Registration Quality Assurance Research Articles

Evaluation of a deformable image registration quality assurance tool for head and neck cancer patients.

IntroductionA challenge in implementing deformable image registration (DIR) in radiation therapy planning is effectively communicating registration accuracy to the radiation oncologist. This study aimed to evaluate the MIM® quality assurance (QA) tool for rating DIR accuracy.MethodsRetrospective DIR was performed on CT images for 35 head and neck cancer patients. The QA tool was used to rate DIR accuracy as good, fair or bad. Thirty registered patient images were assessed independently by three RTs and a further five patients assessed by five RTs. Ratings were evaluated by comparison of Hausdorff Distance (HD), Mean Distance to Agreement (MDA), Dice Similarity Coefficients (DSC) and Jacobian determinants for parotid and mandible subregions on the two CTs post‐DIR. Inter‐operator reliability was assessed using Krippendorff's alpha coefficient (KALPA). Rating time and volume measures for each rating were also calculated.ResultsQuantitative metrics calculated for most anatomical subregions reflected the expected trend by registration accuracy, with good obtaining the most ideal values on average (HD = 7.50 ± 3.18, MDA = 0.64 ± 0.47, DSC = 0.90 ± 0.07, Jacobian = 0.95 ± 0.06). Highest inter‐operator reliability was observed for good ratings and within the parotids (KALPA 0.66–0.93), whilst ratings varied the most in regions of dental artefact. Overall, average rating time was 33 minutes and the least commonly applied rating by volume was fair.ConclusionResults from qualitative and quantitative data, operator rating differences and rating time suggest highlighting only bad regions of DIR accuracy and implementing clinical guidelines and RT training for consistent and efficient use of the QA tool.

Evaluation of a commercial deformable image registration algorithm for dual-energy CT processing.

PurposeSeveral dual‐energy computed tomography (DECT) techniques require a deformable image registration to correct for motion between the acquisition of low and high energy data. However, current DECT software does not provide tools to assess registration accuracy or allow the user to export deformed images, presenting a unique challenge for image registration quality assurance (QA). This work presents a methodology to evaluate the accuracy of DECT deformable registration and to quantify the impact of registration errors on end‐product images.MethodsThe deformable algorithm implemented in Siemen Healthineers's Syngo was evaluated using a deformable abdomen phantom and a rigid phantom to mimic sliding motion in the thorax. Both phantoms were imaged using sequential 80 and 140 kVp scans with motion applied between the two scans. Since Syngo does not allow the export of the deformed images, this study focused on quantifying the accuracy of various end‐product, dual‐energy images resulting from processing of deformed images.ResultsThe Syngo algorithm performed well for the abdomen phantom with a mean registration error of 0.4 mm for landmark analysis, Dice similarity coefficients (DSCs) > 0.90 for five organs contoured, and mean iodine concentrations within 0.2 mg/mL of values measured on static images. For rigid sliding motion, the algorithm performed poorer and resulted in noticeable registration errors toward the superior and inferior scan extents and DSCs as low as 0.41 for iodine rods imaged in the phantom. Additionally, local iodine concentration errors in areas of misregistration exceeded 3 mg/mL.ConclusionsThis work represents the first methodology for DECT image registration QA using commercial software. Our data support the clinical use of the Syngo algorithm for abdominal sites with limited motion (i.e., pancreas and liver). However, dual‐energy images generated with this algorithm should be used with caution for quantitative measurements in areas with sliding motion.

EP-2142: Implementation of registration quality assurance

EP-2142: Implementation of registration quality assurance

EP-1901: Patient-specific deformable image registration quality assurance based on feature points

EP-1901: Patient-specific deformable image registration quality assurance based on feature points

Quantitative Analysis Tools and Digital Phantoms for Deformable Image Registration Quality Assurance.

This article proposes quantitative analysis tools and digital phantoms to quantify intrinsic errors of deformable image registration (DIR) systems and establish quality assurance (QA) procedures for clinical use of DIR systems utilizing local and global error analysis methods with clinically realistic digital image phantoms. Landmark-based image registration verifications are suitable only for images with significant feature points. To address this shortfall, we adapted a deformation vector field (DVF) comparison approach with new analysis techniques to quantify the results. Digital image phantoms are derived from data sets of actual patient images (a reference image set, R, a test image set, T). Image sets from the same patient taken at different times are registered with deformable methods producing a reference DVFref. Applying DVFref to the original reference image deforms T into a new image R'. The data set, R', T, and DVFref, is from a realistic truth set and therefore can be used to analyze any DIR system and expose intrinsic errors by comparing DVFref and DVFtest. For quantitative error analysis, calculating and delineating differences between DVFs, 2 methods were used, (1) a local error analysis tool that displays deformation error magnitudes with color mapping on each image slice and (2) a global error analysis tool that calculates a deformation error histogram, which describes a cumulative probability function of errors for each anatomical structure. Three digital image phantoms were generated from three patients with a head and neck, a lung and a liver cancer. The DIR QA was evaluated using the case with head and neck.

