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X-ray Dose Reduction through Adaptive Exposure in Fluoroscopic Imaging
Published on: September 11, 2011
Evaluation of a radiation dose reduction strategy for pediatric chest CT
1Department of Radiology, Lucile Packard Children's Hospital, Stanford University School of Medicine, 725 Welch Rd, Stanford, CA 94304-5913, USA.
Insights
Pediatric chest CT radiation dose was significantly reduced using a kilovoltage (kVp)-lowering strategy. This approach improved patient safety by decreasing dose while maintaining acceptable image quality.
Area of Science:
- Radiology
- Medical Imaging
- Pediatric Imaging
Background:
- Computed tomography (CT) is a vital diagnostic tool in pediatric care.
- Optimizing CT protocols is crucial to minimize radiation exposure in children.
- Previous strategies focused on tube current modulation (mAs), but kilovoltage (kVp) offers further optimization potential.
Purpose of the Study:
- To quantify the impact of a kilovoltage (kVp)-lowering strategy on patient dose, image quality, and image noise in pediatric chest CT.
- To evaluate the effectiveness of weight-based kVp adjustments in reducing radiation exposure.
- To assess the diagnostic acceptability of images obtained with modified CT protocols.
Main Methods:
- Retrospective analysis of 120 pediatric chest CT scans (60 from 2006, 60 from 2008).
- Comparison of CT protocols: 120 kVp (2006) vs. weight-based 80 kVp (<15 kg) and 100 kVp (15-60 kg) (2008) with adjusted mAs.
- Measurement of radiation dose (CTDIvol, DLP, effective dose) and image noise; subjective evaluation of image quality.
Main Results:
- Significant dose reductions achieved: 73% for <15 kg and 45% for 15-60 kg groups (p < 0.05).
- Radiation dose indicators (CTDIvol, DLP, effective dose) decreased substantially across both weight categories.
- Image noise increased by 55% (<15 kg) and 41% (15-60 kg) (p < 0.05), with all studies deemed diagnostically adequate.
Conclusions:
- Weight-based kilovoltage (kVp) reduction in pediatric chest CT, combined with low tube current (mAs), significantly lowers patient radiation dose.
- The observed increase in image noise is an acceptable trade-off for substantial dose reduction.
- The modified CT protocol ensures diagnostically adequate image quality, enhancing patient safety in pediatric imaging.
Objective:
The purpose of our study was to quantify the effect of changes made to the CT chest protocol on patient dose, image quality, and image noise when using a kilovoltage (kVp)-lowering strategy.
Materials And Methods:
We retrospectively selected 120 children who underwent chest CT: 60 in 2006 and 60 in 2008. In each group there were 30 children weighing less than 15 kg and 30 between 15 and 60 kg. In 2006 the CT protocol was 120 kVp and the reference current (mAs) was 65. In 2008, the kVp was 80 for < 15 kg and 100 for 15-60 kg, with reference mAs of 55. For each examination, the volume CT dose index (CTDI(vol)) and dose-length product (DLP) were recorded. Effective dose (ED) was estimated using the DLP method. Image noise was measured. Overall image quality was subjectively evaluated.
Results:
For a weight < 15.0 kg, the CTDI(vol), DLP, and ED were reduced by 73%, 75%, and 73%, respectively (p < 0.05). For the weight range 15-60 kg, the CTDI(vol), DLP, and ED were reduced by 45%, 44%, and 48%, respectively (p < 0.05). Measured noise increased by 55% in the younger children and 41% in the older group (p < 0.05). All studies were considered diagnostically adequate.
Conclusion:
Significant radiation dose reduction can be achieved for routine pediatric chest CT by weight-based decreases in kVp in addition to low mAs. Increased noise was considered an acceptable trade-off for decreased dose, and image quality was acceptable.
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