Full-field Digital Mammography Unit Research Articles

A comparison of physical image quality of two hologic digital mammography systems that utilise linear and 2D anti-scatter grids

Objective. Full-field digital mammography (FFDM) systems manufactured by Hologic that utilise either a 2D or linear anti-scatter grid have recently been installed in our clinic. The manufacturer advise that for matched dose, both grids deliver comparable image quality. The aim of this study was to test the manufacturer’s claim using advanced physical image quality metrics and to inform whether the different grids are indeed dose neutral. Approach. Effective detective quantum efficiency (eDQE), effective noise equivalent quanta (eNEQ) and effective dose efficiency (eDE) were measured on a Hologic Dimensions (2D grid) and a Hologic 3Dimensions (linear grid) FFDM system, both calibrated at installation to provide matched threshold contrast, according to the EUREF protocol. eDQE, eNEQ and eDE were calculated and compared using 2, 4, 6 and 7 cm thicknesses of poly (methyl methacrylate) (PMMA) to simulate a clinically appropriate range of breast thicknesses. The beam qualities (target/filter and kilovoltage) chosen were identical between the two systems. Main results. All image quality metrics investigated show that the 2D grid outperforms the linear grid across all spatial frequencies. Furthermore, mean glandular dose (MGD) must be increased by up to 38% on those units that utilise the linear grid if eNEQ is to be matched, although MGD to the standard breast remains within NHSBSP tolerance and below the UK diagnostic reference level. The gradient and shape of each curve was the same irrespective of which grid was used, suggesting that subtle lesions (low frequency information) and micro-calcifications (high frequency information) will be imaged just as efficiently with a linear or 2D grid. Significance. If image quality is to be matched between those units utilising 2D and linear grids, dose must be increased on the latter. This information will be useful to the medical physicist tasked with the optimisation and standardisation of Hologic FFDM units.

Real time mass classification for mammographic images: a Driven CADx scheme

Computer-Aided Diagnosis (CADx) schemes have been proposed to serve as a supplementary image analysis tool in mammography. Experienced radiologists tend to be more assertive to such schemes in assisting their interpretation rather than solely relying on their ability to detect suspicious signals. This study focuses on a simplified version of a previously developed mammography CADx scheme, which was initially designed for digitized film, but is now specifically aimed at classifying breast nodules marked as regions of interest on digital images. This “driven” CADx scheme provides prompt indications regarding whether the selected nodule is deemed normal or suspicious. Its performance was evaluated through tests conducted on different mammograms sets – one with large number of images selected from DDSM database for training, testing and validation of classification parameters, and other comprising direct digital images from InBreast database. Remarkably, similar rates were observed for sensitivity, specificity and accuracy across these two sets (83%, 67% and 72%, respectively). The classification attributes were associated to contour, density and texture. Furthermore, a third test was conducted involving radiologists analyzing digital mammograms obtained from a specific full field digital mammography (FFDM) unit. Results showed that the Driven CADx scheme positively influenced the final diagnoses made by 3 radiologists, consistently increasing accuracy rates. This promising result allows establishing this software as a valuable tool for radiologists in the analysis of masses in digital mammography. The scheme can be implemented on any operating system, or even accessed online.

Towards National Diagnostic Reference Levels for Mammography in Serbia.

The objective of this work is to investigate the possibility to set a national diagnostic reference levels (nDRLs) for diagnostic and screening mammography in Serbia based on local practice and available resources. This study included all types of mammography systems that are currently used in Serbia, namely screen-film mammography (SFM), computed radiography (CR) and full-field digital mammography (FFDM). The nDRLs are provided in terms of mean glandular dose (MGD) for different breast thicknesses simulated by polymethyl methacrylate (PMMA) phantom. For each breast thickness, MGD was calculated for the X-ray tube output, using clinically used exposure parameters. DRLs were chosen as the 75th percentile of MGD distribution for 20-, 40-, 45-, 60- and 70-mm phantom thicknesses. For SFM units proposed nDRL values are 0.7, 2.1, 2.7, 4.6 and 6.8mGy; for CR units proposed nDRL values are 0.7, 1.8, 2.4, 4.5 and 5.6mGy; and corresponding values for FFDM units are 0.8, 1.7, 2, 2. and 3.2mGy for 20-, 40-, 45-, 60- and 70-mm PMMA thickness, respectively.