Genre Analysis of Quality Assurance (ISO 9000) Documentation

The paper presents the results of cross-­sectional empirical research exploring the network of genres in the quality assurance domain. The theoretical basis for this research has been to a large extent grounded in the English for Specific Purposes (ESP) genre school. The empirical research method is a two-­staged discourse analysis. During the first stage the data collection tools were semi­-structured interviews with four Lloyd Register Quality Assurance (LRQA) auditors aimed at identifying the recurrent genres pertinent to the domain and describing the social context in which they occur. The second stage involved the genre analysis, namely, moves and steps analysis, in order to define the communicative aims and rhetorical organization of assessment reports. The obtained results highlight the significance of the social context for conducting the genre analysis in the quality assurance domain. They reveal that the genres in the network have hierarchical relations, with the quality standard being the dominating one. Moreover, discursive practices facilitate uncovering constitutive intertextual relations and rhetorical organisation. The topicality of the theme is determined by the scarcity of previous research in the quality assurance domain and the needs to train managers to develop their communicative language competence.

Quality assurance of registration of CT and MRI data sets for treatment planning of radiotherapy for head and neck cancers

We are implementing the use of magnetic resonance (MR) images for head and neck radiotherapy planning, which involves their registration with computed tomography (CT). The quality assurance (QA) of the registration process was an initial step of this program.A phantom was built, and appropriate materials were identified to produce clinically relevant MR T1 and T2 contrast for its constituent “anatomy.” We performed a characterization of the distortion detectable within our phantom. Finally, we assessed the accuracy of image registration by contouring structures in the registered/fused data sets using the treatment planning system. Each structure was contoured using each modality, in turn, blind of the other. The position, area, and perimeter of each structure were assessed as a measure of accuracy of the entire image registration process.Distortion effects in the MR image were shown to be minimized by choosing a suitable (≥±30 kHz) receiver bandwidth. Remaining distortion was deemed clinically acceptable within ±15 cm of the magnetic field isocenter. A coefficient of agreement (A) analysis gave values to be within 9% of unity, where A=RaRp and Ra/p is the ratio of the area/perimeter of a particular structure on CT to that on MR. The center of each structure of interest agreed to within 1.8 mm.A QA process has been developed to assess the accuracy of using multimodality image registration in the planning of radiotherapy for the head and neck; we believe its introduction is feasible and safe.PACS numbers: 87.53.Xd, 87.57.Gg, 87.59.Fm; 87.61.‐c, 87.66.Xa

Quality Assurance of Registration of CT and MRI Data Sets for Treatment Planning of Radiotherapy for Head and Neck Cancers

Quality Assurance of Registration of CT and MRI Data Sets for Treatment Planning of Radiotherapy for Head and Neck Cancers

Quality Assurance of Registration of CT and MRI Data Sets for Treatment Planning of Radiotherapy for Head and Neck Cancers

Quality Assurance of Registration of CT and MRI Data Sets for Treatment Planning of Radiotherapy for Head and Neck Cancers

How can ISO 9000:2000 help companies achieve excellence?

The ISO 9000 standard has been revised as of December 2000. It has been thought that the implications of addressing the changes may be particularly acute for small businesses, for which the impact of requirements and relative commercial costs of compliance can be greatest. In view of this, the Quality Research Group at the University of Leicester in collaboration with the Centre for Enterprise has conducted a research project with representatives from major internationally accredited UKAS certification bodies to explore the implications that the revision to ISO 9000 is likely to have on the small business community. This current paper reports on the study undertaken by the University of Leicester team with financial and collaborative support from Lloyds Register Quality Assurance and SGS Yarsley, two of the largest international ISO 9000 certification bodies. A detailed survey involving more than 1,000 respondents from UK‐based SMEs has provided a detailed empirical profile of the company’s own views of the value of ISO 9000:2000 on the path to excellence and what they will need to do to make it work. Face‐to‐face interviews were also used to provided verification and views from non‐certified companies. The results of the study are very positive and indicate a changing view and use of a standard that used to be seen as bureaucratic, officious and complacent.

Multimodality image registration quality assurance for conformal three-dimensional treatment planning

Purpose: We present a quality assurance methodology to determine the accuracy of multimodality image registration and fusion for the purpose of conformal three-dimensional and intensity-modulated radiation therapy treatment planning. Registration and fusion accuracy between any combination of computed tomography (CT), magnetic resonance (MR), and positron emission computed tomography (PET) imaging studies can be evaluated. Methods and Materials: A commercial anthropomorphic head phantom filled with water and containing CT, MR, and PET visible targets was modified to evaluate the accuracy of multimodality image registration and fusion software. For MR and PET imaging, the water inside the phantom was doped with CuNO 3 and 18F-fluorodeoxyglucose ( 18F-FDG), respectively. Targets consisting of plastic spheres and pins were distributed throughout the cranium section of the phantom. Each target sphere had a conical-shaped bore with its apex at the center of the sphere. The pins had a conical extension or indentation at the free end. The contours of the spheres, sphere centers, and pin tips were used as anatomic landmark models for image registration, which was performed using affine coordinate-transformation tools provided in a commercial multimodality image registration/fusion software package. Four sets of phantom image studies were obtained: primary CT, secondary CT with different phantom immobilization, MR, and PET study. A novel CT, MR, and PET external fiducial marking system was also tested. Results: The registration of CT/CT, CT/MR, and CT/PET images allowed correlation of anatomic landmarks to within 2 mm, verifying the accuracy of the registration software and spatial fidelity of the four multimodality image sets. Conclusions: This straightforward phantom-based quality assurance of the image registration and fusion process can be used in a routine clinical setting or for providing a working image set for development of the image registration and fusion process and new software.

