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- “Instead because the volume CTDI is displayed on the scanner console before the initiation of a scan ( to allow the operator to confirm that the proper scanner output is programmed) and recorded as part of the patients examination information, many users incorrectly assume that it is the dose to that particular patient.”
CT Dose Index and Patient Dose: They Are Not the Same Thing
McCollough CH et al.
Radiology 2011; 259:311-316 - “The CTDI values are included in either a screen captured “patient dose report” or a structured Digital Imaging and Communications in Medicine dose report, which reinforces the incorrect belief that CTDI is a measure of patient dose.”
CT Dose Index and Patient Dose: They Are Not the Same Thing
McCollough CH et al.
Radiology 2011; 259:311-316 - “The CTDI is a standardized measure of the radiation output of a CT system, measured in a cylindrical acrylic phantom, that enables users to guage the amount of emitted radiation and compare the radiation output between different scan protocols or scanners.”
CT Dose Index and Patient Dose: They Are Not the Same Thing
McCollough CH et al.
Radiology 2011; 259:311-316 - “The CTDI is a standardized measure of the radiation output of a CT system, measured in a cylindrical acrylic phantom, that enables users to guage the amount of emitted radiation and compare the radiation output between different scan protocols or scanners. Complex calculations are required to map scanner output to patient dose, taking into account the patients size , irradiated organs, body composition, and scan range.”
CT Dose Index and Patient Dose: They Are Not the Same Thing
McCollough CH et al.
Radiology 2011; 259:311-316 - “Estimates of individual patient risk, and epidemiologic studies assessing potential late effects, must use patient size-specific dose estimates-they cannot use only scanner output (CTDI or DLP). Rather use of the known exponential relationship between patient size and absorbed dose will allow patient size specific dose estimates to be made from scanner output values.”
CT Dose Index and Patient Dose: They Are Not the Same Thing
McCollough CH et al.
Radiology 2011; 259:311-316 - “CTDI provides a very useful way to compare the doses delivered by various scan protocols or to achieve a specific level of image quality for a specific size patient.”
CT Dose Index and Patient Dose: They Are Not the Same Thing
McCollough CH et al.
Radiology 2011; 259:311-316 - “CTDI cannot be used as a surrogate for patient dose, either in epidemiologic assessments of potential late effects or for potential deterministic effects (eg, skin injury). Neither CTDI nor its derivative, dose length product (DLP, which is the product of CTDI and the irradiated scan length) should be used to estimate effective dose or potential cancer risk for any individual patient.”
CT Dose Index and Patient Dose: They Are Not the Same Thing
McCollough CH et al.
Radiology 2011; 259:311-316
- “Radiologists may not be aware of additional resources available at the scanner and the workstation to increase lesion conspicuity and detection as image quality and quantity decrease, including virtual noncontrast data sets from dual-energy CT, 3-D rendering (maximum intensity projection [MIP], volume rendering [VR], and cinematic rendering [CR]), computer-assisted diagnosis, and texture analysis.”
Enhancing Image Quality in the Era of Radiation Dose Reduction: Postprocessing Techniques for Body CT Pamela T. Johnson, Elliot K. Fishman JACR (in press) - “Use of MIP renderings at the workstation can improve detection of lung nodules and renal calculi on noncontrast scans performed with low-dose techniques. For contrast-enhanced scans, MIP renderings increase conspicuity of small hypervascular hepatic metastases (such as neuro- endocrine tumor) on the arterial phase scan.
MIP rendering of arterial phase data sets aids in characterization of solitary hepatic masses by confirming neovascularity in malignant tumors and depicting the classic feeding artery in focal nodular hyperplasia.”
Enhancing Image Quality in the Era of Radiation Dose Reduction: Postprocessing Techniques for Body CT Pamela T. Johnson, Elliot K. Fishman JACR (in press) - “The newest 3-D rendering tool, CR, holds promise for even greater diagnostic capabilities with respect to tumor characterization. The enhanced anatomic detail made possible from CR provides greater textural information about solid organs and tumors than conventional VR.”
