Mean Glandular Dose Research Articles

Integrating mammographic breast density in glandular dose calculation.

This work proposes the use of mammographic breast density (MBD) to estimate actual glandular dose (AGD), and assesses how AGD compares to mean glandular dose (MGD) estimated using Dance et al method. A retrospective sample of anonymised mammograms (52,405) was retrieved from a central database. Technical parameters and patient characteristics were exported from the Digital Imaging and Communication in Medicine (DICOM) header using third party software. LIBRA (Laboratory for Individualized Breast Radiodensity Assessment) software package (University of Pennsylvania, Philadelphia, USA) was used to estimate MBDs for each mammogram included in the data set. MGD was estimated using Dance et al method, while AGD was calculated by replacing Dance et al standard glandularities with LIBRA estimated MBDs. A linear regression analysis was used to assess the association between MGD and AGD, and a Bland-Altman analysis was performed to assess their mean difference. The final data set included 31,097 mammograms from 7728 females. MGD, AGD, and MBD medians were 1.53 , 1.62 mGy and 8% respectively. When stratified per breast thickness ranges, median MBDs were lower than Dance's standard glandularities. There was a strong positive correlation (R2 = 0.987, p < 0.0001) between MGD and AGD although the Bland-Altman analysis revealed a small statistically significant bias of 0.087 mGy between MGD and AGD (p < 0.001). AGD estimated from MBD is highly correlated to MGD from Dance method, albeit the Dance method underestimates dose at smaller CBTs. Advances in knowledge: Our work should provide a stepping-stone towards an individualised dose estimation using automated clinical measures of MBD.

DOSE DISTRIBUTION IN A BREAST UNDERGOING MAMMOGRAPHY BASED ON A 3D DETAILED BREAST MODEL FOR CHINESE WOMEN

Not only the mean glandular dose (MGD) but also the glandular dose distribution is important in describing the radiation exposure to breast in mammography. For a more precise knowledge of the absorbed dose distribution in the breast, experimental measurements with thermoluminescence dosemeter and Monte Carlo simulations with Geant4 were performed in this study. The experimental measurements with homogeneous physical breast phantoms were used to validate Monte Carlo simulations of homogeneous mathematical breast models undergoing mammography. Then a 3D detailed breast model with a compressed breast thickness of 4 cm and a glandular content of 50%, which has been constructed in previous work, was used to study the absorbed dose distribution inside the breast undergoing mammography. Furthermore, the effects of the glandular tissue distribution on MGD were studied by reversing the breast model in head-toe direction to get a breast model with a different distribution of glandular tissues.

Dose and diagnostic performance comparison between phase-contrast mammography with synchrotron radiation and digital mammography: a clinical study report

Two dosimetric quantities [mean glandular dose (MGD) and entrance surface air kerma (ESAK)] and the diagnostic performance of phase-contrast mammography with synchrotron radiation (MSR) are compared to conventional digital mammography (DM). Seventy-one patients (age range, 41 to 82 years) underwent MSR after a DM examination if questionable or suspicious breast abnormalities were not clarified by ultrasonography. The MGD and the ESAK delivered in both examinations were evaluated and compared. Two on-site radiologists rated the images in consensus according to the Breast Imaging Reporting and Data System assessment categories, which were then correlated with the final diagnoses by means of statistical generalized linear models (GLMs). Receiver operating characteristic curves were also used to assess the diagnostic performance by comparing the area under the curve (AUC). An important MGD and ESAK reduction was observed in MSR due to the monoenergetic beam. In particular, an average 43% reduction was observed for the MGD and a reduction of more than 50% for the ESAK. GLM showed higher diagnostic accuracy, especially in terms of specificity, for MSR, confirmed by AUC analysis ([Formula: see text]). The study design implied that the population was characterized by a high prevalence of disease and that the radiologists, who read the DM images before referring the patient to MSR, could have been influenced in their assessments. Within these limitations, the use of synchrotron radiation with the phase-contrast technique applied to mammography showed an important dose reduction and a higher diagnostic accuracy compared with DM. These results could further encourage research on the translation of x-ray phase-contrast imaging into the clinics.

