Low-cost 3D print-based phantom fabrication to facilitate interstitial prostate brachytherapy training program.

PURPOSE: The purpose of this study was to manufacture a realistic and inexpensive prostate phantom to support training programs for ultrasound-based interstitial prostate brachytherapy. METHODS AND MATERIALS: Five phantom material combinations were tested and evaluated for material characteristics; Ecoflex 00-30 silicone, emulsion silicone with 20% or 50% mineral oil, and regular or supersoft polyvinyl chloride (PVC). A prostate phantom which includes an anatomic simulated prostate, urethra, seminal vesicles, rectum, and normal surrounding tissue was created with 3D-printed molds using 20% emulsion silicone and regular and supersoft PVC materials based on speed of sound testing. Needle artifact retention was evaluated at weekly intervals. RESULTS: Speed of sound testing demonstrated PVC to have the closest ultrasound characteristics of the materials tested to that of soft tissue. Several molds were created with 3D-printed PLA directly or cast on 3D-printed PLA with high heat resistant silicone. The prostate phantom fabrication workflow was developed, including a method to produce dummy seeds for low-dose-rate brachytherapy practice. A complete phantom may be fabricated in 1.5-2 h, and the material cost for each phantom was approximated at $23.98. CONCLUSIONS: A low-cost and reusable phantom was developed based on 3D-printed molds for casting. The proposed educational prostate phantom is an ideal cost-effective platform to develop and build confidence in fundamental brachytherapy procedural skills in addition to actual patient caseloads.

Designing a Low-Cost Thyroid Ultrasound Phantom for Medical Student Education.

Using ultrasound for the diagnostic workup of thyroid lesions is a widely accepted technique. An inexpensive phantom model of thyroid lesions would be an invaluable tool for engaging medical students in learning the diagnostic algorithm for thyroid lesions and how to perform fine needle aspiration (FNA). The aim of this study was to devise an inexpensive and reproducible training phantom model for thyroid lesion detection, image interpretation and in vitro FNA using ultrasound guidance. A simple phantom model imitating benign cystic lesions, intermediately suspicious lesions and highly suspicious lesions was developed using a chicken breast, red seedless grapes, pimento olives and blackberries. The phantom was constructed for a total cost of $4.09 per unit and constructed in approximately 3 min. Nine models were constructed in total, demonstrating that the model design is replicable. This thyroid FNA phantom is an inexpensive, easy-to-produce model that allows medical students to practice measuring lesions and performing FNAs using ultrasonography. Future studies could be explored to assess this model's role in medical student education.

Comparison of 3D printed nose bolus to traditional wax bolus for cost-effectiveness, volumetric accuracy and dosimetric effect.

INTRODUCTION: Three-dimensional printing technology has the potential to streamline custom bolus production in radiotherapy. This study evaluates the volumetric, dosimetric and cost differences between traditional wax and 3D printed versions of nose bolus. METHOD: Nose plaster impressions from 24 volunteers were CT scanned and planned. Planned virtual bolus was manufactured in wax and created in 3D print (100% and 18% shell infill density) for comparison. To compare volume variations and dosimetry, each constructed bolus was CT scanned and a plan replicating the reference plan fields generated. Bolus manufacture time and material costs were analysed. RESULTS: Mean volume differences between the virtual bolus (VB) and wax, and the VB and 18% and 100% 3D shells were -3.05 ± 11.06 cm3 , -1.03 ± 8.09 cm3 and 1.31 ± 2.63 cm3 , respectively. While there was no significant difference for the point and mean doses between the 100% 3D shell filled with water and the VB plans (P> 0.05), the intraclass coefficients for these dose metrics for the 100% 3D shell filled with wax compared to VB doses (0.69-0.96) were higher than those for the 18% and 100% 3D shell filled with water and the wax (0.48-0.88). Average costs for staff time and materials were higher for the wax ($138.54 and $20.49, respectively) compared with the 3D shell prints ($10.58 and $13.87, respectively). CONCLUSION: Three-dimensional printed bolus replicated the VB geometry with less cost for manufacture than wax bolus. When shells are printed with 100% infill density, 3D bolus dosimetrically replicates the reference plan.

Building an orthopaedic CT phantom for under £50.

