Mean Glandular Dose Research Articles

Comparisons of glandular breast dose between digital mammography, tomosynthesis and breast CT based on anthropomorphic patient-derived breast phantoms

PurposeTo evaluate the bias to the mean glandular dose (MGD) estimates introduced by the homogeneous breast models in digital breast tomosynthesis (DBT) and to have an insight into the glandular dose distributions in 2D (digital mammography, DM) and 3D (DBT and breast dedicated CT, BCT) x-ray breast imaging by employing breast models with realistic glandular tissue distribution and organ silhouette. MethodsA Monte Carlo software for DM, DBT and BCT simulations was adopted for the evaluation of glandular dose distribution in 60 computational anthropomorphic phantoms. These computational phantoms were derived from 3D breast images acquired via a clinical BCT scanner. Resultsg·c·s·T conversion coefficients based on homogeneous breast model led to a MGD overestimate of 18% in DBT when compared to MGD estimated via anthropomorphic phantoms; this overestimate increased up to 21% for recently computed DgNDBT conversion coefficients. The standard deviation of the glandular dose distribution in BCT resulted 60% lower than in DM and 55% lower than in DBT. The glandular dose peak – evaluated as the average value over the 5% of the gland receiving the highest dose – is 2.8 times the MGD in DM, this factor reducing to 2.6 and 1.6 in DBT and BCT, respectively. ConclusionsConventional conversion coefficients for MGD estimates based on homogeneous breast models overestimate MGD by 18%, when compared to MGD estimated via anthropomorphic phantoms. The ratio between the peak glandular dose and the MGD is 2.8 in DM. This ratio is 8% and 75% higher than in DBT and BCT, respectively.

Radiation Dose of Contrast-Enhanced Mammography: A Two-Center Prospective Comparison.

Simple SummaryContrast-enhanced mammography (CEM) is a dual-energy technique where low- and high-energy images are acquired for each mammographic view after contrast agent administration, and are then recombined to enhance potential contrast uptake. As CEM is increasingly used for both screening and diagnostic applications in breast imaging, but its associated radiation dose has been investigated only by single-center studies, we aimed to evaluate the CEM per-patient radiation dose on a large population in a bicentric setting, pooling data from two prospective studies employing the same model of mammography units. The CEM radiation dose showed a 6.2% difference between the two centers, mainly attributable to the study populations’ characteristics and to manufacturing differences between the two systems. The CEM dose was about 30% higher than that of standard digital mammography. Such an increment was close to the dose increase reported for digital breast tomosynthesis, which is already used in both screening and clinical settings. Thus, considering the extensively demonstrated diagnostic gain granted by CEM over these non-contrast-enhanced techniques, radiation dose concerns should not hinder ever-wider clinical implementations of CEM.The radiation dose associated with contrast-enhanced mammography (CEM) has been investigated only by single-center studies. In this retrospective study, we aimed to compare the radiation dose between two centers performing CEM within two prospective studies, using the same type of equipment. The CEM mean glandular dose (MGD) was computed for low energy (LE) and high energy (HE) images and their sum was calculated for each view. MGD and related parameters (entrance dose, breast thickness, compression, and density) were compared between the two centers using the Mann–Whitney test. Finally, per-patient MGD was calculated by pooling the two datasets and determining the contribution of LE and HE images. A total of 348 CEM examinations were analyzed (228 from Center 1 and 120 from Center 2). The median total MGD per view was 2.33 mGy (interquartile range 2.19–2.51 mGy) at Center 1 and 2.46 mGy (interquartile range 2.32–2.70 mGy) at Center 2, with a 0.15 mGy median difference (p < 0.001) equal to 6.2%. LE-images contributed between 64% and 77% to the total patient dose in CEM, with the remaining 23–36% being associated with HE images. The mean radiation dose for a two-view bilateral CEM exam was 4.90 mGy, about 30% higher than for digital mammography.