Comparison between Recorded and Measured Radiation Doses in Diagnostic Full-field Digital Mammography: A Phantom Study.

Objectives:There are concerns regarding the difference between directly recorded and measured entrance skin dose (ESD) and average glandular dose (AGD) in full-field digital mammography (FFDM). The objective of the study was to evaluate the effect of different exposure parameters on ESD and AGD recorded directly and measured from an FFDM unit using a phantom.Material and Methods:The ESD and AGD of 27 FFDM (craniocaudal [CC] projection) images of tissue-equivalent phantoms were acquired using a general electric (GE Senographe Essential) FFDM unit. The phantoms were used to simulate three different breast thicknesses and compositions. Tube potential, tube load, and target/ filter combinations also were recorded directly from the FFDM unit.Results:The mean differences between the directly recorded and measured ESD and AGD were 0.23 and 0.080, respectively. The 95% confidence intervals for ESD and AGD were 0.1–0.36 and 0.04–0.10, respectively. Results of paired t-test showed statistically significant difference between the directly recorded and measured ESD (P = .001) and AGD (P < .001). A positive and significant correlation was noted between the directly recorded and measured ESD (r = 0.85, P < .001) and AGD (r = 0.91, P < .001).Conclusion:This observation confirms that we can use the directly recorded doses obtained from an FFDM for quality control program.

Mammography diagnostic reference levels in Western Australia.

Mammography dose data has been collected from Western Australian units to establish Diagnostic Reference Levels for the state. Reference levels have been determined for a variety of phantom thicknesses for both full field digital mammography units and digital breast tomosynthesis units. Levels for the American College of Radiology (ACR) Phantom have been established as 1.3mGy and 1.5mGy mean glandular dose for full field digital mammography and digital breast tomosynthesis respectively. 2cm PMMA was 0.9mGy and 1.0mGy and 6cm PMMA had values of 2.0mGy and 2.3mGy. This data can be utilised to help establish national reference levels in the future.

Spatial correlation and breast cancer risk

We present a novel method for evaluating local spatial correlation structure in two-dimensional (2D) mammograms and evaluate its capability for risk prediction as one possible application. Two matched case-control studies were analyzed. Study 1 included women (N = 588 pairs) with mammograms acquired from Hologic Selenia full field digital mammography (FFDM) units or Hologic Dimensions digital breast tomosynthesis units. Study 2 included women (N = 180 pairs) with mammograms acquired from a General Electric Senographe 2000D FFDM unit. Matching variables included age, HRT usage/duration, screening history, and mammography unit. Local autocorrelation functions were determined with Fourier analysis and compared with a template defined as a 2D double-sided exponential function with one spatial extent parameter: n = 4, 12, 24, 50, 74, 100, and 124, where (n + 1) × (n + 1) is the pixel area of the local spatial extent. The difference between the local correlation and template was gauged within an adjustable parameter kernel and summarized, producing two measures: the mean (mn+1), and standard deviation (sn+1). Both adjustable parameters were varied in Study 1. Select measures that produced significant associations with breast cancer were translated to Study 2. Breast cancer associations were evaluated with conditional logistic regression, adjusted for BMI and ethnicity. Odds ratios (ORs) were estimated as per standard deviation increment with 95% confidence intervals (CIs). Two measures were selected for breast cancer association analysis in Study 1: m75 and s25. Both measures revealed significant associations with breast cancer: OR = 1.45 (1.23, 1.66) for m75 and OR = 1.30 (1.14, 1.49) for s25. When translating to Study 2, these measures also revealed significant associations: OR = 1.49 (1.12, 1.96) for m75 and OR = 1.34 (1.06, 1.69) for s25. Novel correlation metrics presented in this work produced significant associations with breast cancer risk. This approach is general and may have applications beyond mammography.

