases. The positioning error along the medio-lateral, dorso-ventral und cranio-caudal axis was 1.4/-0.6/1.8 mm and the standard deviation 4.4/6.8/6.3 mm, respectively. In comparison to the supine position more rotation errors in the sagittal view were observed (37% and 9% respectively) with a media of 5.1 . Six out of 22 patients showed no adhesions of the small bowel and a complete movement out of the tratment field was achieved. 14 out of 16 Patients with adhesions revealed a partial movement of the small bowel out of the treatment field. Comparing 3D-treatment plans in both positions again demonstrated a marked reduction of the irradiated small bowel volume with the use of the open table-top decive. (orig.) [de

[Errors in medicine. Causes, impact and improvement measures to improve patient safety].

Science.gov (United States)

Waeschle, R M; Bauer, M; Schmidt, C E

2015-09-01

The guarantee of quality of care and patient safety is of major importance in hospitals even though increased economic pressure and work intensification are ubiquitously present. Nevertheless, adverse events still occur in 3-4 % of hospital stays and of these 25-50 % are estimated to be avoidable. The identification of possible causes of error and the development of measures for the prevention of medical errors are essential for patient safety. The implementation and continuous development of a constructive culture of error tolerance are fundamental.The origins of errors can be differentiated into systemic latent and individual active causes and components of both categories are typically involved when an error occurs. Systemic causes are, for example out of date structural environments, lack of clinical standards and low personnel density. These causes arise far away from the patient, e.g. management decisions and can remain unrecognized for a long time. Individual causes involve, e.g. confirmation bias, error of fixation and prospective memory failure. These causes have a direct impact on patient care and can result in immediate injury to patients. Stress, unclear information, complex systems and a lack of professional experience can promote individual causes. Awareness of possible causes of error is a fundamental precondition to establishing appropriate countermeasures.Error prevention should include actions directly affecting the causes of error and includes checklists and standard operating procedures (SOP) to avoid fixation and prospective memory failure and team resource management to improve communication and the generation of collective mental models. Critical incident reporting systems (CIRS) provide the opportunity to learn from previous incidents without resulting in injury to patients. Information technology (IT) support systems, such as the computerized physician order entry system, assist in the prevention of medication errors by providing

Patient identification errors are common in a simulated setting.

Science.gov (United States)

Henneman, Philip L; Fisher, Donald L; Henneman, Elizabeth A; Pham, Tuan A; Campbell, Megan M; Nathanson, Brian H

2010-06-01

We evaluate the frequency and accuracy of health care workers verifying patient identity before performing common tasks. The study included prospective, simulated patient scenarios with an eye-tracking device that showed where the health care workers looked. Simulations involved nurses administering an intravenous medication, technicians labeling a blood specimen, and clerks applying an identity band. Participants were asked to perform their assigned task on 3 simulated patients, and the third patient had a different date of birth and medical record number than the identity information on the artifact label specific to the health care workers' task. Health care workers were unaware that the focus of the study was patient identity. Sixty-one emergency health care workers participated--28 nurses, 16 technicians, and 17 emergency service associates--in 183 patient scenarios. Sixty-one percent of health care workers (37/61) caught the identity error (61% nurses, 94% technicians, 29% emergency service associates). Thirty-nine percent of health care workers (24/61) performed their assigned task on the wrong patient (39% nurses, 6% technicians, 71% emergency service associates). Eye-tracking data were available for 73% of the patient scenarios (133/183). Seventy-four percent of health care workers (74/100) failed to match the patient to the identity band (87% nurses, 49% technicians). Twenty-seven percent of health care workers (36/133) failed to match the artifact to the patient or the identity band before performing their task (33% nurses, 9% technicians, 33% emergency service associates). Fifteen percent (5/33) of health care workers who completed the steps to verify patient identity on the patient with the identification error still failed to recognize the error. Wide variation exists among health care workers verifying patient identity before performing everyday tasks. Education, process changes, and technology are needed to improve the frequency and accuracy of

Influence of Marker Movement Errors on Measuring 3 Dimentional Scapular Position and Orientation

Directory of Open Access Journals (Sweden)

Afsoun Nodehi-Moghaddam

2003-12-01

Full Text Available Objective: Scapulothoracic muscles weakness or fatique can result in abnormal scapular positioning and compromising scapulo-humeral rhythm and shoulder dysfunction .The scapula moves in a -3 Dimentional fashion so the use of 2-Dimentional Techniques cannot fully capture scapular motion . One of approaches to positioining markers of kinematic systems is to mount each marker directly on the skin generally over a bony anatomical landmarks . Howerer skin movement and Motion of underlying bony structures are not Necessaritly identical and substantial errors may be introduced in the description of bone movement when using skin –mounted markers. evaluation of Influence of marker movement errors on 3-Dimentional scapular position and orientation. Materials & Methods: 10 Healthy subjects with a mean age 30.50 participated in the study . They were tested in three sessions A 3-dimentiional electro mechanical digitizer was used to measure scapular position and orientation measures were obtained while arm placed at the side of the body and elevated 45٫90٫120 and full Rang of motion in the scapular plane . At each test positions six bony landmarks were palpated and skin markers were mounted on them . This procedure repeated in the second test session in third session Removal of markers was not performed through obtaining entire Range of motion after mounting the markers . Results: The intraclass correlation coefficients (ICC for scapulor variables were higher (0.92-0.84 when markers were replaced and re-mounted on bony landmarks with Increasing the angle of elevation. Conclusion: our findings suggested significant markers movement error on measuring the upward Rotation and posterior tilt angle of scapula.

Initial clinical experience with an interactive, video-based patient-positioning system for head and neck treatment

International Nuclear Information System (INIS)

Johnson, L.; Hadley, Scott W.; Milliken, Barrett D.; Pelizzari, Charles A.; Haraf, Daniel J.; Nguyen, Ai; Chen, George T.Y.

1996-01-01

Objective: To evaluate an interactive, video-based system for positioning head and neck patients. Materials and Methods: System hardware includes two B and W CCD cameras (mounted to provide left-lateral and AP-inferior views), zoom lenses, and a PC equipped with a frame grabber. Custom software is used to acquire and archive video images, as well as to display real-time subtraction images revealing patient misalignment in multiple views. Live subtraction images are obtained by subtracting a reference image (i.e., an image of the patient in the correct position) from real-time video. As seen in the figure, darker regions of the subtraction image indicate where the patient is currently, while lighter regions indicate where the patient should be. Adjustments in the patient's position are updated and displayed in less than 0.07s, allowing the therapist to interactively detect and correct setup discrepancies. Patients selected for study are treated BID and immobilized with conventional litecast straps attached to a baseframe which is registered to the treatment couch. Morning setups are performed by aligning litecast marks and patient anatomy to treatment room lasers. Afternoon setups begin with the same procedure, and then live subtraction images are used to fine-tune the setup. At morning and afternoon setups, video images and verification films are taken after positioning is complete. These are visually registered offline to determine the distribution of setup errors per patient, with and without video assistance. Results: Without video assistance, the standard deviation of setup errors typically ranged from 5 to 7mm and was patient-dependent. With video assistance, standard deviations are reduced to 1 to 4mm, with the result depending on patient coopertiveness and the length of time spent fine-tuning the setups. At current levels of experience, 3 to 4mm accuracy is easily achieved in about 30s, while 1 to 3mm accuracy is achieved in about 1 to 2 minutes. Studies

Identification errors in the blood transfusion laboratory: a still relevant issue for patient safety.

Science.gov (United States)

Lippi, Giuseppe; Plebani, Mario

2011-04-01

Remarkable technological advances and increased awareness have both contributed to decrease substantially the uncertainty of the analytical phase, so that the manually intensive preanalytical activities currently represent the leading sources of errors in laboratory and transfusion medicine. Among preanalytical errors, misidentification and mistransfusion are still regarded as a considerable problem, posing serious risks for patient health and carrying huge expenses for the healthcare system. As such, a reliable policy of risk management should be readily implemented, developing through a multifaceted approach to prevent or limit the adverse outcomes related to transfusion reactions from blood incompatibility. This strategy encompasses root cause analysis, compliance with accreditation requirements, strict adherence to standard operating procedures, guidelines and recommendations for specimen collection, use of positive identification devices, rejection of potentially misidentified specimens, informatics data entry, query host communication, automated systems for patient identification and sample labeling and an adequate and safe environment. Copyright © 2011 Elsevier Ltd. All rights reserved.

A new stochastic model considering satellite clock interpolation errors in precise point positioning

Science.gov (United States)

Wang, Shengli; Yang, Fanlin; Gao, Wang; Yan, Lizi; Ge, Yulong

2018-03-01

Precise clock products are typically interpolated based on the sampling interval of the observational data when they are used for in precise point positioning. However, due to the occurrence of white noise in atomic clocks, a residual component of such noise will inevitable reside within the observations when clock errors are interpolated, and such noise will affect the resolution of the positioning results. In this paper, which is based on a twenty-one-week analysis of the atomic clock noise characteristics of numerous satellites, a new stochastic observation model that considers satellite clock interpolation errors is proposed. First, the systematic error of each satellite in the IGR clock product was extracted using a wavelet de-noising method to obtain the empirical characteristics of atomic clock noise within each clock product. Then, based on those empirical characteristics, a stochastic observation model was structured that considered the satellite clock interpolation errors. Subsequently, the IGR and IGS clock products at different time intervals were used for experimental validation. A verification using 179 stations worldwide from the IGS showed that, compared with the conventional model, the convergence times using the stochastic model proposed in this study were respectively shortened by 4.8% and 4.0% when the IGR and IGS 300-s-interval clock products were used and by 19.1% and 19.4% when the 900-s-interval clock products were used. Furthermore, the disturbances during the initial phase of the calculation were also effectively improved.

Patient Position Verification and Corrective Evaluation Using Cone Beam Computed Tomography (CBCT) in Intensity modulated Radiation Therapy

International Nuclear Information System (INIS)

Do, Gyeong Min; Jeong, Deok Yang; Kim, Young Bum

2009-01-01

Cone beam computed tomography (CBCT) using an on board imager (OBI) can check the movement and setup error in patient position and target volume by comparing with the image of computer simulation treatment in real.time during patient treatment. Thus, this study purposed to check the change and movement of patient position and target volume using CBCT in IMRT and calculate difference from the treatment plan, and then to correct the position using an automated match system and to test the accuracy of position correction using an electronic portal imaging device (EPID) and examine the usefulness of CBCT in IMRT and the accuracy of the automatic match system. The subjects of this study were 3 head and neck patients and 1 pelvis patient sampled from IMRT patients treated in our hospital. In order to investigate the movement of treatment position and resultant displacement of irradiated volume, we took CBCT using OBI mounted on the linear accelerator. Before each IMRT treatment, we took CBCT and checked difference from the treatment plan by coordinate by comparing it with the image of CT simulation. Then, we made correction through the automatic match system of 3D/3D match to match the treatment plan, and verified and evaluated using electronic portal imaging device. When CBCT was compared with the image of CT simulation before treatment, the average difference by coordinate in the head and neck was 0.99 mm vertically, 1.14 mm longitudinally, 4.91 mm laterally, and 1.07 degrees in the rotational direction, showing somewhat insignificant differences by part. In testing after correction, when the image from the electronic portal imaging device was compared with DRR image, it was found that correction had been made accurately with error less than 0.5 mm. By comparing a CBCT image before treatment with a 3D image reconstructed into a volume instead of a 2D image for the patient's setup error and change in the position of the organs and the target, we could measure and

CT for suspected appendicitis in children: an analysis of diagnostic errors

International Nuclear Information System (INIS)

Taylor, George A.; Callahan, Michael J.; Rodriguez, Diana; Smink, Douglas S.

2006-01-01

Mistakes have been made by the use of CT in diagnosing children with suspected appendicitis. Although others have reported the frequency of diagnostic errors, we were unable to find any studies that addressed the specific situations in which diagnostic errors occurred in children with suspected appendicitis. To investigate the frequency and type of diagnostic errors resulting from CT of children with suspected appendicitis when compared to surgical and pathological diagnosis. We reviewed imaging, clinical and pathological data on 1,207 consecutive pediatric patients who underwent CT examination for suspected appendicitis. Imaging findings were categorized as false-positive, false-negative, or indeterminate. Errors were classified as interpretative, technical or unavoidable. Concordance between surgical and pathological findings was also evaluated. The imaging findings of 34 patients (2.8%) were discrepant with the pathological examination or clinical follow-up. The errors in 23 cases were classified as interpretive (68%) and 11 as unavoidable (32%), and no errors were classified as technical. There were 23 false-positive errors (68%), 6 false-negative errors (18%), and 5 indeterminate imaging studies (15%). Isolated CT findings of an enlarged (greater than 6 mm) appendix, fat stranding, thickened bowel or non-visualization of the distal appendix were the most common false-positive CT findings. Of these 34 patients, 22 underwent appendectomy, with 10 (45%) having discordant surgical and pathological findings. (orig.)

Per-beam, planar IMRT QA passing rates do not predict clinically relevant patient dose errors

Energy Technology Data Exchange (ETDEWEB)

Nelms, Benjamin E.; Zhen Heming; Tome, Wolfgang A. [Canis Lupus LLC and Department of Human Oncology, University of Wisconsin, Merrimac, Wisconsin 53561 (United States); Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53705 (United States); Departments of Human Oncology, Medical Physics, and Biomedical Engineering, University of Wisconsin, Madison, Wisconsin 53792 (United States)

2011-02-15

Purpose: The purpose of this work is to determine the statistical correlation between per-beam, planar IMRT QA passing rates and several clinically relevant, anatomy-based dose errors for per-patient IMRT QA. The intent is to assess the predictive power of a common conventional IMRT QA performance metric, the Gamma passing rate per beam. Methods: Ninety-six unique data sets were created by inducing four types of dose errors in 24 clinical head and neck IMRT plans, each planned with 6 MV Varian 120-leaf MLC linear accelerators using a commercial treatment planning system and step-and-shoot delivery. The error-free beams/plans were used as ''simulated measurements'' (for generating the IMRT QA dose planes and the anatomy dose metrics) to compare to the corresponding data calculated by the error-induced plans. The degree of the induced errors was tuned to mimic IMRT QA passing rates that are commonly achieved using conventional methods. Results: Analysis of clinical metrics (parotid mean doses, spinal cord max and D1cc, CTV D95, and larynx mean) vs IMRT QA Gamma analysis (3%/3 mm, 2/2, 1/1) showed that in all cases, there were only weak to moderate correlations (range of Pearson's r-values: -0.295 to 0.653). Moreover, the moderate correlations actually had positive Pearson's r-values (i.e., clinically relevant metric differences increased with increasing IMRT QA passing rate), indicating that some of the largest anatomy-based dose differences occurred in the cases of high IMRT QA passing rates, which may be called ''false negatives.'' The results also show numerous instances of false positives or cases where low IMRT QA passing rates do not imply large errors in anatomy dose metrics. In none of the cases was there correlation consistent with high predictive power of planar IMRT passing rates, i.e., in none of the cases did high IMRT QA Gamma passing rates predict low errors in anatomy dose metrics or vice versa

Effect of cooling on thixotropic position-sense error in human biceps muscle.

Science.gov (United States)

Sekihara, Chikara; Izumizaki, Masahiko; Yasuda, Tomohiro; Nakajima, Takayuki; Atsumi, Takashi; Homma, Ikuo

2007-06-01

Muscle temperature affects muscle thixotropy. However, it is unclear whether changes in muscle temperature affect thixotropic position-sense errors. We studied the effect of cooling on thixotropic position-sense errors induced by short-length muscle contraction (hold-short conditioning) in the biceps of 12 healthy men. After hold-short conditioning of the right biceps muscle in a cooled (5.0 degrees C) or control (36.5 degrees C) environment, subjects perceived greater extension of the conditioned forearm at 5.0 degrees C. The angle differences between the two forearms following hold-short conditioning of the right biceps muscle in normal or cooled conditions were significantly different (-3.335 +/- 1.680 degrees at 36.5 degrees C vs. -5.317 +/- 1.096 degrees at 5.0 degrees C; P=0.043). Induction of a tonic vibration reflex in the biceps muscle elicited involuntary forearm elevation, and the angular velocities of the elevation differed significantly between arms conditioned in normal and cooled environments (1.583 +/- 0.326 degrees /s at 36.5 degrees C vs. 3.100 +/- 0.555 degrees /s at 5.0 degrees C, P=0.0039). Thus, a cooled environment impairs a muscle's ability to provide positional information, potentially leading to poor muscle performance.

Identifying afterloading PDR and HDR brachytherapy errors using real-time fiber-coupled Al2O3:C dosimetry and a novel statistical error decision criterion

International Nuclear Information System (INIS)

Kertzscher, Gustavo; Andersen, Claus E.; Siebert, Frank-Andre; Nielsen, Soren Kynde; Lindegaard, Jacob C.; Tanderup, Kari

2011-01-01

Background and purpose: The feasibility of a real-time in vivo dosimeter to detect errors has previously been demonstrated. The purpose of this study was to: (1) quantify the sensitivity of the dosimeter to detect imposed treatment errors under well controlled and clinically relevant experimental conditions, and (2) test a new statistical error decision concept based on full uncertainty analysis. Materials and methods: Phantom studies of two gynecological cancer PDR and one prostate cancer HDR patient treatment plans were performed using tandem ring applicators or interstitial needles. Imposed treatment errors, including interchanged pairs of afterloader guide tubes and 2-20 mm source displacements, were monitored using a real-time fiber-coupled carbon doped aluminum oxide (Al 2 O 3 :C) crystal dosimeter that was positioned in the reconstructed tumor region. The error detection capacity was evaluated at three dose levels: dwell position, source channel, and fraction. The error criterion incorporated the correlated source position uncertainties and other sources of uncertainty, and it was applied both for the specific phantom patient plans and for a general case (source-detector distance 5-90 mm and position uncertainty 1-4 mm). Results: Out of 20 interchanged guide tube errors, time-resolved analysis identified 17 while fraction level analysis identified two. Channel and fraction level comparisons could leave 10 mm dosimeter displacement errors unidentified. Dwell position dose rate comparisons correctly identified displacements ≥5 mm. Conclusion: This phantom study demonstrates that Al 2 O 3 :C real-time dosimetry can identify applicator displacements ≥5 mm and interchanged guide tube errors during PDR and HDR brachytherapy. The study demonstrates the shortcoming of a constant error criterion and the advantage of a statistical error criterion.

Set-up error in supine-positioned patients immobilized with two different modalities during conformal radiotherapy of prostate cancer

International Nuclear Information System (INIS)

Fiorino, C.; Cattaneo, G.M.; Calandrino, R.; Reni, M.; Bolognesi, A.; Bonini, A.

1998-01-01

Background: Conformal radiotherapy requires reduced margins around the clinical target volume (CTV) with respect to traditional radiotherapy techniques. Therefore, high set-up accuracy and reproducibility are mandatory. Purpose: To investigate the effectiveness of two different immobilization techniques during conformal radiotherapy of prostate cancer with small fields. Materials and methods: 52 patients with prostate cancer were treated by conformal three- or four-field techniques with radical or adjuvant intent between November 1996 and March 1998. In total, 539 portal images were collected on a weekly basis for at least the first 4 weeks of the treatment on lateral and anterior 18 MV X-ray fields. The average number of sessions monitored per patient was 5.7 (range 4-10). All patients were immobilized with an alpha-cradle system; 25 of them were immobilized at the pelvis level (group A) and the remaining 27 patients were immobilized in the legs (group B). The shifts with respect to the simulation condition were assessed by measuring the distances between the same bony landmarks and the field edges. The global distributions of cranio-caudal (CC), posterior-anterior (PA) and left-right (LR) shifts were considered; for each patient random and systematic error components were assessed by following the procedure suggested by Bijhold et al. (Bijhold J, Lebesque JV, Hart AAM, Vijlbrief RE. Maximising set-up accuracy using portal images as applied to a conformal boost technique for prostatic cancer. Radiother. Oncol. 1992;24:261-271). For each patient the average isocentre (3D) shift was assessed as the quadratic sum of the average shifts in the three directions. Results 5 mm equal to 4.4% with respect to the 21.6% of group A (P<0.0001). This value was also better than the corresponding value found in a previously investigated group of 21 non-immobilized patients (Italia C, Fiorino C, Ciocca M, et al. Quality control by portal film analysis of the conformal radiotherapy

Beam-centric algorithm for pretreatment patient position correction in external beam radiation therapy

International Nuclear Information System (INIS)

Bose, Supratik; Shukla, Himanshu; Maltz, Jonathan

2010-01-01

Purpose: In current image guided pretreatment patient position adjustment methods, image registration is used to determine alignment parameters. Since most positioning hardware lacks the full six degrees of freedom (DOF), accuracy is compromised. The authors show that such compromises are often unnecessary when one models the planned treatment beams as part of the adjustment calculation process. The authors present a flexible algorithm for determining optimal realizable adjustments for both step-and-shoot and arc delivery methods. Methods: The beam shape model is based on the polygonal intersection of each beam segment with the plane in pretreatment image volume that passes through machine isocenter perpendicular to the central axis of the beam. Under a virtual six-DOF correction, ideal positions of these polygon vertices are computed. The proposed method determines the couch, gantry, and collimator adjustments that minimize the total mismatch of all vertices over all segments with respect to their ideal positions. Using this geometric error metric as a function of the number of available DOF, the user may select the most desirable correction regime. Results: For a simulated treatment plan consisting of three equally weighted coplanar fixed beams, the authors achieve a 7% residual geometric error (with respect to the ideal correction, considered 0% error) by applying gantry rotation as well as translation and isocentric rotation of the couch. For a clinical head-and-neck intensity modulated radiotherapy plan with seven beams and five segments per beam, the corresponding error is 6%. Correction involving only couch translation (typical clinical practice) leads to a much larger 18% mismatch. Clinically significant consequences of more accurate adjustment are apparent in the dose volume histograms of target and critical structures. Conclusions: The algorithm achieves improvements in delivery accuracy using standard delivery hardware without significantly increasing

Successful remediation of patient safety incidents: a tale of two medication errors.

Science.gov (United States)

Helmchen, Lorens A; Richards, Michael R; McDonald, Timothy B

2011-01-01

As patient safety acquires strategic importance for all stakeholders in the health care delivery chain, one promising mechanism centers on the proactive disclosure of medical errors to patients. Yet, disclosure and apology alone will not be effective in fully addressing patients' concerns after an adverse event unless they are paired with a remediation component. The purpose of this study was to identify key features of successful remediation efforts that accompany the proactive disclosure of medical errors to patients. We describe and contrast two recent and very similar cases of preventable medical error involving inappropriate medication at a large tertiary-care academic medical center in the Midwestern United States. Despite their similarity, the two medical errors led to very different health outcomes and remediation trajectories for the injured patients. Although one error causing no permanent harm was mismanaged to the lasting dissatisfaction of the patient, the other resulted in the death of the patient but was remediated to the point of allowing the family to come to terms with the loss and even restored a modicum of trust in the providers' sincerity. To maximize the opportunities for successful remediation, as soon as possible after the incident, providers should pledge to injured patients and their relatives that they will assist and accompany them in their recovery as long as necessary and then follow through on their pledge. As the two case studies show, it takes training and vigilance to ensure adherence to these principles and reach an optimal outcome for patients and their relatives.

Lateral positioning for critically ill adult patients.

Science.gov (United States)

Hewitt, Nicky; Bucknall, Tracey; Faraone, Nardene M

2016-05-12

Critically ill patients require regular body position changes to minimize the adverse effects of bed rest, inactivity and immobilization. However, uncertainty surrounds the effectiveness of lateral positioning for improving pulmonary gas exchange, aiding drainage of tracheobronchial secretions and preventing morbidity. In addition, it is unclear whether the perceived risk levied by respiratory and haemodynamic instability upon turning critically ill patients outweighs the respiratory benefits of side-to-side rotation. Thus, lack of certainty may contribute to variation in positioning practice and equivocal patient outcomes. To evaluate effects of the lateral position compared with other body positions on patient outcomes (mortality, morbidity and clinical adverse events) in critically ill adult patients. (Clinical adverse events include hypoxaemia, hypotension, low oxygen delivery and global indicators of impaired tissue oxygenation.) We examined single use of the lateral position (i.e. on the right or left side) and repeat use of the lateral position (i.e. lateral positioning) within a positioning schedule. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 5), MEDLINE (1950 to 23 May 2015), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1937 to 23 May 2015), the Allied and Complementary Medicine Database (AMED) (1984 to 23 May 2015), Latin American Caribbean Health Sciences Literature (LILACS) (1901 to 23 May 2015), Web of Science (1945 to 23 May 2015), Index to Theses in Great Britain and Ireland (1950 to 23 May 2015), Trove (2009 to 23 May 2015; previously Australasian Digital Theses Program (1997 to December 2008)) and Proquest Dissertations and Theses (2009 to 23 May 2015; previously Proquest Digital Dissertations (1980 to 23 May 2015)). We handsearched the reference lists of potentially relevant reports and two nursing journals. We included randomized and quasi-randomized trials examining effects of

Observations of geographically correlated orbit errors for TOPEX/Poseidon using the global positioning system

Science.gov (United States)

Christensen, E. J.; Haines, B. J.; Mccoll, K. C.; Nerem, R. S.

1994-01-01

We have compared Global Positioning System (GPS)-based dynamic and reduced-dynamic TOPEX/Poseidon orbits over three 10-day repeat cycles of the ground-track. The results suggest that the prelaunch joint gravity model (JGM-1) introduces geographically correlated errors (GCEs) which have a strong meridional dependence. The global distribution and magnitude of these GCEs are consistent with a prelaunch covariance analysis, with estimated and predicted global rms error statistics of 2.3 and 2.4 cm rms, respectively. Repeating the analysis with the post-launch joint gravity model (JGM-2) suggests that a portion of the meridional dependence observed in JGM-1 still remains, with global rms error of 1.2 cm.

Compensation of position errors in passivity based teleoperation over packet switched communication networks

NARCIS (Netherlands)

Secchi, C; Stramigioli, Stefano; Fantuzzi, C.

Because of the use of scattering based communication channels, passivity based telemanipulation systems can be subject to a steady state position error between master and slave robots. In this paper, we consider the case in which the passive master and slave sides communicate through a packet

[Positioning errors of CT common rail technique in intensity-modulated radiotherapy for nasopharyngeal carcinoma].

Science.gov (United States)

Tian, Fei; Xu, Zihai; Mo, Li; Zhu, Chaohua; Chen, Chaomin

2012-11-01

To evaluate the value of CT common rail technique for application in intensity-modulated radiotherapy for nasopharyngeal carcinoma (NPC). Twenty-seven NPC patients underwent Somatom CT scans using the Siemens CTVision system prior to the commencement of the radiotherapy sessions. The acquired CT images were registered with the planning CT images using the matching function of the system to obtain the linear set-up errors of 3 directions, namely X (left to right), Y (superior to inferior), and Z (anterior to posterior). The errors were then corrected online on the moving couch. The 27 NPC patients underwent a total of 110 CT scans and the displacement deviations of the X, Y and Z directions were -0.16∓1.68 mm, 0.25∓1.66 mm, and 0.33∓1.09 mm, respectively. CT common rail technique can accurately and rapidly measure the space error between the posture and the target area to improve the set-up precision of intensity-modulated radiotherapy for NPC.

Patient positioning and immobilization in static and dynamic adaptive radiotherapy: an integral part of IGRT

International Nuclear Information System (INIS)

Oinam, Arun S.

2016-01-01

Radiotherapy treatment deals with different varieties of treatment procedures depending on type and stages of tumors. These treatments are grossly classified into palliative curative treatment. Immobilizations used in this treatment are designed with respect to this classification as well as the techniques. With the improvements in imaging technology used in Radiotherapy, patient position set up margin can be reduced as compared to the conventional radiotherapy. Still immobilization in patient position setup has been an integral part of Image Guided Radiotherapy (lGRT) and Stereotactic Radio Surgery (SRS) and Radiotherapy (SRT). Immobilization used in this technique should produce a minimum attenuation of radiation beam as well as positioning comfort and this will enhance the reproducibility for the daily position setup and immobilize the patient during the treatment. Advanced dose delivery technique like Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Radiotherapy (VMAT) can do differential dose sculpting around and inside the irregular shape different target volumes while minimizing the dose to the surrounding organs at risk. A small positional error may produce the mistreatment of target and exposure of organs at risk beyond the acceptable dose limits. Such a potential positional error can be reduced if different varieties of good immobilizing devices are properly utilized. The immobilization used in the treatment of Head and Neck and Cranial tumor can produce better immobilization as compared to abdominal and pelvic tumors which are forced to move by the inability to control movements of lung and heart as well as the very large flabby tissues which are attached skeleton bones

Detection of Patients at High Risk of Medication Errors

DEFF Research Database (Denmark)

Sædder, Eva Aggerholm; Lisby, Marianne; Nielsen, Lars Peter

2016-01-01

Medication errors (MEs) are preventable and can result in patient harm and increased expenses in the healthcare system in terms of hospitalization, prolonged hospitalizations and even death. We aimed to develop a screening tool to detect acutely admitted patients at low or high risk of MEs...

Mixing of multi-modal images for conformational radiotherapy: application to patient re positioning; Fusion d`images multi-modales pour la radiotherapie conformationnelle: application au repositionnement du patient

Energy Technology Data Exchange (ETDEWEB)

Vassal, P

1998-06-29

This study shows a procedure of patient re positioning by comparative evaluation between the position of the patient and the theoretical expected position of the patient; the stagger between the two information gives the error of installation in translation and rotation. A correction is calculated and applied to the treatment environment (position and orientation of the patient, position and orientation of the irradiation source). The control system allows to determine the precise position of the tumor volume. The echography allows to determine the position of an organ.The surface captor is used to localize the tumors of the face or of the brain, with the respect to the face, the acquisition and the treatment of information take only few minutes. The X rays imager is applied for the localization of bones structures. (N.C.)

Effect of Body Mass Index on Magnitude of Setup Errors in Patients Treated With Adjuvant Radiotherapy for Endometrial Cancer With Daily Image Guidance

Energy Technology Data Exchange (ETDEWEB)

Lin, Lilie L., E-mail: lin@uphs.upenn.edu [Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, PA (United States); Hertan, Lauren; Rengan, Ramesh; Teo, Boon-Keng Kevin [Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, PA (United States)

2012-06-01

Purpose: To determine the impact of body mass index (BMI) on daily setup variations and frequency of imaging necessary for patients with endometrial cancer treated with adjuvant intensity-modulated radiotherapy (IMRT) with daily image guidance. Methods and Materials: The daily shifts from a total of 782 orthogonal kilovoltage images from 30 patients who received pelvic IMRT between July 2008 and August 2010 were analyzed. The BMI, mean daily shifts, and random and systematic errors in each translational and rotational direction were calculated for each patient. Margin recipes were generated based on BMI. Linear regression and spearman rank correlation analysis were performed. To simulate a less-than-daily IGRT protocol, the average shift of the first five fractions was applied to subsequent setups without IGRT for assessing the impact on setup error and margin requirements. Results: Median BMI was 32.9 (range, 23-62). Of the 30 patients, 16.7% (n = 5) were normal weight (BMI <25); 23.3% (n = 7) were overweight (BMI {>=}25 to <30); 26.7% (n = 8) were mildly obese (BMI {>=}30 to <35); and 33.3% (n = 10) were moderately to severely obese (BMI {>=} 35). On linear regression, mean absolute vertical, longitudinal, and lateral shifts positively correlated with BMI (p = 0.0127, p = 0.0037, and p < 0.0001, respectively). Systematic errors in the longitudinal and vertical direction were found to be positively correlated with BMI category (p < 0.0001 for both). IGRT for the first five fractions, followed by correction of the mean error for all subsequent fractions, led to a substantial reduction in setup error and resultant margin requirement overall compared with no IGRT. Conclusions: Daily shifts, systematic errors, and margin requirements were greatest in obese patients. For women who are normal or overweight, a planning target margin margin of 7 to 10 mm may be sufficient without IGRT, but for patients who are moderately or severely obese, this is insufficient.