Development of MGDA Software for Calculation of Patient Specific Mean Glandular Dose during Mammography

Abstract not availableBangladesh J. Nuclear Med. 18(2): 156-160, July 2015

Investigation of Exposure Factors for Various Breast Composition and Thicknesses in Digital Screening Mammography Related to Breast Dose

Objective: To investigate the effect of exposure factors used in digital screening mammography on image quality of different breast compositions. Material and Methods: A digital mammography unit, with tungsten (W) as target, rhodium (Rh) and silver (Ag) as filters, and amorphous selenium detectors, was used to image Computerized Imaging Reference Systems (CIRS) Model 12A phantoms of thickness 4, 5, and 6 cm. Images of each phantom were obtained using target-filter combinations of W/Rh and W/Ag, at 28, 30, and 32 kVp. Images were evaluated by 5 senior technologists with experience in mammography. Image scores were assigned, for each type of feature present in the phantom. Statistical analysis was performed using nonparametric tests to compare sets of image scores at p = 0.05. Results: A small but statistically significant improvement was detected in the visibility of microcalcifications (8.8 ± 0.2; p = 0.031) for the W/Rh combination but this did not show any differences in the visibility of masses or fibers. The entrance skin dose (ESD) and mean glandular dose (MGD) were lower for the W/Ag (ESD = 1.30–3.70; MGD = 0.44–0.93 mGy) combination compared to W/Rh (ESD = 1.66–5.40; MGD = 0.52–1.12 mGy). The Mann-Whitney test revealed that 30-kV exposure with the W/Rh combination showed a significantly better visibility of specks in the 30/70 phantom compared to other exposures. Conclusion: The use of an Rh filter showed a better image quality for all phantoms. 28 and 30 kVp with the W/Rh combination provided a slightly better image quality, and the MGD is less than 1.2 mGy.

Diagnostic reference levels for mammography examinations in North Eastern Nigeria

Background: Diagnostic reference levels (DRLs) plays an important role in health‑care delivery and radiation safety of patients. This study was carried out as part of a comprehensive project to establish DRLs for the radiological examinations for the first time in North Eastern Nigeria. Objective of the Study: The aim is to establish DRL for mammography examination in North Eastern Nigeria and to compare it with other established works. Materials and Methods: This study is a prospective cross‑sectional study conducted in two university teaching hospitals in North Eastern Nigeria. Sixty patients were recruited for the study. Thermoluminescent dosimeter (TLD) chips were exposed for craniocaudal (CC) and mediolateral examinations to record the entrance skin dose (ESD). TLD readings were obtained at the Center for Energy Research and Training Zaria, Kaduna State, Nigeria. Dance formula was used to convert ESD to mean glandular dose (MGD). Student’s t‑test was used to determine the relationship between the mean ESD obtained in the two centers and Pearson’s correlation was used to determine the relationship between the MGD and anthropotechnical parameters. Statistical significance was set at P < 0.05. Results: The total MGD for this study was 0.31 ± 0.05 mGy and 0.69 ± 0.11 mGy for CC and mediolateral oblique (MLO), respectively. DRL was 0.63 mGy and 1.04 mGy for CC and MLO, respectively. There was no statistically significant relationship (P > 0.05) between the MGD and anthropotechnical parameters. The DRL in this work were higher when compared with international established work. Conclusion: There is need for optimization of our radiology practice in North Eastern Nigeria and most centers in Nigeria. Keywords: Diagnostic reference levels, entrance skin dose, mammography, mean glandular dose, thermoluminescent dosimeter.

