Typical values of z-resolution for different Digital Breast Tomosynthesis systems evaluated in a multicenter study

PURPOSE

The aim of the present study, conducted by a working group of the Italian Association of Medical Physics (AIFM), was to define typical z-resolution values for different digital breast tomosynthesis (DBT) models to be used as a reference for quality control (QC). Currently, there are no typical values published in internationally agreed QC protocols.

METHODS

To characterize the z-resolution of the DBT models, the full width at half maximum (FWHM) of the artifact spread function (ASF), a technical parameter that quantifies the signal intensity of a detail along reconstructed planes, was analyzed. Five different commercial phantoms, CIRS Model 011, CIRS Model 015, Modular DBT phantom, Pixmam 3-D, and Tomophan, were evaluated on reconstructed DBT images and 82 DBT systems (6 vendors, 9 models) in use at 39 centers in Italy were involved.

RESULTS

The ASF was found to be dependent on the detail size, the DBT angular acquisition range, the reconstruction algorithm and applied image processing. In particular, a progressively greater signal spread was observed as the detail size increased and the acquisition angle decreased. However, a clear correlation between signal spread and angular range width was not observed due to the different signal reconstruction and image processing strategies implemented in the algorithms developed by the vendors studied.

CONCLUSIONS

The analysis led to the identification of typical z-resolution values for different DBT model-phantom configurations that could be used as a reference during a QC program.

Stereophotogrammetric three-dimensional photography is an accurate and precise planimetric method for the clinical visualization and quantification of human papilloma virus-induced skin lesions

Background

The quantification of human papilloma virus (HPV)‐induced skin lesions is essential for the clinical assessment of the course of disease and the response to treatment. However, clinical assessments that measure dimensions of lesions using a caliper do not provide complete insight into three‐dimensional (3D) lesions, and its inter‐rater variability is often poor.

Objective

The aim of this study was to validate a stereophotogrammetric 3D camera system for the quantification of HPV‐induced lesions.

Methods

The camera system was validated for accuracy, precision and interoperator and inter‐rater variability. Subsequently, 3D photographs were quantified and compared to caliper measurements for clinical validation by Bland–Altman modelling, based on data from 80 patients with cutaneous warts (CW), 24 with anogenital warts (AGW) patients and 12 with high‐grade squamous intraepithelial lesions of the vulva (vulvar HSIL) with a total lesion count of 220 CW, 74 AGW and 31 vulvar HSIL.

Results

Technical validation showed excellent accuracy [coefficients of variation (CV) ≤ 0.68%] and reproducibility (CVs ≤ 2%), a good to excellent agreement between operators (CVs ≤ 8.7%) and a good to excellent agreement between different raters for all three lesion types (ICCs ≥ 0.86). When comparing 3D with caliper measurements, excellent biases were found for diameter of AGW (long diameter 5%), good biases were found for diameter of AGW (short diameter 10%) and height of CW (8%), and acceptable biases were found for the diameter of CW (11%) and vulvar HSIL (short diameter 14%, long diameter 16%). An unfavourable difference between these methods (bias 25%) was found for the assessment of height of AGWs.

Conclusion

Stereophotogrammetric 3D imaging is an accurate and reliable method for the clinical visualization and quantification of HPV‐induced skin lesions.

Linked Commentary: M. Skerlev et al. J Eur Acad Dermatol Venereol 2019; 33: 1445–1446. https://doi.org/10.1111/jdv.15791.

Comparison of radiation doses to patients undergoing standard radiographic examinations with conventional screen–film radiography, computed radiography and direct digital radiography

New flat-panel direct digital radiography equipment has recently been installed in our Accident and Emergency Department; its characteristics and versatility are well suited to the work undertaken in this environment. The aim of this study was to compare radiation doses to patients undergoing standard radiographic examinations using conventional screen-film radiography, computed radiography and direct digital radiography; entrance surface dose and effective dose were calculated for six standard examinations (a total of 10 projections) using standard patient exposure parameters for the three imaging modalities. It was found that doses for computed radiography (all examinations) were higher than the doses for the other two modalities; effective doses for direct digital radiography were approximately 29% and approximately 43% lower than those for screen-film radiography and computed radiography, respectively. The image quality met the criteria in the European guidelines for all modalities.

Monitoring of the medical radiological exposures of the population of the Emilia–Romagna Region

PURPOSE

The Italian Decree of Law 187/2000 provides for many fulfilments relevant to justification and optimisation of medical exposures that can complicate the daily work of radiology departments if considered as mere legal requirements. On the contrary, this law should be regarded as a good opportunity to analyse and optimise working practices. To this end, the Emilia- Romagna Region carried out an initial assessment of medical exposures to its population in 2001 followed by a second survey taking into account new dosimetric evaluations. This paper illustrates the results of this second survey and analyses the most significant parameters in comparison with similar studies reported in the literature.

MATERIALS AND METHODS

We first determined the examinations to be considered: 12 easily identifiable examinations divided into macroaggregates were selected for conventional radiography and computed tomography (CT). Hospitals of the Emilia-Romagna Region were directly asked to provide the number of examinations performed subdivided by type and grouped by nomenclature code, some technical parameters related to both examination protocol and equipment and the value of dose quantities as measured by local medical physicists.

RESULTS

Study of distribution of the entrance skin dose for different examinations in single hospitals showed no systematic differences in kilovoltage settings versus dose whereas the number of examinations tended to be inversely proportional to dose. These trends could be explained by the fact that in hospitals where many examinations of the same type are performed, operators, equipment and procedures are well integrated, leading to a level of specialisation that allows efficient interaction in order to deliver an "optimal dose". Analysis of the "entrance skin dosemax"/"entrance skin dosemin" ratios for various projections and comparison with literature data seem to show that a "scale factor" has a fundamental role in the variability of entrance skin dose values amongst hospitals and that "chest" examinations are the most critical, with the greatest differences in entrance skin doses.

CONCLUSIONS

The evaluations performed in this study show that this type of analysis heavily relies not only on the cooperation of all professionals responsible for patient radiation protection but also on the experience gained during previous surveys because data collection is a very critical process that can invalidate, if not carefully performed, all subsequent processing.

Normal haematological and serum biochemical values of Eurasian otters (Lutra lutra) from a Scottish rehabilitation centre

Blood samples were taken from 47 clinically normal, wild-born Eurasian otters (Lutra lutra) before they were released from a rehabilitation centre in Scotland between August 1990 and March 1996. Serum biochemistry profiles were determined for 47 animals and haematological profiles for 41, and the results from males, females, and animals under or over one year of age were analysed as separate groups and as pooled populations. The normal ranges for a wide variety of haematological and serum biochemical parameters of the Eurasian otter are presented, and significant differences with age and sex are detailed.

Patient education: bridging the gap between inpatient and ambulatory care

This article describes a model curriculum of perinatal education designed to bridge the gap between prenatal ambulatory care education and labor and delivery, postpartum and well child care in a high-risk population of inner city women. The curriculum, which consists of broad-based, maternal-child health information, was developed, implemented, and evaluated through an interdisciplinary approach. The initiative narrowed the preexisting gap between departments, increased clients' knowledge, and promoted positive changes in clients' behavior. The breadth of the curriculum content addresses the unquestionable need for perinatal education that will enhance compliance and empower clients toward health maintenance.