Effect of Body Mass Index on Magnitude of Setup Errors in Patients Treated With Adjuvant Radiotherapy for Endometrial Cancer With Daily Image Guidance

International Nuclear Information System (INIS)

Lin, Lilie L.; Hertan, Lauren; Rengan, Ramesh; Teo, Boon-Keng Kevin

2012-01-01

Purpose: To determine the impact of body mass index (BMI) on daily setup variations and frequency of imaging necessary for patients with endometrial cancer treated with adjuvant intensity-modulated radiotherapy (IMRT) with daily image guidance. Methods and Materials: The daily shifts from a total of 782 orthogonal kilovoltage images from 30 patients who received pelvic IMRT between July 2008 and August 2010 were analyzed. The BMI, mean daily shifts, and random and systematic errors in each translational and rotational direction were calculated for each patient. Margin recipes were generated based on BMI. Linear regression and spearman rank correlation analysis were performed. To simulate a less-than-daily IGRT protocol, the average shift of the first five fractions was applied to subsequent setups without IGRT for assessing the impact on setup error and margin requirements. Results: Median BMI was 32.9 (range, 23–62). Of the 30 patients, 16.7% (n = 5) were normal weight (BMI <25); 23.3% (n = 7) were overweight (BMI ≥25 to <30); 26.7% (n = 8) were mildly obese (BMI ≥30 to <35); and 33.3% (n = 10) were moderately to severely obese (BMI ≥ 35). On linear regression, mean absolute vertical, longitudinal, and lateral shifts positively correlated with BMI (p = 0.0127, p = 0.0037, and p < 0.0001, respectively). Systematic errors in the longitudinal and vertical direction were found to be positively correlated with BMI category (p < 0.0001 for both). IGRT for the first five fractions, followed by correction of the mean error for all subsequent fractions, led to a substantial reduction in setup error and resultant margin requirement overall compared with no IGRT. Conclusions: Daily shifts, systematic errors, and margin requirements were greatest in obese patients. For women who are normal or overweight, a planning target margin margin of 7 to 10 mm may be sufficient without IGRT, but for patients who are moderately or severely obese, this is insufficient.

Electrophysiological correlates of error processing in borderline personality disorder.

Science.gov (United States)

Ruchsow, Martin; Walter, Henrik; Buchheim, Anna; Martius, Philipp; Spitzer, Manfred; Kächele, Horst; Grön, Georg; Kiefer, Markus

2006-05-01

The electrophysiological correlates of error processing were investigated in patients with borderline personality disorder (BPD) using event-related potentials (ERP). Twelve patients with BPD and 12 healthy controls were additionally rated with the Barratt impulsiveness scale (BIS-10). Participants performed a Go/Nogo task while a 64 channel EEG was recorded. Three ERP components were of special interest: error-related negativity (ERN)/error negativity (Ne), early error positivity (early Pe) reflecting automatic error processing, and the late Pe component which is thought to mirror the awareness of erroneous responses. We found smaller amplitudes of the ERN/Ne in patients with BPD compared to controls. Moreover, significant correlations with the BIS-10 non-planning sub-score could be demonstrated for both the entire group and the patient group. No between-group differences were observed for the early and late Pe components. ERP measures appear to be a suitable tool to study clinical time courses in BPD.

Calculating radiotherapy margins based on Bayesian modelling of patient specific random errors

International Nuclear Information System (INIS)

Herschtal, A; Te Marvelde, L; Mengersen, K; Foroudi, F; Ball, D; Devereux, T; Pham, D; Greer, P B; Pichler, P; Eade, T; Kneebone, A; Bell, L; Caine, H; Hindson, B; Kron, T; Hosseinifard, Z

2015-01-01

Collected real-life clinical target volume (CTV) displacement data show that some patients undergoing external beam radiotherapy (EBRT) demonstrate significantly more fraction-to-fraction variability in their displacement (‘random error’) than others. This contrasts with the common assumption made by historical recipes for margin estimation for EBRT, that the random error is constant across patients. In this work we present statistical models of CTV displacements in which random errors are characterised by an inverse gamma (IG) distribution in order to assess the impact of random error variability on CTV-to-PTV margin widths, for eight real world patient cohorts from four institutions, and for different sites of malignancy. We considered a variety of clinical treatment requirements and penumbral widths. The eight cohorts consisted of a total of 874 patients and 27 391 treatment sessions. Compared to a traditional margin recipe that assumes constant random errors across patients, for a typical 4 mm penumbral width, the IG based margin model mandates that in order to satisfy the common clinical requirement that 90% of patients receive at least 95% of prescribed RT dose to the entire CTV, margins be increased by a median of 10% (range over the eight cohorts −19% to +35%). This substantially reduces the proportion of patients for whom margins are too small to satisfy clinical requirements. (paper)

Poster - 49: Assessment of Synchrony respiratory compensation error for CyberKnife liver treatment

International Nuclear Information System (INIS)

Liu, Ming; Cygler, Joanna; Vandervoort, Eric

2016-01-01

The goal of this work is to quantify respiratory motion compensation errors for liver tumor patients treated by the CyberKnife system with Synchrony tracking, to identify patients with the smallest tracking errors and to eventually help coach patient’s breathing patterns to minimize dose delivery errors. The accuracy of CyberKnife Synchrony respiratory motion compensation was assessed for 37 patients treated for liver lesions by analyzing data from system logfiles. A predictive model is used to modulate the direction of individual beams during dose delivery based on the positions of internally implanted fiducials determined using an orthogonal x-ray imaging system and the current location of LED external markers. For each x-ray pair acquired, system logfiles report the prediction error, the difference between the measured and predicted fiducial positions, and the delivery error, which is an estimate of the statistical error in the model overcoming the latency between x-ray acquisition and robotic repositioning. The total error was calculated at the time of each x-ray pair, for the number of treatment fractions and the number of patients, giving the average respiratory motion compensation error in three dimensions. The 99 th percentile for the total radial error is 3.85 mm, with the highest contribution of 2.79 mm in superior/inferior (S/I) direction. The absolute mean compensation error is 1.78 mm radially with a 1.27 mm contribution in the S/I direction. Regions of high total error may provide insight into features predicting groups of patients with larger or smaller total errors.

Poster - 49: Assessment of Synchrony respiratory compensation error for CyberKnife liver treatment

Energy Technology Data Exchange (ETDEWEB)

Liu, Ming [Carleton University (Canada); Cygler, Joanna [The Ottawa Hospital Cancer Centre, Carleton University, Ottawa University (Canada); Vandervoort, Eric [The Ottawa Hospital Cancer Centre, Ottawa University (Canada)

2016-08-15

The goal of this work is to quantify respiratory motion compensation errors for liver tumor patients treated by the CyberKnife system with Synchrony tracking, to identify patients with the smallest tracking errors and to eventually help coach patient’s breathing patterns to minimize dose delivery errors. The accuracy of CyberKnife Synchrony respiratory motion compensation was assessed for 37 patients treated for liver lesions by analyzing data from system logfiles. A predictive model is used to modulate the direction of individual beams during dose delivery based on the positions of internally implanted fiducials determined using an orthogonal x-ray imaging system and the current location of LED external markers. For each x-ray pair acquired, system logfiles report the prediction error, the difference between the measured and predicted fiducial positions, and the delivery error, which is an estimate of the statistical error in the model overcoming the latency between x-ray acquisition and robotic repositioning. The total error was calculated at the time of each x-ray pair, for the number of treatment fractions and the number of patients, giving the average respiratory motion compensation error in three dimensions. The 99{sup th} percentile for the total radial error is 3.85 mm, with the highest contribution of 2.79 mm in superior/inferior (S/I) direction. The absolute mean compensation error is 1.78 mm radially with a 1.27 mm contribution in the S/I direction. Regions of high total error may provide insight into features predicting groups of patients with larger or smaller total errors.

Teamwork and Clinical Error Reporting among Nurses in Korean Hospitals

Directory of Open Access Journals (Sweden)

Jee-In Hwang, PhD

2015-03-01

Conclusions: Teamwork was rated as moderate and was positively associated with nurses' error reporting performance. Hospital executives and nurse managers should make substantial efforts to enhance teamwork, which will contribute to encouraging the reporting of errors and improving patient safety.

Measuring uncertainty in dose delivered to the cochlea due to setup error during external beam treatment of patients with cancer of the head and neck

Energy Technology Data Exchange (ETDEWEB)

Yan, M.; Lovelock, D.; Hunt, M.; Mechalakos, J.; Hu, Y.; Pham, H.; Jackson, A., E-mail: jacksona@mskcc.org [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10065 (United States)

2013-12-15

Purpose: To use Cone Beam CT scans obtained just prior to treatments of head and neck cancer patients to measure the setup error and cumulative dose uncertainty of the cochlea. Methods: Data from 10 head and neck patients with 10 planning CTs and 52 Cone Beam CTs taken at time of treatment were used in this study. Patients were treated with conventional fractionation using an IMRT dose painting technique, most with 33 fractions. Weekly radiographic imaging was used to correct the patient setup. The authors used rigid registration of the planning CT and Cone Beam CT scans to find the translational and rotational setup errors, and the spatial setup errors of the cochlea. The planning CT was rotated and translated such that the cochlea positions match those seen in the cone beam scans, cochlea doses were recalculated and fractional doses accumulated. Uncertainties in the positions and cumulative doses of the cochlea were calculated with and without setup adjustments from radiographic imaging. Results: The mean setup error of the cochlea was 0.04 ± 0.33 or 0.06 ± 0.43 cm for RL, 0.09 ± 0.27 or 0.07 ± 0.48 cm for AP, and 0.00 ± 0.21 or −0.24 ± 0.45 cm for SI with and without radiographic imaging, respectively. Setup with radiographic imaging reduced the standard deviation of the setup error by roughly 1–2 mm. The uncertainty of the cochlea dose depends on the treatment plan and the relative positions of the cochlea and target volumes. Combining results for the left and right cochlea, the authors found the accumulated uncertainty of the cochlea dose per fraction was 4.82 (0.39–16.8) cGy, or 10.1 (0.8–32.4) cGy, with and without radiographic imaging, respectively; the percentage uncertainties relative to the planned doses were 4.32% (0.28%–9.06%) and 10.2% (0.7%–63.6%), respectively. Conclusions: Patient setup error introduces uncertainty in the position of the cochlea during radiation treatment. With the assistance of radiographic imaging during setup

UNDERSTANDING OR NURSES' REACTIONS TO ERRORS AND USING THIS UNDERSTANDING TO IMPROVE PATIENT SAFETY.

Science.gov (United States)

Taifoori, Ladan; Valiee, Sina

2015-09-01

The operating room can be home to many different types of nursing errors due to the invasiveness of OR procedures. The nurses' reactions towards errors can be a key factor in patient safety. This article is based on a study, with the aim of investigating nurses' reactions toward nursing errors and the various contributing and resulting factors, conducted at Kurdistan University of Medical Sciences in Sanandaj, Iran in 2014. The goal of the study was to determine how OR nurses' reacted to nursing errors with the goal of having this information used to improve patient safety. Research was conducted as a cross-sectional descriptive study. The participants were all nurses employed in the operating rooms of the teaching hospitals of Kurdistan University of Medical Sciences, which was selected by a consensus method (170 persons). The information was gathered through questionnaires that focused on demographic information, error definition, reasons for error occurrence, and emotional reactions for error occurrence, and emotional reactions toward the errors. 153 questionnaires were completed and analyzed by SPSS software version 16.0. "Not following sterile technique" (82.4 percent) was the most reported nursing error, "tiredness" (92.8 percent) was the most reported reason for the error occurrence, "being upset at having harmed the patient" (85.6 percent) was the most reported emotional reaction after error occurrence", with "decision making for a better approach to tasks the next time" (97.7 percent) as the most common goal and "paying more attention to details" (98 percent) was the most reported planned strategy for future improved outcomes. While healthcare facilities are focused on planning for the prevention and elimination of errors it was shown that nurses can also benefit from support after error occurrence. Their reactions, and coping strategies, need guidance and, with both individual and organizational support, can be a factor in improving patient safety.

Clinical measuring system for the form and position errors of circular workpieces using optical fiber sensors

Science.gov (United States)

Tan, Jiubin; Qiang, Xifu; Ding, Xuemei

1991-08-01

Optical sensors have two notable advantages in modern precision measurement. One is that they can be used in nondestructive measurement because the sensors need not touch the surfaces of workpieces in measuring. The other one is that they can strongly resist electromagnetic interferences, vibrations, and noises, so they are suitable to be used in machining sites. But the drift of light intensity and the changing of the reflection coefficient at different measuring positions of a workpiece may have great influence on measured results. To solve the problem, a spectroscopic differential characteristic compensating method is put forward. The method can be used effectively not only in compensating the measuring errors resulted from the drift of light intensity but also in eliminating the influence to measured results caused by the changing of the reflection coefficient. Also, the article analyzes the possibility of and the means of separating data errors of a clinical measuring system for form and position errors of circular workpieces.

Transparency When Things Go Wrong: Physician Attitudes About Reporting Medical Errors to Patients, Peers, and Institutions.

Science.gov (United States)

Bell, Sigall K; White, Andrew A; Yi, Jean C; Yi-Frazier, Joyce P; Gallagher, Thomas H

2017-12-01

Transparent communication after medical error includes disclosing the mistake to the patient, discussing the event with colleagues, and reporting to the institution. Little is known about whether attitudes about these transparency practices are related. Understanding these relationships could inform educational and organizational strategies to promote transparency. We analyzed responses of 3038 US and Canadian physicians to a medical error communication survey. We used bivariate correlations, principal components analysis, and linear regression to determine whether and how physician attitudes about transparent communication with patients, peers, and the institution after error were related. Physician attitudes about disclosing errors to patients, peers, and institutions were correlated (all P's transparent communication with patients and peers/institution included female sex, US (vs Canadian) doctors, academic (vs private) practice, the belief that disclosure decreased likelihood of litigation, and the belief that system changes occur after error reporting. In addition, younger physicians, surgeons, and those with previous experience disclosing a serious error were more likely to agree with disclosure to patients. In comparison, doctors who believed that disclosure would decrease patient trust were less likely to agree with error disclosure to patients. Previous disclosure education was associated with attitudes supporting greater transparency with peers/institution. Physician attitudes about discussing errors with patients, colleagues, and institutions are related. Several predictors of transparency affect all 3 practices and are potentially modifiable by educational and institutional strategies.

On minimizing assignment errors and the trade-off between false positives and negatives in parentage analysis

KAUST Repository

Harrison, Hugo B.

2013-11-04

Genetic parentage analyses provide a practical means with which to identify parent-offspring relationships in the wild. In Harrison et al.\\'s study (2013a), we compare three methods of parentage analysis and showed that the number and diversity of microsatellite loci were the most important factors defining the accuracy of assignments. Our simulations revealed that an exclusion-Bayes theorem method was more susceptible to false-positive and false-negative assignments than other methods tested. Here, we analyse and discuss the trade-off between type I and type II errors in parentage analyses. We show that controlling for false-positive assignments, without reporting type II errors, can be misleading. Our findings illustrate the need to estimate and report both the rate of false-positive and false-negative assignments in parentage analyses. © 2013 John Wiley & Sons Ltd.

On minimizing assignment errors and the trade-off between false positives and negatives in parentage analysis

KAUST Repository

Harrison, Hugo B.; Saenz Agudelo, Pablo; Planes, Serge; Jones, Geoffrey P.; Berumen, Michael L.

2013-01-01

Genetic parentage analyses provide a practical means with which to identify parent-offspring relationships in the wild. In Harrison et al.'s study (2013a), we compare three methods of parentage analysis and showed that the number and diversity of microsatellite loci were the most important factors defining the accuracy of assignments. Our simulations revealed that an exclusion-Bayes theorem method was more susceptible to false-positive and false-negative assignments than other methods tested. Here, we analyse and discuss the trade-off between type I and type II errors in parentage analyses. We show that controlling for false-positive assignments, without reporting type II errors, can be misleading. Our findings illustrate the need to estimate and report both the rate of false-positive and false-negative assignments in parentage analyses. © 2013 John Wiley & Sons Ltd.

Treating depression in HIV-positive patients affects adherence

Directory of Open Access Journals (Sweden)

M Y H Moosa

2012-08-01

Full Text Available Aim. To determine changes in adherence to antiretroviral therapy (ART in HIV-positive patients with depression, following treatment with an antidepressant or psychotherapy. Methods. The study was prospective, randomised and controlled. Consenting volunteers aged ≥18 years and stable on ART for ≥6 months were included in the study. Sociodemographic data were obtained, and a clinical diagnostic evaluation and the Hamilton Depression rating scale (HAMD were performed on all subjects at entry to and at the end of the study. Participants found to be depressed were randomly assigned antidepressant treatment (20 mg citalopram or interpersonal psychotherapy (IPT (5 sessions. Medication was dispensed at each visit and patients were asked to return all unused medication to determine ART adherence. The study was approved by the University of the Witwatersrand. Results. Sixty-two HIV-positive persons receiving ART participated; 30 were not depressed (control group and 32 were depressed (patient group. No significant differences in demographic characteristics existed between the control and patient groups. Mean ART adherence at the start of the study was 99.5% (standard error (SE ±0.46 and 92.1% (SE ±1.69 in the control and patients groups, respectively. Mean ART adherence at the end of the study changed marginally in the control group (99.7%; SE ±0.46 and increased significantly in the patient group (99.5%; SE± 0.13 (p>0.05. The mean ART adherence rate of patients who received pharmacotherapy increased from 92.8% to 99.5%, and of those who received psychotherapy increased from 91.1% to 99.6% (p>0.05. There was no significant association between the increased adherence in the patient group and baseline demographic and clinical characteristics, irrespective of antidepressant therapy or IPT (p>0.05. Conclusion. Successful treatment of depression with an antidepressant or psychotherapy was associated with improved ART adherence, independent of the type

Comparison of community and hospital pharmacists' attitudes and behaviors on medication error disclosure to the patient: A pilot study.

Science.gov (United States)

Kim, ChungYun; Mazan, Jennifer L; Quiñones-Boex, Ana C

To determine pharmacists' attitudes and behaviors on medication errors and their disclosure and to compare community and hospital pharmacists on such views. An online questionnaire was developed from previous studies on physicians' disclosure of errors. Questionnaire items included demographics, environment, personal experiences, and attitudes on medication errors and the disclosure process. An invitation to participate along with the link to the questionnaire was electronically distributed to members of two Illinois pharmacy associations. A follow-up reminder was sent 4 weeks after the original message. Data were collected for 3 months, and statistical analyses were performed with the use of IBM SPSS version 22.0. The overall response rate was 23.3% (n = 422). The average employed respondent was a 51-year-old white woman with a BS Pharmacy degree working in a hospital pharmacy as a clinical staff member. Regardless of practice settings, pharmacist respondents agreed that medication errors were inevitable and that a disclosure process is necessary. Respondents from community and hospital settings were further analyzed to assess any differences. Community pharmacist respondents were more likely to agree that medication errors were inevitable and that pharmacists should address the patient's emotions when disclosing an error. Community pharmacist respondents were also more likely to agree that the health care professional most closely involved with the error should disclose the error to the patient and thought that it was the pharmacists' responsibility to disclose the error. Hospital pharmacist respondents were more likely to agree that it was important to include all details in a disclosure process and more likely to disagree on putting a "positive spin" on the event. Regardless of practice setting, responding pharmacists generally agreed that errors should be disclosed to patients. There were, however, significant differences in their attitudes and behaviors

Reducing wrong patient selection errors: exploring the design space of user interface techniques.

Science.gov (United States)

Sopan, Awalin; Plaisant, Catherine; Powsner, Seth; Shneiderman, Ben

2014-01-01

Wrong patient selection errors are a major issue for patient safety; from ordering medication to performing surgery, the stakes are high. Widespread adoption of Electronic Health Record (EHR) and Computerized Provider Order Entry (CPOE) systems makes patient selection using a computer screen a frequent task for clinicians. Careful design of the user interface can help mitigate the problem by helping providers recall their patients' identities, accurately select their names, and spot errors before orders are submitted. We propose a catalog of twenty seven distinct user interface techniques, organized according to a task analysis. An associated video demonstrates eighteen of those techniques. EHR designers who consider a wider range of human-computer interaction techniques could reduce selection errors, but verification of efficacy is still needed.

SU-G-BRB-03: Assessing the Sensitivity and False Positive Rate of the Integrated Quality Monitor (IQM) Large Area Ion Chamber to MLC Positioning Errors

Energy Technology Data Exchange (ETDEWEB)

Boehnke, E McKenzie; DeMarco, J; Steers, J; Fraass, B [Cedars-Sinai Medical Center, Los Angeles, CA (United States)

2016-06-15

Purpose: To examine both the IQM’s sensitivity and false positive rate to varying MLC errors. By balancing these two characteristics, an optimal tolerance value can be derived. Methods: An un-modified SBRT Liver IMRT plan containing 7 fields was randomly selected as a representative clinical case. The active MLC positions for all fields were perturbed randomly from a square distribution of varying width (±1mm to ±5mm). These unmodified and modified plans were measured multiple times each by the IQM (a large area ion chamber mounted to a TrueBeam linac head). Measurements were analyzed relative to the initial, unmodified measurement. IQM readings are analyzed as a function of control points. In order to examine sensitivity to errors along a field’s delivery, each measured field was divided into 5 groups of control points, and the maximum error in each group was recorded. Since the plans have known errors, we compared how well the IQM is able to differentiate between unmodified and error plans. ROC curves and logistic regression were used to analyze this, independent of thresholds. Results: A likelihood-ratio Chi-square test showed that the IQM could significantly predict whether a plan had MLC errors, with the exception of the beginning and ending control points. Upon further examination, we determined there was ramp-up occurring at the beginning of delivery. Once the linac AFC was tuned, the subsequent measurements (relative to a new baseline) showed significant (p <0.005) abilities to predict MLC errors. Using the area under the curve, we show the IQM’s ability to detect errors increases with increasing MLC error (Spearman’s Rho=0.8056, p<0.0001). The optimal IQM count thresholds from the ROC curves are ±3%, ±2%, and ±7% for the beginning, middle 3, and end segments, respectively. Conclusion: The IQM has proven to be able to detect not only MLC errors, but also differences in beam tuning (ramp-up). Partially supported by the Susan Scott Foundation.

The role of positional errors while interpolating soil organic carbon contents using satellite imagery

NARCIS (Netherlands)

Samsonova, V.P.; Meshalkina, J.L.; Blagoveschensky, Y.N.; Yaroslavtsev, A.M.; Stoorvogel, J.J.

2018-01-01

Increasingly, soil surveys make use of a combination of legacy data, ancillary data and new field data. While combining the different sources of information, positional errors can play a large role. For example, the spatial discrepancy between remote sensing images and field data can depend on

SU-E-J-21: Setup Variability of Colorectal Cancer Patients Treated in the Prone Position and Dosimetric Comparison with the Supine Position

Energy Technology Data Exchange (ETDEWEB)

Kim, A; Foster, J; Chu, W; Karotki, A [Sunnybrook Health Sciences Centre/Odette Cancer Centre, Toronto, Ontario (Canada)

2015-06-15

Purpose: Many cancer centers treat colorectal patients in the prone position on a belly board to minimize dose to the small bowel. That may potentially Result in patient setup instability with corresponding impact on dose delivery accuracy for highly conformal techniques such as IMRT/VMAT. Two aims of this work are 1) to investigate setup accuracy of rectum patients treated in the prone position on a belly board using CBCT and 2) to evaluate dosimetric impact on bladder and small bowel of treating rectum patients in supine vs. prone position. Methods: For the setup accuracy study, 10 patients were selected. Weekly CBCTs were acquired and matched to bone. The CBCT-determined shifts were recorded. For the dosimetric study, 7 prone-setup patients and 7 supine-setup patients were randomly selected from our clinical database. Various clinically relevant dose volume histogram values were recorded for the small bowel and bladder. Results: The CBCT-determined rotational shifts had a wide variation. For the dataset acquired at the time of this writing, the ranges of rotational setup errors for pitch, roll, and yaw were [−3.6° 4.7°], [−4.3° 3.2°], and [−1.4° 1.4°]. For the dosimetric study: the small bowel V(45Gy) and mean dose for the prone position was 5.6±12.1% and 18.4±6.2Gy (ranges indicate standard deviations); for the supine position the corresponding dose values were 12.9±15.8% and 24.7±8.8Gy. For the bladder, the V(30Gy) and mean dose for prone position were 68.7±12.7% and 38.4±3.3Gy; for supine position these dose values were 77.1±13.7% and 40.7±3.1Gy. Conclusion: There is evidence of significant rotational instability in the prone position. The OAR dosimetry study indicates that there are some patients that may still benefit from the prone position, though many patients can be safely treated supine.

Visual memory errors in Parkinson's disease patient with visual hallucinations.

Science.gov (United States)

Barnes, J; Boubert, L

2011-03-01

The occurrences of visual hallucinations seem to be more prevalent in low light and hallucinators tend to be more prone to false positive type errors in memory tasks. Here we investigated whether the richness of stimuli does indeed affect recognition differently in hallucinating and nonhallucinating participants, and if so whether this difference extends to identifying spatial context. We compared 36 Parkinson's disease (PD) patients with visual hallucinations, 32 Parkinson's patients without hallucinations, and 36 age-matched controls, on a visual memory task where color and black and white pictures were presented at different locations. Participants had to recognize the pictures among distracters along with the location of the stimulus. Findings revealed clear differences in performance between the groups. Both PD groups had impaired recognition compared to the controls, but those with hallucinations were significantly more impaired on black and white than on color stimuli. In addition, the group with hallucinations was significantly impaired compared to the other two groups on spatial memory. We suggest that not only do PD patients have poorer recognition of pictorial stimuli than controls, those who present with visual hallucinations appear to be more heavily reliant on bottom up sensory input and impaired on spatial ability.

The introduction of an acute physiological support service for surgical patients is an effective error reduction strategy.

Science.gov (United States)

Clarke, D L; Kong, V Y; Naidoo, L C; Furlong, H; Aldous, C

2013-01-01

Acute surgical patients are particularly vulnerable to human error. The Acute Physiological Support Team (APST) was created with the twin objectives of identifying high-risk acute surgical patients in the general wards and reducing both the incidence of error and impact of error on these patients. A number of error taxonomies were used to understand the causes of human error and a simple risk stratification system was adopted to identify patients who are particularly at risk of error. During the period November 2012-January 2013 a total of 101 surgical patients were cared for by the APST at Edendale Hospital. The average age was forty years. There were 36 females and 65 males. There were 66 general surgical patients and 35 trauma patients. Fifty-six patients were referred on the day of their admission. The average length of stay in the APST was four days. Eleven patients were haemo-dynamically unstable on presentation and twelve were clinically septic. The reasons for referral were sepsis,(4) respiratory distress,(3) acute kidney injury AKI (38), post-operative monitoring (39), pancreatitis,(3) ICU down-referral,(7) hypoxia,(5) low GCS,(1) coagulopathy.(1) The mortality rate was 13%. A total of thirty-six patients experienced 56 errors. A total of 143 interventions were initiated by the APST. These included institution or adjustment of intravenous fluids (101), blood transfusion,(12) antibiotics,(9) the management of neutropenic sepsis,(1) central line insertion,(3) optimization of oxygen therapy,(7) correction of electrolyte abnormality,(8) correction of coagulopathy.(2) CONCLUSION: Our intervention combined current taxonomies of error with a simple risk stratification system and is a variant of the defence in depth strategy of error reduction. We effectively identified and corrected a significant number of human errors in high-risk acute surgical patients. This audit has helped understand the common sources of error in the general surgical wards and will inform

TU-AB-201-05: Automatic Adaptive Per-Operative Re-Planning for HDR Prostate Brachytherapy - a Simulation Study On Errors in Needle Positioning

International Nuclear Information System (INIS)

Borot de Battisti, M; Maenhout, M; Lagendijk, J J W; Van Vulpen, M; Moerland, M A; Senneville, B Denis de; Hautvast, G; Binnekamp, D

2015-01-01

Purpose: To develop adaptive planning with feedback for MRI-guided focal HDR prostate brachytherapy with a single divergent needle robotic implant device. After each needle insertion, the dwell positions for that needle are calculated and the positioning of remaining needles and dosimetry are both updated based on MR imaging. Methods: Errors in needle positioning may occur due to inaccurate needle insertion (caused by e.g. the needle’s bending) and unpredictable changes in patient anatomy. Consequently, the dose plan quality might dramatically decrease compared to the preplan. In this study, a procedure was developed to re-optimize, after each needle insertion, the remaining needle angulations, source positions and dwell times in order to obtain an optimal coverage (D95% PTV>19 Gy) without exceeding the constraints of the organs at risk (OAR) (D10% urethra<21 Gy, D1cc bladder<12 Gy and D1cc rectum<12 Gy). Complete HDR procedures with 6 needle insertions were simulated for a patient MR-image set with PTV, prostate, urethra, bladder and rectum delineated. Random angulation errors, modeled by a Gaussian distribution (standard deviation of 3 mm at the needle’s tip), were generated for each needle insertion. We compared the final dose parameters for the situations (I) without re-optimization and (II) with the automatic feedback. Results: The computation time of replanning was below 100 seconds on a current desk computer. For the patient tested, a clinically acceptable dose plan was achieved while applying the automatic feedback (median(range) in Gy, D95% PTV: 19.9(19.3–20.3), D10% urethra: 13.4(11.9–18.0), D1cc rectum: 11.0(10.7–11.6), D1cc bladder: 4.9(3.6–6.8)). This was not the case without re-optimization (median(range) in Gy, D95% PTV: 19.4(14.9–21.3), D10% urethra: 12.6(11.0–15.7), D1cc rectum: 10.9(8.9–14.1), D1cc bladder: 4.8(4.4–5.2)). Conclusion: An automatic guidance strategy for HDR prostate brachytherapy was developed to compensate

Propagation of positional error in 3D GIS

NARCIS (Netherlands)

Biljecki, Filip; Heuvelink, Gerard B.M.; Ledoux, Hugo; Stoter, Jantien

2015-01-01

While error propagation in GIS is a topic that has received a lot of attention, it has not been researched with 3D GIS data. We extend error propagation to 3D city models using a Monte Carlo simulation on a use case of annual solar irradiation estimation of building rooftops for assessing the

Rail-guided robotic end-effector position error due to rail compliance and ship motion

NARCIS (Netherlands)

Borgerink, Dian; Stegenga, J.; Brouwer, Dannis Michel; Woertche, H.J.; Stramigioli, Stefano

2014-01-01

A rail-guided robotic system is currently being designed for the inspection of ballast water tanks in ships. This robotic system will manipulate sensors toward the interior walls of the tank. In this paper, the influence of rail compliance on the end-effector position error due to ship movement is

Patient identification error among prostate needle core biopsy specimens--are we ready for a DNA time-out?

Science.gov (United States)

Suba, Eric J; Pfeifer, John D; Raab, Stephen S

2007-10-01

Patient identification errors in surgical pathology often involve switches of prostate or breast needle core biopsy specimens among patients. We assessed strategies for decreasing the occurrence of these uncommon and yet potentially catastrophic events. Root cause analyses were performed following 3 cases of patient identification error involving prostate needle core biopsy specimens. Patient identification errors in surgical pathology result from slips and lapses of automatic human action that may occur at numerous steps during pre-laboratory, laboratory and post-laboratory work flow processes. Patient identification errors among prostate needle biopsies may be difficult to entirely prevent through the optimization of work flow processes. A DNA time-out, whereby DNA polymorphic microsatellite analysis is used to confirm patient identification before radiation therapy or radical surgery, may eliminate patient identification errors among needle biopsies.

Change for the better: an innovative model of care delivering positive patient and workforce outcomes.