Measurement of effective detective quantum efficiency for a photon counting scanning mammography system and comparison with two flat panel full-field digital mammography systems

Effective detective quantum efficiency (eDQE) describes the resolution and noise properties of an imaging system along with scatter and primary transmission, all measured under clinically appropriate conditions. Effective dose efficiency (eDE) is the eDQE normalised to mean glandular dose and has been proposed as a useful metric for the optimisation of clinical imaging systems. The aim of this study was to develop a methodology for measuring eDQE and eDE on a Philips microdose mammography (MDM) L30 photon counting scanning system, and to compare performance with two conventional flat panel systems.A custom made lead-blocker was manufactured to enable the accurate determination of dose measurements, and modulation transfer functions were determined free-in-air at heights of 2, 4 and 6 cm above the breast support platform. eDQE were calculated for a Philips MDM L30, Hologic Dimensions and Siemens Inspiration digital mammography system for 2, 4 and 6 cm thick poly(methyl methacrylate) (PMMA). The beam qualities (target/filter and kilovoltage) assessed were those selected by the automatic exposure control, and anti-scatter grids were used where available.Measurements of eDQE demonstrate significant differences in performance between the slit- and scan-directions for the photon counting imaging system. MTF has been shown to be the limiting factor in the scan-direction, which results in a rapid fall in eDQE at mid-to-high spatial frequencies. A comparison with two flat panel mammography systems demonstrates that this may limit image quality for small details, such as micro-calcifications, which correlates with a more conventional image quality assessment with the CDMAM phantom. eDE has shown the scanning photon counting system offers superior performance for low spatial frequencies, which will be important for the detection of large low contrast masses. Both eDQE and eDE are proposed as useful metrics that should enable optimisation of the Philips MDM L30.

Comparative study of mean Glandular dose between two Mammography Systems with Similar Target - Filter Combination

Comparative study of mean Glandular dose between two Mammography Systems with Similar Target - Filter Combination

Mean glandular dose values used for the mammography screening program in Poland according to the type of image registration system

Between 2007–2014, there have been considerable changes in the use of different types of detector systems at mammography facilities undertaking screening programs in Poland. The use of screen-film systems (termed SF systems) has largely decreased and been replaced by either computed radiography (termed CR systems) or digital radiography systems (termed DR systems); this inevitably affecting mean glandular dose values. The study aim was to evaluate changes of mean glandular dose values for a dose exposure of 4.5 cm (MGD 4,5cmPMMA ) achieved by using different image detectors. The study consisted of analysing 1499 protocols for quality control tests carried out by medical physicists at 16 Regional Coordination Offices in 2007, 2011, 2012 and 2013. The mean CR system values were higher than for SF systems; by 25% in 2011, by 26% in 2012, and by 28% in 2013. In subsequent years, the MGD 4,5cmPMMA mean values for DR systems were higher than for SF systems by respectively 15%, 4% and 5%. Also in the subsequent years, the MGD 4,5cmPMMA mean values for CR systems were higher than for DR systems by respectively 13%, 23% and 24%. In all cases, the MGD 4,5cmPMMA mean values were within the acceptable level of 2.5 mGy. The MGD 4,5cmPMMA mean values were different, depending on the detection system used for mammography screening in Poland

Abstract ID: 92 Skin model and its impact on Mean Glandular Dose in digital mammography

The Mean Glandular Dose (MGD) is the main physical quantity used in mammography dosimetry [1] . The skin plays an important role, absorbing part of the incident radiation and, its traditional thickness is overestimated with recent findings [1] . This work investigates the influence of breast skin models on the MGD using the PENELOPE (2014) + penEasy (2015) Monte Carlo code. The simulated geometry includes: a source 66 cm above the detector, a compression and a breast support paddle (PMMA 2 mm thick), the breast (a semi-cylinder with 8 cm radius), and the a-Se detector. The total thickness of the breast varied from 2 to 9 cm and its central region is composed by a homogeneous mixture of glandular and adipose tissue with different proportions [1] . Four breast skin models were implemented: 4 mm skin tissue (I), 5 mm adipose tissue (II), a combination of 1,45 mm skin plus 2 mm adipose (III) and 1,45 mm skin (IV) [2] . Simulations were made with monoenergetic beams from 8 to 60 keV and polyenergetic beams with different Anode/Filter combinations (Mo/Mo, Mo/Rh, Rh/Rh, W/Rh, W/Ag, W/Al) and a potential from 22 kV to 35 kV. For a 2 cm breast, a maximum MGD difference of 80% between the skins models (I)–(II) at 8 keV, decreasing as energy increases. For the polyenergetic spectra (Mo/Mo), a mean difference of 28%, 16% and 16% in comparing the models (II), (III) and (IV), with the model (I), respectively. The MGD differences between the models decreases while increasing tube potential. The composition and thickness of the breast has an impact up to 10% and 15% on the results, respectively. The results highlight the importance of the modelling the skin for accurate dosimetry in mammography.