X-ray dosimetry in breast cancer screening: 2D and 3D mammography

According to the World Health Organization (WHO), at the end of 2020, 7.8 million women alive were diagnosed with breast cancer in the past 5 years, making it the world’s most prevalent cancer. It is largely recognized and demonstrated that early detection represents the first strategy to follow in the fight against cancer. The effectiveness of mammography screening for early breast cancer detection has been proven in several surveys and studies over the last three decades. The estimation of the Mean Glandular Dose (MGD) is important to understand the radiation-associated risk from breast x-ray imaging exams. It continues to be the subject of numerous studies and debates, since its accuracy is directly related to risk estimation and for optimizing breast cancer screening programs.This manuscript reviews the main dosimetry formalisms used to estimate the MGD in mammography and to understand the continuing efforts to reduce the absorbed dose over the last forty years. The dosimetry protocols were formulated initially for mammography. Digital breast tomosynthesis (DBT) either in conjunction with synthesized digital mammogram (SDM) or with digital mammography (DM), is routinely used in many breast cancer screening programs and consequently the dosimetry protocols were extended for these techniques.

Evaluation and comparison of a CdTe based photon counting detector with an energy integrating detector for X-ray phase sensitive imaging of breast cancer.

To compare imaging performance of a cadmium telluride (CdTe) based photon counting detector (PCD) with a CMOS based energy integrating detector (EID) for potential phase sensitive imaging of breast cancer. A high energy inline phase sensitive imaging prototype consisting of a microfocus X-ray source with geometric magnification of 2 was employed. The pixel pitch of the PCD was 55μm, while 50μm for EID. The spatial resolution was quantitatively and qualitatively assessed through modulation transfer function (MTF) and bar pattern images. The edge enhancement visibility was assessed by measuring edge enhancement index (EEI) using the acrylic edge acquired images. A contrast detail (CD) phantom was utilized to compare detectability of simulated tumors, while an American College of Radiology (ACR) accredited phantom for mammography was used to compare detection of simulated calcification clusters. A custom-built phantom was employed to compare detection of fibrous structures. The PCD images were acquired at equal, and 30% less mean glandular dose (MGD) levels as of EID images. Observer studies along with contrast to noise ratio (CNR) and signal to noise ratio (SNR) analyses were performed for comparison of two detection systems. MTF curves and bar pattern images revealed an improvement of about 40% in the cutoff resolution with the PCD. The excellent spatial resolution offered by PCD system complemented superior detection of the diffraction fringes at boundaries of the acrylic edge and resulted in an EEI value of 3.64 as compared to 1.44 produced with EID image. At equal MGD levels (standard dose), observer studies along with CNR and SNR analyses revealed a substantial improvement of PCD acquired images in detection of simulated tumors, calcification clusters, and fibrous structures. At 30% less MGD, PCD images preserved image quality to yield equivalent (slightly better) detection as compared to the standard dose EID images. CdTe-based PCDs are technically feasible to image breast abnormalities (low/high contrast structures) at low radiation dose levels using the high energy inline phase sensitive imaging technique.

Mean glandular dose in the mammary gland and dose of radiation in the thyroid gland and lens in women with and without breast implants during different modalities of mammography

There have always been concerns about the secondary effects of diagnostic methods that use ionizing radiation. During mammography, the parameters to be concerned about are the mean glandular dose and the scatter dose. We evaluated the dose of radiation to the breast, thyroid gland, and lens in digital mammography in women with and without implants, in tomosynthesis in women with and without implants, and in contrast-enhanced mammography. Materials and methodsThe study included 212 women with and without disease who were attended at the Centro Clínico de Estereotaxia, CECLINES, in Caracas, Venezuela, between June 2017 and August 2017; the women were classified into five groups according to the mammographic modality used to evaluate them and whether or not they had implants. The statistical analysis included descriptive statistics for the study population. We used the Mann-Whitney U to compare the mean glandular dose and dose in the thyroid gland and lens between groups. ResultsThe mean glandular dose and the dose of radiation received in the thyroid and lens were within the acceptable range. In a few exceptions, the mean glandular dose per view was slightly higher than 3 mGy. The scatter dose to the thyroid gland and the lens during mammography has a very small contribution to the annual dose equivalent. ConclusionThe mean glandular dose and the scatter dose to the thyroid gland and lens delivered during tomosynthesis and 2D mammography in women with implants were higher than those delivered during other mammographic techniques in women without implants.