Science.gov (United States)

Cann, Tina; Gardner, Anne

2012-01-01

To evaluate patient and workforce outcomes following the implementation of the Practice Partnership Model of Care. Pre-test-post-test design. A 29-bed surgical ward at a tertiary-level regional hospital. Summary de-identified data from all patients and ward nursing staff in the study period. The Practice Partnership Model of Care has four main components: working in partnership; clinical handover at the bedside; comfort rounds; and environmental modifications. These reflect patient-centered and quality focused initiatives and use a total quality improvement framework that aims to transform care at the bedside. Patient outcomes: changes in patient safety (measured by numbers of medication errors and patient falls); satisfaction with care (use of the call bell system, number of complaints and compliments). Workforce outcomes: changes in staff satisfaction (measured through staff sick leave). A statistically significant reduction in use of nurse call bells (p=<0.001) post-implementation. Medication errors and patient falls reduced, with an overall reduction of 4% in staff sick leave. The Practice Partnership Model of Care positively affected patient and workforce outcomes, suggesting further exploration of this model in other hospital contexts is warranted.

Positioning devices for patients

International Nuclear Information System (INIS)

Heavens, M.

1981-01-01

It has been suggested that it is very important to position patients reproducibly at different stages of radiotherapy treatment planning and treatment, or similar procedures. Devices have been described for positioning a patient's upper and lower thorax. This invention provides reproducible positioning for a female patient's breasts, for example in planning treatment of and treating breast tumours. The patient is placed prone, using for example an upper thorax device. A support device is placed central to and beneath her breasts to partially displace them outwards. The device may be triangular in section with one apex contacting the chest wall at the sternum. Restraining straps may be provided to hold the breasts against the support device. Means may be provided to take a healthy breast from the path of radiation through the tumour. (author)

[Patient safety and errors in medicine: development, prevention and analyses of incidents].

Science.gov (United States)

Rall, M; Manser, T; Guggenberger, H; Gaba, D M; Unertl, K

2001-06-01

"Patient safety" and "errors in medicine" are issues gaining more and more prominence in the eyes of the public. According to newer studies, errors in medicine are among the ten major causes of death in association with the whole area of health care. A new era has begun incorporating attention to a "systems" approach to deal with errors and their causes in the health system. In other high-risk domains with a high demand for safety (such as the nuclear power industry and aviation) many strategies to enhance safety have been established. It is time to study these strategies, to adapt them if necessary and apply them to the field of medicine. These strategies include: to teach people how errors evolve in complex working domains and how types of errors are classified; the introduction of critical incident reporting systems that are free of negative consequences for the reporters; the promotion of continuous medical education; and the development of generic problem-solving skills incorporating the extensive use of realistic simulators wherever possible. Interestingly, the field of anesthesiology--within which realistic simulators were developed--is referred to as a model for the new patient safety movement. Despite this proud track record in recent times though, there is still much to be done even in the field of anesthesiology. Overall though, the most important strategy towards a long-term improvement in patient safety will be a change of "culture" throughout the entire health care system. The "culture of blame" focused on individuals should be replaced by a "safety culture", that sees errors and critical incidents as a problem of the whole organization. The acceptance of human fallability and an open-minded non-punitive analysis of errors in the sense of a "preventive and proactive safety culture" should lead to solutions at the systemic level. This change in culture can only be achieved with a strong commitment from the highest levels of an organization. Patient

Design of a system of reference for positioning of patients in radiotherapy of breast cancer

International Nuclear Information System (INIS)

Nebot, P.; Reinado, D.; Salvador, R.; Gonzalez-Pena, R.; Dalmases, F.; Romero, C.; Rosello, J.; Diez, S.; Cibrian, R.

2013-01-01

The objective of this work is the design of a system of repositioning of the patient allowing to minimize errors both in everyday's the same placement as in the position held during the session, so that treatment would be intensified in the area to be treated, avoiding possible damage to other healthy areas. (Author)

Quantitative analysis of the errors positioning of a multi leaf collimator for volumetric arcoterapia treatments

International Nuclear Information System (INIS)

Gomez Gonzalez, N.; Garcia Repiso, S.; Martin Rincon, C.; Cons Perez, N.; Saez Beltran, M.; Delgado Aparicio, J. M.; Perez alvarez, M. E.; Verde Velasco, J. M.; Ramos Pacho, J. A.; Sena Espinel, E. de

2013-01-01

The precision in the positioning of the multi leaf collimation system of a linear accelerator is critical, especially in treatments of IMRT, where small mistakes can cause relevant dosimetry discrepancies regarding the calculated plan. To assess the accuracy and repeatability of the blades positioning can be used controls, including the one known as fence test whose image pattern allows you to find anomalies in a visual way. The objective of this study is to develop a method which allows to quantify the positioning errors of the multi leaf collimator from this test. (Author)

SU-F-J-131: Reproducibility of Positioning Error Due to Temporarily Indwelled Urethral Catheter for Urethra-Sparing Prostate IMRT

International Nuclear Information System (INIS)

Hirose, K; Takai, Y; Sato, M; Hatayama, Y; Kawaguchi, H; Aoki, M; Akimoto, H; Komai, F; Souma, M; Obara, H; Suzuki, M

2016-01-01

Purpose: The purpose of this study was to prospectively assess the reproducibility of positioning errors due to temporarily indwelled catheter in urethra-sparing image-guided (IG) IMRT. Methods: Ten patients received urethra-sparing prostate IG-IMRT with implanted fiducials. After the first CT scan was performed in supine position, 6-Fr catheter was indwelled into urethra, and the second CT images were taken for planning. While the PTV received 80 Gy, 5% dose reduction was applied for the urethral PRV along the catheter. Additional CT scans were also performed at 5th and 30th fraction. Positions of interests (POIs) were set on posterior edge of prostate at beam isocenter level (POI1) and cranial and caudal edge of prostatic urethra on the post-indwelled CT images. POIs were copied into the pre-indwelled, 5th and 30th fraction’s CT images after fiducial matching on these CT images. The deviation of each POI between pre- and post-indwelled CT and the reproducibility of prostate displacement due to catheter were evaluated. Results: The deviation of POI1 caused by the indwelled catheter to the directions of RL/AP/SI (mm) was 0.20±0.27/−0.64±2.43/1.02±2.31, respectively, and the absolute distances (mm) were 3.15±1.41. The deviation tends to be larger if closer to the caudal edge of prostate. Compared with the pre-indwelled CT scan, a median displacement of all POIs (mm) were 0.3±0.2/2.2±1.1/2.0±2.6 in the post-indwelled, 0.4±0.4/3.4±2.1/2.3±2.6 in 5th, and 0.5±0.5/1.7±2.2/1.9±3.1 in 30th fraction’s CT scan with a similar data distribution. There were 6 patients with 5-mm-over displacement in AP and/or CC directions. Conclusion: Reproducibility of positioning errors due to temporarily indwelling catheter was observed. Especially in case of patients with unusually large shifts by indwelling catheter at the planning process, treatment planning should be performed by using the pre-indwelled CT images with transferred contour of the urethra identified by

SU-F-J-131: Reproducibility of Positioning Error Due to Temporarily Indwelled Urethral Catheter for Urethra-Sparing Prostate IMRT

Energy Technology Data Exchange (ETDEWEB)

Hirose, K; Takai, Y [Hirosaki University, Hirosaki (Japan); Southern Tohoku BNCT Research Center, Koriyama (Japan); Sato, M; Hatayama, Y; Kawaguchi, H; Aoki, M; Akimoto, H [Hirosaki University, Hirosaki (Japan); Komai, F; Souma, M; Obara, H; Suzuki, M [Hirosaki University Hospital, Hirosaki (Japan)

2016-06-15

Purpose: The purpose of this study was to prospectively assess the reproducibility of positioning errors due to temporarily indwelled catheter in urethra-sparing image-guided (IG) IMRT. Methods: Ten patients received urethra-sparing prostate IG-IMRT with implanted fiducials. After the first CT scan was performed in supine position, 6-Fr catheter was indwelled into urethra, and the second CT images were taken for planning. While the PTV received 80 Gy, 5% dose reduction was applied for the urethral PRV along the catheter. Additional CT scans were also performed at 5th and 30th fraction. Positions of interests (POIs) were set on posterior edge of prostate at beam isocenter level (POI1) and cranial and caudal edge of prostatic urethra on the post-indwelled CT images. POIs were copied into the pre-indwelled, 5th and 30th fraction’s CT images after fiducial matching on these CT images. The deviation of each POI between pre- and post-indwelled CT and the reproducibility of prostate displacement due to catheter were evaluated. Results: The deviation of POI1 caused by the indwelled catheter to the directions of RL/AP/SI (mm) was 0.20±0.27/−0.64±2.43/1.02±2.31, respectively, and the absolute distances (mm) were 3.15±1.41. The deviation tends to be larger if closer to the caudal edge of prostate. Compared with the pre-indwelled CT scan, a median displacement of all POIs (mm) were 0.3±0.2/2.2±1.1/2.0±2.6 in the post-indwelled, 0.4±0.4/3.4±2.1/2.3±2.6 in 5th, and 0.5±0.5/1.7±2.2/1.9±3.1 in 30th fraction’s CT scan with a similar data distribution. There were 6 patients with 5-mm-over displacement in AP and/or CC directions. Conclusion: Reproducibility of positioning errors due to temporarily indwelling catheter was observed. Especially in case of patients with unusually large shifts by indwelling catheter at the planning process, treatment planning should be performed by using the pre-indwelled CT images with transferred contour of the urethra identified by

Positive phase error from parallel conductance in tetrapolar bio-impedance measurements and its compensation

Directory of Open Access Journals (Sweden)

Ivan M Roitt

2010-01-01

Full Text Available Bioimpedance measurements are of great use and can provide considerable insight into biological processes.  However, there are a number of possible sources of measurement error that must be considered.  The most dominant source of error is found in bipolar measurements where electrode polarisation effects are superimposed on the true impedance of the sample.  Even with the tetrapolar approach that is commonly used to circumvent this issue, other errors can persist. Here we characterise the positive phase and rise in impedance magnitude with frequency that can result from the presence of any parallel conductive pathways in the measurement set-up.  It is shown that fitting experimental data to an equivalent electrical circuit model allows for accurate determination of the true sample impedance as validated through finite element modelling (FEM of the measurement chamber.  Finally, the model is used to extract dispersion information from cell cultures to characterise their growth.

Analyzing temozolomide medication errors: potentially fatal.

Science.gov (United States)

Letarte, Nathalie; Gabay, Michael P; Bressler, Linda R; Long, Katie E; Stachnik, Joan M; Villano, J Lee

2014-10-01

The EORTC-NCIC regimen for glioblastoma requires different dosing of temozolomide (TMZ) during radiation and maintenance therapy. This complexity is exacerbated by the availability of multiple TMZ capsule strengths. TMZ is an alkylating agent and the major toxicity of this class is dose-related myelosuppression. Inadvertent overdose can be fatal. The websites of the Institute for Safe Medication Practices (ISMP), and the Food and Drug Administration (FDA) MedWatch database were reviewed. We searched the MedWatch database for adverse events associated with TMZ and obtained all reports including hematologic toxicity submitted from 1st November 1997 to 30th May 2012. The ISMP describes errors with TMZ resulting from the positioning of information on the label of the commercial product. The strength and quantity of capsules on the label were in close proximity to each other, and this has been changed by the manufacturer. MedWatch identified 45 medication errors. Patient errors were the most common, accounting for 21 or 47% of errors, followed by dispensing errors, which accounted for 13 or 29%. Seven reports or 16% were errors in the prescribing of TMZ. Reported outcomes ranged from reversible hematological adverse events (13%), to hospitalization for other adverse events (13%) or death (18%). Four error reports lacked detail and could not be categorized. Although the FDA issued a warning in 2003 regarding fatal medication errors and the product label warns of overdosing, errors in TMZ dosing occur for various reasons and involve both healthcare professionals and patients. Overdosing errors can be fatal.

Decisions to shoot in a weapon identification task: The influence of cultural stereotypes and perceived threat on false positive errors.

Science.gov (United States)

Fleming, Kevin K; Bandy, Carole L; Kimble, Matthew O

2010-01-01

The decision to shoot a gun engages executive control processes that can be biased by cultural stereotypes and perceived threat. The neural locus of the decision to shoot is likely to be found in the anterior cingulate cortex (ACC), where cognition and affect converge. Male military cadets at Norwich University (N=37) performed a weapon identification task in which they made rapid decisions to shoot when images of guns appeared briefly on a computer screen. Reaction times, error rates, and electroencephalogram (EEG) activity were recorded. Cadets reacted more quickly and accurately when guns were primed by images of Middle-Eastern males wearing traditional clothing. However, cadets also made more false positive errors when tools were primed by these images. Error-related negativity (ERN) was measured for each response. Deeper ERNs were found in the medial-frontal cortex following false positive responses. Cadets who made fewer errors also produced deeper ERNs, indicating stronger executive control. Pupil size was used to measure autonomic arousal related to perceived threat. Images of Middle-Eastern males in traditional clothing produced larger pupil sizes. An image of Osama bin Laden induced the largest pupil size, as would be predicted for the exemplar of Middle East terrorism. Cadets who showed greater increases in pupil size also made more false positive errors. Regression analyses were performed to evaluate predictions based on current models of perceived threat, stereotype activation, and cognitive control. Measures of pupil size (perceived threat) and ERN (cognitive control) explained significant proportions of the variance in false positive errors to Middle-Eastern males in traditional clothing, while measures of reaction time, signal detection response bias, and stimulus discriminability explained most of the remaining variance.

A study of respiration-correlated cone-beam CT scans to correct target positioning errors in radiotherapy of thoracic cancer

Energy Technology Data Exchange (ETDEWEB)

Santoro, J. P.; McNamara, J.; Yorke, E.; Pham, H.; Rimner, A.; Rosenzweig, K. E.; Mageras, G. S. [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York 10065 (United States); Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York 10065 (United States); Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York 10065 (United States)

2012-10-15

Purpose: There is increasingly widespread usage of cone-beam CT (CBCT) for guiding radiation treatment in advanced-stage lung tumors, but difficulties associated with daily CBCT in conventionally fractionated treatments include imaging dose to the patient, increased workload and longer treatment times. Respiration-correlated cone-beam CT (RC-CBCT) can improve localization accuracy in mobile lung tumors, but further increases the time and workload for conventionally fractionated treatments. This study investigates whether RC-CBCT-guided correction of systematic tumor deviations in standard fractionated lung tumor radiation treatments is more effective than 2D image-based correction of skeletal deviations alone. A second study goal compares respiration-correlated vs respiration-averaged images for determining tumor deviations. Methods: Eleven stage II-IV nonsmall cell lung cancer patients are enrolled in an IRB-approved prospective off-line protocol using RC-CBCT guidance to correct for systematic errors in GTV position. Patients receive a respiration-correlated planning CT (RCCT) at simulation, daily kilovoltage RC-CBCT scans during the first week of treatment and weekly scans thereafter. Four types of correction methods are compared: (1) systematic error in gross tumor volume (GTV) position, (2) systematic error in skeletal anatomy, (3) daily skeletal corrections, and (4) weekly skeletal corrections. The comparison is in terms of weighted average of the residual GTV deviations measured from the RC-CBCT scans and representing the estimated residual deviation over the treatment course. In the second study goal, GTV deviations computed from matching RCCT and RC-CBCT are compared to deviations computed from matching respiration-averaged images consisting of a CBCT reconstructed using all projections and an average-intensity-projection CT computed from the RCCT. Results: Of the eleven patients in the GTV-based systematic correction protocol, two required no correction

A study of respiration-correlated cone-beam CT scans to correct target positioning errors in radiotherapy of thoracic cancer

International Nuclear Information System (INIS)

Santoro, J. P.; McNamara, J.; Yorke, E.; Pham, H.; Rimner, A.; Rosenzweig, K. E.; Mageras, G. S.

2012-01-01

Purpose: There is increasingly widespread usage of cone-beam CT (CBCT) for guiding radiation treatment in advanced-stage lung tumors, but difficulties associated with daily CBCT in conventionally fractionated treatments include imaging dose to the patient, increased workload and longer treatment times. Respiration-correlated cone-beam CT (RC-CBCT) can improve localization accuracy in mobile lung tumors, but further increases the time and workload for conventionally fractionated treatments. This study investigates whether RC-CBCT-guided correction of systematic tumor deviations in standard fractionated lung tumor radiation treatments is more effective than 2D image-based correction of skeletal deviations alone. A second study goal compares respiration-correlated vs respiration-averaged images for determining tumor deviations. Methods: Eleven stage II–IV nonsmall cell lung cancer patients are enrolled in an IRB-approved prospective off-line protocol using RC-CBCT guidance to correct for systematic errors in GTV position. Patients receive a respiration-correlated planning CT (RCCT) at simulation, daily kilovoltage RC-CBCT scans during the first week of treatment and weekly scans thereafter. Four types of correction methods are compared: (1) systematic error in gross tumor volume (GTV) position, (2) systematic error in skeletal anatomy, (3) daily skeletal corrections, and (4) weekly skeletal corrections. The comparison is in terms of weighted average of the residual GTV deviations measured from the RC-CBCT scans and representing the estimated residual deviation over the treatment course. In the second study goal, GTV deviations computed from matching RCCT and RC-CBCT are compared to deviations computed from matching respiration-averaged images consisting of a CBCT reconstructed using all projections and an average-intensity-projection CT computed from the RCCT. Results: Of the eleven patients in the GTV-based systematic correction protocol, two required no correction

The dose distribution and DVH change analysis wing to effect of the patient setup error

International Nuclear Information System (INIS)

Kim, Kyung Tae; Ju, Sang Gyu; Ahn, Jae Hong; Park, Young Hwan

2004-01-01

The setup error due to the patient and the staff from radiation treatment as the reason which is important the treatment record could be decided is a possibility of effect. The SET-UP ERROR of the patient analyzes the effect of dose distribution and DVH from radiation treatment of the patient. This test uses human phantom and when C-T scan doing, It rotated the Left direction of the human phantom and it made SET-UP ERROR, Standard plan and 3 mm, 5 mm, 7 mm, 10 mm, 15 mm, 20 mm with to distinguish, it made the C-T scan error. With the result, The SET-UP ERROR got each C-T image Using RTP equipment It used the plan which is used generally from clinical - Box plan, 3 Dimension plan( identical angle 5beam plan) Also, ( CTV+1cm margin, CTV+0.5cm margin, CTV+0.3,cm margin = PTV) it distinguished the standard plan and each set-up error plan and the plan used a dose distribution and the DVH and it analyzed. The Box 4 the plan and 3 Dimension plan which it bites it got similar an dose distribution and DVH in 3 mm, 5 mm From rotation error and Rectilinear movement (0%-2%). Rotation error and rectilinear error 7 mm, 10 mm, 15 mm, 20 mm appeared effect it will go mad to a enough change in treatment (2%-11%) The diminishes the effect of the SET-UP ERROR must reduce move with tension of the patient Also, we are important accessory development and the supply that it reducing of reproducibility and the move.

Responsibility for reporting patient death due to hospital error in Japan when an error occurred at a referring institution.

Science.gov (United States)

Maeda, Shoichi; Starkey, Jay; Kamishiraki, Etsuko; Ikeda, Noriaki

2013-12-01

In Japan, physicians are required to report unexpected health care-associated patient deaths to the police. Patients needing to be transferred to another institution often have complex medical problems. If a medical error occurs, it may be either at the final or the referring institution. Some fear that liability will fall on the final institution regardless of where the error occurred or that the referring facility may oppose such reporting, leading to a failure to report to police or to recommend an autopsy. Little is known about the actual opinions of physicians and risk managers in this regard. The authors sent standardised, self-administered questionnaires to all hospitals in Japan that participate in the national general residency program. Most physicians and risk managers in Japan indicated that they would report a patient's death to the police where the patient has been transferred. Of those who indicated they would not report to the police, the majority still indicated they would recommend an autopsy

Blood specimen labelling errors: Implications for nephrology nursing practice.

Science.gov (United States)

Duteau, Jennifer

2014-01-01

Patient safety is the foundation of high-quality health care, as recognized both nationally and worldwide. Patient blood specimen identification is critical in ensuring the delivery of safe and appropriate care. The practice of nephrology nursing involves frequent patient blood specimen withdrawals to treat and monitor kidney disease. A critical review of the literature reveals that incorrect patient identification is one of the major causes of blood specimen labelling errors. Misidentified samples create a serious risk to patient safety leading to multiple specimen withdrawals, delay in diagnosis, misdiagnosis, incorrect treatment, transfusion reactions, increased length of stay and other negative patient outcomes. Barcode technology has been identified as a preferred method for positive patient identification leading to a definitive decrease in blood specimen labelling errors by as much as 83% (Askeland, et al., 2008). The use of a root cause analysis followed by an action plan is one approach to decreasing the occurrence of blood specimen labelling errors. This article will present a review of the evidence-based literature surrounding blood specimen labelling errors, followed by author recommendations for completing a root cause analysis and action plan. A failure modes and effects analysis (FMEA) will be presented as one method to determine root cause, followed by the Ottawa Model of Research Use (OMRU) as a framework for implementation of strategies to reduce blood specimen labelling errors.

Patients' knowledge and perceived reactions to medical errors in a ...

African Journals Online (AJOL)

Severity of error (88.5%) and the perception of negligence mediated intention to litigate. Voluntary disclosure significantly reduced patients' intention to litigate caregivers (chi2=3.584; df=1; P=0.053). Frustration/anger was not more likely to influence patient to litigate than feelings of resignation/forgiveness (chi2=2.156; df=1; ...

Burnout, engagement and resident physicians' self-reported errors.

Science.gov (United States)

Prins, J T; van der Heijden, F M M A; Hoekstra-Weebers, J E H M; Bakker, A B; van de Wiel, H B M; Jacobs, B; Gazendam-Donofrio, S M

2009-12-01

Burnout is a work-related syndrome that may negatively affect more than just the resident physician. On the other hand, engagement has been shown to protect employees; it may also positively affect the patient care that the residents provide. Little is known about the relationship between residents' self-reported errors and burnout and engagement. In our national study that included all residents and physicians in The Netherlands, 2115 questionnaires were returned (response rate 41.1%). The residents reported on burnout (Maslach Burnout Inventory-Health and Social Services), engagement (Utrecht Work Engagement Scale) and self-assessed patient care practices (six items, two factors: errors in action/judgment, errors due to lack of time). Ninety-four percent of the residents reported making one or more mistake without negative consequences for the patient during their training. Seventy-one percent reported performing procedures for which they did not feel properly trained. More than half (56%) of the residents stated they had made a mistake with a negative consequence. Seventy-six percent felt they had fallen short in the quality of care they provided on at least one occasion. Men reported more errors in action/judgment than women. Significant effects of specialty and clinical setting were found on both types of errors. Residents with burnout reported significantly more errors (p engaged residents reported fewer errors (p burnout and to keep residents engaged in their work.

Organizational safety culture and medical error reporting by Israeli nurses.

Science.gov (United States)

Kagan, Ilya; Barnoy, Sivia

2013-09-01

To investigate the association between patient safety culture (PSC) and the incidence and reporting rate of medical errors by Israeli nurses. Self-administered structured questionnaires were distributed to a convenience sample of 247 registered nurses enrolled in training programs at Tel Aviv University (response rate = 91%). The questionnaire's three sections examined the incidence of medication mistakes in clinical practice, the reporting rate for these errors, and the participants' views and perceptions of the safety culture in their workplace at three levels (organizational, departmental, and individual performance). Pearson correlation coefficients, t tests, and multiple regression analysis were used to analyze the data. Most nurses encountered medical errors from a daily to a weekly basis. Six percent of the sample never reported their own errors, while half reported their own errors "rarely or sometimes." The level of PSC was positively and significantly correlated with the error reporting rate. PSC, place of birth, error incidence, and not having an academic nursing degree were significant predictors of error reporting, together explaining 28% of variance. This study confirms the influence of an organizational safety climate on readiness to report errors. Senior healthcare executives and managers can make a major impact on safety culture development by creating and promoting a vision and strategy for quality and safety and fostering their employees' motivation to implement improvement programs at the departmental and individual level. A positive, carefully designed organizational safety culture can encourage error reporting by staff and so improve patient safety. © 2013 Sigma Theta Tau International.

Effect of patient setup errors on simultaneously integrated boost head and neck IMRT treatment plans

International Nuclear Information System (INIS)

Siebers, Jeffrey V.; Keall, Paul J.; Wu Qiuwen; Williamson, Jeffrey F.; Schmidt-Ullrich, Rupert K.

2005-01-01

Purpose: The purpose of this study is to determine dose delivery errors that could result from random and systematic setup errors for head-and-neck patients treated using the simultaneous integrated boost (SIB)-intensity-modulated radiation therapy (IMRT) technique. Methods and Materials: Twenty-four patients who participated in an intramural Phase I/II parotid-sparing IMRT dose-escalation protocol using the SIB treatment technique had their dose distributions reevaluated to assess the impact of random and systematic setup errors. The dosimetric effect of random setup error was simulated by convolving the two-dimensional fluence distribution of each beam with the random setup error probability density distribution. Random setup errors of σ = 1, 3, and 5 mm were simulated. Systematic setup errors were simulated by randomly shifting the patient isocenter along each of the three Cartesian axes, with each shift selected from a normal distribution. Systematic setup error distributions with Σ = 1.5 and 3.0 mm along each axis were simulated. Combined systematic and random setup errors were simulated for σ = Σ = 1.5 and 3.0 mm along each axis. For each dose calculation, the gross tumor volume (GTV) received by 98% of the volume (D 98 ), clinical target volume (CTV) D 90 , nodes D 90 , cord D 2 , and parotid D 50 and parotid mean dose were evaluated with respect to the plan used for treatment for the structure dose and for an effective planning target volume (PTV) with a 3-mm margin. Results: Simultaneous integrated boost-IMRT head-and-neck treatment plans were found to be less sensitive to random setup errors than to systematic setup errors. For random-only errors, errors exceeded 3% only when the random setup error σ exceeded 3 mm. Simulated systematic setup errors with Σ = 1.5 mm resulted in approximately 10% of plan having more than a 3% dose error, whereas a Σ = 3.0 mm resulted in half of the plans having more than a 3% dose error and 28% with a 5% dose error

Dosimetric impact of systematic MLC positional errors on step and shoot IMRT for prostate cancer: a planning study

International Nuclear Information System (INIS)

Ung, N.M.; Harper, C.S.; Wee, L.

2011-01-01

Full text: The positional accuracy of multileaf collimators (MLC) is crucial in ensuring precise delivery of intensity-modulated radiotherapy (IMRT). The aim of this planning study was to investigate the dosimetric impact of systematic MLC positional errors on step and shoot IMRT of prostate cancer. A total of 12 perturbations of MLC leaf banks were introduced to six prostate IMRT treatment plans to simulate MLC systematic positional errors. Dose volume histograms (DVHs) were generated for the extraction of dose endpoint parameters. Plans were evaluated in terms of changes to the defined endpoint dose parameters, conformity index (CI) and healthy tissue avoidance (HTA) to planning target volume (PTV), rectum and bladder. Negative perturbations of MLC had been found to produce greater changes to endpoint dose parameters than positive perturbations of MLC (p 9 5 of -1.2 and 0.9% respectively. Negative and positive synchronised MLC perturbations of I mm in one direction resulted in median changes in D 9 5 of -2.3 and 1.8% respectively. Doses to rectum were generally more sensitive to systematic MLC en-ors compared to bladder (p < 0.01). Negative and positive synchronised MLC perturbations of I mm in one direction resulted in median changes in endpoint dose parameters of rectum and bladder from 1.0 to 2.5%. Maximum reduction of -4.4 and -7.3% were recorded for conformity index (CI) and healthy tissue avoidance (HT A) respectively due to synchronised MLC perturbation of 1 mm. MLC errors resulted in dosimetric changes in IMRT plans for prostate. (author)

Is ExacTrac x-ray system an alternative to CBCT for positioning patients with head and neck cancers?

International Nuclear Information System (INIS)

Clemente, Stefania; Chiumento, Costanza; Fiorentino, Alba; Cozzolino, Mariella; Oliviero, Caterina; Califano, Giorgia; Caivano, Rocchina; Fusco, Vincenzo; Simeon, Vittorio

2013-01-01

Purpose: To evaluate the usefulness of a six-degrees-of freedom (6D) correction using ExacTrac robotics system in patients with head-and-neck (HN) cancer receiving radiation therapy.Methods: Local setup accuracy was analyzed for 12 patients undergoing intensity-modulated radiation therapy (IMRT). Patient position was imaged daily upon two different protocols, cone-beam computed tomography (CBCT), and ExacTrac (ET) images correction. Setup data from either approach were compared in terms of both residual errors after correction and punctual displacement of selected regions of interest (Mandible, C2, and C6 vertebral bodies).Results: On average, both protocols achieved reasonably low residual errors after initial correction. The observed differences in shift vectors between the two protocols showed that CBCT tends to weight more C2 and C6 at the expense of the mandible, while ET tends to average more differences among the different ROIs.Conclusions: CBCT, even without 6D correction capabilities, seems preferable to ET for better consistent alignment and the capability to see soft tissues. Therefore, in our experience, CBCT represents a benchmark for positioning head and neck cancer patients

A comparative study of set up variations and bowel volumes in supine versus prone positions of patients treated with external beam radiation for carcinoma rectum.

Science.gov (United States)

Rajeev, K R; Menon, Smrithy S; Beena, K; Holla, Raghavendra; Kumar, R Rajaneesh; Dinesh, M

2014-01-01

A prospective study was undertaken to evaluate the influence of patient positioning on the set up variations to determine the planning target volume (PTV) margins and to evaluate the clinical relevance volume assessment of the small bowel (SB) within the irradiated volume. During the period of months from December 2011 to April 2012, a computed tomography (CT) scan was done either in supine position or in prone position using a belly board (BB) for 20 consecutive patients. All the patients had histologically proven rectal cancer and received either post- or pre-operative pelvic irradiation. Using a three-dimensional planning system, the dose-volume histogram for SB was defined in each axial CT slice. Total dose was 46-50 Gy (2 Gy/fraction), delivered using the 4-field box technique. The set up variation of the study group was assessed from the data received from the electronic portal imaging device in the linear accelerator. The shift along X, Y, and Z directions were noted. Both systematic and random errors were calculated and using both these values the PTV margin was calculated. The systematic errors of patients treated in the supine position were 0.87 (X-mm), 0.66 (Y-mm), 1.6 (Z-mm) and in the prone position were 1.3 (X-mm), 0.59 (Y-mm), 1.17 (Z-mm). The random errors of patients treated in the supine positions were 1.81 (X-mm), 1.73 (Y-mm), 1.83 (Z-mm) and in prone position were 2.02 (X-mm), 1.21 (Y-mm), 3.05 (Z-mm). The calculated PTV margins in the supine position were 3.45 (X-mm), 2.87 (Y-mm), 5.31 (Z-mm) and in the prone position were 4.91 (X-mm), 2.32 (Y-mm), 5.08 (Z-mm). The mean volume of the peritoneal cavity was 648.65 cm 3 in the prone position and 1197.37 cm 3 in the supine position. The prone position using BB device was more effective in reducing irradiated SB volume in rectal cancer patients. There were no significant variations in the daily set up for patients treated in both supine and prone positions.

Refractive errors in patients attending a private hospital in Jos, Nigeria

African Journals Online (AJOL)

Six hundred one (20.7%) patients with distant VA which improved with refraction were considered for this analysis. Two hundred twenty one (36.8%) of patients with refractive error were visually impaired (VA <6/12-3/60). Blindness (<3/60 ‑ none perception of light) was seen in 91 (15.1%) of the patients, seven of whom were ...

Condom Use Errors and Problems: A Comparative Study of HIV-Positive Versus HIV-Negative Young Black Men Who Have Sex With Men.