Abstract ID: 33 Monte Carlo evaluation of glandular dose estimates in X-ray breast computed tomography

A few groups have developed cone-beam breast computed tomography scanners dedicated to the breast (BCT) [1] , for breast cancer diagnosis. BCT is a 3D X-ray imaging technique, which aims at reducing the presence of the anatomical noise in X-ray breast images, due to the superposition of breast structures and tissues. The common metric for breast radiation dosimetry in BCT is the Mean Glandular Dose (MGD), i.e. the average absorbed dose in the glandular component of the breast tissue. The MGD is estimated on the basis of air kerma measurements, and normalized glandular dose coefficients (DgN) evaluated via Monte Carlo (MC) simulations [2] . In such a context, the breast is modeled as a homogenous mixture of glandular and adipose tissue embodied in a skin layer. We evaluated the DgN in BCT by modeling the breast as a heterogeneous mixture of adipose and glandular tissues. We realized an MC code based on GEANT4 toolkit simulating the acquisition setup and considering the interactions included in the standard electro-magnetic libraries. The MC code was previously validated vs. data from the AAPM Task Group 195, as well as vs. measured data. The dose was scored in locations inside a grid of cubic voxels designed using patient BCT scans provided by University of California Davis. The voxels were classified in adipose tissue, glandular tissue, skin tissue or air via an opportune segmentation algorithm. Such a voxellized phantom, with a real glandular distribution, was input in the MC code for estimating the MGD. This post-exam estimate was compared with the corresponding estimate evaluated before the exam using a homogeneous tissue mixture approximation. This project received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 692097 for the MaXIMA project: Three dimensional breast cancer models for X-ray imaging research.

Digital Breast Tomosynthesis (DBT) Dose Survey and the establishment of a DRL for a National Breast Screening Service

Digital breast tomosynthesis (DBT) has proven invaluable to BreastCheck as an adjunct to 2D imaging, and since 2014, BreastCheck has commissioned 15 Hologic Selenia Dimensions DBT systems. Risk assessment is one of the many important reasons for performing a breast dose survey. This study is a presentation of the results of the first dose survey performed on the new 3D imaging systems. Mean glandular dose (MGD) is the commonly accepted measure of mammographic radiation risk and was calculated for each 3D image according to Dance et al. The survey used the exposure data from at least 45 examinations per DBT unit and dose calculations were performed using the NCCPM breast dose survey software. Dose survey results were in good agreement with values published in the literature. As expected the average 3D breast dose exceeds the average 2D dose (Ratio = 1.28). The estimate of the 3D imaging DRL (2.6 mGy) was based on the average MGD of an oblique exposure of an average sized breast. Survey results indicated a drop in breast dose for breast thickness greater than 90 mm. The manufacturer has confirmed this occurs by design to minimize long exposure times and focal spot blur which could occur for the larger breast thicknesses. The strong comparison between calculated and displayed doses should simplify future surveys. Digital breast tomosynthesis (DBT) has proven invaluable to BreastCheck as an adjunct to 2D imaging, and since 2014, BreastCheck has commissioned 15 Hologic Selenia Dimensions DBT systems. Risk assessment is one of the many important reasons for performing a breast dose survey. This study is a presentation of the results of the first dose survey performed on the new 3D imaging systems. Mean glandular dose (MGD) is the commonly accepted measure of mammographic radiation risk and was calculated for each 3D image according to Dance et al. The survey used the exposure data from at least 45 examinations per DBT unit and dose calculations were performed using the NCCPM breast dose survey software. Dose survey results were in good agreement with values published in the literature. As expected the average 3D breast dose exceeds the average 2D dose (Ratio = 1.28). The estimate of the 3D imaging DRL (2.6 mGy) was based on the average MGD of an oblique exposure of an average sized breast. Survey results indicated a drop in breast dose for breast thickness greater than 90 mm. The manufacturer has confirmed this occurs by design to minimize long exposure times and focal spot blur which could occur for the larger breast thicknesses. The strong comparison between calculated and displayed doses should simplify future surveys.