P006] DRL’s in mammography: Results from 3 dose audits

Purpose We compare the results of 3 dose audits (2013, 2015 and 2017) for bilateral mammography screening exams performed in a full field digital mammography unit GE Senographe DS. We estimated the average entrance surface dose (ESD) for a sample of at least 50 standard breasts. The results were compared with the European DRL - ESD of the 3rd quartile of the dose survey. We estimated average absorbed dose to the glandular tissue within breast (AGD) for a wide range of breast thicknesses, and converted it into effective dose. Data was presented to the staff to induce a process of optimization as team effort. Methods For each dose audit we selected a sample of more than 150 bilateral mammography screening exams. The percentage glandularity was determined using the qualitative method described by Byng (1994) and compared with Dance (2000) empirical formula. AGD was determined from measurements of the output and exposure data using appropriate conversion factors from IAEA (2007), Dance (2000), Dance (2009). Effective doses were determined using ICRP 103 breast tissue weighting factor 0.12. Results Results (2013): ESD = 5.8 mGy for cranio caudal (CC) and ESD = 6.1 mGy for medio lateral oblique (MLO) projections. These results are considerably below the European DRL’s (10 mGy). E ranged from: E = 0.28 mSv for small breasts (34.5 ± 4.5 mm) to E = 0.69 mSv for very large breasts (84.5 ± 4.5 mm) with larger compressed breast thickness associated with a higher AGD (E); Results (2015): around 30% increase in DRLs: ESD = 8.6 mGy CC and ESD = 8.7 mGy MLO; E ranged from E = 0.38 mSv for small breasts (34.5 ± 4.5 mm) to E = 0.75 mSv for very large breasts (84.5 ± 4.5 mm); Results (2017): within 5% of 2013. Conclusions The 30% increase in the dose results in 2015 resulted from the increased use of Contrast Enhanced Automatic Optimization of Parameters (AOP CNR) mode. This action was investigated and corrected. Dose audits are important part of a quality assurance program.

Exploratory survey of initial image quality in new digital mammography units prior to use in patients in Mexico

In Mexico, previous studies performed to evaluate the image quality in 2D digital mammography facilities show a poor image quality that is not compatible with mammography screening that may modify breast cancer mortality rate. Image quality is lost due to the quality assurance programs are not implemented. We carried out an exploratory survey of thirty-six new (FFDM) units from a single manufacturer installed in several cities of the Mexican Republic with two types of target/filter combination (Mo/Mo and W/Rh). Tests were performed according to NOM-041-SSA1–2011 (Mexico), the regulation indicates that all facilities using digital mammography systems must maintain a QC program equal to the QC program recommended by the manufacturer. However, QC program recommended by the manufacturer meets with FDA and ACR Regulations. Digital mammography units evaluated exceeds quality image standards established by the ACR and FDA, even though, the W/Rh combination achieved a higher performance and reduces the average glandular dose. All mammography units met the quality control standards established by ACR, FDA and Mexican regulations. Then, the objective of this study was to evaluate the initial image quality and compliances with the manufacturer's quality control specifications before use it in patients in new full-field 2D digital mammography (FFDM) units and compares average glandular dose (AGD) with FFDM units using different anode/filter combinations (Mo/Mo and W/Rh).

EXPOSURE PARAMETERS OF MAMMOGRAMS WITH AND WITHOUT MASS LESIONS FROM A SOUTH AFRICAN BREAST CARE CENTRE.

In South African breast care centres, full-field digital mammography units provide breast imaging services to symptomatic and asymptomatic women simultaneously. This study evaluated the technical exposure parameters of 800 mammograms of which 100 mammograms had obvious mass lesions in the fibroglandular tissue. The average breast compression force of mammograms with mass lesions in the fibroglandular tissue was 18.4% less than the average breast compression force of mammograms without mass lesions. The average mean glandular dose (MGD), tube potential (kVp) and compressed breast thickness (CBT) values were 2.14 mGy, 30.5 kVp and 63.9 mm, respectively, for mammograms with mass lesions, and 1.45 mGy, 29.6 kVp and 56.9 mm, respectively, for mammograms without mass lesions. Overall, the average MGD and mean CBT of mammograms with mass lesion were significantly higher compared to those without mass lesions (p < 0.05), although there was no significant difference in their tube potentials (p > 0.05).

