3D-printed Breast Phantoms Research Articles

The Effect of Respiratory Motion in Breast Intensity-modulated Radiation Therapy: 3D-Printed Dynamic Phantom Study.

This study evaluated the dosimetric effect of respiratory motion in intensity-modulated radiation therapy (IMRT) for breast cancer using a three-dimensional (3D)-printed dynamic phantom. Computed tomography (CT) data from breast cancer patients were used to create a 3D-printed breast phantom. Various types of treatment plans were generated using CT images acquired at the exhalation phase. Different infill densities in the 3D-printed phantom were tested to validate their effect on simulating the average human breast tissue density. Plans were delivered to the 3D-printed dynamic phantom in the exhalation position and free-breathing motion. Dosimetric verification was performed using Gafchromic EBT3 films. After changing the infill density to obtain Hounsfield Unit values similar to those of human breast tissue, a realistic patient-specific breast phantom was fabricated using a 3D printer at 80% infill density. The gamma passing rates of the dose distribution delivered in the exhalation phase and free-breathing motion were 92% or more. In addition, the dynamic phantom doses with free-breathing motion were directly compared with the static phantom dose in terms of sagittal dose profiles. Gamma passing rates of >93% and 90% were achieved at 3%/3 mm and 3%/2 mm, respectively. Despite a blurred dose distribution, the dose map of the film measurement with respiratory motion could be delivered without significantly increasing the dose heterogeneity of the tumor bed or loss of target coverage. Our findings demonstrate that the impact of respiration on breast IMRT for whole-breast irradiation was not significant, even in the tumor bed.

Analysis of dual-energy mammography subtraction technique for the dose and image quality evaluation using 3D-printed breast phantom.

This study aimed to quantitatively assess the radiation dose using XR-QA2 and the image quality of the dual-energy subtraction mammography technique on an in-house phantom. The analysis was carried out to investigate the effect of targets/filters on dose value and image quality using an in-house phantom made of PLA + as an object representing compressed breasts. All irradiation parameters were performed in the craniocaudal position with manual mode. Mean glandular dose (MGD) was recorded, followed by the calculation of the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and modulation transfer function (MTF) for image quality assessment parameters. The results showed that the image quality was accepted at dose levels within the IAEA and BAPETEN tolerance limit for 60mm equivalent compressed breast using dual-energy mammography. Furthermore, the target/filter (W/Rh) reduced the dose by 1.03mGy compared to the Mo/Mo and Mo/Rh with an enhancement in image quality. This indicated that the target/filter (W/Rh) combination was optimal due to the image quality improvement obtained with lower MGD.

A nonparametric measure of noise in x-ray diagnostic images—mammography

Objective. In x-ray diagnostics, modern image reconstruction or image processing methods may render established methods of image quality assessment inadequate. Task specific quality assessment by using model observers has the disadvantage of being very labour-intensive. Therefore, it appears highly desirable to develop novel image quality parameters that neither rely on the linearity and the shift-invariace of the imaging system nor require the acquisition of hundreds of images as is necessary for the application of model observers, and which can be derived directly from diagnostic images. Approach. A new measure for the noise based on non-maximum-suppression images is defined and its properties are explored using simulated images before it is applied to an exposure series of mammograms of a homogeneous phantom and a 3D-printed breast phantom to demonstrate its usefulness under realistic conditions. Main results. The new noise parameter cannot only be derived from images with a homogeneous background but it can be extracted directly from images containing anatomic structures and is proportional to the standard deviation of the noise. At present, the applicability is restricted to mammography, which satisfies the assumption of short covariance length of the noise. Significance. The new measure of the noise is but a first step of the development of a set of parameters that are required to quantify image quality directly from diagnostic images without relying on the assumption of a linear, shift-invariant system, e.g. by providing measures of sharpness, contrast and structural complexity, in addition to the noise measure. For mammography, a convenient method is now available to quantify noise in processed diagnostic images.

Comparison of Breast Cancer Radiotherapy Techniques Regarding Secondary Cancer Risk and Normal Tissue Complication Probability - Modelling and Measurements Using a 3D-Printed Phantom.