Enhancing Image Quality in the Era of Radiation Dose Reduction: Postprocessing Techniques for Body CT Pamela T. Johnson, Elliot K. Fishman JACR (in press) - “A postprocessing tool that improves tumor characterization and the radiologist’s role in patient management is texture analysis. The technique provides detailed information about pathology that is beyond the discriminatory capability of the hu- man eye by evaluating pixel heterogeneity and, similar to 3-D rendering, requiring no additional radiation to generate diagnostically useful data. A number of studies have demonstrated that texture analysis correlates with tumor grade, angiogenesis, and other predictors of treatment response.”
Enhancing Image Quality in the Era of Radiation Dose Reduction: Postprocessing Techniques for Body CT Pamela T. Johnson, Elliot K. Fishman JACR (in press) - “Computer-aided detection is an important adjuvant for low-dose chest CT, harnessing automated lung nodule detection to augment radiologists’ interpretations. Ultra low-dose screening CT with computer-aided detection has been shown to be equivalent in sensitivity to standard dose for identification of lung nodules.”
Enhancing Image Quality in the Era of Radiation Dose Reduction: Postprocessing Techniques for Body CT Pamela T. Johnson, Elliot K. Fishman JACR (in press) - “Body CT imagers must embrace the pledge for responsible patient selection and protocol design put forth by the Image Wisely Campaign and the ACR’s newest Choosing Wisely recommendations. The tools described herein can be used to enhance interpretative performance in the face of reductions in image quality that result from low- dose techniques. Innovations such as texture mapping and CR are equally important, because they advance management guidance and further poise radiologists to serve as valuable members of the patient care team.”
Enhancing Image Quality in the Era of Radiation Dose Reduction: Postprocessing Techniques for Body CT Pamela T. Johnson, Elliot K. Fishman JACR (in press)
- “ Although all users should generally use automated tube current modulation, users must be careful about using this software in obese patients, children, and patients with metallic hardware.”
CT Scan Parameters and Radiation Dose: Practical Advise for Radiologists
Raman SP, Mahesh M, Blasko RV, Fishman EK
J Am Coll Radiol 2013;10:840-846 - “ The National Council on Radiation Protection and Measurements will continue working with ACEP, the American College of Radiology, other professional organizations, and government agencies to support and promote effective campaigns such as Image Gently, Image Wisely and Choosing Wisely.”
Applications of Justification and Optimization in Medical Imaging: Examples of Clinical Guidance for Compute Tomography Use in Emergency Medicine
Sierzenski PR et al.
J Am Coll Radiol 2014;11:36-44 - “ The use of all forms of medical imaging is based on physician decisions, including those of emergency physicians and consulting radiologists, with the understanding that the benefit of the chosen procedure should outweigh the patients potential risks of exposure to ionizing radiation (justification).”
Applications of Justification and Optimization in Medical Imaging: Examples of Clinical Guidance for Compute Tomography Use in Emergency Medicine
Sierzenski PR et al.
J Am Coll Radiol 2014;11:36-44
"Potential measures include provision of patient information material, review of CT protocols and indications, promotion of alternative studies, use of decision support software, automatic tube current modulation, bismuth shields, improved image reconstruction algorithms, empowerment of technologists to adjust protocols, and calculation of radiation dose for possible reporting."
CT Radiation Dose: What Can You Do Right Now in Your Practice?
Coakley FV et al.
AJR 2011; 196:619-625"This special report aims to inform the medical community about the many challenges involved in managing radiation in a way that maximizes the benefit-risk ratio. The report discusses the state of current knowledge and key questions in regard to sources of medical imaging radiation exposure, radiation risk estimation, dose reduction strategies, and regulatory options."
Managing Radiation Use in Medical Imaging: A Multifaceted Challenge
Hricak H et al.
Radiology 2011;258:889-905"Compared with the standard dose examination, a 31-64% reduction in radiation dose was estimated for NI levels of 18-25, which corresponds to image noise of 19-27 HU in subcutaneous fat."
Low-Dose CT Examinations in Crohn’s Disease: Impact on Image Quality, Diagnostic Performance, and Radiation Dose
Kambadakone AR et al.
AJR 2010;195:78-88"Processed MDCT images with the introduction of noise to simulate low-dose MDCT examinations with Noise Index (NI) levels of 18-25 allows substantial dose reduction for CT examinations in Crohn’s disease without compromising diagnostic information."
Low-Dose CT Examinations in Crohn’s Disease: Impact on Image Quality, Diagnostic Performance, and Radiation Dose
Kambadakone AR et al.