Abstract ID: 203 Breast model validation for Monte Carlo evaluation of normalized glandular dose coefficients in mammography

In Monte Carlo simulations for estimation of normalized glandular dose coefficients (i.e. the ratio between the mean glandular dose (MGD) and incident air kerma at the breast upper surface), the radiosensitive breast tissue is modelled as a homogeneous mixture of adipose and glandular tissue. However, such an assumption has been shown to lead to an overestimation in MGD by an average of 30% [1] , [2] . This work aimed at comparing the homogeneous breast models proposed by different authors and in different quality assurance protocols to patient specific breast phantoms. To obtain these phantoms, uncompressed breast images were acquired with a CT scanner dedicated to the breast and segmented to classify each voxel into 4 categories: air, skin tissue, adipose tissue and glandular tissue. Then the compression which breasts undergo during a mammography exams was simulated via software in order to obtain 3D compressed patient specific breast phantoms which present an heterogeneous glandular distribution similar to that of the irradiated breast. The homogeneous breast phantom was simulated either with a 4-mm skin thickness (as adopted in the USA protocol), or with a 5-mm adipose layer simulating the skin and the subcutaneous adipose layer (as adopted in the EU protocol) or with a skin thickness of 1.45 mm (i.e. the skin thickness estimated from 3D breast images). A pre-validated Monte Carlo code based on GEANT4 toolkit ver. 10.00 [3] was employed to calculate the dose differences between the standard models and the patient specific breast phantom. This study provided an insight into possible bias of the standard models for breast dosimetry and an indication of new breast model for future normalized glandular dose calculations.

Abstract ID: 199 Monte Carlo evaluation of normalized glandular dose coefficients in mammography

This work aimed at calculating the complete set of monoenergetic (DgN) and polyenergetic (DgNp) normalized glandular dose coefficients for mean glandular dose estimate in mammography. We have developed a Monte Carlo code based on GEANT4 toolkit, for DgN calculation, which relies on the standard physics list Option4. Influence of the breast model, the compression paddle and the bremsstrahlung process on DgN and DgNp normalized glandular dose coefficients in mammography was studied. Breast skin thickness was varied in the range 1.45–5 mm. It was modeled both as an adipose skin layer (5 mm thick – as in EU protocols for mammography) and as a real skin composition (as adopted in USA protocols). Significant differences in the calculated DgN have been observed when 1.45 mm skin thickness is adopted. At 15 keV a skin thickness of 1.45 mm produces values up to 25% or 20% higher than in the model adopted in the USA (4 mm skin) or EU protocol (5 mm adipose layer), respectively. The discrepancy reduces for higher energies. For routinely used mammographic spectra, a skin thickness of 4 mm produces DgNp values up to 32% lower than those with a breast model with 1.45 mm thickness. The bremsstrahlung processes in the breast tissue had small influence on DgN coefficients. Finally, based on the model consideration, DgNp coefficients for spectra used in mammography were provided and compared with those routinely adopted, based on USA and EU protocols.