Breast Radiation Exposure of 3D Digital Breast Tomosynthesis Compared to Full-Field Digital Mammography in a Clinical Follow-Up Setting.

According to a position paper of the European Commission Initiative on Breast Cancer (ECIBC), DBT is close to being introduced in European breast cancer screening programmes. Our study aimed to examine radiation dose delivered by digital breast tomosynthesis (DBT) and digital mammography (FFDM) in comparison to sole FFDM in a clinical follow-up setting and in an identical patient cohort. Retrospectively, 768 breast examinations of 96 patients were included. Patients received both DBT and FFDM between May 2015 and July 2019: (I) FFDM in cranio-caudal (CC) and DBT in mediolateral oblique (MLO) view, as well as a (II) follow-up examination with FFDM in CC and MLO view. The mean glandular dose (MGD) was determined by the mammography system according to Dance’s model. The MGD (standard deviation (SD), interquartile range (IQR)) was distributed as follows: (I) (CCFFDM+MLODBT) (a) left FFDMCC 1.40 mGy (0.36 mGy, 1.13–1.59 mGy), left DBTMLO 1.62 mGy (0.51 mGy, 1.27–1.82 mGy); (b) right FFDMCC 1.36 mGy (0.34 mGy, 1.14–1.51 mGy), right DBTMLO 1.59 mGy (0.52 mGy, 1.27–1.62 mGy). (II) (CCFFDM+MLOFFDM) (a) left FFDMCC 1.35 mGy (0.35 mGy, 1.10–1.60 mGy), left FFDMMLO 1.40 mGy (0.39 mGy, 1.12–1.59 mGy), (b) right FFDMCC 1.35 mGy (0.33 mGy, 1.12–1.48 mGy), right FFDMMLO 1.40 mGy (0.36 mGy, 1.14–1.58 mGy). MGD was significantly higher for DBT mlo views compared to FFDM (p < 0.001). Radiation dose was significantly higher for DBT in MLO views compared to FFDM. However, the MGD of DBT MLO lies below the national diagnostic reference level of 2 mGy for an FFDM view. Hence, our results support the use of either DBT or FFDM as suggested in the ECIBC’s Guidelines.

Diagnostic reference levels in digital mammography: a systematic review

Diagnostic reference levels (DRLs) in digital mammography (DM) serve as a useful benchmark for dose monitoring and optimisation, allowing comparison amongst countries, institutions and mammography units. A systematic review of DRLs in DM, published in 2014, reported a lack of consistent and internationally accepted protocol in DRLs establishment, thereby resulting in wide variations in methodologies which complicates comparability between studies. In 2017, the International Commission of Radiation Protection (ICRP) published additional guidelines and recommendations to provide clarity in the protocol used in DRLs establishment. With the continuing evolvement of technology, optimisation of examinations and updates in guidelines and recommendations, DRLs should be revised at regular intervals. This systematic review aims to provide an update and identify a more consistent protocol in the methodologies used to establish DRLs. Searches were conducted through Web of Science, PubMed-MEDLINE, ScienceDirect, CINAHL and Google Scholar, which resulted in 766 articles, of which 19 articles were included after screening. Relevant data from the included studies were summarised and analysed. While the additional guidelines and recommendations have provided clarifications in the methodologies used in DRLs establishment, such as data source (i.e. the preference to use data derived from patient instead of phantoms to establish DRLs), protocol (i.e. stratification of DRLs by compressed breast thickness and detector technology, and the use of median value for DRLs quantity instead of mean) and percentiles used to establish DRLs (i.e. set at the 75th percentile with a minimum sample size of 50 patients), other differences such as the lack of a standard dose calculation method used to estimate mean glandular dose continues to complicate comparisons between studies and different DM systems. This systematic review update incorporated the updated guidelines and recommendations from ICRP which will serve as a useful resource for future research efforts related to DRLs, dose monitoring and optimisation.