Science.gov (United States)

Crosby, Richard; Mena, Leandro; Yarber, William L; Graham, Cynthia A; Sanders, Stephanie A; Milhausen, Robin R

2015-11-01

To describe self-reported frequencies of selected condom use errors and problems among young (age, 15-29 years) black men who have sex with men (YBMSM) and to compare the observed prevalence of these errors/problems by HIV serostatus. Between September 2012 October 2014, electronic interview data were collected from 369 YBMSM attending a federally supported sexually transmitted infection clinic located in the southern United States. Seventeen condom use errors and problems were assessed. χ(2) Tests were used to detect significant differences in the prevalence of these 17 errors and problems between HIV-negative and HIV-positive men. The recall period was the past 90 days. The overall mean (SD) number of errors/problems was 2.98 (2.29). The mean (SD) for HIV-negative men was 2.91 (2.15), and the mean (SD) for HIV-positive men was 3.18 (2.57). These means were not significantly different (t = 1.02, df = 367, P = 0.31). Only 2 significant differences were observed between HIV-negative and HIV-positive men. Breakage (P = 0.002) and slippage (P = 0.005) were about twice as likely among HIV-positive men. Breakage occurred for nearly 30% of the HIV-positive men compared with approximately 15% among HIV-negative men. Slippage occurred for approximately 16% of the HIV-positive men compared with approximately 9% among HIV-negative men. A need exists to help YBMSM acquire the skills needed to avert breakage and slippage issues that could lead to HIV transmission. Beyond these 2 exceptions, condom use errors and problems were ubiquitous in this population regardless of HIV serostatus. Clinic-based intervention is warranted for these young men, including education about correct condom use and provision of free condoms and long-lasting lubricants.

Stochastic formulation of patient positioning using linac-mounted cone beam imaging with prior knowledge

International Nuclear Information System (INIS)

Hoegele, W.; Loeschel, R.; Dobler, B.; Hesser, J.; Koelbl, O.; Zygmanski, P.

2011-01-01

Purpose: In this work, a novel stochastic framework for patient positioning based on linac-mounted CB projections is introduced. Based on this formulation, the most probable shifts and rotations of the patient are estimated, incorporating interfractional deformations of patient anatomy and other uncertainties associated with patient setup. Methods: The target position is assumed to be defined by and is stochastically determined from positions of various features such as anatomical landmarks or markers in CB projections, i.e., radiographs acquired with a CB-CT system. The patient positioning problem of finding the target location from CB projections is posed as an inverse problem with prior knowledge and is solved using a Bayesian maximum a posteriori (MAP) approach. The prior knowledge is three-fold and includes the accuracy of an initial patient setup (such as in-room laser and skin marks), the plasticity of the body (relative shifts between target and features), and the feature detection error in CB projections (which may vary depending on specific detection algorithm and feature type). For this purpose, MAP estimators are derived and a procedure of using them in clinical practice is outlined. Furthermore, a rule of thumb is theoretically derived, relating basic parameters of the prior knowledge (initial setup accuracy, plasticity of the body, and number of features) and the parameters of CB data acquisition (number of projections and accuracy of feature detection) to the expected estimation accuracy. Results: MAP estimation can be applied to arbitrary features and detection algorithms. However, to experimentally demonstrate its applicability and to perform the validation of the algorithm, a water-equivalent, deformable phantom with features represented by six 1 mm chrome balls were utilized. These features were detected in the cone beam projections (XVI, Elekta Synergy) by a local threshold method for demonstration purposes only. The accuracy of estimation

An intervention to decrease patient identification band errors in a children's hospital.

Science.gov (United States)

Hain, Paul D; Joers, B; Rush, M; Slayton, J; Throop, P; Hoagg, S; Allen, L; Grantham, J; Deshpande, J K

2010-06-01

Patient misidentification continues to be a quality and safety issue. There is a paucity of US data describing interventions to reduce identification band error rates. Monroe Carell Jr Children's Hospital at Vanderbilt. Percentage of patients with defective identification bands. Web-based surveys were sent, asking hospital personnel to anonymously identify perceived barriers to reaching zero defects with identification bands. Corrective action plans were created and implemented with ideas from leadership, front-line staff and the online survey. Data from unannounced audits of patient identification bands were plotted on statistical process control charts and shared monthly with staff. All hospital personnel were expected to "stop the line" if there were any patient identification questions. The first audit showed a defect rate of 20.4%. The original mean defect rate was 6.5%. After interventions and education, the new mean defect rate was 2.6%. (a) The initial rate of patient identification band errors in the hospital was higher than expected. (b) The action resulting in most significant improvement was staff awareness of the problem, with clear expectations to immediately stop the line if a patient identification error was present. (c) Staff surveys are an excellent source of suggestions for combating patient identification issues. (d) Continued audit and data collection is necessary for sustainable staff focus and continued improvement. (e) Statistical process control charts are both an effective method to track results and an easily understood tool for sharing data with staff.

Characteristics of pediatric chemotherapy medication errors in a national error reporting database.

Science.gov (United States)

Rinke, Michael L; Shore, Andrew D; Morlock, Laura; Hicks, Rodney W; Miller, Marlene R

2007-07-01

Little is known regarding chemotherapy medication errors in pediatrics despite studies suggesting high rates of overall pediatric medication errors. In this study, the authors examined patterns in pediatric chemotherapy errors. The authors queried the United States Pharmacopeia MEDMARX database, a national, voluntary, Internet-accessible error reporting system, for all error reports from 1999 through 2004 that involved chemotherapy medications and patients aged error reports, 85% reached the patient, and 15.6% required additional patient monitoring or therapeutic intervention. Forty-eight percent of errors originated in the administering phase of medication delivery, and 30% originated in the drug-dispensing phase. Of the 387 medications cited, 39.5% were antimetabolites, 14.0% were alkylating agents, 9.3% were anthracyclines, and 9.3% were topoisomerase inhibitors. The most commonly involved chemotherapeutic agents were methotrexate (15.3%), cytarabine (12.1%), and etoposide (8.3%). The most common error types were improper dose/quantity (22.9% of 327 cited error types), wrong time (22.6%), omission error (14.1%), and wrong administration technique/wrong route (12.2%). The most common error causes were performance deficit (41.3% of 547 cited error causes), equipment and medication delivery devices (12.4%), communication (8.8%), knowledge deficit (6.8%), and written order errors (5.5%). Four of the 5 most serious errors occurred at community hospitals. Pediatric chemotherapy errors often reached the patient, potentially were harmful, and differed in quality between outpatient and inpatient areas. This study indicated which chemotherapeutic agents most often were involved in errors and that administering errors were common. Investigation is needed regarding targeted medication administration safeguards for these high-risk medications. Copyright (c) 2007 American Cancer Society.

Patient positioning and ventilator-associated pneumonia.

Science.gov (United States)

Hess, Dean R

2005-07-01

Rotational beds, prone position, and semi-recumbent position have been proposed as procedures to prevent ventilator-associated pneumonia (VAP). Rotational therapy uses a special bed designed to turn continuously, or nearly continuously, the patient from side to side; specific designs include kinetic therapy and continuous lateral rotation therapy. A meta-analysis of studies evaluating the effect of rotational bed therapy shows a decrease in the risk of pneumonia but no effect on mortality. Two studies reported a lower risk of VAP in patients placed in a prone position, with no effect on mortality. Studies using radiolabeled enteral feeding solutions in mechanically ventilated patients have reported that aspiration of gastric contents occurs to a greater degree when patients are in the supine position, compared with the semirecumbent position. One study reported a lower rate of VAP in patients randomized to semi-recumbent compared to supine position. Although each of the techniques discussed in this paper has been shown to reduce the risk of VAP, none has been shown to affect mortality. The available evidence suggests that semi-recumbent position should be used routinely, rotational therapy should be considered in selected patients, and prone position should not be used as a technique to reduce the risk of VAP.

Improving Patient Safety With Error Identification in Chemotherapy Orders by Verification Nurses.

Science.gov (United States)

Baldwin, Abigail; Rodriguez, Elizabeth S

2016-02-01

The prevalence of medication errors associated with chemotherapy administration is not precisely known. Little evidence exists concerning the extent or nature of errors; however, some evidence demonstrates that errors are related to prescribing. This article demonstrates how the review of chemotherapy orders by a designated nurse known as a verification nurse (VN) at a National Cancer Institute-designated comprehensive cancer center helps to identify prescribing errors that may prevent chemotherapy administration mistakes and improve patient safety in outpatient infusion units. This article will describe the role of the VN and details of the verification process. To identify benefits of the VN role, a retrospective review and analysis of chemotherapy near-miss events from 2009-2014 was performed. A total of 4,282 events related to chemotherapy were entered into the Reporting to Improve Safety and Quality system. A majority of the events were categorized as near-miss events, or those that, because of chance, did not result in patient injury, and were identified at the point of prescribing.

Phonological analysis of substitution errors of patients with apraxia of speech

Directory of Open Access Journals (Sweden)

Maysa Luchesi Cera

Full Text Available Abstract The literature on apraxia of speech describes the types and characteristics of phonological errors in this disorder. In general, phonemes affected by errors are described, but the distinctive features involved have not yet been investigated. Objective: To analyze the features involved in substitution errors produced by Brazilian-Portuguese speakers with apraxia of speech. Methods: 20 adults with apraxia of speech were assessed. Phonological analysis of the distinctive features involved in substitution type errors was carried out using the protocol for the evaluation of verbal and non-verbal apraxia. Results: The most affected features were: voiced, continuant, high, anterior, coronal, posterior. Moreover, the mean of the substitutions of marked to markedness features was statistically greater than the markedness to marked features. Conclusions: This study contributes toward a better characterization of the phonological errors found in apraxia of speech, thereby helping to diagnose communication disorders and the selection criteria of phonemes for rehabilitation in these patients.

The incidence and types of medication errors in patients receiving antiretroviral therapy in resource-constrained settings.

Directory of Open Access Journals (Sweden)

Kenneth Anene Agu

Full Text Available This study assessed the incidence and types of medication errors, interventions and outcomes in patients on antiretroviral therapy (ART in selected HIV treatment centres in Nigeria.Of 69 health facilities that had program for active screening of medication errors, 14 were randomly selected for prospective cohort assessment. All patients who filled/refilled their antiretroviral medications between February 2009 and March 2011 were screened for medication errors using study-specific pharmaceutical care daily worksheet (PCDW. All potential or actual medication errors identified, interventions provided and the outcomes were documented in the PCDW. Interventions included pharmaceutical care in HIV training for pharmacists amongst others. Chi-square was used for inferential statistics and P0.05. The major medications errors identified were 26.4% incorrect ART regimens prescribed; 19.8% potential drug-drug interaction or contraindication present; and 16.6% duration and/or frequency of medication inappropriate. Interventions provided included 67.1% cases of prescriber contacted to clarify/resolve errors and 14.7% cases of patient counselling and education; 97.4% of potential/actual medication error(s were resolved.The incidence rate of medication errors was somewhat high; and majority of identified errors were related to prescription of incorrect ART regimens and potential drug-drug interactions; the prescriber was contacted and the errors were resolved in majority of cases. Active screening for medication errors is feasible in resource-limited settings following a capacity building intervention.

Two-dimensional errors

International Nuclear Information System (INIS)

Anon.

1991-01-01

This chapter addresses the extension of previous work in one-dimensional (linear) error theory to two-dimensional error analysis. The topics of the chapter include the definition of two-dimensional error, the probability ellipse, the probability circle, elliptical (circular) error evaluation, the application to position accuracy, and the use of control systems (points) in measurements

The alarming reality of medication error: a patient case and review of Pennsylvania and National data.

Science.gov (United States)

da Silva, Brianna A; Krishnamurthy, Mahesh

2016-01-01

A 71-year-old female accidentally received thiothixene (Navane), an antipsychotic, instead of her anti-hypertensive medication amlodipine (Norvasc) for 3 months. She sustained physical and psychological harm including ambulatory dysfunction, tremors, mood swings, and personality changes. Despite the many opportunities for intervention, multiple health care providers overlooked her symptoms. Errors occurred at multiple care levels, including prescribing, initial pharmacy dispensation, hospitalization, and subsequent outpatient follow-up. This exemplifies the Swiss Cheese Model of how errors can occur within a system. Adverse drug events (ADEs) account for more than 3.5 million physician office visits and 1 million emergency department visits each year. It is believed that preventable medication errors impact more than 7 million patients and cost almost $21 billion annually across all care settings. About 30% of hospitalized patients have at least one discrepancy on discharge medication reconciliation. Medication errors and ADEs are an underreported burden that adversely affects patients, providers, and the economy. Medication reconciliation including an 'indication review' for each prescription is an important aspect of patient safety. The decreasing frequency of pill bottle reviews, suboptimal patient education, and poor communication between healthcare providers are factors that threaten patient safety. Medication error and ADEs cost billions of health care dollars and are detrimental to the provider-patient relationship.

The influence of non-rigid anatomy and patient positioning on endoscopy-CT image registration in the head and neck.

Science.gov (United States)

Ingram, W Scott; Yang, Jinzhong; Wendt, Richard; Beadle, Beth M; Rao, Arvind; Wang, Xin A; Court, Laurence E

2017-08-01

To assess the influence of non-rigid anatomy and differences in patient positioning between CT acquisition and endoscopic examination on endoscopy-CT image registration in the head and neck. Radiotherapy planning CTs and 31-35 daily treatment-room CTs were acquired for nineteen patients. Diagnostic CTs were acquired for thirteen of the patients. The surfaces of the airways were segmented on all scans and triangular meshes were created to render virtual endoscopic images with a calibrated pinhole model of an endoscope. The virtual images were used to take projective measurements throughout the meshes, with reference measurements defined as those taken on the planning CTs and test measurements defined as those taken on the daily or diagnostic CTs. The influence of non-rigid anatomy was quantified by 3D distance errors between reference and test measurements on the daily CTs, and the influence of patient positioning was quantified by 3D distance errors between reference and test measurements on the diagnostic CTs. The daily CT measurements were also used to investigate the influences of camera-to-surface distance, surface angle, and the interval of time between scans. Average errors in the daily CTs were 0.36 ± 0.61 cm in the nasal cavity, 0.58 ± 0.83 cm in the naso- and oropharynx, and 0.47 ± 0.73 cm in the hypopharynx and larynx. Average errors in the diagnostic CTs in those regions were 0.52 ± 0.69 cm, 0.65 ± 0.84 cm, and 0.69 ± 0.90 cm, respectively. All CTs had errors heavily skewed towards 0, albeit with large outliers. Large camera-to-surface distances were found to increase the errors, but the angle at which the camera viewed the surface had no effect. The errors in the Day 1 and Day 15 CTs were found to be significantly smaller than those in the Day 30 CTs (P projective measurement errors. In general, these errors are largest when the camera is in the superior pharynx, where it sees large distances and a lot of muscle motion. The

Medication errors: prescribing faults and prescription errors.

Science.gov (United States)

Velo, Giampaolo P; Minuz, Pietro

2009-06-01

1. Medication errors are common in general practice and in hospitals. Both errors in the act of writing (prescription errors) and prescribing faults due to erroneous medical decisions can result in harm to patients. 2. Any step in the prescribing process can generate errors. Slips, lapses, or mistakes are sources of errors, as in unintended omissions in the transcription of drugs. Faults in dose selection, omitted transcription, and poor handwriting are common. 3. Inadequate knowledge or competence and incomplete information about clinical characteristics and previous treatment of individual patients can result in prescribing faults, including the use of potentially inappropriate medications. 4. An unsafe working environment, complex or undefined procedures, and inadequate communication among health-care personnel, particularly between doctors and nurses, have been identified as important underlying factors that contribute to prescription errors and prescribing faults. 5. Active interventions aimed at reducing prescription errors and prescribing faults are strongly recommended. These should be focused on the education and training of prescribers and the use of on-line aids. The complexity of the prescribing procedure should be reduced by introducing automated systems or uniform prescribing charts, in order to avoid transcription and omission errors. Feedback control systems and immediate review of prescriptions, which can be performed with the assistance of a hospital pharmacist, are also helpful. Audits should be performed periodically.

Characteristics of number transcoding errors of Chinese- versus English-speaking Alzheimer's disease patients.

Science.gov (United States)

Ting, Simon Kang Seng; Chia, Pei Shi; Kwek, Kevin; Tan, Wilnard; Hameed, Shahul

2016-10-01

Number processing disorder is an acquired deficit in mathematical skills commonly observed in Alzheimer's disease (AD), usually as a consequence of neurological dysfunction. Common impairments include syntactic errors (800012 instead of 8012) and intrusion errors (8 thousand and 12 instead of eight thousand and twelve) in number transcoding tasks. This study aimed to understand the characterization of AD-related number processing disorder within an alphabetic language (English) and ideographical language (Chinese), and to investigate the differences between alphabetic and ideographic language processing. Chinese-speaking AD patients were hypothesized to make significantly more intrusion errors than English-speaking ones, due to the ideographical nature of both Chinese characters and Arabic numbers. A simplified number transcoding test derived from EC301 battery was administered to AD patients. Chinese-speaking AD patients made significantly more intrusion errors (p = 0.001) than English speakers. This demonstrates that number processing in an alphabetic language such as English does not function in the same manner as in Chinese. The impaired inhibition capability likely contributes to such observations due to its competitive lexical representation in brain for Chinese speakers.

Positive Beliefs about Errors as an Important Element of Adaptive Individual Dealing with Errors during Academic Learning

Science.gov (United States)

Tulis, Maria; Steuer, Gabriele; Dresel, Markus

2018-01-01

Research on learning from errors gives reason to assume that errors provide a high potential to facilitate deep learning if students are willing and able to take these learning opportunities. The first aim of this study was to analyse whether beliefs about errors as learning opportunities can be theoretically and empirically distinguished from…

Dosimetric implications of inter- and intrafractional prostate positioning errors during tomotherapy. Comparison of gold marker-based registrations with native MVCT

Energy Technology Data Exchange (ETDEWEB)

Wust, Peter; Joswig, Marc; Graf, Reinhold; Boehmer, Dirk; Beck, Marcus; Barelkowski, Thomasz; Budach, Volker; Ghadjar, Pirus [Charite Universitaetsmedizin Berlin, Department of Radiation Oncology and Radiotherapy, Berlin (Germany)

2017-09-15

For high-dose radiation therapy (RT) of prostate cancer, image-guided (IGRT) and intensity-modulated RT (IMRT) approaches are standard. Less is known regarding comparisons of different IGRT techniques and the resulting residual errors, as well as regarding their influences on dose distributions. A total of 58 patients who received tomotherapy-based RT up to 84 Gy for high-risk prostate cancer underwent IGRT based either on daily megavoltage CT (MVCT) alone (n = 43) or the additional use of gold markers (n = 15) under routine conditions. Planned Adaptive (Accuray Inc., Madison, WI, USA) software was used for elaborated offline analysis to quantify residual interfractional prostate positioning errors, along with systematic and random errors and the resulting safety margins after both IGRT approaches. Dosimetric parameters for clinical target volume (CTV) coverage and exposition of organs at risk (OAR) were also analyzed and compared. Interfractional as well as intrafractional displacements were determined. Particularly in the vertical direction, residual interfractional positioning errors were reduced using the gold marker-based approach, but dosimetric differences were moderate and the clinical relevance relatively small. Intrafractional prostate motion proved to be quite high, with displacements of 1-3 mm; however, these did not result in additional dosimetric impairments. Residual interfractional positioning errors were reduced using gold marker-based IGRT; however, this resulted in only slightly different final dose distributions. Therefore, daily MVCT-based IGRT without markers might be a valid alternative. (orig.) [German] Bei der hochdosierten Bestrahlung des Prostatakarzinoms sind die bildgesteuerte (IGRT) und die intensitaetsmodulierte Bestrahlung (IMRT) Standard. Offene Fragen gibt es beim Vergleich von IGRT-Techniken im Hinblick auf residuelle Fehler und Beeinflussungen der Dosisverteilung. Bei 58 Patienten, deren Hochrisiko-Prostatakarzinom am

Dosimetric impact of systematic MLC positional errors on step and shoot IMRT for prostate cancer: a planning study

International Nuclear Information System (INIS)

Ung, N.M.; Wee, L.; Harper, C.S.

2010-01-01

Full text: The positional accuracy of multi leaf collimators (MLC) is crucial in ensuring precise delivery of intensity-modulated radiotherapy (IMRT). The aim of this planning study was to investigate the dosimetric impact of systematic MLC errors on step and shoot IMRT of prostate cancer. Twelve MLC leaf banks perturbations were introduced to six prostate IMRT treatment plans to simulate MLC systematic errors. Dose volume histograms (OYHs) were generated for the extraction of dose endpoint parameters. Plans were evaluated in terms of changes to the defined endpoint dose parameters, conformity index (CI) and healthy tissue avoidance (HTA) to planning target volume (PTY), rectum and bladder. Negative perturbations of MLC had been found to produce greater changes to endpoint dose parameters than positive perturbations of MLC (p < 0.05). Negative and positive synchronized MLC perturbations of I mm resulted in median changes of -2.32 and 1.78%, respectively to 095% of PTY whereas asynchronized MLC perturbations of the same direction and magnitude resulted in median changes of 1.18 and 0.90%, respectively. Doses to rectum were generally more sensitive to systematic MLC errors compared to bladder. Synchronized MLC perturbations of I mm resulted in median changes of endpoint dose parameters to both rectum and bladder from about I to 3%. Maximum reduction of -4.44 and -7.29% were recorded for CI and HTA, respectively, due to synchronized MLC perturbation of I mm. In summary, MLC errors resulted in measurable amount of dose changes to PTY and surrounding critical structures in prostate LMRT. (author)

The alarming reality of medication error: a patient case and review of Pennsylvania and National data

Directory of Open Access Journals (Sweden)

Brianna A. da Silva

2016-09-01

Full Text Available Case description: A 71-year-old female accidentally received thiothixene (Navane, an antipsychotic, instead of her anti-hypertensive medication amlodipine (Norvasc for 3 months. She sustained physical and psychological harm including ambulatory dysfunction, tremors, mood swings, and personality changes. Despite the many opportunities for intervention, multiple health care providers overlooked her symptoms. Discussion: Errors occurred at multiple care levels, including prescribing, initial pharmacy dispensation, hospitalization, and subsequent outpatient follow-up. This exemplifies the Swiss Cheese Model of how errors can occur within a system. Adverse drug events (ADEs account for more than 3.5 million physician office visits and 1 million emergency department visits each year. It is believed that preventable medication errors impact more than 7 million patients and cost almost $21 billion annually across all care settings. About 30% of hospitalized patients have at least one discrepancy on discharge medication reconciliation. Medication errors and ADEs are an underreported burden that adversely affects patients, providers, and the economy. Conclusion: Medication reconciliation including an ‘indication review’ for each prescription is an important aspect of patient safety. The decreasing frequency of pill bottle reviews, suboptimal patient education, and poor communication between healthcare providers are factors that threaten patient safety. Medication error and ADEs cost billions of health care dollars and are detrimental to the provider–patient relationship.

VOLUMETRIC ERROR COMPENSATION IN FIVE-AXIS CNC MACHINING CENTER THROUGH KINEMATICS MODELING OF GEOMETRIC ERROR

Directory of Open Access Journals (Sweden)

Pooyan Vahidi Pashsaki

2016-06-01

Full Text Available Accuracy of a five-axis CNC machine tool is affected by a vast number of error sources. This paper investigates volumetric error modeling and its compensation to the basis for creation of new tool path for improvement of work pieces accuracy. The volumetric error model of a five-axis machine tool with the configuration RTTTR (tilting head B-axis and rotary table in work piece side A΄ was set up taking into consideration rigid body kinematics and homogeneous transformation matrix, in which 43 error components are included. Volumetric error comprises 43 error components that can separately reduce geometrical and dimensional accuracy of work pieces. The machining accuracy of work piece is guaranteed due to the position of the cutting tool center point (TCP relative to the work piece. The cutting tool is deviated from its ideal position relative to the work piece and machining error is experienced. For compensation process detection of the present tool path and analysis of the RTTTR five-axis CNC machine tools geometrical error, translating current position of component to compensated positions using the Kinematics error model, converting newly created component to new tool paths using the compensation algorithms and finally editing old G-codes using G-code generator algorithm have been employed.

21 CFR 868.6820 - Patient position support.

Science.gov (United States)

2010-04-01

...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Miscellaneous § 868.6820 Patient position support. (a) Identification. A patient position support is a device intended to maintain the position of an anesthetized... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Patient position support. 868.6820 Section 868...

Positioning accuracy for lung stereotactic body radiotherapy patients determined by on-treatment cone-beam CT imaging

Science.gov (United States)

Richmond, N D; Pilling, K E; Peedell, C; Shakespeare, D; Walker, C P

2012-01-01

Stereotactic body radiotherapy for early stage non-small cell lung cancer is an emerging treatment option in the UK. Since relatively few high-dose ablative fractions are delivered to a small target volume, the consequences of a geometric miss are potentially severe. This paper presents the results of treatment delivery set-up data collected using Elekta Synergy (Elekta, Crawley, UK) cone-beam CT imaging for 17 patients immobilised using the Bodyfix system (Medical Intelligence, Schwabmuenchen, Germany). Images were acquired on the linear accelerator at initial patient treatment set-up, following any position correction adjustments, and post-treatment. These were matched to the localisation CT scan using the Elekta XVI software. In total, 71 fractions were analysed for patient set-up errors. The mean vector error at initial set-up was calculated as 5.3±2.7 mm, which was significantly reduced to 1.4±0.7 mm following image guided correction. Post-treatment the corresponding value was 2.1±1.2 mm. The use of the Bodyfix abdominal compression plate on 5 patients to reduce the range of tumour excursion during respiration produced mean longitudinal set-up corrections of −4.4±4.5 mm compared with −0.7±2.6 mm without compression for the remaining 12 patients. The use of abdominal compression led to a greater variation in set-up errors and a shift in the mean value. PMID:22665927

[Transposition errors during learning to reproduce a sequence by the right- and the left-hand movements: simulation of positional and movement coding].

Science.gov (United States)

Liakhovetskiĭ, V A; Bobrova, E V; Skopin, G N

2012-01-01

Transposition errors during the reproduction of a hand movement sequence make it possible to receive important information on the internal representation of this sequence in the motor working memory. Analysis of such errors showed that learning to reproduce sequences of the left-hand movements improves the system of positional coding (coding ofpositions), while learning of the right-hand movements improves the system of vector coding (coding of movements). Learning of the right-hand movements after the left-hand performance involved the system of positional coding "imposed" by the left hand. Learning of the left-hand movements after the right-hand performance activated the system of vector coding. Transposition errors during learning to reproduce movement sequences can be explained by neural network using either vector coding or both vector and positional coding.

A multiobserver study of the effects of including point-of-care patient photographs with portable radiography: a means to detect wrong-patient errors.

Science.gov (United States)

Tridandapani, Srini; Ramamurthy, Senthil; Provenzale, James; Obuchowski, Nancy A; Evanoff, Michael G; Bhatti, Pamela

2014-08-01

To evaluate whether the presence of facial photographs obtained at the point-of-care of portable radiography leads to increased detection of wrong-patient errors. In this institutional review board-approved study, 166 radiograph-photograph combinations were obtained from 30 patients. Consecutive radiographs from the same patients resulted in 83 unique pairs (ie, a new radiograph and prior, comparison radiograph) for interpretation. To simulate wrong-patient errors, mismatched pairs were generated by pairing radiographs from different patients chosen randomly from the sample. Ninety radiologists each interpreted a unique randomly chosen set of 10 radiographic pairs, containing up to 10% mismatches (ie, error pairs). Radiologists were randomly assigned to interpret radiographs with or without photographs. The number of mismatches was identified, and interpretation times were recorded. Ninety radiologists with 21 ± 10 (mean ± standard deviation) years of experience were recruited to participate in this observer study. With the introduction of photographs, the proportion of errors detected increased from 31% (9 of 29) to 77% (23 of 30; P = .006). The odds ratio for detection of error with photographs to detection without photographs was 7.3 (95% confidence interval: 2.29-23.18). Observer qualifications, training, or practice in cardiothoracic radiology did not influence sensitivity for error detection. There is no significant difference in interpretation time for studies without photographs and those with photographs (60 ± 22 vs. 61 ± 25 seconds; P = .77). In this observer study, facial photographs obtained simultaneously with portable chest radiographs increased the identification of any wrong-patient errors, without substantial increase in interpretation time. This technique offers a potential means to increase patient safety through correct patient identification. Copyright © 2014 AUR. Published by Elsevier Inc. All rights reserved.

Refractive errors in patients attending a private hospital in Jos, Nigeria

African Journals Online (AJOL)

2013-05-02

May 2, 2013 ... of 6/9 or less and showed improvement in distance vision of one or more ... ninety eight patients were seen at the hospital for various eye problems. ... Two hundred twenty one (36.8%) of patients with refractive error were ... Other risk factors are ..... Myopia profile in Copenhagen medical students 1996‑98.

Emotion perception and overconfidence in errors under stress in psychosis.

Science.gov (United States)

Köther, Ulf; Lincoln, Tania M; Moritz, Steffen

2018-03-21

Vulnerability stress models are well-accepted in psychosis research, but the mechanisms that link stress to psychotic symptoms remain vague. Little is known about how social cognition and overconfidence in errors, two putative mechanisms for the pathogenesis of delusions, relate to stress. Using a repeated measures design, we tested four groups (N=120) with different liability to psychosis (schizophrenia patients [n=35], first-degree relatives [n=24], participants with attenuated positive symptoms [n=19] and healthy controls [n=28]) and depression patients (n=14) as a clinical control group under three randomized experimental conditions (no stress, noise and social stress). Parallel versions of the Emotion Perception and Confidence Task, which taps both emotion perception and confidence, were used in each condition. We recorded subjective stress, heart rate, skin conductance level and salivary cortisol to assess the stress response across different dimensions. Independent of the stress condition, patients with schizophrenia showed poorer emotion perception performance and higher confidence in emotion perception errors than participants with attenuated positive symptoms and healthy controls. However, they did not differ from patients with depression or first-degree relatives. Stress did not influence emotion perception or the extent of high-confident errors, but patients with schizophrenia showed an increase in high-confident emotion perception errors conditional on higher arousal. A possible clinical implication of our findings is the necessity to provide stress management programs that aim to reduce arousal. Moreover, patients with schizophrenia might benefit from interventions that help them to reduce overconfidence in their social cognition judgements in times in which they feel being under pressure. Copyright © 2018 Elsevier B.V. All rights reserved.

Prevalence and type of errors in dual-energy X-ray absorptiometry

Energy Technology Data Exchange (ETDEWEB)

Messina, Carmelo; Bandirali, Michele; D' Alonzo, Nathascja Katia [Universita degli Studi di Milano, Scuola di Specializzazione in Radiodiagnostica, Milano (Italy); Sconfienza, Luca Maria; Sardanelli, Francesco [IRCCS Policlinico San Donato, Unita di Radiologia, San Donato Milanese (Italy); Universita degli Studi di Milano, Dipartimento di Scienze Biomediche per la Salute, San Donato Milanese (Italy); Di Leo, Giovanni; Papini, Giacomo Davide Edoardo [IRCCS Policlinico San Donato, Unita di Radiologia, San Donato Milanese (Italy); Ulivieri, Fabio Massimo [IRCCS Fondazione Ca' Granda Ospedale Maggiore Policlinico, Mineralometria Ossea Computerizzata e Ambulatorio Malattie Metabolismo Minerale e Osseo, Servizio di Medicina Nucleare, Milano (Italy)

2015-05-01

Pitfalls in dual-energy x-ray absorptiometry (DXA) are common. Our aim was to assess rate and type of errors in DXA examinations/reports, evaluating a consecutive series of DXA images of patients examined elsewhere and later presenting to our institution for a follow-up DXA. After ethics committee approval, a radiologist retrospectively reviewed all DXA images provided by patients presenting at our institution for a new DXA. Errors were categorized as patient positioning (PP), data analysis (DA), artefacts and/or demographics. Of 2,476 patients, 1,198 had no previous DXA, while 793 had a previous DXA performed in our institution. The remaining 485 (20 %) patients entered the study (38 men and 447 women; mean age ± standard deviation, 68 ± 9 years). Previous DXA examinations were performed at a total of 37 centres. Of 485 reports, 451 (93 %) had at least one error out of a total of 558 errors distributed as follows: 441 (79 %) were DA, 66 (12 %) PP, 39 (7 %) artefacts and 12 (2 %) demographics. About 20 % of patients did not undergo DXA at the same institution as previously. More than 90 % of DXA presented at least one error, mainly of DA. International Society for Clinical Densitometry guidelines are very poorly adopted. (orig.)

