A volumetric approach to risk assessment in mammography: a feasibility study

L. Blot and R. Zwiggelaar, 'A volumetric approach to risk assessment in mammography: a feasibility study', Physics in Medicine and Biology 50 (4), 695-708 (2005)

Two-Dimensional?Three-Dimensional Correspondence in Mammography

R. Marti, C. Rubin, E. Denton and R. Zwiggelaar, '2D-3D correspondence in mammography', Cybernetics and Systems 35 (1), 85-105 (2004)

Outcome and Experience from the Swiss Mammography Screening Pilot Programmes

BACKGROUND:The Swiss breast cancer screening pilot programme was conducted in 3 districts of theFrench-speaking canton of Vaud (ca. 300,000 resident women) between October 1993 and January 1999.Women aged 50 to 69 were invited by mail every 2 years for a free of charge screening mammography (doubleview, multiple reading). This first ever-organised cancer screening programme in Switzerland showed thefeasibility and acceptability of this kind of public health intervention in the liberal Swiss healthcare system, whichwas the main objective of the pilot programme. This mammographic screening programme was extended to thewhole canton in 1999, and contributed to the implementation of similar programmes in 2 neighbouring cantons. OBJECTIVE:To appraise the use, the quality and the effectiveness of the Swiss screening pilot programme. METHODS:About 15,000 women (aged 50-69) were enrolled. Logistic regression analyses were performedseparately to identify determinants of initial and subsequent attendance. Standard indicators of quality,effectiveness and impact of the programme were assessed and compared with European recommendations. Tothis intent, linkage with data from the Vaud Cancer Registry was performed. RESULTS:About half the target population was screened at least once during the pilot trial. Participation washigher among Swiss than foreigners, among widowed or married women than among single, divorced or separatedones. Attendance also increased with age and decreasing distance between residence and the dedicatedscreening centre. Apart from Swiss citizenship, socio-demographic factors were not associated with reattendance.Intensity of prior recruitment, outcome of previous screening test (positive vs. negative) and indicators of women'shealth behaviour (time of last mammography prior to initial screen, smoking status) were the main determinants ofreattendance. Programme performance and quality indicators were, overall, in line with European Guidelines. Theywere overall more favourable among 60-69 than 50-59 year-olds and improved over time. CONCLUSION:The objectives of the pilot programme were met. Even if participation should increase in order toreach European standards, performance indicators overall met quality requirements. Ways to improve screeninguse, quality and effectiveness were devised and taken into account for the generalisation of the programme.

Predictors of PSA test and Mammography use in the Canadian population.

Rapport de recherche

Development of active microwave imaging techniques for applications in mammography

Breast cancer is the most common non - skin malignancy in women and a leading cause of female morality. A potentially important strategy for reducing this menace is the detection at an early stage . The invention of non-invasive and non-ionizing microwave technique, to reveal the internal structure of biological objects was a break through in the field of medical diagnostics. Electrical properties of biological tissues and their interaction with electromagmetic waves have direct impact on human life. This thesis focuses on theoretical and experimental investigations of active microwave imaging techniques for breast cancer detection.

Microcalcification evaluation in computer assisted diagnosis for digital mammography

In order to develop applications for z;isual interpretation of medical images, the early detection and evaluation of microcalcifications in digital mammograms is verg important since their presence is often associated with a high incidence of breast cancers. Accurate classification into benign and malignant groups would help improve diagnostic sensitivity as well as reduce the number of unnecessa y biopsies. The challenge here is the selection of the useful features to distinguish benign from malignant micro calcifications. Our purpose in this work is to analyse a microcalcification evaluation method based on a set of shapebased features extracted from the digitised mammography. The segmentation of the microcalcifications is performed using a fixed-tolerance region growing method to extract boundaries of calcifications with manually selected seed pixels. Taking into account that shapes and sizes of clustered microcalcifications have been associated with a high risk of carcinoma based on digerent subjective measures, such as whether or not the calcifications are irregular, linear, vermiform, branched, rounded or ring like, our efforts were addressed to obtain a feature set related to the shape. The identification of the pammeters concerning the malignant character of the microcalcifications was performed on a set of 146 mammograms with their real diagnosis known in advance from biopsies. This allowed identifying the following shape-based parameters as the relevant ones: Number of clusters, Number of holes, Area, Feret elongation, Roughness, and Elongation. Further experiments on a set of 70 new mammogmms showed that the performance of the classification scheme is close to the mean performance of three expert radiologists, which allows to consider the proposed method for assisting the diagnosis and encourages to continue the investigation in the sense of adding new features not only related to the shape

An automatic correction method for the heel effect in digitized mammography images