OBJECTIVE:: In procuring a CT scanner for orthopaedic imaging, the ability of the scanner to cope with metal artefacts for visualising bone and bone lesions around orthopaedic implants is an important feature. A durable and easily transportable CT phantom would help to compare this feature between CT scanners.The aims of this study were to develop a CT phantom that is easy to build, easily transportable, stable over time, cheap and challenging CT scanner performance. METHODS:: A CT phantom resembling a femur and tibia with a total knee replacement was constructed from spare components of a knee replacement, wall filler and polystyrene. A number of plastic strips and cylinders were placed between metal implant and bone substitute during construction to act as "bone lesions". The phantom was fixed in a watertight acrylic box with epoxy resin. RESULTS:: The total manufacturing time was below 3 h staggered over several days and the total cost was below £50. When empty, the phantom is easily transportable. The box can be filled with water on site visits ensuring a reproducible attenuation. This phantom is stable (i.e. not affected by decay of biological tissue). CONCLUSION:: The phantom was easy to construct and is well transportable and stable in time. The phantom can be used in a procurement process allowing direct comparison of different scanners regarding technical factors and software performance. It can further be used for quality assurance, scan parameter optimisation and research. We conclude that a simple and transportable CT phantom can be built using few resources that allows to compare CT scanners with respect to their ability to visualise bone lesions around metal implants. ADVANCES IN KNOWLEDGE:: It is possible to build a CT knee replacement phantom in a few hours and for less than £50. Other than the total knee implant, this CT phantom can be built with material available from any DIY store and simple tools. This CT phantoms allows objective comparisons in CT procurement. This CT phantom allows objective assessment of imaging protocols for clinical practice.

Construction and validation of a low cost paediatric pelvis phantom.

PURPOSE: Imaging phantoms can be cost prohibitive, therefore a need exists to produce low cost alternatives which are fit for purpose. This paper describes the development and validation of a low cost paediatric pelvis phantom based on the anatomy of a 5-year-old child. METHODS: Tissue equivalent materials representing paediatric bone (Plaster of Paris; PoP) and soft tissue (Poly methyl methacrylate; PMMA) were used. PMMA was machined to match the bony anatomy identified from a CT scan of a 5-year-old child and cavities were created for infusing the PoP. Phantom validation comprised physical and visual measures. Physical included CT density comparison between a CT scan of a 5-year old child and the phantom and Signal to Noise Ratio (SNR) comparative analysis of anteroposterior phantom X-ray images against a commercial anthropomorphic phantom. Visual analysis using a psychometric image quality scale (face validity). RESULTS: CT density, the percentage difference between cortical bone, soft tissue and their equivalent tissue substitutes were -4.7 to -4.1% and -23.4%, respectively. For SNR, (mAs response) there was a strong positive correlation between the two phantoms (r > 0.95 for all kVps). For kVp response, there was a strong positive correlation between 1 and 8 mAs (r = 0.85), this then decreased as mAs increased (r = -0.21 at 20 mAs). Psychometric scale results produced a Cronbach's Alpha of almost 0.8. CONCLUSIONS: Physical and visual measures suggest our low-cost phantom has suitable anatomical characteristics for X-ray imaging. Our phantom could have utility in dose and image quality optimisation studies.

A Low-Cost, Durable and Re-Usable Bladder Phantom: Teaching Intravesical Ultrasound Contrast Administration.

Contrast-enhanced voiding urosonography (ceVUS) is a radiation-free and highly sensitive examination for detecting vesicoureteral reflux and imaging the urethra in children. This examination is performed with ultrasound and intravesical administration of a gas-filled microbubble US contrast agent. The U.S. Food and Drug Administration recently approved the use of a US contrast agent for ceVUS in children. Because of the growing interest among physicians and US technologists in using ceVUS in children, a urinary bladder phantom was developed to teach intravesical ultrasound contrast administration to perform ceVUS procedures. Described here are the preparation and utility of a low-cost, durable and re-usable phantom that simulates the administration, distribution and effects of different US parameters on US contrast agent appearance in the bladder during ceVUS in children.

Use of a Simple, Inexpensive Dual-Modality Phantom as a Learning Tool for Magnetic Resonance Imaging-Ultrasound Fusion Techniques.