MOST COMMON TACTICAL ERRORS IN CHRONIC SYSTOLIC HEART FAILURE PATIENTS MANAGEMENT: PRACTICAL RECOMMENDATIONS

Directory of Open Access Journals (Sweden)

A. S. Poskrebysheva

2012-01-01

Full Text Available Treatment of chronic heart failure (CHF often can be a rather difficult task. Proper selection of therapy and strict adherence to the recommendations is vital in these patients. Unfortunately, in practice we often encounter with free interpretation of the recommendations, which leads to tactical errors and reduce the effectiveness of treatment. This article deals with the most common tactical errors, and contains recommendations for the management of patients with CHF, which can be very useful to the practitioner.

MOST COMMON TACTICAL ERRORS IN CHRONIC SYSTOLIC HEART FAILURE PATIENTS MANAGEMENT: PRACTICAL RECOMMENDATIONS

Directory of Open Access Journals (Sweden)

A. S. Poskrebysheva

2014-07-01

Full Text Available Treatment of chronic heart failure (CHF often can be a rather difficult task. Proper selection of therapy and strict adherence to the recommendations is vital in these patients. Unfortunately, in practice we often encounter with free interpretation of the recommendations, which leads to tactical errors and reduce the effectiveness of treatment. This article deals with the most common tactical errors, and contains recommendations for the management of patients with CHF, which can be very useful to the practitioner.

Three-dimensional patient setup errors at different treatment sites measured by the Tomotherapy megavoltage CT

Energy Technology Data Exchange (ETDEWEB)

Hui, S.K.; Lusczek, E.; Dusenbery, K. [Univ. of Minnesota Medical School, Minneapolis, MN (United States). Dept. of Therapeutic Radiology - Radiation Oncology; DeFor, T. [Univ. of Minnesota Medical School, Minneapolis, MN (United States). Biostatistics and Informatics Core; Levitt, S. [Univ. of Minnesota Medical School, Minneapolis, MN (United States). Dept. of Therapeutic Radiology - Radiation Oncology; Karolinska Institutet, Stockholm (Sweden). Dept. of Onkol-Patol

2012-04-15

Reduction of interfraction setup uncertainty is vital for assuring the accuracy of conformal radiotherapy. We report a systematic study of setup error to assess patients' three-dimensional (3D) localization at various treatment sites. Tomotherapy megavoltage CT (MVCT) images were scanned daily in 259 patients from 2005-2008. We analyzed 6,465 MVCT images to measure setup error for head and neck (H and N), chest/thorax, abdomen, prostate, legs, and total marrow irradiation (TMI). Statistical comparisons of the absolute displacements across sites and time were performed in rotation (R), lateral (x), craniocaudal (y), and vertical (z) directions. The global systematic errors were measured to be less than 3 mm in each direction with increasing order of errors for different sites: H and N, prostate, chest, pelvis, spine, legs, and TMI. The differences in displacements in the x, y, and z directions, and 3D average displacement between treatment sites were significant (p < 0.01). Overall improvement in patient localization with time (after 3-4 treatment fractions) was observed. Large displacement (> 5 mm) was observed in the 75{sup th} percentile of the patient groups for chest, pelvis, legs, and spine in the x and y direction in the second week of the treatment. MVCT imaging is essential for determining 3D setup error and to reduce uncertainty in localization at all anatomical locations. Setup error evaluation should be performed daily for all treatment regions, preferably for all treatment fractions. (orig.)

Medical Error and Moral Luck.

Science.gov (United States)

Hubbeling, Dieneke

2016-09-01

This paper addresses the concept of moral luck. Moral luck is discussed in the context of medical error, especially an error of omission that occurs frequently, but only rarely has adverse consequences. As an example, a failure to compare the label on a syringe with the drug chart results in the wrong medication being administered and the patient dies. However, this error may have previously occurred many times with no tragic consequences. Discussions on moral luck can highlight conflicting intuitions. Should perpetrators receive a harsher punishment because of an adverse outcome, or should they be dealt with in the same way as colleagues who have acted similarly, but with no adverse effects? An additional element to the discussion, specifically with medical errors, is that according to the evidence currently available, punishing individual practitioners does not seem to be effective in preventing future errors. The following discussion, using relevant philosophical and empirical evidence, posits a possible solution for the moral luck conundrum in the context of medical error: namely, making a distinction between the duty to make amends and assigning blame. Blame should be assigned on the basis of actual behavior, while the duty to make amends is dependent on the outcome.

Precise positioning of patients for radiation therapy

International Nuclear Information System (INIS)

Verhey, L.J.; Goitein, M.; McNulty, P.; Munzenrider, J.E.; Suit, H.D.

1982-01-01

A number of immobilization schemes which permit precise daily positioning of patients for radiation therapy are discussed. Pretreatment and post-treatment radiographs have been taken with the patient in the treatment position and analyzed to determine the amount of intratreatment movement. Studies of patients in the supine, seated and decubitus positions indicate mean movements of less than 1 mm with a standard deviation of less than 1 mm. Patients immobilized in the seated position with a bite block and a mask have a mean movement of about 0.5 mm +/- 0.3 mm (s.d.), and patients immobilized in the supine position with their necks hyperextended for submental therapy evidence a mean movement of about 1.4 mm +/- 0.9 mm (s.d.). With the exception of those used for the decubitus position, the immobilization devices are simply fabricated out of thermoplastic casting materials readily available from orthopedic supply houses. A study of day-to-day reproducibility of patient position using laser alignment and pretreatment radiographs for final verification of position indicates that the initial laser alignment can be used to position a patient within 2.2 mm +/- 1.4 mm (s.d.) of the intended position. These results indicate that rigid immobilization devices can improve the precision of radiotherapy, which would be advantageous with respect to both tumor and normal tissue coverage in certain situations

The sensitivity of gamma-index method to the positioning errors of high-definition MLC in patient-specific VMAT QA for SBRT

International Nuclear Information System (INIS)

Kim, Jung-in; Park, So-Yeon; Kim, Hak Jae; Kim, Jin Ho; Ye, Sung-Joon; Park, Jong Min

2014-01-01

To investigate the sensitivity of various gamma criteria used in the gamma-index method for patient-specific volumetric modulated arc therapy (VMAT) quality assurance (QA) for stereotactic body radiation therapy (SBRT) using a flattening filter free (FFF) photon beam. Three types of intentional misalignments were introduced to original high-definition multi-leaf collimator (HD-MLC) plans. The first type, referred to Class Out, involved the opening of each bank of leaves. The second type, Class In, involved the closing of each bank of leaves. The third type, Class Shift, involved the shifting of each bank of leaves towards the ground. Patient-specific QAs for the original and the modified plans were performed with MapCHECK2 and EBT2 films. The sensitivity of the gamma-index method using criteria of 1%/1 mm, 1.5%/1.5 mm, 1%/2 mm, 2%/1 mm and 2%/2 mm was investigated with absolute passing rates according to the magnitudes of MLCs misalignments. In addition, the changes in dose-volumetric indicators due to the magnitudes of MLC misalignments were investigated. The correlations between passing rates and the changes in dose-volumetric indicators were also investigated using Spearman’s rank correlation coefficient (γ). The criterion of 2%/1 mm was able to detect Class Out and Class In MLC misalignments of 0.5 mm and Class Shift misalignments of 1 mm. The widely adopted clinical criterion of 2%/2 mm was not able to detect 0.5 mm MLC errors of the Class Out or Class In types, and also unable to detect 3 mm Class Shift errors. No correlations were observed between dose-volumetric changes and gamma passing rates (γ < 0.8). Gamma criterion of 2%/1 mm was found to be suitable as a tolerance level with passing rates of 90% and 80% for patient-specific VMAT QA for SBRT when using MapCHECK2 and EBT2 film, respectively

Identification of Special Patterns of Numerical Typographic Errors Increases the Likelihood of Finding a Misplaced Patient File

OpenAIRE

Sun, Ying-Chou; Tang, Dah-Dian; Zeng, Qing; Greenes, Robert

2002-01-01

When a typographic error of a patient identification number occurs on a patient document such as an envelope for radiology films or the cover of a patient record, it will result in misplacement of the document. Once misplaced, such documents are often extremely difficult to recover. After analyzing 290 numerical typos, we found that errors do not occur randomly. Instead, many of the typos share certain specific patterns. Six major types of non-random numeral typographic error patterns have be...

Errors in abdominal computed tomography

International Nuclear Information System (INIS)

Stephens, S.; Marting, I.; Dixon, A.K.

1989-01-01

Sixty-nine patients are presented in whom a substantial error was made on the initial abdominal computed tomography report. Certain features of these errors have been analysed. In 30 (43.5%) a lesion was simply not recognised (error of observation); in 39 (56.5%) the wrong conclusions were drawn about the nature of normal or abnormal structures (error of interpretation). The 39 errors of interpretation were more complex; in 7 patients an abnormal structure was noted but interpreted as normal, whereas in four a normal structure was thought to represent a lesion. Other interpretive errors included those where the wrong cause for a lesion had been ascribed (24 patients), and those where the abnormality was substantially under-reported (4 patients). Various features of these errors are presented and discussed. Errors were made just as often in relation to small and large lesions. Consultants made as many errors as senior registrar radiologists. It is like that dual reporting is the best method of avoiding such errors and, indeed, this is widely practised in our unit. (Author). 9 refs.; 5 figs.; 1 tab

A novel method to correct for pitch and yaw patient setup errors in helical tomotherapy

International Nuclear Information System (INIS)

Boswell, Sarah A.; Jeraj, Robert; Ruchala, Kenneth J.; Olivera, Gustavo H.; Jaradat, Hazim A.; James, Joshua A.; Gutierrez, Alonso; Pearson, Dave; Frank, Gary; Mackie, T. Rock

2005-01-01

An accurate means of determining and correcting for daily patient setup errors is important to the cancer outcome in radiotherapy. While many tools have been developed to detect setup errors, difficulty may arise in accurately adjusting the patient to account for the rotational error components. A novel, automated method to correct for rotational patient setup errors in helical tomotherapy is proposed for a treatment couch that is restricted to motion along translational axes. In tomotherapy, only a narrow superior/inferior section of the target receives a dose at any instant, thus rotations in the sagittal and coronal planes may be approximately corrected for by very slow continuous couch motion in a direction perpendicular to the scanning direction. Results from proof-of-principle tests indicate that the method improves the accuracy of treatment delivery, especially for long and narrow targets. Rotational corrections about an axis perpendicular to the transverse plane continue to be implemented easily in tomotherapy by adjustment of the initial gantry angle

Motivational processes from expectancy-value theory are associated with variability in the error positivity in young children.

Science.gov (United States)

Kim, Matthew H; Marulis, Loren M; Grammer, Jennie K; Morrison, Frederick J; Gehring, William J

2017-03-01

Motivational beliefs and values influence how children approach challenging activities. The current study explored motivational processes from an expectancy-value theory framework by studying children's mistakes and their responses to them by focusing on two event-related potential (ERP) components: the error-related negativity (ERN) and the error positivity (Pe). Motivation was assessed using a child-friendly challenge puzzle task and a brief interview measure prior to ERP testing. Data from 50 4- to 6-year-old children revealed that greater perceived competence beliefs were related to a larger Pe, whereas stronger intrinsic task value beliefs were associated with a smaller Pe. Motivation was unrelated to the ERN. Individual differences in early motivational processes may reflect electrophysiological activity related to conscious error awareness. Copyright © 2016 Elsevier Inc. All rights reserved.

Impact of Communication Errors in Radiology on Patient Care, Customer Satisfaction, and Work-Flow Efficiency.

Science.gov (United States)

Siewert, Bettina; Brook, Olga R; Hochman, Mary; Eisenberg, Ronald L

2016-03-01

The purpose of this study is to analyze the impact of communication errors on patient care, customer satisfaction, and work-flow efficiency and to identify opportunities for quality improvement. We performed a search of our quality assurance database for communication errors submitted from August 1, 2004, through December 31, 2014. Cases were analyzed regarding the step in the imaging process at which the error occurred (i.e., ordering, scheduling, performance of examination, study interpretation, or result communication). The impact on patient care was graded on a 5-point scale from none (0) to catastrophic (4). The severity of impact between errors in result communication and those that occurred at all other steps was compared. Error evaluation was performed independently by two board-certified radiologists. Statistical analysis was performed using the chi-square test and kappa statistics. Three hundred eighty of 422 cases were included in the study. One hundred ninety-nine of the 380 communication errors (52.4%) occurred at steps other than result communication, including ordering (13.9%; n = 53), scheduling (4.7%; n = 18), performance of examination (30.0%; n = 114), and study interpretation (3.7%; n = 14). Result communication was the single most common step, accounting for 47.6% (181/380) of errors. There was no statistically significant difference in impact severity between errors that occurred during result communication and those that occurred at other times (p = 0.29). In 37.9% of cases (144/380), there was an impact on patient care, including 21 minor impacts (5.5%; result communication, n = 13; all other steps, n = 8), 34 moderate impacts (8.9%; result communication, n = 12; all other steps, n = 22), and 89 major impacts (23.4%; result communication, n = 45; all other steps, n = 44). In 62.1% (236/380) of cases, no impact was noted, but 52.6% (200/380) of cases had the potential for an impact. Among 380 communication errors in a radiology department, 37

Inter- and intrafractional localisation errors in cone-beam CT guided stereotactic radiation therapy of tumours in the liver and lung

International Nuclear Information System (INIS)

Worm, Esben S.; Hansen, Anders T.; Petersen, Joergen B.; Muren, Ludvig P.; Praestegaard, Lars H.; Hoeyer, Morten

2010-01-01

Background. Localisation errors in cone-beam CT (CBCT) guided stereotactic body radiation therapy (SBRT) were evaluated and compared to positioning using the external coordinates of a stereotactic body frame (SBF) alone. Possible correlations to patient- or treatment-specific factors such as body mass index (BMI), planning time, treatment delivery time, and distance between tumour and spinal cord were explored to determine whether they influenced on the benefit of image-guidance. Material and methods. A total of 34 patients received SBRT (3 fractions) for tumours in the liver (15 patients) or the lung (19 patients). Immobilisation and positioning was obtained with a SBF. Pre- and post-treatment CBCT scans were registered with the bony anatomy of the planning CT to find inter- and intrafractional patient positioning errors (PPE). For lung tumour patients, matching was also performed on the tumours to find the tumour positioning errors (TPE) and baseline shifts relative to bony anatomy. Results. The mean inter- and intrafractional 3D vector PPE was 4.5 ± 2.7 mm (average ± SD) and 1.5 ± 0.6 mm, respectively, for the combined group of patients. For lung tumours, the interfractional misalignment was 5.6 ± 1.8 mm. The baseline shift was 3.9 ± 2.0 mm. Intrafractional TPE and baseline shifts were 2.1 ± 0.7 mm and 1.9 ± 0.6 mm, respectively. The magnitude of interfractional baseline shift was closely correlated with the distance between the tumour and the spinal cord. Intrafractional errors were independent of patient BMI, age or gender. Conclusion. Image-guidance reduced setup errors considerably. The study demonstrated the benefit of CBCT-guidance regardless of patient specific factors such as BMI, age or gender. Protection of the spinal cord was facilitated by the correlation between the tumour position relative to the spinal cord and the magnitude of baseline shift.

SU-E-J-243: Possibility of Exposure Dose Reduction of Cone-Beam Computed Tomography in An Image Guided Patient Positioning System by Using Various Noise Suppression Filters

International Nuclear Information System (INIS)

Kamezawa, H; Arimura, H; Ohki, M; Shirieda, K; Kameda, N

2014-01-01

Purpose: To investigate the possibility of exposure dose reduction of the cone-beam computed tomography (CBCT) in an image guided patient positioning system by using 6 noise suppression filters. Methods: First, a reference dose (RD) and low-dose (LD)-CBCT (X-ray volume imaging system, Elekta Co.) images were acquired with a reference dose of 86.2 mGy (weighted CT dose index: CTDIw) and various low doses of 1.4 to 43.1 mGy, respectively. Second, an automated rigid registration for three axes was performed for estimating setup errors between a planning CT image and the LD-CBCT images, which were processed by 6 noise suppression filters, i.e., averaging filter (AF), median filter (MF), Gaussian filter (GF), bilateral filter (BF), edge preserving smoothing filter (EPF) and adaptive partial median filter (AMF). Third, residual errors representing the patient positioning accuracy were calculated as an Euclidean distance between the setup error vectors estimated using the LD-CBCT image and RD-CBCT image. Finally, the relationships between the residual error and CTDIw were obtained for 6 noise suppression filters, and then the CTDIw for LD-CBCT images processed by the noise suppression filters were measured at the same residual error, which was obtained with the RD-CBCT. This approach was applied to an anthropomorphic pelvic phantom and two cancer patients. Results: For the phantom, the exposure dose could be reduced from 61% (GF) to 78% (AMF) by applying the noise suppression filters to the CBCT images. The exposure dose in a prostate cancer case could be reduced from 8% (AF) to 61% (AMF), and the exposure dose in a lung cancer case could be reduced from 9% (AF) to 37% (AMF). Conclusion: Using noise suppression filters, particularly an adaptive partial median filter, could be feasible to decrease the additional exposure dose to patients in image guided patient positioning systems

SU-E-J-243: Possibility of Exposure Dose Reduction of Cone-Beam Computed Tomography in An Image Guided Patient Positioning System by Using Various Noise Suppression Filters

Energy Technology Data Exchange (ETDEWEB)

Kamezawa, H [Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka (Japan); Fujimoto General Hospital, Miyakonojo, Miyazaki (Japan); Arimura, H; Ohki, M [Faculty of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka (Japan); Shirieda, K; Kameda, N [Fujimoto General Hospital, Miyakonojo, Miyazaki (Japan)

2014-06-01

Purpose: To investigate the possibility of exposure dose reduction of the cone-beam computed tomography (CBCT) in an image guided patient positioning system by using 6 noise suppression filters. Methods: First, a reference dose (RD) and low-dose (LD)-CBCT (X-ray volume imaging system, Elekta Co.) images were acquired with a reference dose of 86.2 mGy (weighted CT dose index: CTDIw) and various low doses of 1.4 to 43.1 mGy, respectively. Second, an automated rigid registration for three axes was performed for estimating setup errors between a planning CT image and the LD-CBCT images, which were processed by 6 noise suppression filters, i.e., averaging filter (AF), median filter (MF), Gaussian filter (GF), bilateral filter (BF), edge preserving smoothing filter (EPF) and adaptive partial median filter (AMF). Third, residual errors representing the patient positioning accuracy were calculated as an Euclidean distance between the setup error vectors estimated using the LD-CBCT image and RD-CBCT image. Finally, the relationships between the residual error and CTDIw were obtained for 6 noise suppression filters, and then the CTDIw for LD-CBCT images processed by the noise suppression filters were measured at the same residual error, which was obtained with the RD-CBCT. This approach was applied to an anthropomorphic pelvic phantom and two cancer patients. Results: For the phantom, the exposure dose could be reduced from 61% (GF) to 78% (AMF) by applying the noise suppression filters to the CBCT images. The exposure dose in a prostate cancer case could be reduced from 8% (AF) to 61% (AMF), and the exposure dose in a lung cancer case could be reduced from 9% (AF) to 37% (AMF). Conclusion: Using noise suppression filters, particularly an adaptive partial median filter, could be feasible to decrease the additional exposure dose to patients in image guided patient positioning systems.

Prevention of prescription errors by computerized, on-line, individual patient related surveillance of drug order entry.

Science.gov (United States)

Oliven, A; Zalman, D; Shilankov, Y; Yeshurun, D; Odeh, M

2002-01-01

Computerized prescription of drugs is expected to reduce the number of many preventable drug ordering errors. In the present study we evaluated the usefullness of a computerized drug order entry (CDOE) system in reducing prescription errors. A department of internal medicine using a comprehensive CDOE, which included also patient-related drug-laboratory, drug-disease and drug-allergy on-line surveillance was compared to a similar department in which drug orders were handwritten. CDOE reduced prescription errors to 25-35%. The causes of errors remained similar, and most errors, on both departments, were associated with abnormal renal function and electrolyte balance. Residual errors remaining on the CDOE-using department were due to handwriting on the typed order, failure to feed patients' diseases, and system failures. The use of CDOE was associated with a significant reduction in mean hospital stay and in the number of changes performed in the prescription. The findings of this study both quantity the impact of comprehensive CDOE on prescription errors and delineate the causes for remaining errors.

Improving patient safety in radiotherapy through error reporting and analysis

International Nuclear Information System (INIS)

Findlay, Ú.; Best, H.; Ottrey, M.

2016-01-01

Aim: To improve patient safety in radiotherapy (RT) through the analysis and publication of radiotherapy errors and near misses (RTE). Materials and methods: RTE are submitted on a voluntary basis by NHS RT departments throughout the UK to the National Reporting and Learning System (NRLS) or directly to Public Health England (PHE). RTE are analysed by PHE staff using frequency trend analysis based on the classification and pathway coding from Towards Safer Radiotherapy (TSRT). PHE in conjunction with the Patient Safety in Radiotherapy Steering Group publish learning from these events, on a triannual and summarised on a biennial basis, so their occurrence might be mitigated. Results: Since the introduction of this initiative in 2010, over 30,000 (RTE) reports have been submitted. The number of RTE reported in each biennial cycle has grown, ranging from 680 (2010) to 12,691 (2016) RTE. The vast majority of the RTE reported are lower level events, thus not affecting the outcome of patient care. Of the level 1 and 2 incidents reported, it is known the majority of them affected only one fraction of a course of treatment. This means that corrective action could be taken over the remaining treatment fractions so the incident did not have a significant impact on the patient or the outcome of their treatment. Analysis of the RTE reports demonstrates that generation of error is not confined to one professional group or to any particular point in the pathway. It also indicates that the pattern of errors is replicated across service providers in the UK. Conclusion: Use of the terminology, classification and coding of TSRT, together with implementation of the national voluntary reporting system described within this report, allows clinical departments to compare their local analysis to the national picture. Further opportunities to improve learning from this dataset must be exploited through development of the analysis and development of proactive risk management strategies

Pitch, roll, and yaw variations in patient positioning

International Nuclear Information System (INIS)

Kaiser, Adeel; Schultheiss, Timothy E.; Wong, Jeffrey Y.C.; Smith, David D.; Han, Chunhui; Vora, Nayana L.; Pezner, Richard D.; Chen Yijen; Radany, Eric H.

2006-01-01

Purpose: To use pretreatment megavoltage-computed tomography (MVCT) scans to evaluate positioning variations in pitch, roll, and yaw for patients treated with helical tomotherapy. Methods and Materials: Twenty prostate and 15 head-and-neck cancer patients were selected. Pretreatment MVCT scans were performed before every treatment fraction and automatically registered to planning kilovoltage CT (KVCT) scans by bony landmarks. Image registration data were used to adjust patient setups before treatment. Corrections for pitch, roll, and yaw were recorded after bone registration, and data from fractions 1-5 and 16-20 were used to analyze mean rotational corrections. Results: For prostate patients, the means and standard deviations (in degrees) for pitch, roll, and yaw corrections were -0.60 ± 1.42, 0.66 ± 1.22, and -0.33 ± 0.83. In head-and-neck patients, the means and standard deviations (in degrees) were -0.24 ± 1.19, -0.12 ± 1.53, and 0.25 ± 1.42 for pitch, roll, and yaw, respectively. No significant difference in rotational variations was observed between Weeks 1 and 4 of treatment. Head-and-neck patients had significantly smaller pitch variation, but significantly larger yaw variation, than prostate patients. No difference was found in roll corrections between the two groups. Overall, 96.6% of the rotational corrections were less than 4 deg. Conclusions: The initial rotational setup errors for prostate and head-and-neck patients were all small in magnitude, statistically significant, but did not vary considerably during the course of radiotherapy. The data are relevant to couch hardware design for correcting rotational setup variations. There should be no theoretical difference between these data and data collected using cone beam KVCT on conventional linacs

The sensitivity of patient specific IMRT QC to systematic MLC leaf bank offset errors

International Nuclear Information System (INIS)

Rangel, Alejandra; Palte, Gesa; Dunscombe, Peter

2010-01-01

Purpose: Patient specific IMRT QC is performed routinely in many clinics as a safeguard against errors and inaccuracies which may be introduced during the complex planning, data transfer, and delivery phases of this type of treatment. The purpose of this work is to evaluate the feasibility of detecting systematic errors in MLC leaf bank position with patient specific checks. Methods: 9 head and neck (H and N) and 14 prostate IMRT beams were delivered using MLC files containing systematic offsets (±1 mm in two banks, ±0.5 mm in two banks, and 1 mm in one bank of leaves). The beams were measured using both MAPCHECK (Sun Nuclear Corp., Melbourne, FL) and the aS1000 electronic portal imaging device (Varian Medical Systems, Palo Alto, CA). Comparisons with calculated fields, without offsets, were made using commonly adopted criteria including absolute dose (AD) difference, relative dose difference, distance to agreement (DTA), and the gamma index. Results: The criteria most sensitive to systematic leaf bank offsets were the 3% AD, 3 mm DTA for MAPCHECK and the gamma index with 2% AD and 2 mm DTA for the EPID. The criterion based on the relative dose measurements was the least sensitive to MLC offsets. More highly modulated fields, i.e., H and N, showed greater changes in the percentage of passing points due to systematic MLC inaccuracy than prostate fields. Conclusions: None of the techniques or criteria tested is sufficiently sensitive, with the population of IMRT fields, to detect a systematic MLC offset at a clinically significant level on an individual field. Patient specific QC cannot, therefore, substitute for routine QC of the MLC itself.

The sensitivity of patient specific IMRT QC to systematic MLC leaf bank offset errors

Energy Technology Data Exchange (ETDEWEB)

Rangel, Alejandra; Palte, Gesa; Dunscombe, Peter [Department of Medical Physics, Tom Baker Cancer Centre, 1331-29 Street NW, Calgary, Alberta T2N 4N2, Canada and Department of Physics and Astronomy, University of Calgary, 2500 University Drive North West, Calgary, Alberta T2N 1N4 (Canada); Department of Medical Physics, Tom Baker Cancer Centre, 1331-29 Street NW, Calgary, Alberta T2N 4N2 (Canada); Department of Medical Physics, Tom Baker Cancer Centre, 1331-29 Street NW, Calgary, Alberta T2N 4N2 (Canada); Department of Physics and Astronomy, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada) and Department of Oncology, Tom Baker Cancer Centre, 1331-29 Street NW, Calgary, Alberta T2N 4N2 (Canada)

2010-07-15

Purpose: Patient specific IMRT QC is performed routinely in many clinics as a safeguard against errors and inaccuracies which may be introduced during the complex planning, data transfer, and delivery phases of this type of treatment. The purpose of this work is to evaluate the feasibility of detecting systematic errors in MLC leaf bank position with patient specific checks. Methods: 9 head and neck (H and N) and 14 prostate IMRT beams were delivered using MLC files containing systematic offsets ({+-}1 mm in two banks, {+-}0.5 mm in two banks, and 1 mm in one bank of leaves). The beams were measured using both MAPCHECK (Sun Nuclear Corp., Melbourne, FL) and the aS1000 electronic portal imaging device (Varian Medical Systems, Palo Alto, CA). Comparisons with calculated fields, without offsets, were made using commonly adopted criteria including absolute dose (AD) difference, relative dose difference, distance to agreement (DTA), and the gamma index. Results: The criteria most sensitive to systematic leaf bank offsets were the 3% AD, 3 mm DTA for MAPCHECK and the gamma index with 2% AD and 2 mm DTA for the EPID. The criterion based on the relative dose measurements was the least sensitive to MLC offsets. More highly modulated fields, i.e., H and N, showed greater changes in the percentage of passing points due to systematic MLC inaccuracy than prostate fields. Conclusions: None of the techniques or criteria tested is sufficiently sensitive, with the population of IMRT fields, to detect a systematic MLC offset at a clinically significant level on an individual field. Patient specific QC cannot, therefore, substitute for routine QC of the MLC itself.

Contribution of refractive errors to visual impairment in patients at ...

African Journals Online (AJOL)

Objective: To determine the contribution of refractive error to visual impairment in visually impaired patients attending Korle-Bu Teaching Hospital, Ghana. Method: This study was conducted over a period of 1 year beginning October 2002 at Korle-Bu Teaching Hospital. Every 4th consecutive new case attending the eye ...

Psychometric properties of the national eye institute refractive error correction quality-of-life questionnaire among Iranian patients

Directory of Open Access Journals (Sweden)

Amir H Pakpour

2013-01-01

Conclusions: The Iranian version of the NEI-RQL-42 is a valid and reliable instrument to assess refractive error correction quality-of-life in Iranian patients. Moreover this questionnaire can be used to evaluate the effectiveness of interventions in patients with refractive errors.

Teamwork and clinical error reporting among nurses in Korean hospitals.

Science.gov (United States)

Hwang, Jee-In; Ahn, Jeonghoon

2015-03-01

To examine levels of teamwork and its relationships with clinical error reporting among Korean hospital nurses. The study employed a cross-sectional survey design. We distributed a questionnaire to 674 nurses in two teaching hospitals in Korea. The questionnaire included items on teamwork and the reporting of clinical errors. We measured teamwork using the Teamwork Perceptions Questionnaire, which has five subscales including team structure, leadership, situation monitoring, mutual support, and communication. Using logistic regression analysis, we determined the relationships between teamwork and error reporting. The response rate was 85.5%. The mean score of teamwork was 3.5 out of 5. At the subscale level, mutual support was rated highest, while leadership was rated lowest. Of the participating nurses, 522 responded that they had experienced at least one clinical error in the last 6 months. Among those, only 53.0% responded that they always or usually reported clinical errors to their managers and/or the patient safety department. Teamwork was significantly associated with better error reporting. Specifically, nurses with a higher team communication score were more likely to report clinical errors to their managers and the patient safety department (odds ratio = 1.82, 95% confidence intervals [1.05, 3.14]). Teamwork was rated as moderate and was positively associated with nurses' error reporting performance. Hospital executives and nurse managers should make substantial efforts to enhance teamwork, which will contribute to encouraging the reporting of errors and improving patient safety. Copyright © 2015. Published by Elsevier B.V.

Identification of Special Patterns of Numerical Typographic Errors to Increases the Likelihood of Finding a Misplaced Patient File

OpenAIRE

Sun, Ying-Chou; Tang, Dah-Dian; Zeng, Qing; Greenes, Robert

2001-01-01

When a typographic error of a patient identification number occurs on a patient document such as an envelope for radiology films or the cover of a patient record, it will result in misplacement of the document. Once misplaced, such documents are often extremely difficult to recover. After analyzing 290 numerical typos, we found that errors do not occur randomly. Instead, many of the typos share certain specific patterns. Six major types of non-random numeral typographic error patterns have be...

Medication Errors: New EU Good Practice Guide on Risk Minimisation and Error Prevention.