AJR 2010;195:78-88"Despite a significant reduction in perceived image quality, diagnostic efficacy in detective active inflammatory Crohn’s disease of the terminal ileum was not significantly reduced by the dose reduction methods"
Effect of Altering Automatic Exposure Control Settings and Quality Reference mAs on Radiation Dose, Image Qualit, and Diagnostic Efficacy in MDCT Enterography of Active Inflammatory Crohn’s Disease
Allen BC et al.
AJR 2010; 195:89-100"Substantial dose reduction can be achieved using weight based quality reference mAs and altering AEC settings without affecting diagnostic efficacy in active inflammatory Crohn’s disease of the terminal ileum. However, subjective image quality can be compromised at these dose settings, depending on radiologist preference."
Effect of Altering Automatic Exposure Control Settings and Quality Reference mAs on Radiation Dose, Image Qualit, and Diagnostic Efficacy in MDCT Enterography of Active Inflammatory Crohn’s Disease
Allen BC et al.
AJR 2010; 195:89-100"For 64-MDCT the CTDI vol decreased from 15.72 to 11.42 mGy and 11.42 to 9.25 mGy between original to intermediate and intermediate to final dose levels."
Effect of Altering Automatic Exposure Control Settings and Quality Reference mAs on Radiation Dose, Image Qualit, and Diagnostic Efficacy in MDCT Enterography of Active Inflammatory Crohn’s Disease
Allen BC et al.
AJR 2010; 195:89-100"Substantial dose reduction can be achieved using weight based quality reference mAs and altering AEC (automatic exposure control) settings without affecting diagnostic efficacy in active inflammatory Crohn’s disease of the terminal ileum."
Effect of Altering Automatic Exposure Control Settings and Quality Reference mAs on Radiation Dose, Image Qualit, and Diagnostic Efficacy in MDCT Enterography of Active Inflammatory Crohn’s Disease
Allen BC et al.
AJR 2010; 195:89-100- Limiting Scan Dosage to the Patient: Pearls
- Limit the field of view to the study ordered. There is no need to scan the lung above the liver or to scan beneath the symphysis in routine cases
- In multiphase studies determine what areas need the multiple acquisitions and which do not
- Choose the right protocol depending on patient size and body habitus - Designing the Optimal Scan Protocol for the patient: Decisions
- What phases of acquisition are needed? (non-contrast, arterial, venous, excretory or delayed phase)
- What slice collimation, slice thickness and interscan spacing is needed for the optimal protocol for the patient?
- Do we use oral and/or IV contrast? If yes decide on the best oral agent (water, positive contrast, VolLumen) and the delay time for the study, as well as selecting the IV contrast agent and defining volumes to use and the specific injection protocols.
- The goal of a customized CT protocol for each patient as opposed to the “one size fits all” approach is one of the trends in dose reduction "On the basis of our results, radiologists with access to a dual source scanner can change their renal mass protocol to a dual phase acquisition, decreasing radiation exposure by 35%."
Dual Energy CT in patients Suspected of Having Renal masses: Can Virtual Nonenhanced Images Replace True Nonenhanced Images?
Graser A et al
Radiology 2009; 252:443-440- "A reduction from 120 kV to 90 kV led to as much as a 35% reduction in the radiation dose, without sacrifice of low contrast detectability at CT."
Radiation Dose Reduction without Degradation of Low Contrast Detectability at Abdominal Multisection CT with a Low-Tube Voltage Technique: Phantom Study
Funama Y et al.
Radiology 2005; 237:905-910 - "The technique with low tube voltage should be used only in patients whose body weight is less than 80 kg."
Radiation Dose Reduction without Degradation of Low Contrast Detectability at Abdominal Multisection CT with a Low-Tube Voltage Technique: Phantom Study
Funama Y et al.
Radiology 2005; 237:905-910 - "By decreasing the tube voltage, the amount of contrast material can be reduced without image quality degradation. In scans obtained with a low tube voltage, the radiation dose can be reduced as much as 56.8%, and higher contrast material enhancement can be achieved."
Abdominal CT with Low Tube Voltage: Preliminary Observations about radiation Dose, Contrast Enhancement, Image Quality, and Noise
Nakayama Y et al.
Radiology 2005; 237:945-951