The most significant radiation field nonuniformity is the well-known Heel effect. This nonuniform beam effect has a negative influence on the results of computer-aided diagnosis of mammograms, which is frequently used for early cancer detection. This paper presents a method to correct all pixels in the mammography image according to the excess or lack on radiation to which these have been submitted as a result of the this effect. The current simulation method calculates the intensities at all points of the image plane. In the simulated image, the percentage of radiation received by all the points takes the center of the field as reference. In the digitized mammography, the percentages of the optical density of all the pixels of the analyzed image are also calculated. The Heel effect causes a Gaussian distribution around the anode-cathode axis and a logarithmic distribution parallel to this axis. Those characteristic distributions are used to determine the center of the radiation field as well as the cathode-anode axis, allowing for the automatic determination of the correlation between these two sets of data. The measurements obtained with our proposed method differs on average by 2.49 mm in the direction perpendicular to the anode-cathode axis and 2.02 mm parallel to the anode-cathode axis of commercial equipment. The method eliminates around 94% of the Heel effect in the radiological image and the objects will reflect their x-ray absorption. To evaluate this method, experimental data was taken from known objects, but could also be done with clinical and digital images.

Conversion coefficients from air kerma to personal dose equivalent in mammography

In this work, the scattered X-ray beams produced by a mammography unit with a Mo/Mo, Mo/Rh and W/Rh anode/filter combinations were applied in the evaluation of the Hp(10, 0) and mean conversion coefficients from air kerma to the personal dose equivalent ((C) over barH(p(10,0 degrees))). The higher values of H(p)(10,0 degrees) are related to the Mo/Rh combination whereas the lower ones are for the W/Rh target/filter. (C) over barH(p(10,0 degrees)) values are in the range 0.19-0.54 Sv/Gy, where the higher values comprise the W/Rh combination. (C) 2009 Elsevier Ltd. All rights reserved.

X-ray spectroscopy applied to radiation shielding calculation in mammography

The protective shielding design of a mammography facility requires the knowledge of the scattered radiation by the patient and image receptor components. The shape and intensity of secondary x-ray beams depend on the kVp applied to the x-ray tube, target/filter combination, primary x-ray field size, and scattering angle. Currently, shielding calculations for mammography facilities are performed based on scatter fraction data for Mo/Mo target/filter, even though modern mammography equipment is designed with different anode/filter combinations. In this work we present scatter fraction data evaluated based on the x-ray spectra produced by a Mo/Mo, Mo/Rh and W/Rh target/filter, for 25, 30 and 35 kV tube voltages and scattering angles between 30 and 165 degrees. Three mammography phantoms were irradiated and the scattered radiation was measured with a CdZnTe detector. The primary x-ray spectra were computed with a semiempirical model based on the air kerma and HVL measured with an ionization chamber. The results point out that the scatter fraction values are higher for W/Rh than for Mo/Mo and Mo/Rh, although the primary and scattered air kerma are lower for W/Rh than for Mo/Mo and Mo/Rh target/filter combinations. The scatter fractions computed in this work were applied in a shielding design calculation in order to evaluate shielding requirements for each of these target/filter combinations. Besides, shielding requirements have been evaluated converting the scattered air kerma from mGy/week to mSv/week adopting initially a conversion coefficient from air kerma to effective dose as 1 Sv/Gy and then a mean conversion coefficient specific for the x-ray beam considered. Results show that the thickest barrier should be provided for Mo/Mo target/filter combination. They also point out that the use of the conversion coefficient from air kerma to effective dose as 1 Sv/Gy is conservatively high in the mammography energy range and overestimate the barrier thickness. (c) 2008 American Association of Physicists in Medicine.

Pain during mammography: implications for breast screening programmes

Pain experienced during mammography can deter women from attending for breast cancer screening. Review of the current literature on pain experienced during mammography reveals three main areas of interest: reports of the frequency of pain, identification of predictors of pain and strategies for responding to pain. Implications of this literature for breast screening programmes include the need for appropriate measurements of pain during mammography that are valid for screening populations, a further understanding of organizational factors involved in screening programmes that may be predictors of pain and for the development of valid strategies for responding to pain within breast screening programmes.