BackgroundRadiotherapy after breast-conserving therapy is a standard postoperative treatment of breast cancer, which can be carried out with a variety of irradiation techniques. The treatment planning must take into consideration detrimental effects on the neighbouring organs at risk—the lung, the heart, and the contralateral breast, which can include both short- and long-term effects represented by the normal tissue complication probability and secondary cancer risk.Patients and MethodsIn this planning study, we investigate intensity-modulated (IMRT) and three-dimensional conformal (3D-CRT) radiotherapy techniques including sequential or simultaneously integrated boosts as well as interstitial multicatheter brachytherapy boost techniques of 38 patients with breast-conserving surgery retrospectively. We furthermore develop a 3D-printed breast phantom add-on to allow for catheter placement and to measure the out-of-field dose using thermoluminescent dosimeters placed inside an anthropomorphic phantom. Finally, we estimate normal tissue complication probabilities using the Lyman–Kutcher–Burman model and secondary cancer risks using the linear non-threshold model (out-of-field) and the model by Schneider et al. (in-field).ResultsThe results depend on the combination of primary whole-breast irradiation and boost technique. The normal tissue complication probabilities for various endpoints are of the following order: 1%–2% (symptomatic pneumonitis, ipsilateral lung), 2%–3% (symptomatic pneumonitis, whole lung), and 1%–2% (radiation pneumonitis grade ≥ 2, whole lung). The additional relative risk of ischemic heart disease ranges from +25% to +35%. In-field secondary cancer risk of the ipsilateral lung in left-sided treatment is around 50 per 10,000 person-years for 20 years after exposure at age 55. Out-of-field estimation of secondary cancer risk results in approximately 5 per 10,000 person-years each for the contralateral lung and breast.ConclusionsIn general, 3D-CRT shows the best risk reduction in contrast to IMRT. Regarding the boost concepts, brachytherapy is the most effective method in order to minimise normal tissue complication probability and secondary cancer risk compared to teletherapy boost concepts. Hence, the 3D-CRT technique in combination with an interstitial multicatheter brachytherapy boost is most suitable in terms of risk avoidance for treating breast cancer with techniques including boost concepts.

Abstract P3-01-13: Comparing portable and clinical ultrasound systems using 3D printed breast phantom inserts

Abstract Background: Late-stage breast cancer rates in the Pacific where mammography services are limited are exceedingly high. Therefore, alternative accessible breast cancer screening technologies such as portable ultrasound is needed. However, little is known about the performance of portable ultrasound when compared to clinical ultrasound for use in breast cancer screening. By utilizing 3D printing technology, it is possible to design breast phantom inserts to replicate various types of lesions. In this study, we utilized 3D printed breast phantom inserts to compare portable and clinical ultrasound lesion detection performance. Methods: Four different breast inserts were designed using FreeCAD (version 0.19) to replicate different lesion detection properties. The first insert compares lesion shape, the second insert investigates depth and size, the third insert looks at fiber diameter, and the fourth insert looks at clusters. The four inserts were printed using a photopolymer resign (Formlabs Inc Rigid resign, Somerville, MA, USA) and then placed in a gelatin-based breast phantom designed for ultrasound use. Using the portable ultrasound (GE Vscan Extend) and clinical ultrasound (Philips EPIQ 5G), various images were captured of identical angle and orientation for both devices. The number of lesions visualized were counted and presented as a percentage of lesions detected. Results: The portable ultrasound had a 100% lesion detection rate for breast insert 1, 90.3% for breast insert 2, 70% for breast insert 3 and 55.8% for breast insert 4. Clinical ultrasound had 100% lesion detection rate for breast insert 1, 93.1% for breast insert 2, 76.6% for breast insert 3, and 99% for breast insert 4. Conclusion: Portable ultrasound shows comparable lesion detection capabilities to clinical ultrasound in 3 of the 4 breast phantom insert tests. Portable ultrasound may have potential as a capable accessible breast cancer screening device in areas without mammography. Citation Format: Dustin Valdez, Jami Fukui, Thomas Wolfgruber, Lambert Leong, Gertraud Maskarinec, John Shepherd. Comparing portable and clinical ultrasound systems using 3D printed breast phantom inserts [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-01-13.