Science.gov (United States)

Goedecke, Thomas; Ord, Kathryn; Newbould, Victoria; Brosch, Sabine; Arlett, Peter

2016-06-01

A medication error is an unintended failure in the drug treatment process that leads to, or has the potential to lead to, harm to the patient. Reducing the risk of medication errors is a shared responsibility between patients, healthcare professionals, regulators and the pharmaceutical industry at all levels of healthcare delivery. In 2015, the EU regulatory network released a two-part good practice guide on medication errors to support both the pharmaceutical industry and regulators in the implementation of the changes introduced with the EU pharmacovigilance legislation. These changes included a modification of the 'adverse reaction' definition to include events associated with medication errors, and the requirement for national competent authorities responsible for pharmacovigilance in EU Member States to collaborate and exchange information on medication errors resulting in harm with national patient safety organisations. To facilitate reporting and learning from medication errors, a clear distinction has been made in the guidance between medication errors resulting in adverse reactions, medication errors without harm, intercepted medication errors and potential errors. This distinction is supported by an enhanced MedDRA(®) terminology that allows for coding all stages of the medication use process where the error occurred in addition to any clinical consequences. To better understand the causes and contributing factors, individual case safety reports involving an error should be followed-up with the primary reporter to gather information relevant for the conduct of root cause analysis where this may be appropriate. Such reports should also be summarised in periodic safety update reports and addressed in risk management plans. Any risk minimisation and prevention strategy for medication errors should consider all stages of a medicinal product's life-cycle, particularly the main sources and types of medication errors during product development. This article

Error reduction in health care: a systems approach to improving patient safety

National Research Council Canada - National Science Library

Spath, Patrice

2011-01-01

.... The book pinpoints how to reduce and eliminate medical mistakes that threaten the health and safety of patients and teaches how to identify the root cause of medical errors, implement strategies...

A systematic review of patient medication error on self-administering medication at home.

Science.gov (United States)

Mira, José Joaquín; Lorenzo, Susana; Guilabert, Mercedes; Navarro, Isabel; Pérez-Jover, Virtudes

2015-06-01

Medication errors have been analyzed as a health professionals' responsibility (due to mistakes in prescription, preparation or dispensing). However, sometimes, patients themselves (or their caregivers) make mistakes in the administration of the medication. The epidemiology of patient medication errors (PEs) has been scarcely reviewed in spite of its impact on people, on therapeutic effectiveness and on incremental cost for the health systems. This study reviews and describes the methodological approaches and results of published studies on the frequency, causes and consequences of medication errors committed by patients at home. A review of research articles published between 1990 and 2014 was carried out using MEDLINE, Web-of-Knowledge, Scopus, Tripdatabase and Index Medicus. The frequency of PE was situated between 19 and 59%. The elderly and the preschooler population constituted a higher number of mistakes than others. The most common were: incorrect dosage, forgetting, mixing up medications, failing to recall indications and taking out-of-date or inappropriately stored drugs. The majority of these mistakes have no negative consequences. Health literacy, information and communication and complexity of use of dispensing devices were identified as causes of PEs. Apps and other new technologies offer several opportunities for improving drug safety.

Efficient Use of Automatic Exposure Control Systems in Computed Tomography Requires Correct Patient Positioning

Energy Technology Data Exchange (ETDEWEB)

Gudjonsdottir, J.; Jonsdottir, B. (Roentgen Domus Medica, Reykjavik (Iceland)); Svensson, J.R.; Campling, S. (Faculty of Health and Social Care, Anglia Ruskin Univ., Cambridge (United Kingdom)); Brennan, P.C. (Diagnostic Imaging, Biological Imaging Research, UCD School of Medicine and Medical Science, Univ. College Dublin, Belfield, Dublin (Ireland))

2009-11-15

Background: Image quality and radiation dose to the patient are important factors in computed tomography (CT). To provide constant image quality, tube current modulation (TCM) performed by automatic exposure control (AEC) adjusts the tube current to the patient's size and shape. Purpose: To evaluate the effects of patient centering on tube current-time product (mAs) and image noise. Material and Methods: An oval-shaped acrylic phantom was scanned in various off-center positions, at 30-mm intervals within a 500-mm field of view, using three different CT scanners. Acquisition parameters were similar to routine abdomen examinations at each site. The mAs was recorded and noise measured in the images. The correlation of mAs and noise with position was calculated using Pearson correlation. Results: In all three scanners, the mAs delivered by the AEC changed with y-position of the phantom (P<0.001), with correlation values of 0.98 for scanners A and B and -0.98 for scanner C. With x-position, mAs changes were 4.9% or less. As the phantom moved into the y-positions, compared with the iso-center, the mAs varied by up to +70%, -34%, and +56% in scanners A, B, and C, respectively. For scanners A and B, noise in two regions of interest in the lower part of the phantom decreased with elevation, with correlation factors from -0.95 to -0.86 (P<0.02). In the x-direction, significant noise relationships (P<0.005) were only seen in scanner A. Conclusion: This study demonstrates that patient centering markedly affects the efficacy of AEC function and that tube current changes vary between scanners. Tube position when acquiring the scout projection radiograph is decisive for the direction of the mAs change. Off-center patient positions cause errors in tube current modulation that can outweigh the dose reduction gained by AEC use, and image quality is affected

Errors in measuring transverse and energy jitter by beam position monitors

Energy Technology Data Exchange (ETDEWEB)

Balandin, V.; Decking, W.; Golubeva, N.

2010-02-15

The problem of errors, arising due to finite BPMresolution, in the difference orbit parameters, which are found as a least squares fit to the BPM data, is one of the standard and important problems of accelerator physics. Even so for the case of transversely uncoupled motion the covariance matrix of reconstruction errors can be calculated ''by hand'', the direct usage of obtained solution, as a tool for designing of a ''good measurement system'', does not look to be fairly straightforward. It seems that a better understanding of the nature of the problem is still desirable. We make a step in this direction introducing dynamic into this problem, which at the first glance seems to be static. We consider a virtual beam consisting of virtual particles obtained as a result of application of reconstruction procedure to ''all possible values'' of BPM reading errors. This beam propagates along the beam line according to the same rules as any real beam and has all beam dynamical characteristics, such as emittances, energy spread, dispersions, betatron functions and etc. All these values become the properties of the BPM measurement system. One can compare two BPM systems comparing their error emittances and rms error energy spreads, or, for a given measurement system, one can achieve needed balance between coordinate and momentum reconstruction errors by matching the error betatron functions in the point of interest to the desired values. (orig.)

Errors in measuring transverse and energy jitter by beam position monitors

International Nuclear Information System (INIS)

Balandin, V.; Decking, W.; Golubeva, N.

2010-02-01

The problem of errors, arising due to finite BPMresolution, in the difference orbit parameters, which are found as a least squares fit to the BPM data, is one of the standard and important problems of accelerator physics. Even so for the case of transversely uncoupled motion the covariance matrix of reconstruction errors can be calculated ''by hand'', the direct usage of obtained solution, as a tool for designing of a ''good measurement system'', does not look to be fairly straightforward. It seems that a better understanding of the nature of the problem is still desirable. We make a step in this direction introducing dynamic into this problem, which at the first glance seems to be static. We consider a virtual beam consisting of virtual particles obtained as a result of application of reconstruction procedure to ''all possible values'' of BPM reading errors. This beam propagates along the beam line according to the same rules as any real beam and has all beam dynamical characteristics, such as emittances, energy spread, dispersions, betatron functions and etc. All these values become the properties of the BPM measurement system. One can compare two BPM systems comparing their error emittances and rms error energy spreads, or, for a given measurement system, one can achieve needed balance between coordinate and momentum reconstruction errors by matching the error betatron functions in the point of interest to the desired values. (orig.)

Comparison of megavoltage position verification for prostate irradiation based on bony anatomy and implanted fiducials

International Nuclear Information System (INIS)

Nederveen, Aart J.; Dehnad, Homan; Heide, Uulke A. van der; Moorselaar, R. Jeroen A. van; Hofman, Pieter; Lagendijk, Jan J.W.

2003-01-01

Purpose: The patient position during radiotherapy treatment of prostate cancer can be verified with the help of portal images acquired during treatment. In this study we quantify the clinical consequences of the use of image-based verification based on the bony anatomy and the prostate target itself. Patients and methods: We analysed 2025 portal images and 23 computed tomography (CT) scans from 23 patients with prostate cancer. In all patients gold markers were implanted prior to CT scanning. Statistical data for both random and systematic errors were calculated for displacements of bones and markers and we investigated the effectiveness of an off-line correction protocol. Results: Standard deviations for systematic marker displacement are 2.4 mm in the lateral (LR) direction, 4.4 mm in the anterior-posterior (AP) direction and 3.7 mm in the caudal-cranial direction (CC). Application of off-line position verification based on the marker positions results in a shrinkage of the systematic error to well below 1 mm. Position verification based on the bony anatomy reduces the systematic target uncertainty to 50% in the AP direction and in the LR direction. No reduction was observed in the CC direction. For six out of 23 patients we found an increase of the systematic error after application of bony anatomy-based position verification. Conclusions: We show that even if correction based on the bony anatomy is applied, considerable margins have to be set to account for organ motion. Our study highlights that for individual patients the systematic error can increase after application of bony anatomy-based position verification, whereas the population standard deviation will decrease. Off-line target-based position verification effectively reduces the systematic error to well below 1 mm, thus enabling significant margin reduction

Apologies and Medical Error

Science.gov (United States)

2008-01-01

One way in which physicians can respond to a medical error is to apologize. Apologies—statements that acknowledge an error and its consequences, take responsibility, and communicate regret for having caused harm—can decrease blame, decrease anger, increase trust, and improve relationships. Importantly, apologies also have the potential to decrease the risk of a medical malpractice lawsuit and can help settle claims by patients. Patients indicate they want and expect explanations and apologies after medical errors and physicians indicate they want to apologize. However, in practice, physicians tend to provide minimal information to patients after medical errors and infrequently offer complete apologies. Although fears about potential litigation are the most commonly cited barrier to apologizing after medical error, the link between litigation risk and the practice of disclosure and apology is tenuous. Other barriers might include the culture of medicine and the inherent psychological difficulties in facing one’s mistakes and apologizing for them. Despite these barriers, incorporating apology into conversations between physicians and patients can address the needs of both parties and can play a role in the effective resolution of disputes related to medical error. PMID:18972177

[Patient identification errors and biological samples in the analytical process: Is it possible to improve patient safety?].

Science.gov (United States)

Cuadrado-Cenzual, M A; García Briñón, M; de Gracia Hills, Y; González Estecha, M; Collado Yurrita, L; de Pedro Moro, J A; Fernández Pérez, C; Arroyo Fernández, M

2015-01-01

Patient identification errors and biological samples are one of the problems with the highest risk factor in causing an adverse event in the patient. To detect and analyse the causes of patient identification errors in analytical requests (PIEAR) from emergency departments, and to develop improvement strategies. A process and protocol was designed, to be followed by all professionals involved in the requesting and performing of laboratory tests. Evaluation and monitoring indicators of PIEAR were determined, before and after the implementation of these improvement measures (years 2010-2014). A total of 316 PIEAR were detected in a total of 483,254 emergency service requests during the study period, representing a mean of 6.80/10,000 requests. Patient identification failure was the most frequent in all the 6-monthly periods assessed, with a significant difference (Perrors. However, we must continue working with this strategy, promoting a culture of safety for all the professionals involved, and trying to achieve the goal that 100% of the analytical and samples are properly identified. Copyright © 2015 SECA. Published by Elsevier Espana. All rights reserved.

Parenteral nutrition in patients with inborn errors of metabolism - a therapeutic problem.

Science.gov (United States)

Kaluzny, L; Szczepanik, M; Siwinska-Mrozek, Z; Borkowska-Klos, M; Cichy, W; Walkowiak, J

2014-06-01

Parenteral nutrition is now a standard part of supportive treatment in pediatric departments. We describe four cases in which parenteral nutrition was extremely difficult due to coincidence with inborn errors of metabolism. The first two cases was fatty acid beta-oxidation disorders associated with necrotizing enterocolitis and congenital heart disease. Thus, limitations of intravenous lipid intake made it difficult to maintain a good nutritional status. The third case was phenylketonuria associated with a facial region tumour (rhabdomyosarcoma), in which parenteral nutrition was complicated because of a high phenylalanine content in the amino acid formulas for parenteral nutrition. The fourth patient was a child with late-diagnosed tyrosinemia type 1, complicated with encephalopathy - during intensive care treatment the patient needed nutritional support, including parenteral nutrition - we observed amino acid formula problems similar to those in the phenylketonuria patient. Parenteral nutrition in children with inborn errors of metabolism is a rare, but very important therapeutic problem. Total parenteral nutrition formulas are not prepared for this group of diseases.

[Measures to prevent patient identification errors in blood collection/physiological function testing utilizing a laboratory information system].

Science.gov (United States)

Shimazu, Chisato; Hoshino, Satoshi; Furukawa, Taiji

2013-08-01

We constructed an integrated personal identification workflow chart using both bar code reading and an all in-one laboratory information system. The information system not only handles test data but also the information needed for patient guidance in the laboratory department. The reception terminals at the entrance, displays for patient guidance and patient identification tools at blood-sampling booths are all controlled by the information system. The number of patient identification errors was greatly reduced by the system. However, identification errors have not been abolished in the ultrasound department. After re-evaluation of the patient identification process in this department, we recognized that the major reason for the errors came from excessive identification workflow. Ordinarily, an ultrasound test requires patient identification 3 times, because 3 different systems are required during the entire test process, i.e. ultrasound modality system, laboratory information system and a system for producing reports. We are trying to connect the 3 different systems to develop a one-time identification workflow, but it is not a simple task and has not been completed yet. Utilization of the laboratory information system is effective, but is not yet perfect for patient identification. The most fundamental procedure for patient identification is to ask a person's name even today. Everyday checks in the ordinary workflow and everyone's participation in safety-management activity are important for the prevention of patient identification errors.

A randomised trial of Supine versus Prone breast radiotherapy (SuPr study): Comparing set-up errors and respiratory motion

International Nuclear Information System (INIS)

Kirby, Anna M.; Evans, Philip M.; Helyer, Sarah J.; Donovan, Ellen M.; Convery, Helen M.; Yarnold, John R.

2011-01-01

Purpose: To test a prone position against the international-standard supine position in women undergoing whole-breast-radiotherapy (WBRT) after wide-local-excision (WLE) of early breast cancer (BC) in terms of feasibility, set-up errors, and respiratory motion. Methods: Following WLE of BC with insertion of tumour-bed clips, patients underwent 4D-CT for WBRT-planning in supine and prone positions (the latter using an in-house-designed platform). Patients were randomised to undergo WBRT fractions 1-7 in one position, switching to the alternate position for fractions 8-15 (40 Gy/15-fractions total). Cone-beam CT-images (CBCT) were acquired prior to fractions 1, 4, 7, 8, 11 and 14. CBCT data were matched to planning-CT data using (i) chest-wall and (ii) clips. Systematic and random errors were calculated. Maximal displacement of chest-wall and clips with respiration was measured on 4D-CT. Clinical- to planning-target-volume (CTV-PTV) margins were calculated. Patient-comfort-scores and treatment-times were evaluated. Results: Twenty-five patients were randomized. 192/192 (100%) planned supine fractions and 173/192 (90%) prone fractions were completed. 3D population systematic errors were 1.3-1.9 mm (supine) and 3.1-4.3 mm (prone) (p = 0.02) and random errors 2.6-3.2 mm (supine) and 3.8-5.4 mm (prone) (p = 0.02). Prone positioning reduced chest-wall and clip motion (0.5 ± 0.2 mm (prone) versus 2.7 ± 0.5 mm (supine) (p < 0.001)) with respiration. Calculated CTV-PTV margins were greater for prone (12-16 mm) than for supine treatment (10 mm). Patient-comfort-scores and treatment times were comparable (p = 0.06). Conclusions: Set-up errors were greater using our prone technique than for our standard supine technique, resulting in the need for larger CTV-PTV margins in the prone position. Further work is required to optimize the prone treatment-platform and technique before it can become a standard treatment option at our institution.

Erro médico em pacientes hospitalizados Medical errors in hospitalized patients

Directory of Open Access Journals (Sweden)

Manoel de Carvalho

2002-01-01

sistema, e encarados como oportunidade de revisão do processo e aprimoramento da assistência prestada ao paciente.Objective: to review the current literature and to discuss medical errors in hospitalized patients emphasizing its incidence, predisposing factors and prevention mechanism. Special attention is given to medication errors and adverse drug events in newborn infants and pediatric patients. Sources: bibliographic review of the current literature through electronic search in Medline data-base, with selection of the most relevant articles. Summary of the findings: even though most medical errors are not reported, it is important to notice that its incidence is greater than previously assumed. In the USA, approximately one million of patients/year are victims of medical errors and adverse drug events. Today, deaths resulting from these episodes are the fourth cause of mortality in the USA. In neonatal and pediatric intensive care units, where the complexity and frequency of technical procedures are high, medical errors are frequent. Fifteen percent of all admissions to a neonatal intensive care unit is followed by medical errors. Most of these errors occur during night shifts and include incorrect administration of drugs (35% and errors regarding the interpretation of medical prescription (26%. Environmental factors (noise, heat, psychological factors (anxiety, stress and physiologic factors (fatigue, absence of sleep contribute to the occurrence of errors. Recent study shows that after working 24 hours without sleeping, the performance of a health professional is similar to a legally drunk person (serum alcohol level > 0.08%. Conclusions: errors are part of human behavior. The prevention of errors should include a careful review of the organizational system. Medical errors should be seen as an opportunity to change or re-structure the system and to improve the quality of health care delivered and patient safety.

Positivity, discontinuity, finite resources, and nonzero error for arbitrarily varying quantum channels

International Nuclear Information System (INIS)

Boche, H.; Nötzel, J.

2014-01-01

This work is motivated by a quite general question: Under which circumstances are the capacities of information transmission systems continuous? The research is explicitly carried out on finite arbitrarily varying quantum channels (AVQCs). We give an explicit example that answers the recent question whether the transmission of messages over AVQCs can benefit from assistance by distribution of randomness between the legitimate sender and receiver in the affirmative. The specific class of channels introduced in that example is then extended to show that the unassisted capacity does have discontinuity points, while it is known that the randomness-assisted capacity is always continuous in the channel. We characterize the discontinuity points and prove that the unassisted capacity is always continuous around its positivity points. After having established shared randomness as an important resource, we quantify the interplay between the distribution of finite amounts of randomness between the legitimate sender and receiver, the (nonzero) probability of a decoding error with respect to the average error criterion and the number of messages that can be sent over a finite number of channel uses. We relate our results to the entanglement transmission capacities of finite AVQCs, where the role of shared randomness is not yet well understood, and give a new sufficient criterion for the entanglement transmission capacity with randomness assistance to vanish

[Prospective assessment of medication errors in critically ill patients in a university hospital].

Science.gov (United States)

Salazar L, Nicole; Jirón A, Marcela; Escobar O, Leslie; Tobar, Eduardo; Romero, Carlos

2011-11-01

Critically ill patients are especially vulnerable to medication errors (ME) due to their severe clinical situation and the complexities of their management. To determine the frequency and characteristics of ME and identify shortcomings in the processes of medication management in an Intensive Care Unit. During a 3 months period, an observational prospective and randomized study was carried out in the ICU of a university hospital. Every step of patient's medication management (prescription, transcription, dispensation, preparation and administration) was evaluated by an external trained professional. Steps with higher frequency of ME and their therapeutic groups involved were identified. Medications errors were classified according to the National Coordinating Council for Medication Error Reporting and Prevention. In 52 of 124 patients evaluated, 66 ME were found in 194 drugs prescribed. In 34% of prescribed drugs, there was at least 1 ME during its use. Half of ME occurred during medication administration, mainly due to problems in infusion rates and schedule times. Antibacterial drugs had the highest rate of ME. We found a 34% rate of ME per drug prescribed, which is in concordance with international reports. The identification of those steps more prone to ME in the ICU, will allow the implementation of an intervention program to improve the quality and security of medication management.

Making Residents Part of the Safety Culture: Improving Error Reporting and Reducing Harms.

Science.gov (United States)

Fox, Michael D; Bump, Gregory M; Butler, Gabriella A; Chen, Ling-Wan; Buchert, Andrew R

2017-01-30

Reporting medical errors is a focus of the patient safety movement. As frontline physicians, residents are optimally positioned to recognize errors and flaws in systems of care. Previous work highlights the difficulty of engaging residents in identification and/or reduction of medical errors and in integrating these trainees into their institutions' cultures of safety. The authors describe the implementation of a longitudinal, discipline-based, multifaceted curriculum to enhance the reporting of errors by pediatric residents at Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center. The key elements of this curriculum included providing the necessary education to identify medical errors with an emphasis on systems-based causes, modeling of error reporting by faculty, and integrating error reporting and discussion into the residents' daily activities. The authors tracked monthly error reporting rates by residents and other health care professionals, in addition to serious harm event rates at the institution. The interventions resulted in significant increases in error reports filed by residents, from 3.6 to 37.8 per month over 4 years (P error reporting correlated with a decline in serious harm events, from 15.0 to 8.1 per month over 4 years (P = 0.01). Integrating patient safety into the everyday resident responsibilities encourages frequent reporting and discussion of medical errors and leads to improvements in patient care. Multiple simultaneous interventions are essential to making residents part of the safety culture of their training hospitals.

[Medication reconciliation errors according to patient risk and type of physician prescriber identified by prescribing tool used].

Science.gov (United States)

Bilbao Gómez-Martino, Cristina; Nieto Sánchez, Ángel; Fernández Pérez, Cristina; Borrego Hernando, Mª Isabel; Martín-Sánchez, Francisco Javier

2017-01-01

To study the frequency of medication reconciliation errors (MREs) in hospitalized patients and explore the profiles of patients at greater risk. To compare the rates of errors in prescriptions written by emergency physicians and ward physicians, who each used a different prescribing tool. Prospective cross-sectional study of a convenience sample of patients admitted to medical, geriatric, and oncology wards over a period of 6 months. A pharmacist undertook the medication reconciliation report, and data were analyzed for possible associations with risk factors or prescriber type (emergency vs ward physician). A total of 148 patients were studied. Emergency physicians had prescribed for 68 (45.9%) and ward physicians for 80 (54.1%). A total of 303 MREs were detected; 113 (76.4%) patients had at least 1 error. No statistically significant differences were found between prescriber types. Factors that conferred risk for a medication error were use polypharmacy (odds ratio [OR], 3.4; 95% CI, 1.2-9.0; P=.016) and multiple chronic conditions in patients under the age of 80 years (OR, 3.9; 95% CI, 1.1-14.7; P=.039). The incidence of MREs is high regardless of whether the prescriber is an emergency or ward physician. The patients who are most at risk are those taking several medications and those under the age of 80 years who have multiple chronic conditions.

An overview of intravenous-related medication administration errors as reported to MEDMARX, a national medication error-reporting program.

Science.gov (United States)

Hicks, Rodney W; Becker, Shawn C

2006-01-01

Medication errors can be harmful, especially if they involve the intravenous (IV) route of administration. A mixed-methodology study using a 5-year review of 73,769 IV-related medication errors from a national medication error reporting program indicates that between 3% and 5% of these errors were harmful. The leading type of error was omission, and the leading cause of error involved clinician performance deficit. Using content analysis, three themes-product shortage, calculation errors, and tubing interconnectivity-emerge and appear to predispose patients to harm. Nurses often participate in IV therapy, and these findings have implications for practice and patient safety. Voluntary medication error-reporting programs afford an opportunity to improve patient care and to further understanding about the nature of IV-related medication errors.

Avoiding Errors in the Management of Pediatric Polytrauma Patients.

Science.gov (United States)

Chin, Kenneth; Abzug, Joshua; Bae, Donald S; Horn, Bernard D; Herman, Martin; Eberson, Craig P

2016-01-01

Management of pediatric polytrauma patients is one of the most difficult challenges for orthopaedic surgeons. Multisystem injuries frequently include complex orthopaedic surgical problems that require intervention. The physiology and anatomy of children and adolescent trauma patients differ from the physiology and anatomy of an adult trauma patient, which alters the types of injuries sustained and the ideal methods for management. Errors of pediatric polytrauma care are included in two broad categories: missed injuries and inadequate fracture treatment. Diagnoses may be missed most frequently because of a surgeon's inability to reliably assess patients who have traumatic brain injuries and painful distracting injuries. Cervical spine injuries are particularly difficult to identify in a child with polytrauma and may have devastating consequences. In children who have multiple injuries, the stabilization of long bone fractures with pediatric fixation techniques, such as elastic nails and other implants, allows for easier care and more rapid mobilization compared with cast treatments. Adolescent polytrauma patients who are approaching skeletal maturity, however, are ideally treated as adults to avoid complications, such as loss of fixation, and to speed rehabilitation.

Route learning in amnesia: a comparison of trial-and-error and errorless learning in patients with the Korsakoff syndrome.

Science.gov (United States)

Kessels, Roy P C; van Loon, Eke; Wester, Arie J

2007-10-01

To examine the errorless learning approach using a procedural memory task (i.e. learning of actual routes) in patients with amnesia, as compared to trial-and-error learning. Counterbalanced self-controlled cases series. Psychiatric hospital (Korsakoff clinic). A convenience sample of 10 patients with the Korsakoff amnestic syndrome. All patients learned a route in four sessions on separate days using an errorless approach and a different route using trial-and-error. Error rate was scored during route learning and standard neuro-psychological tests were administered (i.e. subtest route recall of the Rivermead Behavioural Memory Test (RBMT) and the Dutch version of the California Verbal Learning Test (VLGT)). A significant learning effect was found in the trial-and-error condition over consecutive sessions (P = 0.006), but no performance difference was found between errorless and trial-and-error learning of the routes. VLGT performance was significantly correlated with a trial-and-error advantage (P Korsakoff syndrome (severe amnesia).

Prevalence of positive autoimmune biomarkers in the brucellosis patients.

Science.gov (United States)

Ahmadinejad, Zahra; Abdollahi, Alireza; Ziaee, Vahid; Domiraei, Zeinab; Najafizadeh, Seyed-Reza; Jafari, Sirus; Ahmadinejad, Mahdi

2016-10-01

Brucellosis is a chronic infectious disease with articular involvement. Discrimination between brucellosis and rheumatologic disorders is difficult in regions endemic for brucellosis. There are few studies about the rate of positive autoantibodies as rheumatologic biomarkers in brucellosis, and the prevalence is variable. In this study, the rheumatologic tests were studied in brucellosis patients. This cross sectional study was performed in two teaching hospitals in Tehran, Iran. Forty-nine patients with brucella infection and 42 healthy participants were enrolled in this study. Brucellosis was diagnosed on the basis of the clinical symptoms and positive serology for brucellosis. Rheumatic factor (RF) and antinuclear antibodies (ANA) were evaluated in all patients. Cyclic citrullinated peptides antibody (ACPA) and anti-double strand DNA (anti-dsDNA) were checked in all patients and control groups. Out of 49 patients, 15 (30.6 %) were RF positive and 4 (8.2 %) were ANA positive. Anti-dsDNA was concurrently positive with ANA in 1 patient (2 %) but ACPA titer was positive in 8 patients (16.3 %). None of the patients with positive autoantibody biomarkers fulfilled the criteria for rheumatologic disorders. The rate of positive RF in healthy people was significantly lower than patient group (2.4 vs. 30.6 %), but the positiveness rate of other biomarkers did not have significant difference in two groups. Sixty percent of the patients with positive RF and 75 % with positive ACPA had skeletal involvement (P brucellosis. Rheumatologists should be aware of brucellosis in patients with musculoskeletal involvement and positive autoantibody biomarkers in endemic regions.

Errors in clinical laboratories or errors in laboratory medicine?

Science.gov (United States)

Plebani, Mario

2006-01-01

Laboratory testing is a highly complex process and, although laboratory services are relatively safe, they are not as safe as they could or should be. Clinical laboratories have long focused their attention on quality control methods and quality assessment programs dealing with analytical aspects of testing. However, a growing body of evidence accumulated in recent decades demonstrates that quality in clinical laboratories cannot be assured by merely focusing on purely analytical aspects. The more recent surveys on errors in laboratory medicine conclude that in the delivery of laboratory testing, mistakes occur more frequently before (pre-analytical) and after (post-analytical) the test has been performed. Most errors are due to pre-analytical factors (46-68.2% of total errors), while a high error rate (18.5-47% of total errors) has also been found in the post-analytical phase. Errors due to analytical problems have been significantly reduced over time, but there is evidence that, particularly for immunoassays, interference may have a serious impact on patients. A description of the most frequent and risky pre-, intra- and post-analytical errors and advice on practical steps for measuring and reducing the risk of errors is therefore given in the present paper. Many mistakes in the Total Testing Process are called "laboratory errors", although these may be due to poor communication, action taken by others involved in the testing process (e.g., physicians, nurses and phlebotomists), or poorly designed processes, all of which are beyond the laboratory's control. Likewise, there is evidence that laboratory information is only partially utilized. A recent document from the International Organization for Standardization (ISO) recommends a new, broader definition of the term "laboratory error" and a classification of errors according to different criteria. In a modern approach to total quality, centered on patients' needs and satisfaction, the risk of errors and mistakes

Medication errors: an overview for clinicians.

Science.gov (United States)

Wittich, Christopher M; Burkle, Christopher M; Lanier, William L

2014-08-01

Medication error is an important cause of patient morbidity and mortality, yet it can be a confusing and underappreciated concept. This article provides a review for practicing physicians that focuses on medication error (1) terminology and definitions, (2) incidence, (3) risk factors, (4) avoidance strategies, and (5) disclosure and legal consequences. A medication error is any error that occurs at any point in the medication use process. It has been estimated by the Institute of Medicine that medication errors cause 1 of 131 outpatient and 1 of 854 inpatient deaths. Medication factors (eg, similar sounding names, low therapeutic index), patient factors (eg, poor renal or hepatic function, impaired cognition, polypharmacy), and health care professional factors (eg, use of abbreviations in prescriptions and other communications, cognitive biases) can precipitate medication errors. Consequences faced by physicians after medication errors can include loss of patient trust, civil actions, criminal charges, and medical board discipline. Methods to prevent medication errors from occurring (eg, use of information technology, better drug labeling, and medication reconciliation) have been used with varying success. When an error is discovered, patients expect disclosure that is timely, given in person, and accompanied with an apology and communication of efforts to prevent future errors. Learning more about medication errors may enhance health care professionals' ability to provide safe care to their patients. Copyright © 2014 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.