We describe an easily constructed, customizable phantom for magnetic resonance imaging-ultrasound fusion imaging and demonstrate its role as a learning tool to initiate clinical use of this emerging modality. Magnetic resonance imaging-ultrasound fusion can prove unwieldy to integrate into routine practice. We demonstrate real-time fusion with single-sequence magnetic resonance imaging uploaded to the ultrasound console. Phantom training sessions allow radiologists and sonographers to practice fiducial marker selection and improve efficiency with the fusion hardware and software interfaces. Such a tool is useful when the modality is first introduced to a practice and in settings of sporadic use, in which intermittent training may be useful.

The subresolution DaTSCAN phantom: a cost-effective, flexible alternative to traditional phantom technology.

The Alderson striatal phantom is frequently used to assess I-FP-CIT (Ioflupane) image quality and to test semi-quantification software. However, its design is associated with a number of limitations, in particular: unrealistic image appearances and inflexibility. A new physical phantom approach is proposed on the basis of subresolution phantom technology. The design incorporates thin slabs of attenuating material generated through additive manufacturing, and paper sheets with radioactive ink patterns printed on their surface, created with a conventional inkjet printer. The paper sheets and attenuating slabs are interleaved before scanning. Use of thin layers ensures that they cannot be individually resolved on reconstructed images. An investigation was carried out to demonstrate the performance of such a phantom in producing simplified I-FP-CIT uptake patterns. Single photon emission computed tomography imaging was carried out on an assembled phantom designed to mimic a healthy patient. Striatal binding ratio results and linear striatal dimensions were calculated from the reconstructed data and compared with that of 22 clinical patients without evidence of Parkinsonian syndrome, determined from clinical follow-up. Striatal binding ratio results for the fully assembled phantom were: 3.1, 3.3, 2.9 and 2.6 for the right caudate, left caudate, right putamen and right caudate, respectively. All were within two SDs of results derived from a cohort of clinical patients. Medial-lateral and anterior-posterior dimensions of the simulated striata were also within the range of values seen in clinical data. This work provides the foundation for the generation of a range of more clinically realistic, physical phantoms.

Technical Note: A safe, cheap, and easy-to-use isotropic diffusion MRI phantom for clinical and multicenter studies.

PURPOSE: Since Diffusion Weighted Imaging (DWI) data acquisition and processing are not standardized, substantial differences in DWI derived measures such as Apparent Diffusion Coefficient (ADC) may arise which are related to the acquisition or MRI processing method, but not to the sample under study. Quality assurance using a standardized test object, or phantom, is a key factor in standardizing DWI across scanners. METHODS: Current diffusion phantoms are either complex to use, not available in larger quantities, contain substances unwanted in a clinical environment, or are expensive. A diffusion phantom based on a polyvinylpyrrolidone (PVP) solution, together with a phantom holder, is presented and compared to existing diffusion phantoms for use in clinical DWI scans. An ADC vs. temperature calibration curve was obtained. RESULTS: ADC of the phantom (808 to 857 ± 0.2 mm2 /s) is in the same range as ADC values found in brain tissue. ADC measurements are highly reproducible across time with an intra-class correlation coefficient of > 0.8. ADC as function of temperature (in Kelvin) can be estimated as ADCm(T)=[exp(-7.09)·exp-2903.81T-1293.55] with a total uncertainty (95% confidence limit) of ± 1.7%. CONCLUSION: We present an isotropic diffusion MRI phantom, together with its temperature calibration curve, that is easy-to-use in a clinical environment, cost-effective, reproducible to produce, and that contains no harmful substances.

Low-cost tissue simulating phantoms with adjustable wavelength-dependent scattering properties in the visible and infrared ranges.

We present a method for low-cost fabrication of polydimethylsiloxane (PDMS) tissue simulating phantoms with tunable scattering spectra, spanning visible, and near-infrared regimes. These phantoms use optical polishing agents (aluminum oxide powders) at various grit sizes to approximate in vivo tissue scattering particles across multiple size distributions (range: 17 to 3 µm). This class of tunable scattering phantoms is used to mimic distinct changes in wavelength-dependent scattering properties observed in tissue pathologies such as partial thickness burns. Described by a power-law dependence on wavelength, the scattering magnitude of these phantoms scale linearly with particle concentration over a physiologic range [µs'=(0.5 to 2.0 mm−1)] whereas the scattering spectra, specific to each particle size distribution, correlate to distinct exponential coefficients (range: 0.007 to 0.32). Aluminum oxide powders used in this investigation did not detectably contribute to the absorption properties of these phantoms. The optical properties of these phantoms are verified through inverse adding-doubling methods and the tolerances of this fabrication method are discussed.