Mean glandular doses in mammography: a comparison of values displayed by a mammography unit with in-house values, both using the method proposed by Dance

The purpose of this work is to compare the mean glandular dose (MGD) displayed by the mammography system and the MGD calculated according to the method proposed by Dance for women. This study also attempts to analyse whether the relationship between the calculated and the displayed values is constant and what factors influence this relationship. Material for this study included data from 1200 exposures (i.e. six series; each series consisting of 200 exposures) performed with one full-field digital mammography unit. Based on collected parameters of exposures, values of the MGD for individual mammography examinations were calculated according to the methods proposed by Dance. Obtained values of the MGD were compared with the values displayed by the mammography system. The MGD displayed by the mammography system and the MGD calculated according to the method proposed by Dance for women are significantly different. This result emphasises the importance of verifying MGD values for patient radiation protection, particularly after machine servicing.

Performance evaluation of contrast-detail in full field digital mammography systems using ideal (Hotelling) observer vs. conventional automated analysis of CDMAM images for quality control of contrast-detail characteristics

PurposeThe purpose of this work was to evaluate the contrast-detail performance of full field digital mammography (FFDM) systems using ideal (Hotelling) observer Signal-to-Noise Ratio (SNR) methodology and ascertain whether it can be considered an alternative to the conventional, automated analysis of CDMAM phantom images. MethodsFive FFDM units currently used in the national breast screening programme were evaluated, which differed with respect to age, detector, Automatic Exposure Control (AEC) and target/filter combination. Contrast-detail performance was analysed using CDMAM and ideal observer SNR methodology. The ideal observer SNR was calculated for input signal originating from gold discs of varying thicknesses and diameters, and then used to estimate the threshold gold thickness for each diameter as per CDMAM analysis. The variability of both methods and the dependence of CDMAM analysis on phantom manufacturing discrepancies also investigated. ResultsResults from both CDMAM and ideal observer methodologies were informative differentiators of FFDM systems' contrast-detail performance, displaying comparable patterns with respect to the FFDM systems' type and age. CDMAM results suggested higher threshold gold thickness values compared with the ideal observer methodology, especially for small-diameter details, which can be attributed to the behaviour of the CDMAM phantom used in this study. In addition, ideal observer methodology results showed lower variability than CDMAM results. ConclusionThe Ideal observer SNR methodology can provide a useful metric of the FFDM systems' contrast detail characteristics and could be considered a surrogate for conventional, automated analysis of CDMAM images.

Calibrated breast density methods for full field digital mammography: a system for serial quality control and inter-system generalization.

The authors are developing a system for calibrated breast density measurements using full field digital mammography (FFDM). Breast tissue equivalent (BTE) phantom images are used to establish baseline (BL) calibration curves at time zero. For a given FFDM unit, the full BL dataset is comprised of approximately 160 phantom images, acquired prior to calibrating prospective patient mammograms. BL curves are monitored serially to ensure they produce accurate calibration and require updating when calibration accuracy degrades beyond an acceptable tolerance, rather than acquiring full BL datasets repeatedly. BL updating is a special case of generalizing calibration datasets across FFDM units, referred to as cross-calibration. Serial monitoring, BL updating, and cross-calibration techniques were developed and evaluated. BL curves were established for three Hologic Selenia FFDM units at time zero. In addition, one set of serial phantom images, comprised of equal proportions of adipose and fibroglandular BTE materials (50/50 compositions) of a fixed height, was acquired biweekly and monitored with the cumulative sum (Cusum) technique. These 50/50 composition images were used to update the BL curves when the calibration accuracy degraded beyond a preset tolerance of ±4 standardized units. A second set of serial images, comprised of a wide-range of BTE compositions, was acquired biweekly to evaluate serial monitoring, BL updating, and cross-calibration techniques. Calibration accuracy can degrade serially and is a function of acquisition technique and phantom height. The authors demonstrated that all heights could be monitored simultaneously while acquiring images of a 50/50 phantom with a fixed height for each acquisition technique biweekly, translating into approximately 16 image acquisitions biweekly per FFDM unit. The same serial images are sufficient for serial monitoring, BL updating, and cross-calibration. Serial calibration accuracy was maintained within ±4 standardized unit variation from the ideal when applying BL updating. BL updating is a special case of cross-calibration; the BL dataset of unit 1 can be converted to the BL dataset for another similar unit (i.e., unit 2) at any given time point using the 16 serial monitoring 50/50 phantom images of unit 2 (or vice versa) acquired near this time point while maintaining the ±4 standardized unit tolerance. A methodology for monitoring and maintaining serial calibration accuracy for breast density measurements was evaluated. Calibration datasets for a given unit can be translated forward in time with minimal phantom imaging effort. Similarly, cross-calibration is a method for generalizing calibration datasets across similar units without additional phantom imaging. This methodology will require further evaluation with mammograms for complete validation.