RRIMS: Radiation Risk In Mammography Screening – a novel model for predicting the lifetime dose and risk of radiation-induced breast cancer from the first screening visit

Objectives: Radiation Risk In Mammography Screening (RRIMS) builds on the prototype, formerly known as Breast-iRRISC, to develop a model that aims to establish a dose and risk profile for females by calculating their lifetime mean glandular dose (MGD) for each age of screening between 40 and 75 years, using only the information from her first screening visit. This is then used to allocate her to a dose category and estimate the lifetime risk of radiation-induced breast cancer incidence and mortality for a population of females in that category. Methods: This model training was developed using a large dataset of Hologic images containing a total of 20,232 images from 5,076 visits from 4,154 females. The female’s breast characteristics and exposure parameters were extracted from the images to calculate the female’s MGD throughout a lifetime of screening from just her first screening visit, using modelling of various parameters and their change through time. Results: This development has ultimately provided a model that uses the female’s first screening visit to calculate the received MGD for all ages of potential screening. This has enabled the allocation of females to either a low-, medium-, or high-dose category, ultimately followed by the lifetime effective risk (LER) estimation for any screening attendance pattern. A female in the low-dose category undergoing biennial screening from 50 to 74 years would expect a risk of radiation-induced breast cancer incidence and mortality of 8.64 and 2.61 cases per 100,000 females, respectively. Similarly, a female in the medium- or high-dose category undergoing the same regimen would expect an incidence and mortality risk of 11.76 and 3.55, and 15.08 and 4.55 cases per 100,000 females, respectively. Conclusions: This novel approach of establishing a female’s dose profile and lifetime risk from a single visit will further assist females in their informed consent on breast screening attendance and help inform policy-makers when exploring the benefits and drawbacks of various screening patterns and frequencies. Advances in knowledge: RRIMS is a novel tool that enables the assessment of a female’s lifetime dose and risk profile using only the information from her first screening visit.

Comparison of displayed and measured mean glandular dose in digital mammography

Comparison of displayed and measured mean glandular dose in digital mammography

PERFORMANCE COMPARISON OF SYSTEMS WITH FULL-FIELD DIGITAL MAMMOGRAPHY, DIGITAL BREAST TOMOSYNTHESIS AND CONTRAST-ENHANCED SPECTRAL MAMMOGRAPHY.

The purpose is to compare full-field digital mammography (FFDM), digital breast tomosynthesis (DBT) and contrast-enhanced spectral mammography (CESM) technologies on three mammography systems in terms of image quality and patient dose. Two Senographe Essential with DBT and CESM (denoted S1 and S2) and one Selenia Dimensions (S3) with FFDM and DBT were considered. Dosimetry methods recommended in the European protocol were used. Image quality was tested with CDMAM in FFDM and DBT and with ideal observer method in FFDM. Mean values of mean glandular dose (MGD) from whole patient samples on S1, S2 and S3 were as follows: FFDM 1.65, 1.84 and 2.23mGy; DBT 2.03, 1.96 and 2.87mGy; CESM 2.65 and 3.16mGy, respectively. S3 exhibited better low-contrast detectability for the smallest sized discs of CDMAM and ideal observer in FFDM, and for the largest sized discs in DBT, at similar dose levels.

STATISTICAL MODELING OF GLANDULARITY FROM MAMMOGRAPHY IMAGES.

This study presents a methodology for estimation of breast glandularity, which is an important factor to assess radiological risk in mammography patients. The investigation took place in an institution located at department of Antioquia-Colombia, where 200 patients participated. The models were obtained using partial least squares regression, where Dance's model was used as reference; parameters of mammography images, equipment and patient were used as predicting variables (kV, mAs, patient's weight, breast area and mean gray value of breast images). Coefficients of correlation equal to 89 and 88 were obtained for training and validation respectively in mediolateral oblique (MLO) and 84 and 89 for craniocaudal (CC). These models were used to estimate the mean glandular dose for all patients and later to obtain the institutional reference levels, 0.87 and 0.96mGy for CC and MLO, respectively, following the recommendations of the ICRP publication No. 135. This study suggests that glandularity could be estimated with few parameters from equipment and patient.