Dosimetric Characterization and Image Quality Assessment in Breast Tomosynthesis

The aim of this paper was to investigate the diagnostic potential of tomosynthesis imaging compared with the performance of 2-D digital mammography in terms of radiation dose and image quality. In particular, suitable dosimeter and phantom were used for quantifying the average glandular dose and image quality parameters, respectively. First, according to standard protocols and European guidelines, the characterization of the used tomosynthesis system was carried out to verify the reliability of characteristic parameters of the system. Successively, the absorbed dose was calculated by means of experimental measurements and the application of estimation methods. The calculated dose was then compared with the value provided by the system; this approach has confirmed the tendency of mammography equipment manufacturers to underestimate the mean glandular dose. Finally, the detection capability of different details with different contrasts was objectively assessed for both breast tomosynthesis and 2-D mammography.

Diagnostic performance of digital breast tomosynthesis and full-field digital mammography with new reconstruction and new processing for dose reduction.

The main barrier to adoption of digital breast tomosynthesis (DBT) plus full-field digital mammography (FFDM) is radiation exposure dose. The purpose of this study was to evaluate the diagnostic performance of DBT plus FFDM, both with newly developed technology (nd), at a dose comparable to that of the conventional FFDM alone. Nine hundred and thirteen participants were recruited from May 2014 to January 2016 consecutively. For each subject, the exposure setting for DBT(nd)+FFDM(nd) was also used for the conventional FFDM alone. Retrospective reader studies were performed: DBT(nd)+FFDM(nd) (142 cases, including 42 cancer cases) and conventional FFDM (258 cases, including 87 cancer cases). Eight radiologists provided Japanese categorizations and probability of malignancy independently. Diagnostic performance was assessed by comparing sensitivity, specificity, and area under the receiver operating characteristic curve (AUC). Two-sided P values were calculated. DBT(nd)+FFDM(nd) showed sensitivity and AUC significantly increased over the conventional FFDM (85.4 vs. 80.3%, P=0.015 and 90.9 vs. 88.3%, P=0.049) and specificity did not significantly increase (89.6 vs. 88.4%, P=0.52). The mean glandular dose (MGD) difference of DBT(nd)+FFDM(nd) and conventional FFDM was not significant (difference -0.11mGy, P=0.08). In this study population, DBT plus FFDM, both with newly developed technology, provided diagnostic performance improved over the conventional FFDM alone, even at comparable MGD.

Average glandular dose coefficients for pendant-geometry breast CT using realistic breast phantoms.

To design volume-specific breast phantoms from breast CT (bCT) data sets and estimate the associated normalized mean glandular dose coefficients for breast CT using Monte Carlo methods. A large cohort of bCT data sets (N = 215) was used to evaluate breast volume into quintiles (plus the top 5%). The average radius profile was then determined for each of the six volume-specific groups and used to both fabricate physical phantoms and generate mathematical phantoms (V1-V6; "V" denotes classification by volume). The MCNP6 Monte Carlo code was used to model a prototype bCT system fabricated at our institution; and this model was validated against physical measurements in the fabricated phantoms. The mathematical phantoms were used to simulate normalized mean glandular dose coefficients for both monoenergetic source photons "DgNCT (E)" (8-70 keV in 1 keV intervals) and polyenergetic x-ray beams "pDgNCT " (35-70 kV in 1 kV intervals). The Monte Carlo code was used to study the influence of breast size (V1 vs. V5) and glandular fraction (6.4% vs. 45.8%) on glandular dose. The pDgNCT coefficients estimated for the V1, V3, and V5 phantoms were also compared to those generated using simple, cylindrical phantoms with equivalent volume and two geometrical constraints including; (a) cylinder radius determined at the breast phantom chest wall "Rcw "; and (b) cylinder radius determined at the breast phantom center-of-mass "RCOM ". Satisfactory agreement was observed for dose estimations using MCNP6 compared with both physical measurements in the V1, V3, and V5 phantoms (R2 = 0.995) and reference bCT dose coefficients using simple phantoms (R2 = 0.999). For a 49 kV spectrum with 1.5 mm Al filtration, differences in glandular fraction [6.5% (5th percentile) vs. 45.8% (95th percentile)] had a 13.2% influence on pDgNCT for the V3 phantom, and differences in breast size (V1 vs. V5) had a 16.6% influence on pDgNCT for a breast composed of 17% (median) fibroglandular tissue. For cylindrical phantoms with a radius of RCOM , the differences were 1.5%, 0.1%, and 2.1% compared with the V1, V3, and V5 phantoms, respectively. Breast phantoms were designed using a large cohort of bCT data sets across a range of six breast sizes. These phantoms were then fabricated and used for the estimation of glandular dose in breast CT. The mathematical phantoms and associated glandular dose coefficients for a range of breast sizes (V1-V6) and glandular fractions (5th to 95th percentiles) are available for interested users.