Versatile, Reusable, and Inexpensive Ultrasound Phantom Procedural Trainers.

We have constructed simple and inexpensive models for ultrasound-guided procedural training using synthetic ballistic gelatin. These models are durable, leak resistant, and able to be shaped to fit a variety of simulation scenarios to teach procedures. They provide realistic tactile and sonographic training for our learners in a safe, idealized setting.

A low cost training phantom model for radio-guided localization techniques in occult breast lesions.

Radio-guided localization (RGL) for identifying occult breast lesions has been widely accepted as an alternative technique to other localization methods, including those using wire guidance. An appropriate phantom model would be an invaluable tool for practitioners interested in learning the technique of RGL prior to clinical application. The aim of this study was to devise an inexpensive and reproducible training phantom model for RGL. We developed a simple RGL phantom model imitating an occult breast lesion from inexpensive supplies including a pimento olive, a green pea and a turkey breast. The phantom was constructed for a total cost of less than $20 and prepared in approximately 10 min. After the first model's construction, we constructed approximately 25 additional models and demonstrated that the model design was easily reproducible. The RGL phantom is a time- and cost-effective model that accurately simulates the RGL technique for non-palpable breast lesions. Future studies are warranted to further validate this model as an effective teaching tool.

Cost-effective, Reusable, Leak-resistant Ultrasound-guided Vascular Access Trainer.

BACKGROUND: Ultrasound guidance for insertion of a peripheral venous catheter is becoming common practice in many emergency departments in the difficult-to-access patient, and simulation has become an important tool for health care practitioners to learn this technique. Commercial trainers are expensive, and low-cost alternatives described to date provide a sub-optimal training experience. We introduce ballistics gel as a new material for the creation of simulating phantoms. MATERIALS AND METHODS: Directions describe construction of a simulating phantom composed of 10% ballistic gelatin and commonly available latex tubing. The model's success as used by one residency training program and medical school is described. RESULTS: Cost per phantom was $22.83, with less than an hour preparation time per phantom. We found these phantoms to offer a comparable user experience to commercially available products and better than other homemade products. DISCUSSION: Ballistics gel is a novel material for production of simulation phantoms that provides a low-cost, realistic simulation experience. The clear gel material works well for novice learners, and opacifying agents can be added to increase difficulty for more advanced learners. The material offers flexibility in design to make models for a broad range of skill instruction. CONCLUSION: A relatively quick and easy process using ballistics gel allowed us to create a simulation experience similar to commercially available trainers at a fraction of the cost.

Shooting with sound: optimizing an affordable ballistic gelatin recipe in a graded ultrasound phantom education program.

OBJECTIVES: The goal of this study was to investigate the durability and longevity of gelatin formulas for the production of staged ultrasound phantoms for education. METHODS: Gelatin phantoms were prepared from Knox gelatin (Kraft Foods, Northfield, IL) and a standard 10%-by-mass ordinance gelatin solution. Phantoms were durability tested by compressing to a 2-cm depth until cracking was visible. Additionally, 16 containers with varying combinations of phenol, container type, and storage location were tested for longevity against desiccation and molding. Once formulation was determined, 4 stages of phantoms from novice to clinically relevant were poured, and clinicians with ultrasound training ranked them on a 7-point Likert scale based on task difficulty, phantom suitability, and fidelity. RESULTS: On durability testing, the ballistic gelatin outperformed the Knox gelatin by more than 200 compressions. On longevity testing, gelatin with a 0.5% phenol concentration stored with a lid and refrigeration lasted longest, whereas containers without a lid had desiccation within 1 month, and those without phenol became moldy within 6 weeks. Ballistic gelatin was more expensive when buying in small quantities but was 7.4% less expensive when buying in bulk. The staged phantoms were deemed suitable for training, but clinicians did not consistently rank the phantoms in the intended order of 1 to 4 (44%). CONCLUSIONS: Refrigerated and sealed ballistic gelatin with phenol was a cost-effective method for creating in-house staged ultrasound phantoms suitable for large-scale ultrasound educational training needs. Clinician ranking of phantoms may be influenced by current training methods that favor biological tissue scanning as easier.

