In radiology (X-ray, CT, MRI, nuclear medicine and ultrasound), the quality of medical images is essential for accurate diagnosis and treatment of various diseases. The interpretation of medical images requires the detection and characterization of small changes in anatomy or function, which can be affected by various factors such as image noise, artifacts, and resolution. Therefore, it is crucial to ensure that the medical images are of appropriate quality for the respective diagnostic task. The development of task-specific phantoms and test objects is an essential aspect of image quality assurance and optimization. It allows for the evaluation of imaging system performance under various clinical scenarios, such as detection of small lesions, or the evaluation of contrast resolution. By using task-specific test phantoms, researchers can identify the strengths and weaknesses of imaging systems and develop new imaging technologies or adapted and optimized acquisition parameters that better meet the needs of clinicians and patients. Additive manufacturing and 3D printing have added tremendous and rapidly increasing possibilities and opportunities to design and build such phantoms and test objects, since new additive manufacturing tools, hard- and software, and materials are constantly being introduced.
Task-specific test objects are designed to simulate specific clinical scenarios and can be used to evaluate various aspects of imaging system performance, such as spatial resolution, contrast resolution, and noise. This can be done in various approaches.
In particular, we welcome papers with relevance to one or more of the following general areas:
1) Physical test phantoms are models that simulate parts of the human body and its various tissues and organs. Especially anthropomorphic phantoms are essential for the assessment of image quality in radiology because they provide a realistic representation of the human anatomy and enable the evaluation of the imaging system's performance in a controlled and standardized manner. The use of anthropomorphic phantoms in radiology allows for the simulation of various clinical scenarios, such as the detection of small lesions or the evaluation of the contrast resolution of the imaging system. The phantoms are designed to mimic the physical properties of human tissue, such as the attenuation and scattering of X-rays or ultrasound waves, as well as nuclear spin density and relaxation times for magnetic resonance imaging, which allows for a realistic assessment of the imaging systems’ performance. They provide a standardized and reproducible method for assessing image quality of different imaging systems and protocols, allowing to compare the performance of different imaging systems and protocols under identical conditions.
2) Functional phantoms capable of mimicking for example patient motion or tissue perfusion are essential to characterize and validate imaging procedures that target the visualization of dynamic physiological processes or the correction of related image artifacts. Thereby, the timescale at which these phantoms operate represents a crucial aspect requiring high accuracy and reproducibility. Importantly, these phantoms have to be suitable for the environmental conditions defined by the respective imaging system, e.g. withstanding of ionizing radiation or compatibility with high electromagnetic fields.
3) Another important prerequisite to address these issues is the need for a observer independent assessment of the images. The most appropriate solution to automated evaluation is represented by the concept of model observers (MO). A model observer is a computational tool that simulates human observers' performance in interpreting medical images. Model observers are designed to provide a standardized and objective assessment of image quality and diagnostic accuracy, which can help radiologists and ultrasound technicians to improve their interpretation skills as well as optimizing imaging system performance and usage. Nevertheless, the validity of such MOs has to be validated by human expert assessment, which requires valid test objects like anthropomorphic phantoms.
4) Numerical simulations are a valuable supplementary tool in medical imaging, and in particular for the development of test objects. They are able to quickly and efficiently reproduce experimental results by employing proper mathematical models and numerical schemes. Once their accuracy is verified, which can be done, for instance, by comparison with the results obtained from phantoms, numerical simulations can be used for a variety of tasks, including prediction of the output of an imaging device for arbitrary test objects or experimental setups, and identification of weak spots or defects of the imaging device at hand. In some situations, when the design of phantoms and test objects becomes prohibitively expensive or complicated, computer simulations may even serve as a proper substitute.
In radiology (X-ray, CT, MRI, nuclear medicine and ultrasound), the quality of medical images is essential for accurate diagnosis and treatment of various diseases. The interpretation of medical images requires the detection and characterization of small changes in anatomy or function, which can be affected by various factors such as image noise, artifacts, and resolution. Therefore, it is crucial to ensure that the medical images are of appropriate quality for the respective diagnostic task. The development of task-specific phantoms and test objects is an essential aspect of image quality assurance and optimization. It allows for the evaluation of imaging system performance under various clinical scenarios, such as detection of small lesions, or the evaluation of contrast resolution. By using task-specific test phantoms, researchers can identify the strengths and weaknesses of imaging systems and develop new imaging technologies or adapted and optimized acquisition parameters that better meet the needs of clinicians and patients. Additive manufacturing and 3D printing have added tremendous and rapidly increasing possibilities and opportunities to design and build such phantoms and test objects, since new additive manufacturing tools, hard- and software, and materials are constantly being introduced.
Task-specific test objects are designed to simulate specific clinical scenarios and can be used to evaluate various aspects of imaging system performance, such as spatial resolution, contrast resolution, and noise. This can be done in various approaches.
In particular, we welcome papers with relevance to one or more of the following general areas:
1) Physical test phantoms are models that simulate parts of the human body and its various tissues and organs. Especially anthropomorphic phantoms are essential for the assessment of image quality in radiology because they provide a realistic representation of the human anatomy and enable the evaluation of the imaging system's performance in a controlled and standardized manner. The use of anthropomorphic phantoms in radiology allows for the simulation of various clinical scenarios, such as the detection of small lesions or the evaluation of the contrast resolution of the imaging system. The phantoms are designed to mimic the physical properties of human tissue, such as the attenuation and scattering of X-rays or ultrasound waves, as well as nuclear spin density and relaxation times for magnetic resonance imaging, which allows for a realistic assessment of the imaging systems’ performance. They provide a standardized and reproducible method for assessing image quality of different imaging systems and protocols, allowing to compare the performance of different imaging systems and protocols under identical conditions.
2) Functional phantoms capable of mimicking for example patient motion or tissue perfusion are essential to characterize and validate imaging procedures that target the visualization of dynamic physiological processes or the correction of related image artifacts. Thereby, the timescale at which these phantoms operate represents a crucial aspect requiring high accuracy and reproducibility. Importantly, these phantoms have to be suitable for the environmental conditions defined by the respective imaging system, e.g. withstanding of ionizing radiation or compatibility with high electromagnetic fields.
3) Another important prerequisite to address these issues is the need for a observer independent assessment of the images. The most appropriate solution to automated evaluation is represented by the concept of model observers (MO). A model observer is a computational tool that simulates human observers' performance in interpreting medical images. Model observers are designed to provide a standardized and objective assessment of image quality and diagnostic accuracy, which can help radiologists and ultrasound technicians to improve their interpretation skills as well as optimizing imaging system performance and usage. Nevertheless, the validity of such MOs has to be validated by human expert assessment, which requires valid test objects like anthropomorphic phantoms.
4) Numerical simulations are a valuable supplementary tool in medical imaging, and in particular for the development of test objects. They are able to quickly and efficiently reproduce experimental results by employing proper mathematical models and numerical schemes. Once their accuracy is verified, which can be done, for instance, by comparison with the results obtained from phantoms, numerical simulations can be used for a variety of tasks, including prediction of the output of an imaging device for arbitrary test objects or experimental setups, and identification of weak spots or defects of the imaging device at hand. In some situations, when the design of phantoms and test objects becomes prohibitively expensive or complicated, computer simulations may even serve as a proper substitute.
