PVCP phantoms and their use
Inventors
Vogt, William • Pfefer, Thomas Joshua • Jia, Congxian • Wear, Keith • Garra, Brian
Assignees
US Department of Health and Human Services
Publication Number
US-9920188-B2
Publication Date
2018-03-20
Expiration Date
2036-11-02
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Abstract
Novel phantoms are provided herein that can accurately mimic the optical and/or acoustic properties of living tissue. The disclosed phantoms are constructed of one or more polyvinyl chloride plastisol (PVCP) gels comprising a PVC and a binary plasticizer. The phantoms can be used, for example, to calibrate or test an optical and/or acoustic detection system, such as a photoacoustic imaging system or an ultrasound imaging system.
Core Innovation
The invention provides novel phantoms constructed of one or more polyvinyl chloride plastisol (PVCP) gels comprising poly(vinyl chloride) (PVC) and a binary plasticizer comprising benzyl butyl phthalate (BBP) and di(2-ethylhexyl) adipate (DEHA). These phantoms accurately mimic the optical and acoustic properties of living tissue, enabling standardized assessment, calibration, and testing of optical and acoustic detection systems such as photoacoustic imaging systems and ultrasound imaging systems.
The disclosed PVCP phantoms solve the problem of existing tissue-simulating phantoms that only successfully mimic either optical or acoustic properties, but not both. Prior PVCP phantoms demonstrated poor acoustic properties, particularly lower and less tissue-relevant speed of sound and acoustic attenuation values, limiting their utility in photoacoustic and ultrasound system quality control and device performance assessment. Additionally, hydrogels used in prior art suffer from poor mechanical strength, short shelf life, desiccation, and instability, which PVCP phantoms overcome.
The novel combination of PVC and a binary plasticizer comprising BBP and DEHA allows for tuning of the speed of sound within the phantom from 1400 to 1520 m/s, overlapping with relevant soft tissue sound speeds. By adding optical and acoustic absorbers and scatterers such as black plastic colorant, titanium dioxide, and glass microparticles, the optical and acoustic properties of these phantoms can be independently adjusted to mimic specific tissue types, including fatty and fibroglandular breast tissue, skin, abdominal fat, brain, liver, and skeletal muscle. The phantoms may be shaped to simulate organs, body parts, or whole animals and can include various inclusions or fluid channels as targets for calibrating or testing imaging systems.
Claims Coverage
There are multiple inventive features described in the independent claims relating to the composition of PVCP phantoms, methods of producing phantoms, and their use with detection systems.
PVCP phantom composition with binary plasticizer
The phantom comprises a PVCP gel that includes poly(vinyl chloride) (PVC) and a binary plasticizer consisting of benzyl butyl phthalate (BBP) and di(2-ethylhexyl) adipate (DEHA), configured to simulate the optical and acoustic properties of living tissue.
Adjustable PVC and plasticizer ratios for tuning properties
The PVCP gel composition includes from 2% to 20% m/m PVC/binary plasticizer, with the binary plasticizer comprising BBP and DEHA at volume ratios ranging broadly between 1000:1 to 1:1000, enabling tuning of acoustic and optical properties.
Inclusion of optical and acoustic additives
The PVCP gel can further include additives such as black plastic colorant as optical absorber, titanium dioxide as optical scatterer, and glass microparticles as acoustic absorbers and scatterers, to mimic particular tissue optical and acoustic properties.
Phantom shaped and configured with biologically relevant morphology
The phantom may be formed into shapes simulating morphology, optical, and acoustic properties of living organs, tissues, body parts, or whole animals, including multi-layer phantoms simulating heterogeneous tissues with layered PVCP gels having differing properties.
Embedded heterogeneous inclusions and fluid channels
The phantom can include embedded filaments, solid inclusions with different optical and acoustic properties, and fluid channels filled with solutions containing optical or acoustic absorbers/scatterers to provide targets for calibrating or testing photoacoustic and ultrasound detection systems.
Methods of producing phantoms with molds and retractable wires
Phantoms are produced by providing the PVCP composition and forming it into the desired shape, including making fluid channels by pouring molten gel into molds containing retractable wires that are removed after solidification.
Methods of using the phantoms to calibrate or test detection systems
Methods involve directing optical pulses and/or acoustic waves to the phantom and detecting the optical and acoustic signals produced, using photoacoustic imaging systems or ultrasound imaging systems to calibrate, test, or train users on the systems.
Detection systems including the phantom as a target
Photoacoustic imaging systems and ultrasound detection systems include the phantom as a target, with the system comprising an optical or ultrasound source, transducers to detect signals produced in response, and signal processors to generate imaging or spectroscopic data.
The inventive features encompass the novel PVCP phantom composition using a binary plasticizer for tissue-relevant acoustic and optical properties, methods to produce phantoms with tunable components and heterogeneous architectures, use of additives and inclusions for precise mimicking of tissue characteristics, and methods and detection systems that employ these phantoms for calibration, testing, and imaging.
Stated Advantages
The disclosed PVCP phantoms provide stability and superior mechanical strength compared to hydrogels, enabling long-term use without desiccation.
They offer biologically-relevant and tunable acoustic properties, including speed of sound and acoustic attenuation overlapping with real soft tissue values, which prior PVCP phantoms lacked.
Optical and acoustic properties can be independently tuned via additives, allowing simulation of multiple tissue types and heterogeneous tissues with reduced imaging artifacts due to matching interfacial properties.
Phantoms can be molded into anatomically realistic shapes or multi-layer constructs with inclusions and fluid channels, supporting standardized assessment and calibration of optical and acoustic detection systems.
Use of the disclosed phantoms reduces reliance on in vivo or ex vivo tissues, improving test consistency, convenience, and reducing risks in medical device development.
Documented Applications
Calibration and testing of optical and acoustic detection and imaging systems, such as photoacoustic imaging (PAI) and ultrasound imaging systems.
Standardized performance assessment, quality control, and inter-comparison of photoacoustic and ultrasound devices and systems.
Development and optimization of medical imaging device instrumentation and software.
System qualification during manufacturing, maintenance, repair, and clinical trial standardization.
Training and education of users on optical and acoustic detection systems.
Dosimetry and safety testing, including temperature measurements using embedded sensors.
Basic research on optical and acoustic phenomena in tissue and verification of computational models of physical processes.
Testing the effect of heterogeneous tissue properties on image quality, such as with layered phantoms simulating breast tissue and vascular inclusions.
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