The Quality control system at the “severstal” company has been approved by lloyd's register quality assurance

The Quality control system at the “severstal” company has been approved by lloyd's register quality assurance

What lessons can be learned for cancer registration quality assurance from data users? Skin cancer as an example.

In cancer registration, data cleaning (i.e. amendments made by data users to datasets released by registries) is potentially informative for quality assurance, but generally underreported. To assess the scope for learning lessons about cancer registration quality assurance from a data user (using skin cancer as the example). The main design features were: (i) A descriptive study identifying, qualitatively and quantitatively, the breadth, depth, and impact of quality assurance issues raised by a user cleaning Merseyside and Cheshire Cancer Registry skin cancer data. Errors were rectified and pitfalls for interpretation were identified. (ii) A nested validation of morphology and site coding on random samples of cutaneous malignant melanomas, basal cell carcinomas (BCC), and squamous cell carcinomas. The 33132-record dataset comprised: all registered skin lesions, except metastases; most recorded variables (about patient, lesion, treatment, outcome); for Merseyside and Cheshire residents diagnosed 1970-1991. (i) Ineligible cases represented 0.3% (97/33132), and were detected best by morphology checks. Most quality assurance issues identified related to local custom and practice, staff training, and computerization, being particularly illustrated by problematic BCC registration practice (e.g. records written over unchallenged by range checks; and idiosyncratic use of variables). (ii) Post-cleaning, morphology coding errors were minimal in the random samples. There is great scope for data users to contribute to cancer registration quality assurance. Ultimately, the study dataset appeared fit for epidemiological analysis and important quality assurance messages emerged. Shared explicit standard guidelines for data preparation and validation are needed by users, whose insights could and should be better recognized by cancer registries.

Aardvark to zulu

An electronic process-based management system has been developed from a traditional paper-based system. Subject matter is presented as concise topics containing minimum prescription, and may be accessed in numerous quite different ways. The complete system contains only one-third of the number of words in the original version. Users gain access to topics via an on-screen alphabetic keyboard, business processes, topic groups, the European Model for Total Quality Management, or the requirements of ISO 9001. A word-processor-style search facility is also provided. The level of detail presented to the screen is controlled by users. Default topics present a full description of minimum requirements, but each screen offers the option of going up or down a level of detail. The management system includes cross-references to ISO 9001 and TickIT, hot-spotted business process diagrams linked to lists of related topics, and electronic forms. Two change logs provide cumulative and topic-by-topic change information, in both cases linked to the relevant changed topics. The management system is delivered on the World-wide Web, a world-wide hypermedia system and part of the Internet, and has been approved by Lloyd‘s Register Quality Assurance.

The Integrated Management System of BNFL Transport

Quality Assurance (QA) is a requirement of the International Atomic Energy Agency (IAEA) Safety Series No 6 Regulations for the Safe Transport of Radioactive Materials and is also increasingly becoming a customer requirement. BNFL Transport has established an integrated management system which includes quality, safety and environmental aspects and covers the design, manufacture, testing, documentation, use, maintenance, inspection and decommissioning of all packages used for the transport of radioactive materials. The management system also covers planning, programming and transport operations, and covers all modes of transport by road, rail, sea and air. The management system, which was certificated in 1994 to ISO 9001 and BS 5882 by an independent third-party certification body, Lloyds Register Quality Assurance Limited (LRQA), was developed to enable BNFL Transport to demonstrate to Competent Authorities, customers and the general public that the arrangements are in place, being adhered to and meet all regulatory requirements. The requirements of the quality and environmental standards that the Company has adopted are described.

Coping with ISO certification

Achieving the quality management certification ISO 9000 is increasingly becoming a requirement for companies in all manufacturing industries, including the pump industry. Although the process can seem daunting, Steve Williams, technical helpdesk manager for Lloyd's Register Quality Assurance in Coventry, UK, explains that it need not be.

How to get your approval into print

Once ISO 9000 has been achieved, it is important that customers and potential customers should be aware of this. The best way to do this is to get it into print. Lloyd’s Register Quality Assurance (LRQA) has produced a guide to achieving maximum and cost‐effective press coverage. Discusses the best presentation format, and advises about photographic material and how to target the most appropriate publications.