Publications by authors named "Angela Davey"

5 Publications

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Optimising use of 4D-CT phase information for radiomics analysis in lung cancer patients treated with stereotactic body radiotherapy.

Phys Med Biol 2021 Apr 21. Epub 2021 Apr 21.

Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom., The University of Manchester, Manchester, Manchester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND.

Purpose: 4D-CT is routine imaging for lung cancer patients treated with stereotactic body radiotherapy. No studies have investigated optimal 4D phase selection for radiomics. We aim to determine how phase data should be used to identify prognostic biomarkers for distant failure, and test whether stability assessment is required. A phase selection approach will be developed to aid studies with different 4D protocols, and account for patient differences.

Methods: 186 features were extracted from the tumour and peritumour on all phases for 258 patients. Feature values were selected from phase features using four methods: A) mean across phases, B) median across phases, C) 50% phase, and D) the most stable phase (closest in value to two neighbours), coined personalised selection. Four levels of stability assessment were also analysed, with inclusion of: 1) all features, 2) stable features across all phases, 3) stable features across phase and neighbour phases, and 4) features averaged over neighbour phases. Clinical-radiomics models were built for twelve combinations of feature type and assessment method. Model performance was assessed by concordance index and fraction of new information from radiomic features.

Results: The most stable phase spanned the whole range but was most often near exhale. All radiomic signatures provided new information for distant failure prediction. The personalised model had the highest concordance index (0.77), and 58% of new information was provided by radiomic features when no stability assessment was performed.

Conclusion: The most stable phase varies per-patient and selecting this improves model performance compared to standard methods. We advise the single most stable phase should be determined by minimising feature differences to neighbour phases. Stability assessment over all phases decreases performance by excessively removing features. Instead, averaging of neighbour phases should be used when stability is of concern. The models suggest that higher peritumoural intensity predicts distant failure.
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April 2021

Automated gross tumor volume contour generation for large-scale analysis of early-stage lung cancer patients planned with 4D-CT.

Med Phys 2021 Feb 30;48(2):724-732. Epub 2020 Dec 30.

Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.

Purpose: Patients with early-stage lung cancer undergoing stereotactic ablative radiotherapy receive four-dimensional computed tomography (4D-CT) for treatment planning. Often, an internal gross target volume (iGTV), which approximates the motion envelope of a tumor over the breathing cycle, is delineated without defining a gross tumor volume (GTV). However, the GTV volume and shape are important parameters for prognostic and dose modelling, and there is interest in radiomic features extracted from the GTV and surrounding tissue. We demonstrate and validate a method to generate the GTV from an iGTV contour to aid retrospective analysis on routine data.

Method: It is possible to reconstruct the geometry of a tumor with knowledge of tumor motion and the motion envelope formed during respiration. To demonstrate this, the tumor motion path was estimated with local rigid registration, and the iGTV positioned incrementally at stations along the reverse path. It is shown that the tumor volume is the largest set common to the intersection of the iGTV at these positions, hence can be derived. This was implemented for 521 lung lesions on 4D-CT. Eleven patients with a GTV delineation performed by a radiation oncologist on a reference phase (50%) were used for validation. The generated GTV was compared to that delineated by the expert using distance-to-agreement (DTA), volume, and distance between centres of mass. An overall success rate was determined by detecting registration inaccuracy and performing a quality check on the routine iGTV. For successfully generated contours, GTV volume was compared to iGTV volume in a prognostic model for overall survival.

Results: For the validation dataset, DTA mean (0.79 - 1.55 mm) and standard deviation (0.68 - 1.51 mm) were comparable to expected observer variation. Difference in volume was < 5 cm , and average difference in position was 1.21 mm. Deviations in shape and position were mainly caused by observer differences in iGTV and GTV interpretation as opposed to algorithm performance. For the complete dataset, an acceptable contour was generated for 94% of patients using statistical and visual assessment to detect failures. Generated GTV volumes improved prognostic model performance over iGTV volumes.

