Effect of X-ray Tube Parameters, Iodine Concentration, and Patient Size on Image Quality in Pulmonary Computed Tomography Angiography: A Chest-Phantom-Study

Szücs-Farkas, Zsolt; Verdun, Francis R.; Allmen, Gabriel von; Mini, R.; Vock, Peter

doi:10.1097/rli.0b013e3181690042

Cited by 81 publications

(52 citation statements)

References 22 publications

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“…hardened x-ray spectrum. Lower enhancement values of contrast material are, therefore, observed for increasing phantom diameters at single-energy CT. 28 However, monochromatic x-ray beams are not hardened, so in theory, the attenuation coefficients in VMS images are independent of the path length through the phantom or patient. 17 Consistent with theory, the CT numbers we observed for all contrast media were independent of phantom size.…”

Section: Discussionmentioning

confidence: 99%

Complementary contrast media for metal artifact reduction in dual-energy computed tomography

et al. 2015

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Abstract. Metal artifacts have been a problem associated with computed tomography (CT) since its introduction. Recent techniques to mitigate this problem have included utilization of high-energy (keV) virtual monochromatic spectral (VMS) images, produced via dual-energy CT (DECT). A problem with these high-keV images is that contrast enhancement provided by all commercially available contrast media is severely reduced. Contrast agents based on higher atomic number elements can maintain contrast at the higher energy levels where artifacts are reduced. This study evaluated three such candidate elements: bismuth, tantalum, and tungsten, as well as two conventional contrast elements: iodine and barium. A water-based phantom with vials containing these five elements in solution, as well as different artifact-producing metal structures, was scanned with a DECT scanner capable of rapid operating voltage switching. In the VMS datasets, substantial reductions in the contrast were observed for iodine and barium, which suffered from contrast reductions of 97% and 91%, respectively, at 140 versus 40 keV. In comparison under the same conditions, the candidate agents demonstrated contrast enhancement reductions of only 20%, 29%, and 32% for tungsten, tantalum, and bismuth, respectively. At 140 versus 40 keV, metal artifact severity was reduced by 57% to 85% depending on the phantom configuration.

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Section: Discussionmentioning

confidence: 99%

Complementary contrast media for metal artifact reduction in dual-energy computed tomography

et al. 2015

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“…4,24,39,40 Many studies focused on low kV protocols; however, one must ensure to concordantly increase mAs to avoid excessive image noise. 19,41,42 For future optimization, it may prove beneficial to further define the optimal IDR values and CM volumes per weight category that ensure a mean attenuation of 180-300 HU for all kV settings regularly used in clinics, e.g. 120, 100 and 80 kV.…”

Section: Discussionmentioning

confidence: 99%

Individually tailored contrast enhancement in CT pulmonary angiography

Hendriks

Kok

Mihl

et al. 2016

BJR

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Objective: The purpose was to evaluate individually shaped contrast media (CM) delivery in CT pulmonary angiography (CTPA) for suspected pulmonary embolism (PE). Methods: 100 consecutive emergency patients with clinical suspicion of PE were evaluated. High-pitch CTPA was performed on a second-generation dual-source CT using the following parameters: 100 kV, 200-250 mAsref, rotation time 0.28 s, 128 3 0.6 mm col. and image reconstruction 1.0/0.8 mm (B30f). Group 1 (n 5 50) then received a fixed CM bolus (300 5 mgI ml 21, volume 5 90 ml and flow rate 5 6 ml s 21 ); Group 2 (n 5 50) received a body weightadapted CM bolus determined by dedicated contrast injection software. For analysis, groups were further subdivided into low-weight (40-75 kg) and high-weight (76-117 kg) groups. Technical image quality was graded using a four-point Likert scale (1 5 non-diagnostic; 2 5 diagnostic; 3 5 good and 4 5 excellent image quality) at the level of the pulmonary trunk and pulmonary arteries. Objective image quality analysis was performed by measuring contrast enhancement in Hounsfield units (HU) at the same levels. Attenuation levels . 180 HU were considered diagnostic. Results: All examinations were graded as diagnostic at each level. The individual minimum pulmonary attenuation was 184 and 270 HU for Group 1 and 2, respectively. Mean attenuation was as follows: Group 1: 475 6 105 HU (40-75 kg) and 402 6 115 HU (76-117 kg), p , 0.03. Group 2: 424 6 76 HU (40-75 kg) and 418 6 100 HU (76-117 kg), p 5 0.8. For Group 2, CM volumes were: 55 6 5 ml (40-75 kg) and 66 6 5 ml (76-117 kg), leading to 16-51% CM reduction. Conclusion: Even under emergency conditions, individualized CM protocols can provide diagnostic and robust image quality in CTPA for PE with a substantial reduction of CM volume for lower weight patients, compared with a fixed CM protocol. Advances in knowledge: CM volume can substantially be reduced by using individualized CM protocols in CT angiography for PE without compromising the diagnostic image quality.

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“…A number of advanced technologies and practice changes are now used to lower radiation dose with CT, such as automatic tube current modulation (ATCM) [2], a variety of de-noising techniques enabling reduced patient exposure [3], reducing kVp for smaller patient size [4], and reducing the number of contrast phase acquisitions [5]. One additional source of potential unnecessary exposure to a patient can occur due to excessive Z-axis coverage.…”

Section: Introductionmentioning

confidence: 99%

Automated Detection of Z-Axis Coverage with Abdomen-Pelvis Computed Tomography Examinations

et al. 2014

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Excessive cephalocaudal anatomic (Z-axis) coverage can lead to unnecessary radiation exposure to a patient. In this study, an automated computing model was developed for identifying instances of potentially excessive Z-axis coverage with abdomen-pelvis examinations. Eight patient and imaging attributes including patient gender, age, height, weight, volume CT dose index (CTDIvol), dose length product (DLP), maximum abdomen width, and maximum abdomen thickness were used to build a feedforward neural network model to predict a target Z-axis coverage whether it is an excessive or non-excessive Z-axis coverage scans. 264 CT abdomen-pelvis exams were used to develop the model which is validated using 10-fold cross validation. The result showed that 244 out of 264 exams (92.4 %) correctly predicted Z-axis excessive coverage. The promising results indicate that this tool has the potential to be used for CT exams of the chest and colon, urography, and other site-specified CT studies having defined limited length.

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Effect of X-ray Tube Parameters, Iodine Concentration, and Patient Size on Image Quality in Pulmonary Computed Tomography Angiography: A Chest-Phantom-Study

Cited by 81 publications

References 22 publications

Complementary contrast media for metal artifact reduction in dual-energy computed tomography

Complementary contrast media for metal artifact reduction in dual-energy computed tomography

Individually tailored contrast enhancement in CT pulmonary angiography

Automated Detection of Z-Axis Coverage with Abdomen-Pelvis Computed Tomography Examinations

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