Solid-state dosimeters: a new approach for mammography measurements.

To compare responses of modern commercially available solid-state dosimeters (SStDs) used in mammography medical physics surveys for two major vendors of current digital mammography units. To compare differences in dose estimates among SStD responses with ionization chamber (IC) measurements for several target/filter (TF) combinations and report their characteristics. To review scientific bases for measurements of quantities required for mammography for traditional measurement procedures and SStDs. SStDs designed for use with modern digital mammography units were acquired for evaluation from four manufacturers. Each instrument was evaluated under similar conditions with the available mammography beams provided by two modern full-field digital mammography units in clinical use: a GE Healthcare Senographe Essential (Essential) and a Hologic Selenia Dimensions 5000 (Dimensions), with TFs of Mo/Mo, Mo/Rh; and Rh/Rh and W/Rh, W/Ag, and W/Al, respectively. Measurements were compared among the instruments for the TFs over their respective clinical ranges of peak tube potentials for kVp and half-value layer (HVL) measurements. Comparisons for air kerma (AK) and their associated relative calculated average glandular doses (AGDs), i.e., using fixed mAs, were evaluated over the limited range of 28-30 kVp. Measurements were compared with reference IC measurements for AK, reference HVLs and calculated AGD, for two compression paddle heights for AK, to evaluate scatter effects from compression paddles. SStDs may require different positioning from current mammography measurement protocols. Measurements of kVp were accurate in general for the SStDs (within -1.2 and +1.1 kVp) for all instruments over a wide range of set kVp's and TFs and most accurate for Mo/Mo and W/Rh. Discrepancies between measurements and reference values were greater for HVL and AK. Measured HVL values differed from reference values by -6.5% to +3.5% depending on the SStD and TF. AK measurements over limited (28-30) kVp's ranged from -6% to +7% for SStDs, compared with IC reference values. Relative AGDs for each SStD using its associated measurements of kVp, HVL and AK underestimated AGD in nearly all cases, compared with reference IC values, with discrepancies of <-1% to ∼-10%. Some differences in AGD were related to differences in contributions of compression paddle scatter to AK measurements made by ICs. Applying measured factors for scatter effects in AK measurements for three SStDs reduced discrepancies between -6.2% and +1.3%, shifting AGDs from SStDs closer to IC AGDs. This study revealed that SStD measurements yielded good agreement with set kVp, poor agreement with standard HVL determinations, and AK measurements that were substantially different from IC measurements. Discrepancies are partly related to the scattered radiation measured by ICs in determining AK. As a result, IC measurements required for AGD, using currently accepted methodology, typically result in higher AGDs than SStDs, because current methodologies do not account for differing instrument responses to scatter. HVLs reported by SStDs contribute to discrepancies in calculated AGD that depend on kVp and TF. Medical physicists are encouraged to compare their results for SStD instruments using a similar methodology for potential discrepancies with their traditional instruments.

An assessment of reference exposure in analogic and digital mammographic units

Abstract In this study, the incident air kerma ( K i,a ), half-value layer (HVL), output and voltage accuracy for 28 mammography services were evaluated. All mammographs had high frequency rectification, a focus-film distance greater than 60 cm, automatic exposure control, a Mo–Mo anode-filter combination, and compression system. Twenty-three evaluations were made of analogic imaging systems and 21 of digital imaging systems, two of which were full field digital mammography units. The K i,a was measured in the beam radiation with a 6 cm 3 ionization chamber, calibrated for a mammography range of energy. A standard American College of Radiology mammographic phantom simulated a skull caudal incidence. The average, minimum, and maximum K i,a values were 10.13 mGy, 3.92 mGy, and 30.41 mGy, respectively. However, when the analogic and digital systems are analyzed separately in two subsets, the values were 8.13 mGy, 3.92 mGy, and 11.78 mGy for the analogic systems and 12.33 mGy, 5.21 mGy, and 30.41 mGy for the digital systems, respectively. The results show that the K i,a values found in digital systems were higher than those in analogic systems, highlighting the differences between these acquisition systems. All HVL values, measured in the primary beam at 28 kV were found between 0.33 mm Al and 0.43 mm Al. Although the manufacture time of the equipment was approximately 146 months (~12 years) prior, the variation in output was between 0.071 mGy/mAs and 0.164 mGy/mAs for the entire sample.