Comparison of Mean Glandular Dose between Full-Field Digital Mammography and Digital Breast Tomosynthesis.

Early detection of breast cancer is diagnosed using mammography, the gold standard in breast screening. However, its increased use also provokes radiation-induced breast malignancy. Thus, monitoring and regulating the mean glandular dose (MGD) is essential. The purpose of this study was to determine MGD for full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT) in the radiology department of a single centre. We also analysed the exposure factors as a function of breast thickness. A total of 436 patients underwent both FFDM and DBT. MGD was auto calculated by the mammographic machine for each projection. Patients’ data included compressed breast thickness (CBT), peak kilovoltage (kVp), milliampere-seconds (mAs) and MGD (mGy). Result analysis showed that there is a significant difference in MGD between the two systems, namely FFDM and DBT. However, the MGD values in our centre were comparable to other centres, as well as the European guideline (<2.5 mGy) for a standard breast. Although DBT improves the clinical outcome and quality of diagnosis, the risk of radiation-induced carcinogenesis should not be neglected. Regular quality control testing on mammography equipment must be performed for dose monitoring in women following a screening mammography in the future.

At Which Mean Glandular Dose Does the Benefit of Breast Cancer Deaths Averted Equal the Risk of Lives Lost to Screening From Radiation-induced Malignancy for Mammography With and Without Tomosynthesis?

To estimate benefit-to-radiation-risk mean glandular dose (MGD) equivalence values for screening mammography, defined as the yearly MGD (over a 10-year period) at which the estimated benefit of mammography in terms of deaths averted equals the estimated risk of lives lost to screening due to radiation exposure (a benefit-to-risk ratio of 1). Benefit-to-risk ratios were calculated as the ratio of breast cancer deaths averted and lives lost to screening over 10-year intervals starting at age 40 for mammography and tomosynthesis using previously published methodology. The MGD values at which estimated benefit equals risk were tabulated. The MGD values at which benefit-to-risk equivalence points were met for digital screening mammography are 63 milligray (mGy) (ages 40-49), 88 mGy (ages 50-59), 176 mGy (ages 60-69), and 336 mGy (ages 70-79). The MGD values that met benefit-to-risk equivalence for screening tomosynthesis plus digital mammography or synthetic mammography are 80 mGy (ages 40-49), 111 mGy (ages 50-59), 224 mGy (ages 60-69), and 427 mGy (ages 70-79). Cutoff MGD values at which the estimated benefit from screening equals the estimated risk are well above standard screening MGD exposures. Care is necessary to ensure that threshold values are not exceeded during a screening exam, particularly for women ages 40-49 years old when using digital mammography plus tomosynthesis (due to an approximate doubling of dose per exam that will more readily exceed cutoff MGD values) and when many additional views are obtained.

OD162 - Monte Carlo calculation for dedicated mean glandular dose estimates in commercial DBT scanners using homogeneous phantoms

OD162 - Monte Carlo calculation for dedicated mean glandular dose estimates in commercial DBT scanners using homogeneous phantoms

Technical note: MC-GPU breast dosimetry validations with other Monte Carlo codes and phase space file implementation.