Characterization of a dielectric phantom for high-field magnetic resonance imaging applications.

PURPOSE: In this work, a generic recipe for an inexpensive and nontoxic phantom was developed within a range of biologically relevant dielectric properties from 150 MHz to 4.5 GHz. METHODS: The recipe includes deionized water as the solvent, NaCl to primarily control conductivity, sucrose to primarily control permittivity, agar-agar to gel the solution and reduce heat diffusivity, and benzoic acid to preserve the gel. Two hundred and seventeen samples were prepared to cover the feasible range of NaCl and sucrose concentrations. Their dielectric properties were measured using a commercial dielectric probe and were fitted to a 3D polynomial to generate a recipe describing the properties as a function of NaCl concentration, sucrose concentration, and frequency. RESULTS: Results indicated that the intuitive linear and independent relationships between NaCl and conductivity and between sucrose and permittivity are not valid. A generic polynomial recipe was developed to characterize the complex relationship between the solutes and the resulting dielectric values and has been made publicly available as a web application. In representative mixtures developed to mimic brain and muscle tissue, less than 2% difference was observed between the predicted and measured conductivity and permittivity values. CONCLUSIONS: It is expected that the recipe will be useful for generating dielectric phantoms for general magnetic resonance imaging (MRI) coil development at high magnetic field strength, including coil safety evaluation as well as pulse sequence evaluation (including B1(+) mapping, B1(+) shimming, and selective excitation pulse design), and other non-MRI applications which require biologically equivalent dielectric properties.

A training phantom for ultrasound-guided needle insertion and suturing.

PURPOSE: During gynecologic brachytherapy (BT), suturing and image-guided needle insertions are highly skill-dependent tasks. Medical residents often have to practice these techniques in the operating room; this is sub-optimal for many reasons. We present a fast and low-cost method of building realistic and disposable gynecologic phantoms, which can be used to train physicians new to gynecologic BT. METHODS: Phantoms comprised a rectal cavity large enough to accommodate a standard transrectal ultrasound (US) probe, a vaginal cavity, a uterus, a uterine canal, and a cervix, all embedded in a gelatin matrix. The uterus was made of gelatin and coated with rubber to mimic the texture of soft tissue and for computed tomography (CT) and US image contrast. The phantom's durability, longevity, construction times, materials costs, CT, and US image quality were recorded. The speed of sound in the gelatin was measured using pulse echo measurements. RESULTS: Anatomic structures were distinguishable using CT and US. For the first phantom, material costs were under $200, curing time was approximately 48 hours, and active participation time was 3 hours. Reusable parts allowed for reduction in time and cost for subsequent phantoms: under $20, 24 hours curing time, and 1 hour active participation time. The speed of sound in the gelatin ranged from 1495 to 1506 m/s. CONCLUSION: A method for constructing gelatin gynecologic phantoms was developed. It can be used for training in image-guided BT needle insertion, placing a suture on the vaginal wall, and suturing the cervical lip.

Time-lapse microscopy using smartphone with augmented reality markers.

A prototype system that replaces the conventional time-lapse imaging in microscopic inspection for use with smartphones is presented. Existing time-lapse imaging requires a video data feed between a microscope and a computer that varies depending on the type of image grabber. Even with proper hardware setups, a series of tedious and repetitive tasks is still required to relocate to the region-of-interest (ROI) of the specimens. In order to simplify the system and improve the efficiency of time-lapse imaging tasks, a smartphone-based platform utilizing microscopic augmented reality (µ-AR) markers is proposed. To evaluate the feasibility and efficiency of the proposed system, a user test was designed and performed, measuring the elapse time for a trial of the task starting from the execution of the application software to the completion of restoring and imaging of an ROI saved in advance. The results of the user test showed that the average elapse time was 65.3 ± 15.2 s with 6.86 ± 3.61 µm of position error and 0.08 ± 0.40 degrees of angle error. This indicates that the time-lapse imaging task was accomplished rapidly with a high level of accuracy. Thus, simplification of both the system and the task was achieved via our proposed system.