Radiation dose with digital breast tomosynthesis compared to digital mammography: per-view analysis.

To compare radiation dose delivered by digital mammography (FFDM) and breast tomosynthesis (DBT) for a single view. 4,780 FFDM and 4,798 DBT images from 1,208 women enrolled in a screening trial were used to ground dose comparison. Raw images were processed by an automatic software to determine volumetric breast density (VBD) and were used together with exposure data to compute the mean glandular dose (MGD) according to Dance's model. DBT and FFDM were compared in terms of operation of the automatic exposure control (AEC) and MGD level. Statistically significant differences were found between FFDM and DBT MGDs for all views (CC: MGDFFDM=1.366 mGy, MGDDBT=1.858 mGy; p<0.0001; MLO: MGDFFDM=1.374 mGy, MGDDBT=1.877 mGy; p<0.0001). Considering the 4,768 paired views, Bland-Altman analysis showed that the average increase of DBT dose compared to FFDM is 38 %, and a range between 0 % and 75 %. Our findings show a modest increase of radiation dose to the breast by tomosynthesis compared to FFDM. Given the emerging role of DBT, its use in conjunction with synthetic 2D images should not be deterred by concerns regarding radiation burden, and should draw on evidence of potential clinical benefit. • Most studies compared tomosynthesis in combination with mammography vs. mammography alone. • There is some concern about the dose increase with tomosynthesis. • Clinical data show a small increase in radiation dose with tomosynthesis. • Synthetic 2D images from tomosynthesis at zero dose reduce potential harm. • The small dose increase should not be a barrier to use of tomosynthesis.

Low-Dose Contrast-Enhanced Breast CT Using Spectral Shaping Filters: An Experimental Study.

Iodinated contrast-enhanced X-ray imaging of the breast has been studied with various modalities, including full-field digital mammography (FFDM), digital breast tomosynthesis (DBT), and dedicated breast CT. Contrast imaging with breast CT has a number of advantages over FFDM and DBT, including the lack of breast compression, and generation of fully isotropic 3-D reconstructions. Nonetheless, for breast CT to be considered as a viable tool for routine clinical use, it would be desirable to reduce radiation dose. One approach for dose reduction in breast CT is spectral shaping using X-ray filters. In this paper, two high atomic number filter materials are studied, namely, gadolinium (Gd) and erbium (Er), and compared with Al and Cu filters currently used in breast CT systems. Task-based performance is assessed by imaging a cylindrical poly(methyl methacrylate) phantom with iodine inserts on a benchtop breast CT system that emulates clinical breast CT. To evaluate detectability, a channelized hoteling observer (CHO) is used with sums of Laguerre-Gauss channels. It was observed that spectral shaping using Er and Gd filters substantially increased the dose efficiency (defined as signal-to-noise ratio of the CHO divided by mean glandular dose) as compared with kilovolt peak and filter settings used in commercial and prototype breast CT systems. These experimental phantom study results are encouraging for reducing dose of breast CT, however, further evaluation involving patients is needed.

Evaluation of mean glandular dose and assessment of the risk of radiation induced carcinogenesis in women following screening mammography in a low resource setting

Roentgen in 1895 discovered X-rays and identified the clinical use of X-rays for imaging anatomical structures in humans (Agar, 2012). Two types of photons released by x-rays are the bremsstrahlung...