Evaluation of inter-fraction error during prostate radiotherapy

International Nuclear Information System (INIS)

Komiyama, Takafumi; Nakamura, Koji; Motoyama, Tsuyoshi; Onishi, Hiroshi; Sano, Naoki

2008-01-01

The purpose of this study was to evaluate inter-fraction error (inter-fraction set-up error+inter-fraction internal organ motion) between treatment planning and delivery during radiotherapy for localized prostate cancer. Twenty three prostate cancer patients underwent image-guided radical irradiation with the CT-linac system. All patients were treated in the supine position. After set-up with external skin markers, using CT-linac system, pretherapy CT images were obtained and isocenter displacement was measured. The mean displacement of the isocenter was 1.8 mm, 3.3 mm, and 1.7 mm in the left-right, ventral-dorsal, and cranial-caudal directions, respectively. The maximum displacement of the isocenter was 7 mm, 12 mm, and 9 mm in the left-right, ventral-dorsal, and cranial-caudal directions, respectively. The mean interquartile range of displacement of the isocenter was 1.8 mm, 3.7 mm, and 2.0 mm in the left-right, ventral-dorsal, and cranial-caudal directions, respectively. In radiotherapy for localized prostate cancer, inter-fraction error was largest in the ventral-dorsal directions. Errors in the ventral-dorsal directions influence both local control and late adverse effects. Our study suggested the set-up with external skin markers was not enough for radical radiotherapy for localized prostate cancer, thereby those such as a CT-linac system for correction of inter-fraction error being required. (author)

SU-E-J-12: An Image-Guided Soft Robotic Patient Positioning System for Maskless Head-And-Neck Cancer Radiotherapy: A Proof-Of-Concept Study

International Nuclear Information System (INIS)

Ogunmolu, O; Gans, N; Jiang, S; Gu, X

2015-01-01

Purpose: We propose a surface-image-guided soft robotic patient positioning system for maskless head-and-neck radiotherapy. The ultimate goal of this project is to utilize a soft robot to realize non-rigid patient positioning and real-time motion compensation. In this proof-of-concept study, we design a position-based visual servoing control system for an air-bladder-based soft robot and investigate its performance in controlling the flexion/extension cranial motion on a mannequin head phantom. Methods: The current system consists of Microsoft Kinect depth camera, an inflatable air bladder (IAB), pressured air source, pneumatic valve actuators, custom-built current regulators, and a National Instruments myRIO microcontroller. The performance of the designed system was evaluated on a mannequin head, with a ball joint fixed below its neck to simulate torso-induced head motion along flexion/extension direction. The IAB is placed beneath the mannequin head. The Kinect camera captures images of the mannequin head, extracts the face, and measures the position of the head relative to the camera. This distance is sent to the myRIO, which runs control algorithms and sends actuation commands to the valves, inflating and deflating the IAB to induce head motion. Results: For a step input, i.e. regulation of the head to a constant displacement, the maximum error was a 6% overshoot, which the system then reduces to 0% steady-state error. In this initial investigation, the settling time to reach the regulated position was approximately 8 seconds, with 2 seconds of delay between the command start of motion due to capacitance of the pneumatics, for a total of 10 seconds to regulate the error. Conclusion: The surface image-guided soft robotic patient positioning system can achieve accurate mannequin head flexion/extension motion. Given this promising initial Result, the extension of the current one-dimensional soft robot control to multiple IABs for non-rigid positioning control

SU-E-J-12: An Image-Guided Soft Robotic Patient Positioning System for Maskless Head-And-Neck Cancer Radiotherapy: A Proof-Of-Concept Study

Energy Technology Data Exchange (ETDEWEB)

Ogunmolu, O; Gans, N [The University of Texas at Dallas, Richardson, TX (United States); Jiang, S; Gu, X [UT Southwestern Medical Center, Dallas, TX (United States)

2015-06-15

Purpose: We propose a surface-image-guided soft robotic patient positioning system for maskless head-and-neck radiotherapy. The ultimate goal of this project is to utilize a soft robot to realize non-rigid patient positioning and real-time motion compensation. In this proof-of-concept study, we design a position-based visual servoing control system for an air-bladder-based soft robot and investigate its performance in controlling the flexion/extension cranial motion on a mannequin head phantom. Methods: The current system consists of Microsoft Kinect depth camera, an inflatable air bladder (IAB), pressured air source, pneumatic valve actuators, custom-built current regulators, and a National Instruments myRIO microcontroller. The performance of the designed system was evaluated on a mannequin head, with a ball joint fixed below its neck to simulate torso-induced head motion along flexion/extension direction. The IAB is placed beneath the mannequin head. The Kinect camera captures images of the mannequin head, extracts the face, and measures the position of the head relative to the camera. This distance is sent to the myRIO, which runs control algorithms and sends actuation commands to the valves, inflating and deflating the IAB to induce head motion. Results: For a step input, i.e. regulation of the head to a constant displacement, the maximum error was a 6% overshoot, which the system then reduces to 0% steady-state error. In this initial investigation, the settling time to reach the regulated position was approximately 8 seconds, with 2 seconds of delay between the command start of motion due to capacitance of the pneumatics, for a total of 10 seconds to regulate the error. Conclusion: The surface image-guided soft robotic patient positioning system can achieve accurate mannequin head flexion/extension motion. Given this promising initial Result, the extension of the current one-dimensional soft robot control to multiple IABs for non-rigid positioning control

Field error lottery

Energy Technology Data Exchange (ETDEWEB)

Elliott, C.J.; McVey, B. (Los Alamos National Lab., NM (USA)); Quimby, D.C. (Spectra Technology, Inc., Bellevue, WA (USA))

1990-01-01

The level of field errors in an FEL is an important determinant of its performance. We have computed 3D performance of a large laser subsystem subjected to field errors of various types. These calculations have been guided by simple models such as SWOOP. The technique of choice is utilization of the FELEX free electron laser code that now possesses extensive engineering capabilities. Modeling includes the ability to establish tolerances of various types: fast and slow scale field bowing, field error level, beam position monitor error level, gap errors, defocusing errors, energy slew, displacement and pointing errors. Many effects of these errors on relative gain and relative power extraction are displayed and are the essential elements of determining an error budget. The random errors also depend on the particular random number seed used in the calculation. The simultaneous display of the performance versus error level of cases with multiple seeds illustrates the variations attributable to stochasticity of this model. All these errors are evaluated numerically for comprehensive engineering of the system. In particular, gap errors are found to place requirements beyond mechanical tolerances of {plus minus}25{mu}m, and amelioration of these may occur by a procedure utilizing direct measurement of the magnetic fields at assembly time. 4 refs., 12 figs.

Radiodiagnostic errors by X-ray pictures of the chest taken at bed resting patients

Energy Technology Data Exchange (ETDEWEB)

Ross, D.; Deininger, H.K.

1981-03-01

The roentgenological findings of 383 cases have been compared with the anatomical and pathological diagnosis of the autopsy report. In 29% the radiodiagnosis was incorrect. About 70% of the X-ray examinations had to be carried out succenturiately at bed side in bedridden patients. The error rate of the interpretation of these examinations was higher than in examinations under standardized conditions. Especially, carcinomatous lymphangiosis, miliary tuberculosis and pulmonary embolism can be diagnosed badly in those incomplete X-ray pictures caused by the clinical situation of the bed resting patients. The publication analyses the most common errors in the diagnosis of cardiac and pulmonary diseases, and they will be demonstrated in examples.

Relationship Between Patients' Perceptions of Care Quality and Health Care Errors in 11 Countries: A Secondary Data Analysis.

Science.gov (United States)

Hincapie, Ana L; Slack, Marion; Malone, Daniel C; MacKinnon, Neil J; Warholak, Terri L

2016-01-01

Patients may be the most reliable reporters of some aspects of the health care process; their perspectives should be considered when pursuing changes to improve patient safety. The authors evaluated the association between patients' perceived health care quality and self-reported medical, medication, and laboratory errors in a multinational sample. The analysis was conducted using the 2010 Commonwealth Fund International Health Policy Survey, a multinational consumer survey conducted in 11 countries. Quality of care was measured by a multifaceted construct developed using Rasch techniques. After adjusting for potentially important confounding variables, an increase in respondents' perceptions of care coordination decreased the odds of self-reporting medical errors, medication errors, and laboratory errors (P < .001). As health care stakeholders continue to search for initiatives that improve care experiences and outcomes, this study's results emphasize the importance of guaranteeing integrated care.

Improvement in Detection of Wrong-Patient Errors When Radiologists Include Patient Photographs in Their Interpretation of Portable Chest Radiographs.

Science.gov (United States)

Tridandapani, Srini; Olsen, Kevin; Bhatti, Pamela

2015-12-01

This study was conducted to determine whether facial photographs obtained simultaneously with radiographs improve radiologists' detection rate of wrong-patient errors, when they are explicitly asked to include the photographs in their evaluation. Radiograph-photograph combinations were obtained from 28 patients at the time of portable chest radiography imaging. From these, pairs of radiographs were generated. Each unique pair consisted of one new and one old (comparison) radiograph. Twelve pairs of mismatched radiographs (i.e., pairs containing radiographs of different patients) were also generated. In phase 1 of the study, 5 blinded radiologist observers were asked to interpret 20 pairs of radiographs without the photographs. In phase 2, each radiologist interpreted another 20 pairs of radiographs with the photographs. Radiologist observers were not instructed about the purpose of the photographs but were asked to include the photographs in their review. The detection rate of mismatched errors was recorded along with the interpretation time for each session for each observer. The two-tailed Fisher exact test was used to evaluate differences in mismatch detection rates between the two phases. A p value of error detection rates without (0/20 = 0%) and with (17/18 = 94.4%) photographs were different (p = 0.0001). The average interpretation times for the set of 20 radiographs were 26.45 (SD 8.69) and 20.55 (SD 3.40) min, for phase 1 and phase 2, respectively (two-tailed Student t test, p = 0.1911). When radiologists include simultaneously obtained photographs in their review of portable chest radiographs, there is a significant improvement in the detection of labeling errors. No statistically significant difference in interpretation time was observed. This may lead to improved patient safety without affecting radiologists' throughput.

Positive Affect and Health Behaviors Across 5 Years in Patients With Coronary Heart Disease: The Heart and Soul Study.

Science.gov (United States)

Sin, Nancy L; Moskowitz, Judith Tedlie; Whooley, Mary A

2015-01-01

Positive psychological states are linked to superior health and longevity, possibly due to behavioral factors. We evaluated cross-sectional and 5-year associations between positive affect and health behaviors in patients with coronary heart disease (CHD). Outpatients with CHD reported positive affect, physical activity, sleep quality, medication adherence, cigarette smoking, and alcohol use at baseline (n = 1022) and 5 years later (n = 662). Covariates in regression analyses included demographics, cardiac disease severity, and depressive symptoms. At baseline, higher positive affect (per 1 standard deviation) was associated with better health behaviors: physical activity (odds ratio [OR] = 1.52, 95% 95% confidence interval [CI] = 1.30-1.77, p positive affect did not predict health behaviors at follow-up, accounting for baseline behaviors. However, increases in positive affect across 5 years co-occurred with improvements in physical activity (B = 0.023, standard error [SE] = 0.008, p = .002), sleep quality (B = 0.011, SE = 0.005, p = .039), and medication adherence (B = 0.014, SE = 0.004, p Positive affect was associated with health behaviors among patients with CHD. Efforts to sustain or enhance positive affect may be promising for promoting better health behaviors.

Barriers and facilitators to recovering from e-prescribing errors in community pharmacies.

Science.gov (United States)

Odukoya, Olufunmilola K; Stone, Jamie A; Chui, Michelle A

2015-01-01

To explore barriers and facilitators to recovery from e-prescribing errors in community pharmacies and to explore practical solutions for work system redesign to ensure successful recovery from errors. Cross-sectional qualitative design using direct observations, interviews, and focus groups. Five community pharmacies in Wisconsin. 13 pharmacists and 14 pharmacy technicians. Observational field notes and transcribed interviews and focus groups were subjected to thematic analysis guided by the Systems Engineering Initiative for Patient Safety (SEIPS) work system and patient safety model. Barriers and facilitators to recovering from e-prescription errors in community pharmacies. Organizational factors, such as communication, training, teamwork, and staffing levels, play an important role in recovering from e-prescription errors. Other factors that could positively or negatively affect recovery of e-prescription errors include level of experience, knowledge of the pharmacy personnel, availability or usability of tools and technology, interruptions and time pressure when performing tasks, and noise in the physical environment. The SEIPS model sheds light on key factors that may influence recovery from e-prescribing errors in pharmacies, including the environment, teamwork, communication, technology, tasks, and other organizational variables. To be successful in recovering from e-prescribing errors, pharmacies must provide the appropriate working conditions that support recovery from errors.

When doctors share visit notes with patients: a study of patient and doctor perceptions of documentation errors, safety opportunities and the patient-doctor relationship.

Science.gov (United States)

Bell, Sigall K; Mejilla, Roanne; Anselmo, Melissa; Darer, Jonathan D; Elmore, Joann G; Leveille, Suzanne; Ngo, Long; Ralston, James D; Delbanco, Tom; Walker, Jan

2017-04-01

Patient advocates and safety experts encourage adoption of transparent health records, but sceptics worry that shared notes may offend patients, erode trust or promote defensive medicine. As electronic health records disseminate, such disparate views fuel policy debates about risks and benefits of sharing visit notes with patients through portals. Presurveys and postsurveys from 99 volunteer doctors at three US sites who participated in OpenNotes and postsurveys from 4592 patients who read at least one note and submitted a survey. Patients read notes to be better informed and because they were curious; about a third read them to check accuracy. In total, 7% (331) of patients reported contacting their doctor's office about their note. Of these, 29% perceived an error, and 85% were satisfied with its resolution. Nearly all patients reported feeling better (37%) or the same (62%) about their doctor. Patients who were older (>63), male, non-white, had fair/poor self-reported health or had less formal education were more likely to report feeling better about their doctor. Among doctors, 26% anticipated documentation errors, and 44% thought patients would disagree with notes. After a year, 53% believed patient satisfaction increased, and 51% thought patients trusted them more. None reported ordering more tests or referrals. Despite concerns about errors, offending language or defensive practice, transparent notes overall did not harm the patient-doctor relationship. Rather, doctors and patients perceived relational benefits. Traditionally more vulnerable populations-non-white, those with poorer self-reported health and those with fewer years of formal education-may be particularly likely to feel better about their doctor after reading their notes. Further informing debate about OpenNotes, the findings suggest transparent records may improve patient satisfaction, trust and safety. Published by the BMJ Publishing Group Limited. For permission to use (where not already

How Do Simulated Error Experiences Impact Attitudes Related to Error Prevention?

Science.gov (United States)

Breitkreuz, Karen R; Dougal, Renae L; Wright, Melanie C

2016-10-01

The objective of this project was to determine whether simulated exposure to error situations changes attitudes in a way that may have a positive impact on error prevention behaviors. Using a stratified quasi-randomized experiment design, we compared risk perception attitudes of a control group of nursing students who received standard error education (reviewed medication error content and watched movies about error experiences) to an experimental group of students who reviewed medication error content and participated in simulated error experiences. Dependent measures included perceived memorability of the educational experience, perceived frequency of errors, and perceived caution with respect to preventing errors. Experienced nursing students perceived the simulated error experiences to be more memorable than movies. Less experienced students perceived both simulated error experiences and movies to be highly memorable. After the intervention, compared with movie participants, simulation participants believed errors occurred more frequently. Both types of education increased the participants' intentions to be more cautious and reported caution remained higher than baseline for medication errors 6 months after the intervention. This study provides limited evidence of an advantage of simulation over watching movies describing actual errors with respect to manipulating attitudes related to error prevention. Both interventions resulted in long-term impacts on perceived caution in medication administration. Simulated error experiences made participants more aware of how easily errors can occur, and the movie education made participants more aware of the devastating consequences of errors.

Heuristic errors in clinical reasoning.

Science.gov (United States)

Rylander, Melanie; Guerrasio, Jeannette

2016-08-01

Errors in clinical reasoning contribute to patient morbidity and mortality. The purpose of this study was to determine the types of heuristic errors made by third-year medical students and first-year residents. This study surveyed approximately 150 clinical educators inquiring about the types of heuristic errors they observed in third-year medical students and first-year residents. Anchoring and premature closure were the two most common errors observed amongst third-year medical students and first-year residents. There was no difference in the types of errors observed in the two groups. Errors in clinical reasoning contribute to patient morbidity and mortality Clinical educators perceived that both third-year medical students and first-year residents committed similar heuristic errors, implying that additional medical knowledge and clinical experience do not affect the types of heuristic errors made. Further work is needed to help identify methods that can be used to reduce heuristic errors early in a clinician's education. © 2015 John Wiley & Sons Ltd.

Can stimulating massage improve joint repositioning error in patients with knee osteoarthritis?

DEFF Research Database (Denmark)

Lund, Hans; Henriksen, Marius; Bartels, Else M

2009-01-01

PURPOSE: The purpose of this study was to investigate the effect of massage applied to the thigh muscles on joint repositioning error (JRE) in patients suffering from osteoarthritis (OA).We hypothesized that stimulating massage of the muscles around an osteoarthritic knee joint, could improve the...

Quantitative analysis of the errors positioning of a multi leaf collimator for volumetric arcoterapia treatments; Analisis cuantitativo de los errores de posicionamiento de un colimador multilaminas para tratamientos de arcoterapia volumetrica

Energy Technology Data Exchange (ETDEWEB)

Gomez Gonzalez, N.; Garcia Repiso, S.; Martin Rincon, C.; Cons Perez, N.; Saez Beltran, M.; Delgado Aparicio, J. M.; Perez alvarez, M. E.; Verde Velasco, J. M.; Ramos Pacho, J. A.; Sena Espinel, E. de

2013-07-01

The precision in the positioning of the multi leaf collimation system of a linear accelerator is critical, especially in treatments of IMRT, where small mistakes can cause relevant dosimetry discrepancies regarding the calculated plan. To assess the accuracy and repeatability of the blades positioning can be used controls, including the one known as fence test whose image pattern allows you to find anomalies in a visual way. The objective of this study is to develop a method which allows to quantify the positioning errors of the multi leaf collimator from this test. (Author)

An Experimental Study of Medical Error Explanations: Do Apology, Empathy, Corrective Action, and Compensation Alter Intentions and Attitudes?

Science.gov (United States)

Nazione, Samantha; Pace, Kristin

2015-01-01

Medical malpractice lawsuits are a growing problem in the United States, and there is much controversy regarding how to best address this problem. The medical error disclosure framework suggests that apologizing, expressing empathy, engaging in corrective action, and offering compensation after a medical error may improve the provider-patient relationship and ultimately help reduce the number of medical malpractice lawsuits patients bring to medical providers. This study provides an experimental examination of the medical error disclosure framework and its effect on amount of money requested in a lawsuit, negative intentions, attitudes, and anger toward the provider after a medical error. Results suggest empathy may play a large role in providing positive outcomes after a medical error.

Development of a Simple Radioactive marker System to Reduce Positioning Errors in Radiation Treatment

International Nuclear Information System (INIS)

William H. Miller; Dr. Jatinder Palta

2007-01-01

The objective of this research is to implement an inexpensive, quick and simple monitor that provides an accurate indication of proper patient position during the treatment of cancer by external beam X-ray radiation and also checks for any significant changes in patient anatomy. It is believed that this system will significantly reduce the treatment margin, provide an additional, independent quality assurance check of positioning accuracy prior to all treatments and reduce the probability of misadministration of therapeutic dose

Radiodiagnostic errors by X-ray pictures of the chest taken at bed resting patients

International Nuclear Information System (INIS)

Ross, D.; Deininger, H.K.

1981-01-01

The roentgenological findings of 383 cases have been compared with the anatomical and pathological diagnosis of the autopsy report. In 29% the radiodiagnosis was incorrect. About 70% of the X-ray examinations had to be carried out succenturiately at bed side in bedridden patients. The error rate of the interpretation of these examinations was higher than in examinations under standardized conditions. Especially, carcinomatous lymphangiosis, miliary tuberculosis and pulmonary embolism can be diagnosed badly in those incomplete X-ray pictures caused by the clinical situation of the bed resting patients. The publication analyses the most common errors in the diagnosis of cardiac and pulmonary diseases, and they will be demonstrated in examples. (orig.) [de

Medication Administration Errors Involving Paediatric In-Patients in a ...

African Journals Online (AJOL)

The drug mostly associated with error was gentamicin with 29 errors (1.2 %). Conclusion: During the study, a high frequency of error was observed. There is a need to modify the way information is handled and shared by professionals as wrong time error was the most implicated error. Attention should also be given to IV ...

Dosimetric consequences of translational and rotational errors in frame-less image-guided radiosurgery

International Nuclear Information System (INIS)

Guckenberger, Matthias; Roesch, Johannes; Baier, Kurt; Sweeney, Reinhart A; Flentje, Michael

2012-01-01

To investigate geometric and dosimetric accuracy of frame-less image-guided radiosurgery (IG-RS) for brain metastases. Single fraction IG-RS was practiced in 72 patients with 98 brain metastases. Patient positioning and immobilization used either double- (n = 71) or single-layer (n = 27) thermoplastic masks. Pre-treatment set-up errors (n = 98) were evaluated with cone-beam CT (CBCT) based image-guidance (IG) and were corrected in six degrees of freedom without an action level. CBCT imaging after treatment measured intra-fractional errors (n = 64). Pre- and post-treatment errors were simulated in the treatment planning system and target coverage and dose conformity were evaluated. Three scenarios of 0 mm, 1 mm and 2 mm GTV-to-PTV (gross tumor volume, planning target volume) safety margins (SM) were simulated. Errors prior to IG were 3.9 mm ± 1.7 mm (3D vector) and the maximum rotational error was 1.7° ± 0.8° on average. The post-treatment 3D error was 0.9 mm ± 0.6 mm. No differences between double- and single-layer masks were observed. Intra-fractional errors were significantly correlated with the total treatment time with 0.7mm±0.5mm and 1.2mm±0.7mm for treatment times ≤23 minutes and >23 minutes (p<0.01), respectively. Simulation of RS without image-guidance reduced target coverage and conformity to 75% ± 19% and 60% ± 25% of planned values. Each 3D set-up error of 1 mm decreased target coverage and dose conformity by 6% and 10% on average, respectively, with a large inter-patient variability. Pre-treatment correction of translations only but not rotations did not affect target coverage and conformity. Post-treatment errors reduced target coverage by >5% in 14% of the patients. A 1 mm safety margin fully compensated intra-fractional patient motion. IG-RS with online correction of translational errors achieves high geometric and dosimetric accuracy. Intra-fractional errors decrease target coverage and conformity unless compensated with appropriate

SU-F-T-381: Fast Calculation of Three-Dimensional Dose Considering MLC Leaf Positional Errors for VMAT Plans

Energy Technology Data Exchange (ETDEWEB)

Katsuta, Y [Takeda General Hospital, Aizuwakamatsu City, Fukushima (Japan); Tohoku University Graduate School of Medicine, Sendal, Miyagi (Japan); Kadoya, N; Jingu, K [Tohoku University Graduate School of Medicine, Sendal, Miyagi (Japan); Shimizu, E; Majima, K [Takeda General Hospital, Aizuwakamatsu City, Fukushima (Japan)

2016-06-15

Purpose: In this study, we developed a system to calculate three dimensional (3D) dose that reflects dosimetric error caused by leaf miscalibration for head and neck and prostate volumetric modulated arc therapy (VMAT) without additional treatment planning system calculation on real time. Methods: An original system called clarkson dose calculation based dosimetric error calculation to calculate dosimetric error caused by leaf miscalibration was developed by MATLAB (Math Works, Natick, MA). Our program, first, calculates point doses at isocenter for baseline and modified VMAT plan, which generated by inducing MLC errors that enlarged aperture size of 1.0 mm with clarkson dose calculation. Second, error incuced 3D dose was generated with transforming TPS baseline 3D dose using calculated point doses. Results: Mean computing time was less than 5 seconds. For seven head and neck and prostate plans, between our method and TPS calculated error incuced 3D dose, the 3D gamma passing rates (0.5%/2 mm, global) are 97.6±0.6% and 98.0±0.4%. The dose percentage change with dose volume histogram parameter of mean dose on target volume were 0.1±0.5% and 0.4±0.3%, and with generalized equivalent uniform dose on target volume were −0.2±0.5% and 0.2±0.3%. Conclusion: The erroneous 3D dose calculated by our method is useful to check dosimetric error caused by leaf miscalibration before pre treatment patient QA dosimetry checks.

Mucocutaneous disorders in Hiv positive patients

Directory of Open Access Journals (Sweden)

Kar H

1996-01-01

Full Text Available Twenty eight HIV positive patients were included in this study. They were evaluated for their mucocutaneous disorders, sexually transmitted diseases and other systemic disorders between 1994-95 in the department of Dermatology and STD Dr R M L Hospital of New Delhi. The heterosexual contact with commercial sex workers (CSWs was the most common route of HIV transmission. Chancroid, syphilis and genital warts were common STDs found in HIV positive patients. Oral thrush (67.9% was the commonest mucocutaneous disorder found in these patients followed by herpes zoster (25% and seborrhoeic dermatitis (21.4%. There was no unusual clinical presentation seen in mucocutaneous disorders and STDs.

Analysis of liquid medication dose errors made by patients and caregivers using alternative measuring devices.

Science.gov (United States)

Ryu, Gyeong Suk; Lee, Yu Jeung

2012-01-01

Patients use several types of devices to measure liquid medication. Using a criterion ranging from a 10% to 40% variation from a target 5 mL for a teaspoon dose, previous studies have found that a considerable proportion of patients or caregivers make errors when dosing liquid medication with measuring devices. To determine the rate and magnitude of liquid medication dose errors that occur with patient/caregiver use of various measuring devices in a community pharmacy. Liquid medication measurements by patients or caregivers were observed in a convenience sample of community pharmacy patrons in Korea during a 2-week period in March 2011. Participants included all patients or caregivers (N = 300) who came to the pharmacy to buy over-the-counter liquid medication or to have a liquid medication prescription filled during the study period. The participants were instructed by an investigator who was also a pharmacist to select their preferred measuring devices from 6 alternatives (etched-calibration dosing cup, printed-calibration dosing cup, dosing spoon, syringe, dispensing bottle, or spoon with a bottle adapter) and measure a 5 mL dose of Coben (chlorpheniramine maleate/phenylephrine HCl, Daewoo Pharm. Co., Ltd) syrup using the device of their choice. The investigator used an ISOLAB graduated cylinder (Germany, blue grad, 10 mL) to measure the amount of syrup dispensed by the study participants. Participant characteristics were recorded including gender, age, education level, and relationship to the person for whom the medication was intended. Of the 300 participants, 257 (85.7%) were female; 286 (95.3%) had at least a high school education; and 282 (94.0%) were caregivers (parent or grandparent) for the patient. The mean (SD) measured dose was 4.949 (0.378) mL for the 300 participants. In analysis of variance of the 6 measuring devices, the greatest difference from the 5 mL target was a mean 5.552 mL for 17 subjects who used the regular (etched) dosing cup and 4

Lower limb immobilization device induced small setup errors in the radiotherapy.

Science.gov (United States)

Lu, Yuting; Ni, Xinye; Yu, Jingping; Ni, Xinchu; Sun, Zhiqiang; Wang, Jianlin; Sun, Suping; Wang, Jian

2018-04-01

The aim of this study was to design a lower limb immobilization device and investigate its clinical application in the radiotherapy of the lower limbs.Around 38 patients who underwent lower limb radiotherapy using the designed immobilization device were included in this study. The setup errors were calculated by comparison of the portal images and the simulator films or digital reconstructed radiographs (DRRs).From all 38 patients accomplished the radiotherapy using this device, 178 anteroposterior portal images and 178 lateral portal images were used for the analysis of the positional accuracy. Significant differences were observed in the setup error of the head-foot direction compared with the left-right direction (t = 3.404, P = .002) and the anterior-posterior directions (t = 3.188, P = .003). No statistical differences were identified in the setup error in the left-right direction and anterior-posterior direction (t = 0.497, P = .622).The use of the in-house designed lower limb immobilization device allowed for relatively small setup errors. Furthermore, it showed satisfactory accuracy and repeatability.

Social aspects of clinical errors.

Science.gov (United States)

Richman, Joel; Mason, Tom; Mason-Whitehead, Elizabeth; McIntosh, Annette; Mercer, Dave

2009-08-01

Clinical errors, whether committed by doctors, nurses or other professions allied to healthcare, remain a sensitive issue requiring open debate and policy formulation in order to reduce them. The literature suggests that the issues underpinning errors made by healthcare professionals involve concerns about patient safety, professional disclosure, apology, litigation, compensation, processes of recording and policy development to enhance quality service. Anecdotally, we are aware of narratives of minor errors, which may well have been covered up and remain officially undisclosed whilst the major errors resulting in damage and death to patients alarm both professionals and public with resultant litigation and compensation. This paper attempts to unravel some of these issues by highlighting the historical nature of clinical errors and drawing parallels to contemporary times by outlining the 'compensation culture'. We then provide an overview of what constitutes a clinical error and review the healthcare professional strategies for managing such errors.

Feasibility study of patient motion monitoring using tactile array sensor

International Nuclear Information System (INIS)

Kim, Tae Ho; Kang, Seong Hee; Kim, Dong Su; Cho, Min Seok; Kim, Kyeong Hyeon; Suh, Tae Suk; Kim, Si Yong

2014-01-01

The aim of this study is to evaluate patient pretreatment set-up error and intra-fraction motion using the tactile array sensors (Pressure Profile Systems Inc, Los Angeles, CA) which could measure distributed pressure profiles along the contacting surface and to check a feasibility of the sensor (tactile array sensor) in the patient motion monitoring. Laser alignment and optical camera based monitoring system are very useful for reduce patient set-up error but these systems could not monitor the blind area like patient's back position. Actually after patient alignment using laser or optical monitoring system, it was assumed that there is no error in the patient's back position (pressure profile distribution). But if an error occurs in the patient's back position, it will affect the radiation therapy accuracy. In spite of optical motion monitoring or using the immobilization tool, distributed pressure profiles of patient's back position was changed during inter and intra-fraction. For more accurate patient set-up, blind area (patient's back) monitoring was necessary. We expect that the proposed method will be very useful for make up for the weakness of optical monitoring method

Feasibility study of patient motion monitoring using tactile array sensor

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae Ho; Kang, Seong Hee; Kim, Dong Su; Cho, Min Seok; Kim, Kyeong Hyeon; Suh, Tae Suk [Dept. of Biomedical Engineering, Research Institute of Biomedical Engineering, the Catholic University of Korea, Seoul (Korea, Republic of); Kim, Si Yong [Dept. of Radiation Oncology, Virginia Commonwealth University, Richmond (United States)

2014-11-15

The aim of this study is to evaluate patient pretreatment set-up error and intra-fraction motion using the tactile array sensors (Pressure Profile Systems Inc, Los Angeles, CA) which could measure distributed pressure profiles along the contacting surface and to check a feasibility of the sensor (tactile array sensor) in the patient motion monitoring. Laser alignment and optical camera based monitoring system are very useful for reduce patient set-up error but these systems could not monitor the blind area like patient's back position. Actually after patient alignment using laser or optical monitoring system, it was assumed that there is no error in the patient's back position (pressure profile distribution). But if an error occurs in the patient's back position, it will affect the radiation therapy accuracy. In spite of optical motion monitoring or using the immobilization tool, distributed pressure profiles of patient's back position was changed during inter and intra-fraction. For more accurate patient set-up, blind area (patient's back) monitoring was necessary. We expect that the proposed method will be very useful for make up for the weakness of optical monitoring method.

Croatian Recommendations for Dialysis of HIV-Positive Patients

Directory of Open Access Journals (Sweden)

Gulin Marijana

2016-06-01

Full Text Available Human immunodeficiency virus (HIV infection may be associated with renal impairment since about 0.4% of all HIV-positive patients develop end-stage renal disease. The share of patients with HIV infection in hemodialysis centers throughout the world ranges from 0.3% to as high as 38%. In Croatia, renal replacement therapy was needed by 1% of all the HIV-positive patients from 1985 until the end of 2014. Healthcare professionals (HP should be aware of the risks of occupational exposure to blood-borne infections in their daily work. Performing dialysis in HIV-positive patients increases the risk of exposure to HIV during the extracorporeal circulation of the infected blood. However, post-exposure prophylaxis (PEP with effective antiretroviral drugs significantly reduces the risk of infection after occupational exposure. On behalf of the Croatian Society of Nephrology, Dialysis and Transplantation, the authors of this paper have proposed recommendations for the management of HIVpositive patients on dialysis, which aim to prevent the transmission of HIV among patients and HPs. The important recommendations include the following: 1. when the need arises, it is necessary to provide HIV-positive patients with dialysis in the vicinity of their place of residence. 2. HIV-positive patients should be dialyzed with a separate hemodialysis machine in an isolated area. Alternatively, they can be dialyzed in an area for the hemodialysis of HCV-positive and/or HBVpositive patients. 3. Specialized and trained personnel should be provided during the hemodialysis procedure, together with strict compliance with the standard precautions for the prevention of blood-borne infections. 4. There should be a good and prompt cooperation with the National Referral Center for HIV infection.

Error Estimation for Indoor 802.11 Location Fingerprinting

DEFF Research Database (Denmark)

Lemelson, Hendrik; Kjærgaard, Mikkel Baun; Hansen, Rene

2009-01-01

providers could adapt their delivered services based on the estimated position error to achieve a higher service quality. Finally, system operators could use the information to inspect whether a location system provides satisfactory positioning accuracy throughout the covered area. For position error...

