Patient-specific organ dose and in-vivo image quality assessment in clinical CT.
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2025-06-26
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Abstract
PURPOSE: To develop and characterize individualized dose and quality measures at organ level compared to their generic counterparts across a clinical CT dataset. MATERIALS AND METHODS: The study included 9801 chest-abdomen-pelvis and abdomen-pelvis CT exams (7,763 patients, mean age, 56 ± 17 years; 4113 women) representing 20 unique protocols. For each exam, patient-specific organ dose of all radiosensitive organs was estimated using a validated method by generating personalized computational phantoms and Monte Carlo simulations. Effective dose (EOD) was calculated by weighted sum of the organ doses. Liver dose, ODliver, noise in the liver, Nliver, and observer model detectability, d', were assessed within the liver as examples of individualized, organ-based image assessment measurements. The organ-based measurements (ODliver, EOD, and Nliver) were compared to their generic counterparts: ssize-specific ddose estimates (SSDE), effective dose based on dose length product (EDLP), and whole-body noise (Nglobal), respectively. RESULTS: Generic dose values were substantially higher than individualized estimates for SSDE vs. ODliver (median of all exams: 51.2 %, p < 0.001) and EDLP vs. EDOD (median: 41.0 %, p < 0.001). Nglobal was generally lower than Nliver (median: -7.2 %, p < 0.001). The correlation relationships of EOD and d' were substantially varied (R2 range: 0-0.5) for different patient sizes and scan parameters. CONCLUSIONS: Demonstrated across a population of exams, individualized organ-based measurements of dose and quality are feasible. Generic measures cannot fully represent individualized organ-based values. The correlation relationships between individualized dose and image quality values varies for different vendors and protocols, implying imaging optimization is best when done semi-independently for each factor using individualized measurements.
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Fu, Wanyi, Shobhit Sharma, Justin Solomon, Francesco Ria, Hananiel Setiawan, Aiping Ding, William P Segars, Ehsan Samei, et al. (2025). Patient-specific organ dose and in-vivo image quality assessment in clinical CT. Phys Med, 136. p. 105017. 10.1016/j.ejmp.2025.105017 Retrieved from https://hdl.handle.net/10161/32520.
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Scholars@Duke
Justin Solomon
Francesco Ria
Dr. Francesco Ria is a medical physicist and he serves as an Assistant Professor in the Department of Radiology. Francesco has an extensive expertise in the assessment of procedure performances in radiology. In particular, his research activities focus on the simultaneous evaluation of radiation dose and image quality in vivo in computed tomography providing a comprehensive evaluation of radiological exams. Moreover, Francesco is developing and investigating novel mathematical models that, uniquely in the radiology field, can incorporate a comprehensive and quantitative risk-to-benefit assessment of the procedures; he is continuing to apply his expertise towards the definition of new patient specific risk metrics, and in the assessment of image quality in vivo also using state-of-the-art imaging technology, such as photon counting computed tomography scanners, and machine learning reconstruction algorithms.
Dr. Ria is a member of the American Association of Physicists in Medicine (AAPM) task group 392 (Investigation and Quality Control of Automatic Exposure Control System in CT), of the AAPM task group 430 (Comprehensive quantification and dissemination of patient-model-based organ and effective dose estimations and their associated uncertainties for CT examinations), of the AAPM Medicine Public Education working group (WGATE), and of the Italian Association of Medical Physics task group Dose Monitoring in Diagnostic Imaging.
William Paul Segars
Our current research involves the use of computer-generated phantoms and simulation techniques to investigate and optimize medical imaging systems and methods. Medical imaging simulation involves virtual experiments carried out entirely on the computer using computational models for the patients as well as the imaging devices. Simulation is a powerful tool for characterizing, evaluating, and optimizing medical imaging systems. A vital aspect of simulation is to have realistic models of the subject's anatomy as well as accurate models for the physics of the imaging process. Without this, the results of the simulation may not be indicative of what would occur in actual clinical studies and would, therefore, have limited practical value. We are leading the development of realistic simulation tools for use toward human and small animal imaging research.
These tools have a wide variety of applications in many different imaging modalities to investigate the effects of anatomical, physiological, physical, and instrumentational factors on medical imaging and to research new image acquisition strategies, image processing and reconstruction methods, and image visualization and interpretation techniques. We are currently applying them to the field of x-ray CT. The motivation for this work is the lack of sufficiently rigorous methods for optimizing the image quality and radiation dose in x-ray CT to the clinical needs of a given procedure. The danger of unnecessary radiation exposure from CT applications, especially for pediatrics, is just now being addressed. Optimization is essential in order for new and emerging CT applications to be truly useful and not represent a danger to the patient. Given the relatively high radiation doses required of current CT systems, thorough optimization is unlikely to ever be done in live patients. It would be prohibitively expensive to fabricate physical phantoms to simulate a realistic range of patient sizes and clinical needs especially when physiologic motion needs to be considered. The only practical approach to the optimization problem is through the use of realistic computer simulation tools developed in our work.
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