Correlates of screening mammography for Italian and Anglo-Australian women

The first aim of the research was to determine the applicability of certain variables from the Health Belief Model (HBM), the Theory of Reasoned Action (TRA), the risk dimensions from the Psychometric Paradigm, the Common-Sense Model of Illness Representations and the Locus of Control to Italian women’s beliefs and behaviours in relation to screening mammography. These models have predominantly been derived and evaluated with English-speaking persons. The study used quantitative and qualitative methods to enable explanation of research-driven and participant-driven issues. The second aim was to include Italian women in health behaviour research and to contrast the Italian sample with the Anglo-Australian sample to determine if differences exist in relation to their beliefs. In Australia many studies in health behaviour research do not include women whose first language is not English. The third aim was to evaluate the Anti-Cancer Council of Victoria’s (ACCV) Community Language Program (CLP) by: (a) identifying the strengths and weaknesses of the program as seen by the participants; and (b) assessing the impact of the program on women’s knowledge and beliefs about breast cancer, early detection of breast cancer, self-reported and intended breast screening behaviours. The CLP is an information service that uses women’s first language to convey information to women whose first language is not English. The CLP was designed to increase knowledge about breast and cervical cancer. The research used a pre-test-intervention-post-test design with 174 Italian-born and 138 Anglo-Australian women aged 40 years and over. Interviews for the Italian sample were conducted in Italian. The intervention was an information session that related to breast health and screening mammography. Demographic variables were collected in the Pre-Test only. Qualitative open-ended questions that related specifically to the information session were collected in the Post-Test phase of the study. Direct logistic regression was used with the participants’ beliefs and behaviours to identify the relevant variables for language (Italian speaking and English-speaking), attendance to an information session, mammography screening and breast self-examination (BSE) behaviour. Pre- and Post-Test comparisons were conducted using chi-square tests for the non-parametric data and paired sample t-tests for the parametric data. Differences were found between the Italian and Anglo-Australian women in relation to their beliefs about breast cancer screening. The Italian women were: (1) more likely to state that medical experts understood the causes of breast cancer; (2) more likely to feel that they had less control over their personal risk of getting breast cancer; (3) more likely to be upset and frightened by thinking about breast cancer; (4) less likely to perceive breast cancer as serious; (4) more likely to only do what their doctor told them to do; and (5) less likely to agree that there were times when a person has cancer and they don’t know it. A pattern emerged for the Italian and Anglo-Australian women from the logistic regression analyses. The Italian women were much more likely to comply with medical authority and advice. The Anglo-Australian women were more likely to feel that they had some control over their health. Specifically, the risk variable ‘dread’ was more applicable to the Italian women’s behaviour and internal locus of control variable was more relevant to the Anglo-Australian women. The qualitative responses also differed for the two samples. The Italian women’s comments were more general, less specific, and more limited than that of the Anglo-Australian women. The Italian women talked about learning how to do BSE whereas the Anglo-Australian women said that attending the session had reminded them to do BSE more regularly. The key findings and contributions of the present research were numerous. The focus on one cultural group ensured comprehensive analyses, as did the inclusion of an adequate sample size to enable the use of multivariate statistics. Separating the Italian and Anglo-Australian samples in the analyses provided theoretical implications that would have been overlooked if the two groups were combined. The use of both qualitative and quantitative data capitalised on the strengths of both techniques. The inclusion of an Anglo-Australian group highlighted key theoretical findings, differences between the two groups and unique contributions made by both samples during the collection of the qualitative data. The use of a pre-test-intervention-post-test design emphasised the reticence of the Italian sample to participate and talk about breast cancer and confirmed and validated the consistency of the responses across the two interviews for both samples. The inclusion of non-cued responses allowed the researcher to identify the key salient issues relevant to the two groups. The limitations of the present research were the lack of many women who were not screening and reliance on self-report responses, although few differences were observed between the Pre- and Post-Test comparisons. The theoretical contribution of the HBM and the TRA variables was minimal in relation to screening mammography or attendance at the CLP. The applicability of these health behaviour theories may be less relevant for women today as they clearly knew the benefits of and the seriousness of breast cancer screening. The present research identified the applicability of the risk variables to the Italian women and the relevance of the locus of control variables to the Anglo-Australian women. Thus, clear cultural differences occurred between the two groups. The inclusion of the illness representations was advantageous as the responses highlighted ideas and personal theories salient to the women not identified by the HBM. The use of the illness representations and the qualitative responses further confirmed the relevance of the risk variables to the Italian women and the locus of control variables to the Anglo-Australian women. Attendance at the CLP did not influence the women to attend for mammography screening. Behavioural changes did not occur between the Pre- and Post-Test interviews. Small incremental changes as defined by the TTM and the stages of change may have occurred. Key practical implications for the CLP were identified. Improving the recruitment methods to gain a higher proportion of women who do not screen is imperative for the CLP promoters. The majority of the Italian and Anglo-Australian women who attended the information sessions were women who screen. The fact that Italian women do not like talking or thinking about cancer presents a challenge to promoters of the CLP. The key theoretical finding that Italian women dread breast cancer but comply with their doctor provides clear strategies to improve attendance at mammography screening. In addition, the inclusion of lay health advisors may be one way of increasing attendance to the CLP by including Italian women already attending screening and likely to have attended a CLP session. The present research identified the key finding that improving Anglo-Australian attendance at an information session is related to debunking the myth surrounding familial risk of breast cancer and encouraging the Anglo-Australian women to take more control of their health. Improving attendance for Italian women is related to reducing the fear and dread of breast cancer and building on the compliance pattern with medical authority. Therefore, providing an information session in the target language is insufficient to attract non-screeners to the session and then to screen for breast cancer. Suggestions for future research in relation to screening mammography were to include variables from more than one theory or model, namely the risk, locus of control and illness representations. The inclusion of non-cued responses to identify salient beliefs is advantageous. In addition, it is imperative to describe the profile of the cultural sample in detail, include detailed descriptions of the translation process and be aware of the tendency of Italian women to acquiesce with medical authority.