Three-dimensional dose distribution in contrast-enhanced digital mammography using Gafchromic XR-QA2 films: Feasibility study

This study was aimed to establish three-dimensional dose distributions for contrast-enhanced digital mammography (CEDM) using self-developed Gafchromic XR-QA2 films. Dose calibration and distribution evaluations were performed on a full-field digital mammography unit with dual energy (DE) contrast-enhanced option. Strategy for dose calibration of films in the DE mode was based on the data obtained from common target/filter/kVp combinations used clinically and the dose response model modified from Rampado's model. Dose derived from films were also verified by measured data from an ionization chamber. The average difference of dose was 8.9% in the dose range for clinical uses. Three-dimensional dose distributions were estimated using triangular acrylic phantom equipped with the mammography system. Five pieces of film sheets were separately placed between the acrylic slabs to evaluate the dose distribution at different depths. After normalizing the dose in each pixel to the maximum dose at the top-center position of the acrylic, normalized dose distribution for transverse, coronal and sagittal planes, could thus be obtained. The depth dose distribution evaluated in this study may further serve as a reference for evaluating the patient glandular dose at different depths based on the entrance exposure information.

A comparison of calibration data from full field digital mammography units for breast density measurements

BackgroundBreast density is a significant breast cancer risk factor measured from mammograms. The most appropriate method for measuring breast density for risk applications is still under investigation. Calibration standardizes mammograms to account for acquisition technique differences prior to making breast density measurements. We evaluated whether a calibration methodology developed for an indirect x-ray conversion full field digital mammography (FFDM) technology applies to direct x-ray conversion FFDM systems.MethodsBreast tissue equivalent (BTE) phantom images were used to establish calibration datasets for three similar direct x-ray conversion FFDM systems. The calibration dataset for each unit is a function of the target/filter combination, x-ray tube voltage, current × time (mAs), phantom height, and two detector fields of view (FOVs). Methods were investigated to reduce the amount of calibration data by restricting the height, mAs, and FOV sampling. Calibration accuracy was evaluated with mixture phantoms. We also compared both intra- and inter-system calibration characteristics and accuracy.ResultsCalibration methods developed previously apply to direct x-ray conversion systems with modification. Calibration accuracy was largely within the acceptable range of ± 4 standardized units from the ideal value over the entire acquisition parameter space for the direct conversion units. Acceptable calibration accuracy was maintained with a cubic-spline height interpolation, representing a modification to previous work. Calibration data is unit specific, can be acquired with the large FOV, and requires a minimum of one reference mAs sample. The mAs sampling, calibration accuracy, and the necessity for machine specific calibration data are common characteristics and in agreement with our previous work.ConclusionThe generality of our calibration approach was established under ideal conditions. Evaluation with patient data using breast cancer status as the endpoint is required to demonstrate that the approach produces a breast density measure associated with breast cancer.

New diagnostic reference level for full-field digital mammography units

The diagnostic reference level (DRL) has generally been defined as the 75th percentile of the distributions of mean doses observed on a sample of standard-sized patients, but for mammography, the 95th percentile has been used. In this study, the 75th and 95th percentiles are estimated for 26 full-field digital mammography units, representing six models from four manufacturers. Systematic differences between categories of manufacture/models are investigated with respect to mean glandular dose (MGD) and figure of merit (FOM), defined as signal difference to noise ratio squared divided by the MGD. The MGDs per unit range from 0.7 to 2.1 mGy, with overall 75th and 95th percentiles of 1.4 and 2.0 mGy, respectively. The different manufacture/models show differences in both dose distributions and FOMs. As national DRL, the 95th percentile is proposed to determine which units can be accepted for use. To identify the need for optimisation, it is proposed to use the 75th percentile for the different manufacture/models, along with the FOM.

