Related Experiment Video
Updated: Feb 12, 2026
Implementation of a Reference Interferometer for Nanodetection
Published on: April 26, 2014
Implementation of Size-Dependent Local Diagnostic Reference Levels for CT Angiography
Hub Boere1, Nienke G Eijsvoogel1,2, Anna M Sailer1,3
11 Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands.
Insights
This study introduces size-dependent local diagnostic reference levels (LDRLs) for CT scans, improving radiation dose assessment for individual patients. Size-dependent LDRLs are more relevant than size-independent ones for patient-specific dose evaluation.
Area of Science:
- Medical Imaging
- Radiology
- Radiation Dosimetry
Background:
- Diagnostic reference levels (DRLs) are typically set for standard-sized patients.
- Patient radiation dose in CT examinations is significantly influenced by patient size.
- Existing DRLs may not accurately reflect appropriate dose levels for diverse patient populations.
Purpose of the Study:
- To introduce a method for establishing size-dependent local diagnostic reference levels (LDRLs) in CT.
- To evaluate the efficacy of size-dependent LDRLs compared to size-independent LDRLs.
- To assess the impact of size-dependent LDRLs on image quality in CT angiography (CTA).
Main Methods:
- Included 184 aortic CTA examinations from dual-source CT scanners (CT1 and CT2).
- Retrieved volume CT dose index (CTDIvol) and patient water-equivalent diameter.
- Established size-dependent DRLs via linear regression and size-independent DRLs using percentiles.
- Assessed objective image quality (SNR) and subjective image quality.
Main Results:
- CTDIvol demonstrated dependence on patient size and scanner type (R²=0.72-0.78).
- Size-independent DRLs misclassified a significant percentage of outliers when patient size was considered (30-67%).
- Size-dependent DRLs identified outliers missed by size-independent DRLs (30-70%).
- Negative correlation observed between SNR and CTDIvol, yet all outliers met sufficient subjective image quality standards.
Conclusions:
- A novel method for setting size-dependent LDRLs in CTA has been developed.
- Size-dependent LDRLs provide a more accurate assessment of radiation dose appropriateness for individual patients.
- This approach enhances radiation safety and dose optimization in CT imaging.
Objective:
Diagnostic reference levels (DRLs) are established for standard-sized patients; however, patient dose in CT depends on patient size. The purpose of this study was to introduce a method for setting size-dependent local diagnostic reference levels (LDRLs) and to evaluate these LDRLs in comparison with size-independent LDRLs and with respect to image quality.
Materials And Methods:
One hundred eighty-four aortic CT angiography (CTA) examinations performed on either a second-generation or third-generation dual-source CT scanner were included; we refer to the second-generation dual-source CT scanner as "CT1" and the third-generation dual-source CT scanner as "CT2." The volume CT dose index (CTDIvol) and patient diameter (i.e., the water-equivalent diameter) were retrieved by dose-monitoring software. Size-dependent DRLs based on a linear regression of the CTDIvol versus patient size were set by scanner type. Size-independent DRLs were set by the 5th and 95th percentiles of the CTDIvol values. Objective image quality was assessed using the signal-to-noise ratio (SNR), and subjective image quality was assessed using a 4-point Likert scale.
Results:
The CTDIvol depended on patient size and scanner type (R2 = 0.72 and 0.78, respectively; slope = 0.05 and 0.02 mGy/mm; p < 0.001). Of the outliers identified by size-independent DRLs, 30% (CT1) and 67% (CT2) were adequately dosed when considering patient size. Alternatively, 30% (CT1) and 70% (CT2) of the outliers found with size-dependent DRLs were not identified using size-independent DRLs. A negative correlation was found between SNR and CTDIvol (R2 = 0.36 for CT1 and 0.45 for CT2). However, all outliers had a subjective image quality score of sufficient or better.
Conclusion:
We introduce a method for setting size-dependent LDRLs in CTA. Size-dependent LDRLs are relevant for assessing the appropriateness of the radiation dose for an individual patient on a specific CT scanner.
More Related Videos
Related Concept Videos
01:15Nursing Implementation
The five steps to implementing effective nursing care include reassessing the patient, reviewing and revising the existing nursing care plan, organizing the resources and care delivery, anticipating and preventing complications, and implementing nursing interventions.
01:03Inertial Frames of Reference
01:27Non-inertial Frames of Reference
01:22Cell Size
Surface Area
Cells can take in nutrients and water via diffusion through the plasma membrane itself or through specific channels in the membrane. The area of the membrane surrounding...
01:17Chemical Shift: Internal References and Solvent Effects
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
01:29Leveling Effect