Residual rotational set-up errors after daily cone-beam CT image guided radiotherapy of locally advanced cervical cancer

International Nuclear Information System (INIS)

Laursen, Louise Vagner; Elstrøm, Ulrik Vindelev; Vestergaard, Anne; Muren, Ludvig P.; Petersen, Jørgen Baltzer; Lindegaard, Jacob Christian; Grau, Cai; Tanderup, Kari

2012-01-01

Purpose: Due to the often quite extended treatment fields in cervical cancer radiotherapy, uncorrected rotational set-up errors result in a potential risk of target miss. This study reports on the residual rotational set-up error after using daily cone beam computed tomography (CBCT) to position cervical cancer patients for radiotherapy treatment. Methods and materials: Twenty-five patients with locally advanced cervical cancer had daily CBCT scans (650 CBCTs in total) prior to treatment delivery. We retrospectively analyzed the translational shifts made in the clinic prior to each treatment fraction as well as the residual rotational errors remaining after translational correction. Results: The CBCT-guided couch movement resulted in a mean translational 3D vector correction of 7.4 mm. Residual rotational error resulted in a target shift exceeding 5 mm in 57 of the 650 treatment fractions. Three patients alone accounted for 30 of these fractions. Nine patients had no shifts exceeding 5 mm and 13 patients had 5 or less treatment fractions with such shifts. Conclusion: Twenty-two of the 25 patients have none or few treatment fractions with target shifts larger than 5 mm due to residual rotational error. However, three patients display a significant number of shifts suggesting a more systematic set-up error.

Correction of electrode modelling errors in multi-frequency EIT imaging.

Science.gov (United States)

Jehl, Markus; Holder, David

2016-06-01

The differentiation of haemorrhagic from ischaemic stroke using electrical impedance tomography (EIT) requires measurements at multiple frequencies, since the general lack of healthy measurements on the same patient excludes time-difference imaging methods. It has previously been shown that the inaccurate modelling of electrodes constitutes one of the largest sources of image artefacts in non-linear multi-frequency EIT applications. To address this issue, we augmented the conductivity Jacobian matrix with a Jacobian matrix with respect to electrode movement. Using this new algorithm, simulated ischaemic and haemorrhagic strokes in a realistic head model were reconstructed for varying degrees of electrode position errors. The simultaneous recovery of conductivity spectra and electrode positions removed most artefacts caused by inaccurately modelled electrodes. Reconstructions were stable for electrode position errors of up to 1.5 mm standard deviation along both surface dimensions. We conclude that this method can be used for electrode model correction in multi-frequency EIT.

Dosimetric consequences of translational and rotational errors in frame-less image-guided radiosurgery

Directory of Open Access Journals (Sweden)

Guckenberger Matthias

2012-04-01

Full Text Available Abstract Background To investigate geometric and dosimetric accuracy of frame-less image-guided radiosurgery (IG-RS for brain metastases. Methods and materials Single fraction IG-RS was practiced in 72 patients with 98 brain metastases. Patient positioning and immobilization used either double- (n = 71 or single-layer (n = 27 thermoplastic masks. Pre-treatment set-up errors (n = 98 were evaluated with cone-beam CT (CBCT based image-guidance (IG and were corrected in six degrees of freedom without an action level. CBCT imaging after treatment measured intra-fractional errors (n = 64. Pre- and post-treatment errors were simulated in the treatment planning system and target coverage and dose conformity were evaluated. Three scenarios of 0 mm, 1 mm and 2 mm GTV-to-PTV (gross tumor volume, planning target volume safety margins (SM were simulated. Results Errors prior to IG were 3.9 mm ± 1.7 mm (3D vector and the maximum rotational error was 1.7° ± 0.8° on average. The post-treatment 3D error was 0.9 mm ± 0.6 mm. No differences between double- and single-layer masks were observed. Intra-fractional errors were significantly correlated with the total treatment time with 0.7mm±0.5mm and 1.2mm±0.7mm for treatment times ≤23 minutes and >23 minutes (p5% in 14% of the patients. A 1 mm safety margin fully compensated intra-fractional patient motion. Conclusions IG-RS with online correction of translational errors achieves high geometric and dosimetric accuracy. Intra-fractional errors decrease target coverage and conformity unless compensated with appropriate safety margins.

Electronic portal image assisted reduction of systematic set-up errors in head and neck irradiation

International Nuclear Information System (INIS)

Boer, Hans C.J. de; Soernsen de Koste, John R. van; Creutzberg, Carien L.; Visser, Andries G.; Levendag, Peter C.; Heijmen, Ben J.M.

2001-01-01

Purpose: To quantify systematic and random patient set-up errors in head and neck irradiation and to investigate the impact of an off-line correction protocol on the systematic errors. Material and methods: Electronic portal images were obtained for 31 patients treated for primary supra-glottic larynx carcinoma who were immobilised using a polyvinyl chloride cast. The observed patient set-up errors were input to the shrinking action level (SAL) off-line decision protocol and appropriate set-up corrections were applied. To assess the impact of the protocol, the positioning accuracy without application of set-up corrections was reconstructed. Results: The set-up errors obtained without set-up corrections (1 standard deviation (SD)=1.5-2 mm for random and systematic errors) were comparable to those reported in other studies on similar fixation devices. On an average, six fractions per patient were imaged and the set-up of half the patients was changed due to the decision protocol. Most changes were detected during weekly check measurements, not during the first days of treatment. The application of the SAL protocol reduced the width of the distribution of systematic errors to 1 mm (1 SD), as expected from simulations. A retrospective analysis showed that this accuracy should be attainable with only two measurements per patient using a different off-line correction protocol, which does not apply action levels. Conclusions: Off-line verification protocols can be particularly effective in head and neck patients due to the smallness of the random set-up errors. The excellent set-up reproducibility that can be achieved with such protocols enables accurate dose delivery in conformal treatments

Errors in Neonatology

OpenAIRE

Antonio Boldrini; Rosa T. Scaramuzzo; Armando Cuttano

2013-01-01

Introduction: Danger and errors are inherent in human activities. In medical practice errors can lean to adverse events for patients. Mass media echo the whole scenario. Methods: We reviewed recent published papers in PubMed database to focus on the evidence and management of errors in medical practice in general and in Neonatology in particular. We compared the results of the literature with our specific experience in Nina Simulation Centre (Pisa, Italy). Results: In Neonatology the main err...

A Case of Transfusion Error in a Trauma Patient With Subsequent Root Cause Analysis Leading to Institutional Change.

Science.gov (United States)

Clifford, Sean Patrick; Mick, Paul Brian; Derhake, Brian Matthew

2016-01-01

A 28-year-old man presented emergently to the operating room following a gun-shot injury to his right groin. Our hospital's Massive Transfusion Protocol was initiated as the patient entered the operating room actively hemorrhaging and severely hypotensive. During the aggressive resuscitation efforts, the patient was inadvertently transfused 2 units of packed red blood cells intended for another patient due to a series of errors. Fortunately, the incorrect product was compatible, and the patient recovered from his near-fatal injuries. Root cause analysis was used to review the transfusion error and develop an action plan to help prevent future occurrences.

Medication errors versus time of admission in a subpopulation of stroke patients undergoing inpatient rehabilitation complications and considerations.

Science.gov (United States)

Pitts, Eric P

2011-01-01

This study looked at the medication ordering error frequency and the length of inpatient hospital stay in a subpopulation of stroke patients (n-60) as a function of time of patient admission to an inpatient rehabilitation hospital service. A total of 60 inpatient rehabilitation patients, 30 arriving before 4 pm, and 30 arriving after 4 pm, with as admitting diagnosis of stroke were randomly selected from a larger sample (N=426). There was a statistically significant increase in medication ordering errors and the number of inpatient rehabilitation hospital days in the group of patients who arrived after 4 pm.

The method to evaluate the position error in graphic positioning technology

Institute of Scientific and Technical Information of China (English)

Huiqing Lu(卢慧卿); Baoguang Wang(王宝光); Lishuang Liu(刘力双); Yabiao Li(李亚标)

2004-01-01

In the measurement of automobile body-in-white, it has been widely studied to position the two dimensional(2D)visual sensors with high precision. In this paper a graphic positioning method is proposed,a hollow tetrahedron is used for a positioning target to replace all the edges of a standard automobile body.A 2D visual sensor can be positioned through adjusting two triangles to be superposed on a screen of the computer, so it is very important to evaluate the superposition precision of the two triangles. Several methods are discussed and the least square method is adopted at last, it makes the adjustment more easy and intuitive with high precision.

Sources of medical error in refractive surgery.

Science.gov (United States)

Moshirfar, Majid; Simpson, Rachel G; Dave, Sonal B; Christiansen, Steven M; Edmonds, Jason N; Culbertson, William W; Pascucci, Stephen E; Sher, Neal A; Cano, David B; Trattler, William B

2013-05-01

To evaluate the causes of laser programming errors in refractive surgery and outcomes in these cases. In this multicenter, retrospective chart review, 22 eyes of 18 patients who had incorrect data entered into the refractive laser computer system at the time of treatment were evaluated. Cases were analyzed to uncover the etiology of these errors, patient follow-up treatments, and final outcomes. The results were used to identify potential methods to avoid similar errors in the future. Every patient experienced compromised uncorrected visual acuity requiring additional intervention, and 7 of 22 eyes (32%) lost corrected distance visual acuity (CDVA) of at least one line. Sixteen patients were suitable candidates for additional surgical correction to address these residual visual symptoms and six were not. Thirteen of 22 eyes (59%) received surgical follow-up treatment; nine eyes were treated with contact lenses. After follow-up treatment, six patients (27%) still had a loss of one line or more of CDVA. Three significant sources of error were identified: errors of cylinder conversion, data entry, and patient identification error. Twenty-seven percent of eyes with laser programming errors ultimately lost one or more lines of CDVA. Patients who underwent surgical revision had better outcomes than those who did not. Many of the mistakes identified were likely avoidable had preventive measures been taken, such as strict adherence to patient verification protocol or rigorous rechecking of treatment parameters. Copyright 2013, SLACK Incorporated.

Servo control booster system for minimizing following error

Science.gov (United States)

Wise, W.L.

1979-07-26

A closed-loop feedback-controlled servo system is disclosed which reduces command-to-response error to the system's position feedback resolution least increment, ..delta..S/sub R/, on a continuous real-time basis, for all operational times of consequence and for all operating speeds. The servo system employs a second position feedback control loop on a by exception basis, when the command-to-response error greater than or equal to ..delta..S/sub R/, to produce precise position correction signals. When the command-to-response error is less than ..delta..S/sub R/, control automatically reverts to conventional control means as the second position feedback control loop is disconnected, becoming transparent to conventional servo control means. By operating the second unique position feedback control loop used herein at the appropriate clocking rate, command-to-response error may be reduced to the position feedback resolution least increment. The present system may be utilized in combination with a tachometer loop for increased stability.

Intrafractional setup errors in patients undergoing non-invasive fixation using an immobilization system during hypofractionated stereotactic radiotherapy for lung tumors

International Nuclear Information System (INIS)

Watanabe, Meguru; Onishi, Hiroshi; Kuriyama, Kengo

2013-01-01

Intrafractional setup errors during hypofractionated stereotactic radiotherapy (SRT) were investigated on the patient under voluntary breath-holding conditions with non-invasive immobilization on the CT-linac treatment table. A total of 30 patients with primary and metastatic lung tumors were treated with the hypofractionated SRT with a total dose of 48-60 Gy with four treatment fractions. The patient was placed supine and stabilized on the table with non-invasive patient fixation. Intrafractional setup errors in Right/Left (R.L.), Posterior/Anterior (P.A.), and Inferior/Superior (I.S.) dimensions were analyzed with pre- and post-irradiation CT images. The means and one standard deviation of the intrafractional errors were 0.9±0.7 mm (R.L.), 0.9±0.7 mm (P.A.) and 0.5±1.0 mm (I.S.). Setup errors in each session of the treatment demonstrated no statistically significant difference in the mean value between any two sessions. The frequency within 3 mm displacement was 98% in R.L., 98% in P.A. and 97% in I.S. directions. SRT under the non-invasive patient fixation immobilization system with a comparatively loose vacuum pillow demonstrated satisfactory reproducibility of minimal setup errors with voluntary breath-holding conditions that required a small internal margin. (author)

Error induced by the estimation of the corneal power and the effective lens position with a rotationally asymmetric refractive multifocal intraocular lens.

Science.gov (United States)

Piñero, David P; Camps, Vicente J; Ramón, María L; Mateo, Verónica; Pérez-Cambrodí, Rafael J

2015-01-01

To evaluate the prediction error in intraocular lens (IOL) power calculation for a rotationally asymmetric refractive multifocal IOL and the impact on this error of the optimization of the keratometric estimation of the corneal power and the prediction of the effective lens position (ELP). Retrospective study including a total of 25 eyes of 13 patients (age, 50 to 83y) with previous cataract surgery with implantation of the Lentis Mplus LS-312 IOL (Oculentis GmbH, Germany). In all cases, an adjusted IOL power (PIOLadj) was calculated based on Gaussian optics using a variable keratometric index value (nkadj) for the estimation of the corneal power (Pkadj) and on a new value for ELP (ELPadj) obtained by multiple regression analysis. This PIOLadj was compared with the IOL power implanted (PIOLReal) and the value proposed by three conventional formulas (Haigis, Hoffer Q and Holladay I). PIOLReal was not significantly different than PIOLadj and Holladay IOL power (P>0.05). In the Bland and Altman analysis, PIOLadj showed lower mean difference (-0.07 D) and limits of agreement (of 1.47 and -1.61 D) when compared to PIOLReal than the IOL power value obtained with the Holladay formula. Furthermore, ELPadj was significantly lower than ELP calculated with other conventional formulas (P<0.01) and was found to be dependent on axial length, anterior chamber depth and Pkadj. Refractive outcomes after cataract surgery with implantation of the multifocal IOL Lentis Mplus LS-312 can be optimized by minimizing the keratometric error and by estimating ELP using a mathematical expression dependent on anatomical factors.

Accuracy of robotic patient positioners used in ion beam therapy

International Nuclear Information System (INIS)

Nairz, Olaf; Winter, Marcus; Heeg, Peter; Jäkel, Oliver

2013-01-01

In this study we investigate the accuracy of industrial six axes robots employed for patient positioning at the Heidelberg Ion Beam Therapy Center. In total 1018 patient setups were monitored with a laser tracker and subsequently analyzed. The measurements were performed in the two rooms with a fixed horizontal beam line. Both, the 3d translational errors and the rotational errors around the three table axes were determined. For the first room the 3d error was smaller than 0.72 mm in 95 percent of all setups. The standard deviation of the rotational errors was at most 0.026° for all axes. For the second room Siemens implemented an improved approach strategy to the final couch positions. The 95 percent quantile of the 3d error could in this room be reduced to 0.53 mm; the standard deviation of the rotational errors was also at most 0.026°. Robots are very flexible tools for patient positioning in six degrees of freedom. This study proved that the robots are able to achieve clinically acceptable accuracy in real patient setups, too

Forecast errors in IEA-countries' energy consumption

DEFF Research Database (Denmark)

Linderoth, Hans

2002-01-01

Every year Policy of IEA Countries includes a forecast of the energy consumption in the member countries. Forecasts concerning the years 1985,1990 and 1995 can now be compared to actual values. The second oil crisis resulted in big positive forecast errors. The oil price drop in 1986 did not have...... the small value is often the sum of large positive and negative errors. Almost no significant correlation is found between forecast errors in the 3 years. Correspondingly, no significant correlation coefficient is found between forecasts errors in the 3 main energy sectors. Therefore, a relatively small...

Frequency of medication errors in an emergency department of a large teaching hospital in southern Iran

Directory of Open Access Journals (Sweden)

Vazin A

2014-12-01

Full Text Available Afsaneh Vazin,1 Zahra Zamani,1 Nahid Hatam2 1Department of Clinical Pharmacy, Faculty of Pharmacy, 2School of Management and Medical Information Sciences, Shiraz University of Medical Sciences, Shiraz, Iran Abstract: This study was conducted with the purpose of determining the frequency of medication errors (MEs occurring in tertiary care emergency department (ED of a large academic hospital in Iran. The incidence of MEs was determined through the disguised direct observation method conducted by a trained observer. A total of 1,031 medication doses administered to 202 patients admitted to the tertiary care ED were observed over a course of 54 6-hour shifts. Following collection of the data and analysis of the errors with the assistance of a clinical pharmacist, frequency of errors in the different stages was reported and analyzed in SPSS-21 software. For the 202 patients and the 1,031 medication doses evaluated in the present study, 707 (68.5% MEs were recorded in total. In other words, 3.5 errors per patient and almost 0.69 errors per medication are reported to have occurred, with the highest frequency of errors pertaining to cardiovascular (27.2% and antimicrobial (23.6% medications. The highest rate of errors occurred during the administration phase of the medication use process with a share of 37.6%, followed by errors of prescription and transcription with a share of 21.1% and 10% of errors, respectively. Omission (7.6% and wrong time error (4.4% were the most frequent administration errors. The less-experienced nurses (P=0.04, higher patient-to-nurse ratio (P=0.017, and the morning shifts (P=0.035 were positively related to administration errors. Administration errors marked the highest share of MEs occurring in the different medication use processes. Increasing the number of nurses and employing the more experienced of them in EDs can help reduce nursing errors. Addressing the shortcomings with further research should result in reduction

Film techniques in radiotherapy for treatment verification, determination of patient exit dose, and detection of localization error

International Nuclear Information System (INIS)

Haus, A.G.; Marks, J.E.

1974-01-01

In patient radiation therapy, it is important to know that the diseased area is included in the treatment field and that normal anatomy is properly shielded or excluded. Since 1969, a film technique developed for imaging of the complete patient radiation exposure has been applied for treatment verification and for the detection and evaluation of localization errors that may occur during treatment. The technique basically consists of placing a film under the patient during the entire radiation exposure. This film should have proper sensitivity and contrast in the exit dose exposure range encountered in radiotherapy. In this communication, we describe how various exit doses fit the characteristic curve of the film; examples of films exposed to various exit doses; the technique for using the film to determine the spatial distribution of the absorbed exit dose; and types of errors commonly detected. Results are presented illustrating that, as the frequency of use of this film technique is increased, localization error is reduced significantly

Increased Patient Satisfaction and a Reduction in Pre-Analytical Errors Following Implementation of an Electronic Specimen Collection Module in Outpatient Phlebotomy.

Science.gov (United States)

Kantartjis, Michalis; Melanson, Stacy E F; Petrides, Athena K; Landman, Adam B; Bates, David W; Rosner, Bernard A; Goonan, Ellen; Bixho, Ida; Tanasijevic, Milenko J

2017-08-01

Patient satisfaction in outpatient phlebotomy settings typically depends on wait time and venipuncture experience, and many patients equate their experiences with their overall satisfaction with the hospital. We compared patient service times and preanalytical errors pre- and postimplementation of an integrated electronic health record (EHR)-laboratory information system (LIS) and electronic specimen collection module. We also measured patient wait time and assessed patient satisfaction using a 5-question survey. The percentage of patients waiting less than 10 minutes increased from 86% preimplementation to 93% postimplementation of the EHR-LIS (P ≤.001). The median total service time decreased significantly, from 6 minutes (IQR, 4-8 minutes), to 5 minutes (IQR, 3-6 minutes) (P = .005). The preanalytical errors decreased significantly, from 3.20 to 1.93 errors per 1000 specimens (P ≤.001). Overall patient satisfaction improved, with an increase in excellent responses for all 5 questions (P ≤.001). We found several benefits of implementing an electronic specimen collection module, including decreased wait and service times, improved patient satisfaction, and a reduction in preanalytical errors. © American Society for Clinical Pathology, 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Average beta-beating from random errors

CERN Document Server

Tomas Garcia, Rogelio; Langner, Andy Sven; Malina, Lukas; Franchi, Andrea; CERN. Geneva. ATS Department

2018-01-01

The impact of random errors on average β-beating is studied via analytical derivations and simulations. A systematic positive β-beating is expected from random errors quadratic with the sources or, equivalently, with the rms β-beating. However, random errors do not have a systematic effect on the tune.

A Case of Transfusion Error in a Trauma Patient With Subsequent Root Cause Analysis Leading to Institutional Change

Directory of Open Access Journals (Sweden)

Sean Patrick Clifford MD

2016-05-01

Full Text Available A 28-year-old man presented emergently to the operating room following a gun-shot injury to his right groin. Our hospital’s Massive Transfusion Protocol was initiated as the patient entered the operating room actively hemorrhaging and severely hypotensive. During the aggressive resuscitation efforts, the patient was inadvertently transfused 2 units of packed red blood cells intended for another patient due to a series of errors. Fortunately, the incorrect product was compatible, and the patient recovered from his near-fatal injuries. Root cause analysis was used to review the transfusion error and develop an action plan to help prevent future occurrences.

Association of medication errors with drug classifications, clinical units, and consequence of errors: Are they related?

Science.gov (United States)

Muroi, Maki; Shen, Jay J; Angosta, Alona

2017-02-01

Registered nurses (RNs) play an important role in safe medication administration and patient safety. This study examined a total of 1276 medication error (ME) incident reports made by RNs in hospital inpatient settings in the southwestern region of the United States. The most common drug class associated with MEs was cardiovascular drugs (24.7%). Among this class, anticoagulants had the most errors (11.3%). The antimicrobials was the second most common drug class associated with errors (19.1%) and vancomycin was the most common antimicrobial that caused errors in this category (6.1%). MEs occurred more frequently in the medical-surgical and intensive care units than any other hospital units. Ten percent of MEs reached the patients with harm and 11% reached the patients with increased monitoring. Understanding the contributing factors related to MEs, addressing and eliminating risk of errors across hospital units, and providing education and resources for nurses may help reduce MEs. Copyright © 2016 Elsevier Inc. All rights reserved.

MR diagnosis of meniscal tears of the knee: analysis of error patterns.

Science.gov (United States)

Van Dyck, Pieter; Gielen, Jan; D'Anvers, Jan; Vanhoenacker, Filip; Dossche, Lieven; Van Gestel, Jozef; Parizel, Paul M

2007-11-01

Despite high accuracy of magnetic resonance imaging (MRI) for diagnosing meniscal tears, MR findings do not always agree with surgical findings. We performed a blinded, retrospective study to analyze the nature and frequency of errors in the MR diagnosis of meniscal tears. Medical records of 100 consecutive patients who underwent MR and arthroscopy of the knee at our institution were reviewed. Twelve patients underwent prior meniscal surgery. Twenty-three patients had 27 discrepancies between MR and surgical findings. These were independently reviewed by two additional musculoskeletal radiologists in a double blinded fashion. Original incorrect diagnoses were categorized as either unavoidable, interpretation error or equivocal for meniscal tear. MR accuracy was 88% for the medial and 85% for the lateral meniscus. Of 27 incorrect MR diagnoses, 12 (44%) were unavoidable, 10 (37%) equivocal and 5 (19%) interpretation errors. Of the 67 medial meniscal tears, 12 (18%) were missed. Eight (67%) of these 12 were categorized as equivocal, including three postoperative menisci. Of 30 lateral tears, 12 (40%) were missed, 7 (58%) of which were categorized as unavoidable. Of these 12, 11 (92%) showed fraying of the inner edge, which was shaved at arthroscopy (n = 8) or had stable tear treated conservatively (n = 3). There were three false-positive diagnoses, all occuring in the lateral meniscus, two of which were unavoidable and one interpretation error. Of all missed lateral meniscal tears, most are unavoidable and related to confusion between what represents fraying and what represents a tear. Unavoidable false-positive diagnoses are infrequent and may be related to incomplete arthroscopic evaluation. Subtle or equivocal findings still make MR diagnosis difficult, even for experienced radiologists.

Variability of centric relation position in TMD patients.

NARCIS (Netherlands)

Zonnenberg, A.J.J.; Mulder, J.

2006-01-01

Reproducibility of the centric relation position for patients with temporomandibular disorders (TMD) is not documented in the current literature. It was the objective of this study to assess clinical variability of the centric relation position for TMD patients with a muscle-determined technique by

Set-up errors in patients undergoing image guided radiation treatment. Relationship to body mass index and weight loss

DEFF Research Database (Denmark)

Johansen, Jørgen; Bertelsen, Anders; Hansen, Christian Rønn

2008-01-01

by the relative weight change over time. Results: The SD of the translational and rotational random set-up errors during the first three sessions for H&N were 0.9 mm (Left-Right), 1.1mm (Anterior-Posterior), 0.7 mm (Cranio-Caudal) and 0.7 degrees (LR-axis), 0.5 degrees (AP-axis), and 0.7 degrees (CC......-axis). The equivalent data for lung cancer patients were 1.1 mm (LR), 1.1mm (AP), 1.5 mm (CC) and 0.5 degrees (LR-axis), 0.6 degrees (AP-axis), and 0.4 degrees (CC-axis). The median BMI for H&N and lung was 25.8 (17.6-39.7) and 23.7 (17.4-38.8), respectively. The median weekly weight change for H&N was -0.3% (-2.0 to 1...... (H&N) and 20 lung cancer patients were investigated. Patients were positioned using customized immobilization devices consisting of vacuum cushions and thermoplastic shells. Treatment was given on an Elekta Synergy accelerator. Cone-beam acquisitions were obtained according to a standardized Action...

The patient position for PNL: does it matter?

Science.gov (United States)

Cracco, Cecilia Maria; Scoffone, Cesare Marco; Poggio, Massimiliano; Scarpa, Roberto Mario

2010-03-01

Currently, PNL is the treatment of choice for large and/or otherwise complex urolithiasis. PNL was initially performed with the patient in a supine-oblique position, but later on the prone position became the conventional one for habit and handiness. The prone position provides a larger area for percutaneous renal access, a wider space for instrument manipulation, and a claimed lower risk of splanchnic injury. Nonetheless, it implies important anaesthesiological risks, including circulatory, haemodynamic, and ventilatory difficulties; need of several nurses to be present for intraoperative changes of the decubitus in case of simultaneous retrograde instrumentation of the ureter, implying evident risks related to pressure points; an increased radiological hazard to the urologist's hands; patient discomfort. To overcome these drawbacks, various safe and effective changes in patient positioning for PNL have been proposed over the years, including the reverse lithotomy position, the prone split-leg position, the lateral decubitus, the supine position, and the Galdakao-modified supine Valdivia (GMSV) position. Among these, the GMSV position is safe and effective, and seems profitable and ergonomic. It allows optimal cardiopulmonary control during general anaesthesia; an easy puncture of the kidney; a reduced risk of colonic injury; simultaneous antero-retrograde approach to the renal cavities (PNL and retrograde ureteroscopy = ECIRS, Endoscopic Combined IntraRenal Surgery), with no need of intraoperative repositioning of the anaesthetized patient, less need for nurses in the operating room, less occupational risk due to shifting of heavy loads, less risk of pressure injuries related to inaccurate repositioning, and reduced duration of the procedure; facilitated spontaneous evacuation of stone fragments; a comfortable sitting position and a restrained X-ray exposure of the hands for the urologist. But, first of all, GMSV position fully supports a new comprehensive

Patient position matching between SPECT and CT

International Nuclear Information System (INIS)

Eubig, C.; Lodhi, L.M.; Trueblood, J.H.; Kingsbury, T.; Burke, G.; Flickenger, F.

1990-01-01

Since the authors had previously developed an ability for accurate repositioning of patients by means of video imaging of their external features, it was their purpose to determine if separate video systems placed in SPECT and CT rooms could be positioned and a calibration procedure for each modality developed to assure easy identification and acquisition of corresponding congruent axial image sections through the patient. A video frame grabber is used to acquire an image of the patient in one room and superimpose it on a similar image of the patient in the other room. A radioactive ruler visible at CT images obtained with a gamma camera computer, and a CT scout image are used to adjust the initial relative position of the video cameras and calibrate the acquisition parameters of both systems. The success of this alignment procedure was tested with a body phantom. The body phantom studies indicate that this method of positioning the patient and acquiring corresponding aligned CT and SPECT axial sections can be successful where internal organ shift between the acquisitions is minimal. This should lead to a reduction of the time and computer resources necessary to fuse or superimpose images of corresponding patient sections acquired with different modalities

Preparing Emergency Medicine Residents to Disclose Medical Error Using Standardized Patients

Directory of Open Access Journals (Sweden)

Carmen N. Spalding

2017-12-01

Full Text Available Introduction Emergency Medicine (EM is a unique clinical learning environment. The American College of Graduate Medical Education Clinical Learning Environment Review Pathways to Excellence calls for “hands-on training” of disclosure of medical error (DME during residency. Training and practicing key elements of DME using standardized patients (SP may enhance preparedness among EM residents in performing this crucial skill in a clinical setting. Methods This training was developed to improve resident preparedness in DME in the clinical setting. Objectives included the following: the residents will be able to define a medical error; discuss ethical and professional standards of DME; recognize common barriers to DME; describe key elements in effective DME to patients and families; and apply key elements during a SP encounter. The four-hour course included didactic and experiential learning methods, and was created collaboratively by core EM faculty and subject matter experts in conflict resolution and healthcare simulation. Educational media included lecture, video exemplars of DME communication with discussion, small group case-study discussion, and SP encounters. We administered a survey assessing for preparedness in DME pre-and post-training. A critical action checklist was administered to assess individual performance of key elements of DME during the evaluated SP case. A total of 15 postgraduate-year 1 and 2 EM residents completed the training. Results After the course, residents reported increased comfort with and preparedness in performing several key elements in DME. They were able to demonstrate these elements in a simulated setting using SP. Residents valued the training, rating the didactic, SP sessions, and overall educational experience very high. Conclusion Experiential learning using SP is effective in improving resident knowledge of and preparedness in performing medical error disclosure. This educational module can be adapted

MO-FG-BRA-06: Electromagnetic Beacon Insertion in Lung Cancer Patients and Resultant Surrogacy Errors for Dynamic MLC Tumour Tracking

Energy Technology Data Exchange (ETDEWEB)

Hardcastle, N; Booth, J; Caillet, V; Haddad, C; Crasta, C [Royal North Shore Hospital, St. Leonards, NSW (Australia); O’Brien, R; Keall, P [University of Sydney, Sydney, NSW (Australia); Szymura, K [Royal North Shore Hospital, Sydney, NSW (Australia)

2016-06-15

Purpose: To assess endo-bronchial electromagnetic beacon insertion and to quantify the geometric accuracy of using beacons as a surrogate for tumour motion in real-time multileaf collimator (MLC) tracking of lung tumours. Methods: The LIGHT SABR trial is a world-first clinical trial in which the MLC leaves move with lung tumours in real time on a standard linear accelerator. Tracking is performed based on implanted electromagnetic beacons (CalypsoTM, Varian Medical Systems, USA) as a surrogate for tumour motion. Five patients have been treated and have each had three beacons implanted endo-bronchially under fluoroscopic guidance. The centre of mass (C.O.M) has been used to adapt the MLC in real-time. The geometric error in using the beacon C.O.M as a surrogate for tumour motion was measured by measuring the tumour and beacon C.O.M in all phases of the respiratory cycle of a 4DCT. The surrogacy error was defined as the difference in beacon and tumour C.O.M relative to the reference phase (maximum exhale). Results: All five patients have had three beacons successfully implanted with no migration between simulation and end of treatment. Beacon placement relative to tumour C.O.M varied from 14 to 74 mm and in one patient spanned two lobes. Surrogacy error was measured in each patient on the simulation 4DCT and ranged from 0 to 3 mm. Surrogacy error as measured on 4DCT was subject to artefacts in mid-ventilation phases. Surrogacy error was a function of breathing phase and was typically larger at maximum inhale. Conclusion: Beacon placement and thus surrogacy error is a major component of geometric uncertainty in MLC tracking of lung tumours. Surrogacy error must be measured on each patient and incorporated into margin calculation. Reduction of surrogacy error is limited by airway anatomy, however should be taken into consideration when performing beacon insertion and planning. This research is funded by Varian Medical Systems via a collaborative research agreement.