Evaluation of testicular tumour calcification with digital orchiography

To analyse the calcification of testicular tumours in the orchiectomy specimens detected by digital orchiography obtained in a full-field digital mammography (FFDM) unit. Orchiectomy specimens of 37 consecutive patients were imaged by FFDM. Detected foci of calcification were stratified as: type 1, dense microcalcification; type 2, faint microcalcification; type 3, macrocalcification. Histopathology identified the tumour types, the presence of intratubular germ cell neoplasia (IGCN) and associated calcifications. Orchiography results correlated with the histopathology. On orchiography, 32/37of the specimens (86 %) had co-existing foci of calcification. Histopathology results revealed foci of calcification in 23/37 (62 %) of orchiectomy specimens. Of the 20 IGCN cases, 80 % presented with calcifications on orchiography. Fifty-six percent (14/25) of type 1, 70 % (12/17) of type 2, and 30 % (2/6) of type 3 foci of calcification were observed in IGCN-positive cases. This study classifies the morphology of testicular tumour calcification in three main groups by digital orchiography. In half of the testicular cancers, histopathologically proven IGCN is also found in addition to the index tumour. Type 2 foci of microcalcification detected by orchiography may be related to IGCN and may prompt further clinical assessment. • Orchiography can detect and classify calcification in 86 % of testicular cancers. • Intratubular germ cell neoplasia (IGCN) co-exists in 54 % of testicular cancers. • Type 2 foci of microcalcification detected by orchiography may be related to IGCN. • Orchiography may play a possible future role in the diagnosis of testicular IGCN.

Comparison of percent density from raw and processed full-field digital mammography data

IntroductionMammographic density has been established as a strong risk factor for breast cancer, primarily using digitized film mammograms. Full-field digital mammography (FFDM) is replacing film mammography, has different properties than film, and provides both raw and processed clinical display representation images. We evaluated and compared FFDM raw and processed breast density measures and their associations with breast cancer.MethodsA case-control study of 180 cases and 180 controls matched by age, postmenopausal hormone use, and screening history was conducted. Mammograms were acquired from a General Electric Senographe 2000D FFDM unit. Percent density (PD) was assessed for each FFDM representation using the operator-assisted Cumulus method. Reproducibility within image type (n = 80) was assessed using Lin's concordance correlation coefficient (rc). Correlation of PD between image representations (n = 360) was evaluated using Pearson's correlation coefficient (r) on the continuous measures and the weighted kappa statistic (κ) for quartiles. Conditional logistic regression was used to estimate odds ratios (ORs) for the PD and breast cancer associations for both image representations with 95% confidence intervals. The area under the receiver operating characteristic curve (AUC) was used to assess the discriminatory accuracy.ResultsPercent density from the two representations provided similar intra-reader reproducibility (rc= 0.92 for raw and rc= 0.87 for processed images) and was correlated (r = 0.82 and κ = 0.64). When controlling for body mass index, the associations of quartiles of PD with breast cancer and discriminatory accuracy were similar for the raw (OR: 1.0 (ref.), 2.6 (1.2 to 5.4), 3.1 (1.4 to 6.8), 4.7 (2.1 to 10.6); AUC = 0.63) and processed representations (OR: 1.0 (ref.), 2.2 (1.1 to 4.1), 2.2 (1.1 to 4.4), 3.1 (1.5 to 6.6); AUC = 0.64).ConclusionsPercent density measured with an operator-assisted method from raw and processed FFDM images is reproducible and correlated. Both percent density measures provide similar associations with breast cancer.

Scatter radiation intensities around full-field digital mammography units.

The aim of this study was to investigate the scatter radiation intensity around digital mammography systems and apply these data to standard shielding calculations to reveal whether shielding design of existing breast screening rooms is adequate for the use of digital mammography systems. Three digital mammography systems from GE Healthcare, Hologic and Philips were employed in the study. A breast-equivalent phantom was imaged under clinical workload conditions and scatter radiation intensities around the digital mammography systems were measured for a range of angles in three planes using an ionisation chamber. The results were compared with those from previous studies of film-screen systems. It may be deduced from the results that scattering in the backward direction is significant for all three systems, while scattering in the forward direction can be significant for some planes around the GE and Hologic systems. Measurements at typical clinical settings on each system revealed the Philips system to have markedly lower scatter radiation intensities than the other systems. Substituting the measured scattered radiation intensity into shielding calculations yielded barrier requirements similar to those already in place at the screening centres operating these systems. Current radiation protection requirements based on film-screen technology remain sufficient when applied to rooms with digital mammography installations and no alteration is required to the structural shielding.