The impact on CT dose of the variability in tube current modulation technology: a theoretical investigation

Li, Xiang; Segars, W. Paul; Samei, Ehsan

doi:10.1088/0031-9155/59/16/4525

Cited by 40 publications

(64 citation statements)

References 31 publications

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“…Li et al estimated organ dose for chest and abdominopelvic scans for a XCAT phantom under five modulation strengths. 1 The study derived a weighted organ-specific CTDI vol , which included not only the effect of local mAs variation but F. 7.…”

Section: Discussionmentioning

confidence: 99%

“…1 The algorithm estimated the attenuation at a given gantry angle, taking into account the geometry of the CT system, the fan angle of the x-ray beam, the polyenergetic x-ray energy spectrum, and the attenuation through the bowtie filter and the patient. A total of five mA modulation profiles were generated for each patient with a values of 0, 0.25, 0.5, 0.75, and 1 (Fig.…”

Section: C Tube Current Modulation Profilementioning

confidence: 99%

“…The prior studies have been able to use the concept of regional CTDI vol in conjunction with organ dose coefficients to assess organ dose. 1,12 However, the methodology has been applied to a limited number of human models, and is further oriented toward retrospective dose estimation for specific models.…”

Section: Introductionmentioning

confidence: 99%

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Prospective estimation of organ dose in CT under tube current modulation

Tian

Segars

et al. 2015

Medical Physics

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Purpose: Computed tomography (CT) has been widely used worldwide as a tool for medical diagnosis and imaging. However, despite its significant clinical benefits, CT radiation dose at the population level has become a subject of public attention and concern. In this light, optimizing radiation dose has become a core responsibility for the CT community. As a fundamental step to manage and optimize dose, it may be beneficial to have accurate and prospective knowledge about the radiation dose for an individual patient. In this study, the authors developed a framework to prospectively estimate organ dose for chest and abdominopelvic CT exams under tube current modulation (TCM). Methods: The organ dose is mainly dependent on two key factors: patient anatomy and irradiation field. A prediction process was developed to accurately model both factors. To model the anatomical diversity and complexity in the patient population, the authors used a previously developed library of computational phantoms with broad distributions of sizes, ages, and genders. A selected clinical patient, represented by a computational phantom in the study, was optimally matched with another computational phantom in the library to obtain a representation of the patient's anatomy. To model the irradiation field, a previously validated Monte Carlo program was used to model CT scanner systems. The tube current profiles were modeled using a ray-tracing program as previously reported that theoretically emulated the variability of modulation profiles from major CT machine manufacturers Li et al., [Phys. Med. Biol. 59, 4525-4548 (2014)]. The prediction of organ dose was achieved using the following process: (1) CTDI vol -normalized-organ dose coefficients (h organ ) for fixed tube current were first estimated as the prediction basis for the computational phantoms; (2) each computation phantom, regarded as a clinical patient, was optimally matched with one computational phantom in the library; (3) to account for the effect of the TCM scheme, a weighted organ-specific CTDI vol [denoted as (CTDI vol ) organ,weighted ] was computed for each organ based on the TCM profile and the anatomy of the "matched" phantom; (4) the organ dose was predicted by multiplying the weighted organ-specific CTDI vol with the organ dose coefficients (h organ ). To quantify the prediction accuracy, each predicted organ dose was compared with the corresponding organ dose simulated from the Monte Carlo program with the TCM profile explicitly modeled. Results: The predicted organ dose showed good agreements with the simulated organ dose across all organs and modulation profiles. The average percentage error in organ dose estimation was generally within 20% across all organs and modulation profiles, except for organs located in the pelvic and shoulder regions. For an average CTDI vol of a CT exam of 10 mGy, the average error at full modulation strength (α = 1) across all organs was 0.91 mGy for chest exams, and 0.82 mGy for abdominopelvic exams. relation to a targeted level of image q...

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Section: Discussionmentioning

confidence: 99%

Section: C Tube Current Modulation Profilementioning

confidence: 99%

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Prospective estimation of organ dose in CT under tube current modulation

Tian

Segars

et al. 2015

Medical Physics

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“…When combined with the XCAT models, the MC program can provide accurate dose estimates for specific patients 78 . The MC program can be used to simulate different imaging devices and protocols for comparison 79–81 .…”

Section: Radiation Dosimetrymentioning

confidence: 99%

Application of the 4-D XCAT Phantoms in Biomedical Imaging and Beyond

Segars

Tsui

Cai

et al. 2018

IEEE Trans. Med. Imaging

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The four dimensional (4D) eXtended CArdiac-Torso (XCAT) series of phantoms was developed to provide accurate computerized models of the human anatomy and physiology. The XCAT series encompasses a vast population of phantoms of varying ages from newborn to adult, each including parameterized models for the cardiac and respiratory motions. With great flexibility in the XCAT’s design, any number of body sizes, different anatomies, cardiac or respiratory motions or patterns, patient positions and orientations, and spatial resolutions can be simulated. As such, the XCAT phantoms are gaining a wide use in biomedical imaging research. There they can provide a virtual patient base from which to quantitatively evaluate and improve imaging instrumentation, data acquisition, techniques and image reconstruction and processing methods which can lead to improved image quality and more accurate clinical diagnoses. The phantoms have also found great use in radiation dosimetry, radiation therapy, medical device design, and even the security and defense industry. This review paper highlights some specific areas in which the XCAT phantoms have found use within biomedical imaging and other fields. From these examples, we illustrate the increasingly important role that computerized phantoms and computer simulation are playing in the research community.

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“…The organ is affected not only by the scanner radiation output level, usually characterized by CTDI, but also by various other factors, such as patient size, study protocol, scanner model, and x-ray energy spectrum. A number of studies have been conducted with the aim of developing a robust yet simple method with acceptable accuracy for organ dose estimation (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). These studies employed either experimental methods using physical phantoms or numerical methods using validated Monte Carlo programs, although the majority of them were based on the latter because of the flexibility of simulation.…”

Section: Introductionmentioning

confidence: 99%