OL101 - Patient-derived 3D printed breast phantoms for mammography and digital breast tomosynthesis

OL101 - Patient-derived 3D printed breast phantoms for mammography and digital breast tomosynthesis

Validation of a mammographic image quality modification algorithm using 3D-printed breast phantoms.

Purpose: To validate a previously proposed algorithm that modifies a mammogram to appear as if it was acquired with different technique factors using realistic phantom-based mammograms. Approach: Two digital mammography systems (an indirect- and a direct-detector-based system) were used to acquire realistic mammographic images of five 3D-printed breast phantoms with the technique factors selected by the automatic exposure control and at various other conditions (denoted by the original images). Additional images under other simulated conditions were also acquired: higher or lower tube voltages, different anode/filter combinations, or lower tube current-time products (target images). The signal and noise in the original images were modified to simulate the target images (simulated images). The accuracy of the image modification algorithm was validated by comparing the target and simulated images using the local mean, local standard deviation (SD), local variance, and power spectra (PS) of the image signals. The absolute relative percent error between the target and simulated images for each parameter was calculated at each sub-region of interest (local parameters) and frequency (PS), and then averaged. Results: The local mean signal, local SD, local variance, and PS of the target and simulated images were very similar, with a relative percent error of 5.5%, 3.8%, 7.8%, and 4.4% (indirect system), respectively, and of 3.7%, 3.8%, 7.7%, and 7.5% (direct system), respectively. Conclusions: The algorithm is appropriate for simulating different technique factors. Therefore, it can be used in various studies, for instance to evaluate the impact of technique factors in cancer detection using clinical images.

Spiral breast computed tomography (CT): signal-to-noise and dose optimization using 3D-printed phantoms

ObjectivesTo investigate the dependence of signal-to-noise ratio (SNR) and calculated average dose per volume of spiral breast-CT (B-CT) on breast size and breast density and to provide a guideline for choosing the optimal tube current for each B-CT examination.Materials and methodsThree representative B-CT datasets (small, medium, large breast size) were chosen to create 3D-printed breast phantoms. The phantoms were filled with four different agarose-oil-emulsions mimicking differences in breast densities. Phantoms were scanned in a B-CT system with systematic variation of the tube current (6, 12.5, 25, 32, 40, 50, 64, 80, 100, 125 mA). Evaluation of SNR and the average dose per volume using Monte Carlo simulations were performed for high (HR) and standard (STD) spatial resolution.ResultsSNR and average dose per volume increased with increasing tube current. Artifacts had negligible influence on image evaluation. SNR values ≥ 35 (HR) and ≥ 100 (STD) offer sufficient image quality for clinical evaluation with SNR being more dependent on breast density than on breast size. For an average absorbed dose limit of 6.5 mGy for the medium and large phantoms and 7 mGy for the small phantom, optimal tube currents were either 25 or 32 mA.ConclusionsB-CT offers the possibility to vary the X-ray tube current, allowing image quality optimization based on individual patient’s characteristics such as breast size and density. This study describes the optimal B-CT acquisition parameters, which provide diagnostic image quality for various breast sizes and densities, while keeping the average dose at a level similar to digital mammography.Key Points• Image quality optimization based on breast size and density varying the tube current using spiral B-CT.

Dosimetric analysis of the effects of a temporary tissue expander on the radiotherapy technique.

The current study aimed to evaluate the dose effect of a temporary tissue expander (TTE) according to the radiotherapy technique for breast cancer patients. Computed tomography images of a 3D-printed breast phantom with a TTE were acquired for dosimetric analysis. For dose measurement during 180cGy of radiotherapy, 13 EBT3 films were attached to the TTE while including the metal port area. Treatment planning was performed for three-dimensional conformal radiotherapy (3DCRT), field-in-field radiotherapy, intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT) while considering whether a bolus was used and whether artifacts were corrected. The difference at each point between the measured mean and calculated doses was analyzed to determine the association with the radiotherapy techniques. The effect of the metal port on the radiation dose was associated with the treatment technique. The dose difference between the measured and calculated doses was 6.8% (191.6cGy vs. 179.5cGy) for cases treated with 3DCRT with bolus and artifact correction. The dose difference for cases treated with VMAT and 3DCRT without bolus and with artifact correction was 5.8% (190.2cGy vs. 179.8cGy) and 5.6% (193.3cGy vs. 183.1cGy), respectively. IMRT with the bolus showed a minimum difference of 0.3% (180.7cGy vs. 181.3cGy). The presence of the metal port within the TTE in radiation fields resulted to insignificant increased dose differences according to the treatment technique. Future studies should assess whether this dose difference could affect clinical outcomes.