To validate the MC-GPU Monte Carlo (MC) code for dosimetric studies in X-ray breast imaging modalities:mammography, digital breast tomosynthesis, contrast enhanced digital mammography, and breast-CT. Moreover, to implement and validate a phase space file generation routine. The MC-GPU code (v.1.5 DBT) was modified in order to generate phase space files and to be compatible with PENELOPE v.2018 derived cross-section database. Simulations were performed with homogeneous and anthropomorphic breast phantoms for different breast imaging techniques. The glandular dose was computed for each case and compared with results from the PENELOPE (v.2014) + penEasy (v.2015) and egs brachy (EGSnrc) MC codes. Afterward, several phase space files were generated with MC-GPU and the scored photon spectra were compared between the codes. The phase space files generated in MC-GPU were used in PENELOPE and EGSnrc to calculate the glandular dose, and compared with the original dose scored in MC-GPU. MC-GPU showed good agreement with the other codes when calculating the glandular dose distribution for mammography, mean glandular dose for digital breast tomosynthesis, and normalized glandular dose for breast-CT. The latter case showed average/maximum relative differences of 2.3%/27%, respectively, compared to other literature works, with the larger differences observed at low energies (around 10 keV). The recorded photon spectra entering a voxel were similar (within statistical uncertainties) between the three MC codes. Finally, the reconstructed glandular dose in a voxel from a phase space file differs by less than 0.65%, with an average of 0.18%-0.22% between the different MC codes, agreement within approximately statistical uncertainties. In some scenarios, the simulations performed in MC-GPU were from 20 up to 40 times faster than those performed by PENELOPE. The results indicate that MC-GPU code is suitable for breast dosimetric studies for different X-ray breast imaging modalities, with the advantage of a high performance derived from GPUs. The phase space file implementation was validated and is compatible with the IAEA standard, allowing multiscale MC simulations with a combination of CPU and GPUcodes.

Influence of double layer filter on mean glandular dose (MGD) and image quality in low energy image of contrast enhanced spectral mammography (LE-CESM)

IntroductionThe aim of this study was to evaluate mean glandular dose (MGD) and image quality in low energy imaging from contrast-enhanced spectral mammography (CESM) when using double-layer filtration. MethodologyA dedicated phantom was used to quantitatively estimate the MGD and image quality. The target slab of the phantom consisted of three iodine coins having a concentration of 1.0 mgI/cm3, 2.0 mgI/cm3, 4.0 mgI/cm3, a 100% adipose equivalent coin and a 100% glandular equivalent coin. The phantom was exposed using a semiautomated function at 28 k, 30 kV and 32 kV. MGD. Contrast to noise ratio (CNR) and figure of merit (FOM) were estimated for Mo/Rh, Mo/Rh + Cu, Mo/Rh + Al and Mo/Rh + Cd combinations using three breast equivalent compositions. ResultsMGD was reduced up to a maximum of 1.03 mGy from 1.17 mGy for 100% adipose tissue. 1.18 mGy from 1.34 mGy for 50% glandular tissue and 1.39 mGy from 1.72 mGy for the 100% glandular phantom when using double-layer filtration. All of the above-mentioned results were obtained for the 50 mm phantom using 32 kV. CNR and FOM values were not significantly reduced with a double-layer filter when compared to a single-layer filter. ConclusionThe present study concluded that Mo/Rh + Cu is the best combination to reduce the MGD significantly when compared to Mo/Rh + Al or Mo/Rh + Cd. Mo/Rh + Cu also achieved optimal image quality when compared to the Mo/Rh single filter combination. Implications of practiceThe use of a double-layer filter in low energy imaging of CESM results in a significant reduction in MGD without degrading the quality of the image.

Mean Glandular Dose Measurement in Three Mammography Centers in Kashan: An approach to Provide a Local DRL

Purpose: Mammography is the most important diagnostic modality for early detection of breast cancer, however, concerns related to the side effects induced by ionizing radiation are still present. In the current study, the Mean Glandular Dose (MGD) values for mammography examinations as well as a local Diagnostic Reference Level (DRL) were obtained for mammography centers in Kashan, Iran. Materials and Methods: Three mammography devices from three radiology centers were selected to obtain the MGD values of mammography examinations. To assess the MGD values, the technical parameters for patients’ imaging at these three radiology centers were extracted. Then, the incident air kerma (in mGy) value received by each patient was measured by a UNIDOS E electrometer (PTW, Germany) along with a SFD mammography ionization chamber (PTW, Germany). Finally, the incident air kerma values were converted to the MGD values by specific conversion factors. Based on the obtained MGD values, a local DRL was also established for mammography examinations. Results: Mean MGD values per exposure were obtained 2.39 ± 1.46 mGy for Right Craniocaudal (RCC), 2.64 ± 1.67 mGy for Left Craniocaudal (LCC), 2.82 ± 1.89 mGy for Right Mediolateral Oblique (RMLO), and 3.09 ± 1.90 mGy for left mediolateral oblique views. Moreover, a local DRL obtained from mammography examinations, which was established as the overall median of MGD value, was 1.72 mGy (1.91 mGy for digital and 1.32 mGy for analog mammography). Conclusion: The MGD values for different views obtained in this study are in the range of previously reported values. Considering the European guidelines for quality assurance in breast cancer screening and diagnosis, it can be mentioned that the obtained DRL was less than the recommended dose level (2.0 mGy).

