Relationship between radiographic techniques (kilovolt and milliampere-second) and CTDIVOL

Elojeimy, Saeed; Tipnis, Sameer; Huda, Walter

doi:10.1093/rpd/ncq138

Cited by 43 publications

(17 citation statements)

References 13 publications

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“…Since this patient was injected with 181.3 MBq, the final dose to the fetus was of 3.6 mGy. Even when adding the dose of the transmission scan used for attenuation correction, which in this case was estimated at about 5 mGy (Elojeimy et al 2010), the fetal absorbed dose from [ 18 F]-FDG PET/CT scans remains well within the ‘‘safe’’ levels. At this stage of pregnancy, the threshold dose is 650 mGy for mental retardation and 500 mGy for small head size and growth retardation (Steenvoorde et al 1998).…”

Section: Discussionmentioning

confidence: 98%

Radiation dose to the fetus from [18F]-FDG administration during the second trimester of pregnancy

et al. 2012

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We estimated the fetal radiation dose from [18F]-FDG in a rare case of a woman who underwent a PET/CT scan during the second trimester of pregnancy. The patient, a 27-year-old female with a paraganglioma, received 181.3 MBq [18F]-FDG. From the concentrations of radioactivity measured on the images, we derived the time-integrated activity coefficients of the fetus and the placenta. The time-integrated activity coefficients of the mother’s organs were taken from the standard values of the ICRP publication 106. The final fetal dose was calculated using the 6 month pregnant model of the OLINDA/EXM software. The fetus showed an overall low and homogeneous [18F]-FDG uptake, with an average concentration of 2.41 kBq cm−3. The uptake in the placenta was generally higher (average concentration = 3.69 kBq cm−3). The estimated time-integrated activity coefficients were 0.0130 and 0.0058 Bq hr Bq−1 for the fetus and the placenta respectively. The final average dose to the fetus was 1.97 × 10−2 mGy MBq−1 (3.6 mGy in this patient who received 181.3 MBq). Therefore, the dose to the fetus from [18F]-FDG administration during the second trimester of pregnancy is low. When medically indicated, pregnancy should not be a categorical basis for withholding [18F]-FDG PET scans.

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Section: Discussionmentioning

confidence: 98%

Radiation dose to the fetus from [18F]-FDG administration during the second trimester of pregnancy

et al. 2012

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“…The image noise dependence on dose can be expanded by taking into account that the dose varies linearly with tube current and with exposure time. In addition, image noise dependence on tube peak voltage can be introduced since the radiation dose varies as

D \propto k V p^{n}

where kVp is the peak voltage and n is a kilovoltage dependency factor that has been estimated to have a value of approximately 2.6 (14) . The value n depends on the radiation quality of the beam, tube output, and detector response.…”

Section: Methodsmentioning

confidence: 99%

Quality control of CT systems by automated monitoring of key performance indicators: a two‐year study

Nowik

Bujila

Poludniowski

et al. 2015

J Applied Clin Med Phys

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The purpose of this study was to develop a method of performing routine periodical quality controls (QC) of CT systems by automatically analyzing key performance indicators (KPIs), obtainable from images of manufacturers' quality assurance (QA) phantoms. A KPI pertains to a measurable or determinable QC parameter that is influenced by other underlying fundamental QC parameters. The established KPIs are based on relationships between existing QC parameters used in the annual testing program of CT scanners at the Karolinska University Hospital in Stockholm, Sweden. The KPIs include positioning, image noise, uniformity, homogeneity, the CT number of water, and the CT number of air. An application (MonitorCT) was developed to automatically evaluate phantom images in terms of the established KPIs. The developed methodology has been used for two years in clinical routine, where CT technologists perform daily scans of the manufacturer's QA phantom and automatically send the images to MonitorCT for KPI evaluation. In the cases where results were out of tolerance, actions could be initiated in less than 10 min. 900 QC scans from two CT scanners have been collected and analyzed over the two‐year period that MonitorCT has been active. Two types of errors have been registered in this period: a ring artifact was discovered with the image noise test, and a calibration error was detected multiple times with the CT number test. In both cases, results were outside the tolerances defined for MonitorCT, as well as by the vendor. Automated monitoring of KPIs is a powerful tool that can be used to supplement established QC methodologies. Medical physicists and other professionals concerned with the performance of a CT system will, using such methods, have access to comprehensive data on the current and historical (trend) status of the system such that swift actions can be taken in order to ensure the quality of the CT examinations, patient safety, and minimal disruption of servicePACS numbers: 87.57.C‐, 87.57.N‐, 87.57.Q‐

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“…A decrease in tube voltage will also lead to a decrease in radiation dose at the expense of a potential increase in image noise (16). While radiation dose decreases linearly with a decrease in tube current, radiation dose decreases by a power of 2.6 with tube voltage reduction (17,18), which makes this a powerful technique with which to decrease radiation exposure. X-ray tube voltage reduction has been successfully applied to CT angiography, as well as to imaging of thinner patients and pediatric patients (19,20).…”

Section: Patient Population and Bowel Preparationmentioning

confidence: 99%

Reducing Radiation Dose at CT Colonography: Decreasing Tube Voltage to 100 kVp

Chang¹,

Caovan²,

Grand³

et al. 2013

Radiology

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Purpose:To assess the effect of a decrease in tube voltage from 120 kVp to 100 kVp on dose, contrast-to-noise ratio (CNR), and three-dimensional (3D) image quality in patients undergoing computed tomographic (CT) colonography as well as to determine how these changes are affected by patient size. Materials and Methods:This HIPAA-compliant and institutional review board-approved retrospective study included 63 consecutive patients who underwent CT colonography and who waived informed consent. Scanning was performed with patients in the supine (120 kVp) and prone (100 kVp) positions, with other parameters unchanged. Volume CT dose index (CTDI vol ), dose-length product (DLP), image noise, attenuation of selected materials, and CNR were compared with the Wilcoxon matched-pairs signed rank test. Two readers blinded to tube voltage independently assessed 3D endoluminal image quality. The k coefficients were calculated for interobserver agreement. Average image quality ratings were compared with the Wilcoxon signed rank test. All recorded data were stratified by patient anteroposterior diameter to determine effects of patient size. Results:Decreasing tube voltage from 120 to 100 kVp resulted in a 20% decrease in CTDI vol (P , .001) and a 16% decrease in DLP (P , .001). Image noise increased by 32% (P , .001). Mean attenuation of tagged fluid increased from 395 to 487 HU (P , .001). There was no change in mean CNR of tagged fluid (17.1 at 120 kVp, 16.8 at 100 kVp; P = .37), regardless of patient size. The 3D image quality decreased slightly from a median score of 5 out of 5 to 4 out of 5 (P , .001). There was substantial interobserver agreement. Conclusion:A decrease in tube voltage from 120 to 100 kVp results in a significant decrease in radiation dose but only a minimal decrease in 3D image quality at all patient sizes.q RSNA, 2012

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Relationship between radiographic techniques (kilovolt and milliampere-second) and CTDIVOL

Cited by 43 publications

References 13 publications

Radiation dose to the fetus from [18F]-FDG administration during the second trimester of pregnancy

Radiation dose to the fetus from [18F]-FDG administration during the second trimester of pregnancy

Quality control of CT systems by automated monitoring of key performance indicators: a two‐year study

Reducing Radiation Dose at CT Colonography: Decreasing Tube Voltage to 100 kVp

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