The Application of an Iterative Structure to the Delay-and-Sum and the Delay-Multiply-and-Sum Beamformers in Breast Microwave Imaging.

Breast microwave imaging (BMI) is a potential breast cancer screening method. This manuscript presents a novel iterative delay-and-sum (DAS) based reconstruction algorithm for BMI. This iterative-DAS (itDAS) algorithm uses a forward radar model to iteratively update an image estimate. A variation of the itDAS reconstruction algorithm that uses the delay-multiply-and-sum (DMAS) beamformer was also implemented (the itDMAS algorithm). Both algorithms were used to reconstruct images from experimental scans of an array of 3D-printed MRI-based breast phantoms performed with a clinical BMI system. The signal-to-clutter ratio (SCR) and signal-to-mean ratio (SMR) were used to compare the performance of the itDAS and itDMAS methods to the DAS and DMAS beamformers. While no significant difference between the itDAS and itDMAS methods was observed in most images, the itDAS algorithm produced reconstructions that had significantly higher SMR than the non-iterative methods, increasing contrast by as much as 19 dB over DAS and 13 dB over DMAS. The itDAS algorithm also increased the SCR of reconstructions by up to 5 dB over DAS and 4 dB over DMAS, indicating that both high-intensity and background clutter are reduced in images reconstructed by the itDAS algorithm.

Development of patient-specific 3D-printed breast phantom using silicone and peanut oils for magnetic resonance imaging.

Despite increasing reports of 3D printing in medical applications, the use of 3D printing in breast imaging is limited, thus, personalized 3D-printed breast model could be a novel approach to overcome current limitations in utilizing breast magnetic resonance imaging (MRI) for quantitative assessment of breast density. The aim of this study is to develop a patient-specific 3D-printed breast phantom and to identify the most appropriate materials for simulating the MR imaging characteristics of fibroglandular and adipose tissues. A patient-specific 3D-printed breast model was generated using 3D-printing techniques for the construction of the hollow skin and fibroglandular region shells. Then, the T1 relaxation times of the five selected materials (agarose gel, silicone rubber with/without fish oil, silicone oil, and peanut oil) were measured on a 3T MRI system to determine the appropriate ones to represent the MR imaging characteristics of fibroglandular and adipose tissues. Results were then compared to the reference values of T1 relaxation times of the corresponding tissues: 1,324.42±167.63 and 449.27±26.09 ms, respectively. Finally, the materials that matched the T1 relaxation times of the respective tissues were used to fill the 3D-printed hollow breast shells. The silicone and peanut oils were found to closely resemble the T1 relaxation times and imaging characteristics of these two tissues, which are 1,515.8±105.5 and 405.4±15.1 ms, respectively. The agarose gel with different concentrations, ranging from 0.5 to 2.5 wt%, was found to have the longest T1 relaxation times. A patient-specific 3D-printed breast phantom was successfully designed and constructed using silicone and peanut oils to simulate the MR imaging characteristics of fibroglandular and adipose tissues. The phantom can be used to investigate different MR breast imaging protocols for the quantitative assessment of breast density.

Imaging properties of 3D printed breast phantoms for lesion localization and Core needle biopsy training