A phase sensitive x-ray breast tomosynthesis system: Preliminary patient images with cancer lesions

Phase-sensitive x-ray imaging continues to attract research for its ability to visualize weakly absorbing details like those often encountered in biology and medicine. We have developed and assembled the first inline-based high-energy phase sensitive breast tomosynthesis (PBT) system, which is currently undergoing patient imaging testing at a clinical site. The PBT system consists of a microfocus polychromatic x-ray source and a direct conversion-based flat panel detector coated with a 1 mm thick amorphous selenium layer allowing a high detective quantum efficiency at high energies. The PBT system scans a compressed breast over 15° with 9 angular projection views. The high-energy scan parameters are carefully selected to ensure similar or lower mean glandular dose levels to the clinical standard of care systems. Phase retrieval and data binning are applied to the phase contrast angular projection views and a filtered back-projection algorithm is used to reconstruct the final images. This article reports the distributions of radiation dose versus thickness of the compressed breasts at 59 and 89 kV and sample PBT images acquired from 3 patients. Preliminary PBT images demonstrate the feasibility of this new imaging modality to acquire breast images at lower radiation dose as compared to the clinical digital breast tomosynthesis system with enhanced lesion characteristics (i.e. lesion spiculation and margins).

Screening Digital Breast Tomosynthesis: Radiation Dose Among Patients With Breast Implants.

To compare the mean glandular dose (MGD), cancer detection rate (CDR), and recall rate (RR) among screening examinations of patients with breast implants utilizing various digital breast tomosynthesis (DBT)-based imaging protocols. This IRB-approved retrospective study included 1998 women with breast implants who presented for screening mammography between December 10, 2013, and May 29, 2020. Images were obtained using various protocol combinations of DBT and 2D digital mammography. Data collected included MGD, implant type and position, breast density, BI-RADS final assessment category, CDR, and RR. Statistical analysis utilized type II analysis of variance and the chi-square test. The highest MGD was observed in the DBT only protocol, while the 2D only protocol had the lowest (10.29 mGy vs 5.88 mGy, respectively). Statistically significant difference in MGD was observed across protocols (P < 0.0001). The highest per-view MGD was among DBT full-field (FF) views in both craniocaudal and mediolateral oblique projections (P < 0.0001). No significant difference was observed in RR among protocols (P = 0.17). The combined 2D (FF only) + DBT implant-displaced (ID) views protocol detected the highest number of cancers (CDR, 7.2 per 1000), but this was not significantly different across protocols (P = 0.48). The combination of 2D FF views and DBT ID views should be considered for women with breast implants in a DBT-based screening practice when aiming to minimize radiation exposure without compromising the sensitivity of cancer detection. Avoidance of DBT FF in this patient population is recommended to minimize radiation dose.

THREE-DIMENSIONAL DOSIMETRY OF MAMMOGRAPHY USING A BLOCK CUBE BREAST PHANTOM AND RADIOCHROMIC FILM.

This study developed a phantom with a shape similar to that of the breast and use GAFCHROMIC films that can be placed inside the phantom to measure the detailed breast dose distribution in mammography. GAFCHROMIC EBT3 was placed on the block cube breast phantom and irradiated with a mammography device to measure the absorbed dose distribution inside the phantom in the horizontal and depth directions. The dose distribution in the horizontal plane was the highest in the centre on the chest wall side, and it decreased in a fan shape. Along the depth of the phantom, the doses absorbed across the entire cross-section were 16.15mGy at the surface and 7.51, 3.25 and 1.68mGy at depths of 10, 20 and 30mm, respectively. Compared with the mean glandular dose, the proposed method can measure breast dose distributions in greater detail and is applicable to various breast shapes.