Conclusion: A method to generate a GTV from an iGTV and 4D-CT dataset was developed. This method facilitates data analysis of patients with early-stage lung cancer treated in the routine setting, that is, data mining, prognostic modeling, and radiomics. Generation failure detection removes the need for visual assessment of all contours, reducing a time-consuming aspect of big-data analysis. Favorable prognostic performance of generated GTV volumes over iGTV ones demonstrates opportunities to use this methodology for future study.
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February 2021

Is tumour sphericity an important prognostic factor in patients with lung cancer?

Radiother Oncol 2020 02 28;143:73-80. Epub 2019 Aug 28.

Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Department of Radiotherapy Related Research, The Christie NHS Foundation Trust, Manchester, United Kingdom.

Background And Purpose: Quantitative tumour shape features extracted from radiotherapy planning scans have shown potential as prognostic markers. In this study, we investigated if sphericity of the gross tumour volume (GTV) on planning computed tomography (CT) is an independent predictor of overall survival (OS) in lung cancer patients treated with standard radiotherapy. In the analysis, we considered whether tumour sphericity is correlated with clinical prognostic factors or influenced by the inclusion of lymph nodes in the GTV.

Materials And Methods: Sphericity of single GTV delineation was extracted for 457 lung cancer patients. Relationships between sphericity, and common patient and tumour characteristics were investigated via correlation analysis and multivariate Cox regression to assess prognostic value of GTV sphericity. A subset analysis was performed for 290 nodal stage N0 patients to determine prognostic value of primary tumour sphericity.

Results: Sphericity is correlated with clinical variables: tumour volume, mean lung dose, N stage, and T stage. Sphericity is strongly associated with OS (p < 0.001, hazard ratio (HR) (95% confidence interval (CI)) = 0.13 (0.04-0.41)) in univariate analysis. However, this association did not remain significant in multivariate analysis (p = 0.826, HR (95% CI) = 0.83 (0.16-4.31), and inclusion of sphericity to a clinical model did not improve model performance. In addition, no significant relationship between sphericity and OS was detected in univariate (p = 0.072) or multivariate (p = 0.920) analysis of N0 subset.

Conclusion: Sphericity correlates clearly with clinical prognostic factors, which are often unaccounted for in radiomic studies. Sphericity is also influenced by the presence of nodal involvement within the GTV contour.
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February 2020

Mifepristone and prostaglandin for termination of pregnancy: contraindications for use, reasons and rationale.

Angela Davey

Contraception 2006 Jul 6;74(1):16-20. Epub 2006 May 6.

Exelgyn S.A, 216 Boulevard St. Germain, 75007 Paris.

Drug therapies are usually contraindicated in specific patient populations where evidence suggests that administration may result in a serious reaction or may seriously and negatively alter the risk benefit of treatment. There are few absolute contraindications to licensed regimens of mifepristone and prostaglandin for termination of pregnancy. However, those that are specified on "summary of product characteristics" [product labeling (PL)] differ from country to country. Differences reflect the dynamic environment of emerging scientific evidence, local experience and guidelines, and local regulatory processes, which all influence the resultant PL. The reasons and rationale for specific contraindications for mifepristone and prostaglandin for the termination of pregnancy are detailed, and the reasons for the differences between PL in different countries are explained.
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July 2006

Evaluating genetic counseling: client expectations, psychological adjustment and satisfaction with service.

J Genet Couns 2005 Jun;14(3):197-206

Genomics Directorate, Department of Health, Perth, Western Australia, Australia.

Periodic evaluations of genetic counseling services are useful for determining the effectiveness of counseling in meetings its psycho-educational aims, as well as identifying where improvements to the service may be made. This study aimed to evaluate the genetic counseling services provided by Genetic Services of Western Australia (GSWA) to determine the impact of counseling on client expectations, satisfaction with the service, and psychological adjustment, defined as wellbeing and perceived personal control (PPC). A total of 122 clients participated in a self-administered survey conducted pre- and post-counseling. Client expectations of the service as a means of providing information were met, and opportunities for counselors to meet client's expectations of psychological support were identified. Furthermore, counseling was found to maintain and enhance psychological wellbeing of clients. The role of counseling in facilitating the development of PPC was a key contributor to a high sense of satisfaction in clients.
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June 2005