BackgroundBreast cancer is the most commonly diagnosed malignancy in females and frequently requires core needle biopsy (CNB) to guide management. Adequate training resources for CNB suffer tremendous limitations in reusability, accurate simulation of breast tissue, and cost. The relatively recent advent of 3D printing offers an alternative for the development of breast phantoms for training purposes. However, the feasibility of this technology for the purpose of ultrasound (US) guided breast intervention has not been thoroughly studied.MethodsWe designed three breast phantom models that were printed in multiple resins available through Stratasys, including VeroClear, TangoPlus and Tissue Matrix. We also constructed several traditional breast phantoms using chicken breast and Knox gelatin for comparison. These phantoms were compared side-by-side for ultrasound penetrance, simulation of breast tissue integrity, anatomic accuracy, reusability, and cost.Results3D printed breast phantoms were more anatomically accurate models than traditional breast phantoms. The chicken breast phantom provided acceptable US beam penetration and material hardness for simulation of human breast tissue integrity. Sonographic image quality of the chicken breast phantom was the most accurate overall. The gelatin-based phantom also had acceptable US beam penetration and image quality; however, this material was too soft and poorly simulated breast tissue integrity. 3D printed phantoms were not visible under US.ConclusionsThere is a large unmet need for a printable material that is truly compatible with multimodality imaging for breast and other soft tissue intervention. Further research is warranted to create a realistic, reusable and affordable material to 3D print phantoms for US-guided intervention training.

Early detection of cancerous tissues in human breast utilizing near field microwave holography

AbstractThis work demonstrates an application of near field indirect microwave holography for the detection of malignant tissues in human breast in an effective way. The holograms are recorded by two directive antennas aligned along each other's boresight while performing a raster scan over a 2D plane utilizing XY‐linear motorized translation stage and a uniform reference wave. The whole information that is, amplitude and phase of an object has been provided by indirect holography at microwave frequencies. The extracted phase values are used to determine the dielectric permittivity values which are further utilized for the identification and validating the positions of malignant tissues in the breast phantom. The experimental evaluations performed on the in‐house designed and developed tissue mimicking 3D printed breast phantoms. The experimental results demonstrate the ability of microwave holography using directive antennas in detecting and identifying the tumors upto the minimum size of 4 mm and maximum depth of 25 mm in fabricated phantom. The quantitative results present the potential of the Near Field Indirect Holographic Imaging (NFIHI) in order to develop an efficient and economical tool for breast cancer detection.

Breast phantoms for 2D digital mammography with realistic anatomical structures and attenuation characteristics based on clinical images using 3D printing

The aim of this work was to develop a production process for breast phantoms for 2D digital mammography (DM) with realistic anatomical structures and attenuation characteristics based on clinical images using 3D printing.The presented production process is based on PolyJet 3D printing technology using a polypropylene like printing material. First, an attenuation calibration function for this material and the achievable lateral resolution of the printing process of about 200 µm was determined. Subsequently, to generate the digital 3D model of the breast phantom, the pixel intensities of the unprocessed clinical image that are related to the attenuation along the z-axis of the breast, were converted to corresponding phantom heights using the calibration function.To validate the process, an image of the 3D printed breast phantom was acquired on the full field digital mammography (FFDM) system used for calibration and compared with the clinical image in terms of anatomical structures and associated attenuation characteristics. The exposure parameters and image impression of the phantom were evaluated using five other FFDM systems of different manufacturers and types.Results demonstrated that the anatomical structures in the images and the attenuation characteristics of a female breast and the derived phantom agreed on the FFDM system used for calibration. The automatic exposure control segmentation, the automatically selected exposure parameters and the image postprocessing of the clinical and phantom image indicated a high level of conformity. As shown, the phantom is also suitable for other FFDM systems.In conclusion, an approach to produce anthropomorphic breast phantoms for DM offering realistic anatomical structures and attenuation characteristics based on clinical images was successfully developed. As shown, the phantom realistically simulated the original female breast. Therefore, it is expected that such phantoms are promising to support bridging the gap between physical-technical and diagnostic image quality assessment. In addition, they enable a variety of practical and scientific applications for which present technical phantoms are not suitable.

SAR analysis of directive antenna on anatomically real breast phantoms for microwave holography

AbstractMicrowave holography utilizes antennae for the detection of cancerous tissues in the human breast. The safety assessment of an antenna is required prior to its radiation interaction with biological tissues. In this work, a specially designed and developed Vivaldi antenna with directivity at 45° for microwave holographic imaging has been presented. A detailed simulation of Specific Absorption Rate (SAR) and thermal analysis due to the radiation exposure of the designed antenna on self‐designed anatomically real breast phantoms is performed in CST environment. SAR values for 3D printed breast phantoms are also calculated experimentally. The quantitative results of SAR reveal the variation of ±10% in between the simulation and experimental results. It has been found that SAR due to the radiation of the designed antenna lies in the permissible limit. The thermal analysis in CST shows the rise of 0.096% in temperature after the exposure of 2 hours. Hence, the antenna can be used in microwave holography for breast cancer detection.

3D-printed breast phantom for multi-purpose and multi-modality imaging.

Breast imaging technology plays an important role in breast cancer planning and treatment. Recently, three-dimensional (3D) printing technology has become a trending issue in phantom constructions for medical applications, with its advantages of being customizable and cost-efficient. However, there is no current practice in the field of multi-purpose breast phantom for quality control (QC) in multi-modalities imaging. The purpose of this study was to fabricate a multi-purpose breast phantom with tissue-equivalent materials via a 3D printing technique for QC in multi-modalities imaging. We used polyvinyl chloride (PVC) based materials and a 3D printing technique to construct a breast phantom. The phantom incorporates structures imaged in the female breast such as microcalcifications, fiber lesions, and tumors with different sizes. Moreover, the phantom was used to assess the sensitivity of lesion detection, depth resolution, and detectability thresholds with different imaging modalities. Phantom tissue equivalent properties were determined using computed tomography (CT) attenuation [Hounsfield unit (HU)] and magnetic resonance imaging (MRI) relaxation times. The 3D-printed breast phantom had an average background value of 36.2 HU, which is close to that of glandular breast tissue (40 HU). T1 and T2 relaxation times had an average relaxation time of 206.81±17.50 and 20.22±5.74 ms, respectively. Mammographic imaging had improved detection of microcalcification compared with ultrasound and MRI with multiple sequences [T1WI, T2WI and short inversion time inversion recovery (STIR)]. Soft-tissue lesion detection and cylindrical tumor contrast were superior with mammography and MRI compared to ultrasound. Hemispherical tumor detection was similar regardless of the imaging modality used. We developed a multi-purpose breast phantom using a 3D printing technique and determined its value for multi-modal breast imaging studies.

OA245] Channelized hotelling observer performance in acquired mammographic images of an anthropomorphic breast phantom

Purpose To study the feasibility of a quality control framework composed of an anthropomorphic breast phantom and a mathematical model observer (MO) for the objective evaluation of detectability of calcification-like signals in system-processed mammographic images. Methods A 3D-printed anthropomorphic breast phantom was imaged with two brands of digital mammography systems (Selenia, Hologic, USA & Amulet Innovality, Fujifilm, Japan) at four different dose levels. The phantom consisted of two transverse slabs, allowing for the insertion of a sheet with calcification-like signals. These signals were 0.25 mm diameter gold discs deposited on aluminum squares of 1 cm width. From the acquired processed and unprocessed images, signal-present and signal-absent regions of interest (ROIs) were extracted. The ROIs were evaluated with a channelized Hotelling observer (CHO) MO using four different formulations of difference-of-Gaussian (DoG) channel-sets, and by three human observers in two-alternative forced-choice experiments. We compared the human and CHO performance in detecting calcification-like discs in the processed and unprocessed ROIs. Detection performance was measured using the proportion of correct responses of the humans ( PC H ) and the CHO ( PC CHO ) . The correlation between PC H and PC CHO was analyzed using a mixed-effect regression model. Correlation results, including the goodness of fit (r 2 ) of PC H and PC CHO for all parameters investigated, were evaluated to determine whether CHO MO can be used to predict human observer performance. Results A strong correlation of the CHO detection performance with the performance of the humans was obtained, with r 2 = 0.93–0.96. However, the slight, but not significant, differences in intercept and slope suggest some system dependence (p > 0.05). The correlation was not considerably affected by the choice of the DoG channel-set. The image processing did not have a significant impact on the PC H or PC CHO results (p > 0.05). Conclusions The CHO with DoG channel-sets can predict human performance on the detection of calcification-like signals under the tested conditions. Therefore, there is potential for the framework to be used for the evaluation of detectability of calcification-like signals in system-processed mammographic images. However, additional systems need to be evaluated to investigate this system-dependency in the correlation between human and the MO, further.

A Numerical Voxel Model for 3D-printed Uncompressed Breast Phantoms

A Numerical Voxel Model for 3D-printed Uncompressed Breast Phantoms