Ionizing Radiation Exposure, Quality Improvement
Conditions
Keywords
CT scan, CT exam, ionizing radiation, medical imaging, cat scan, radiation
Brief summary
This is a pragmatic stepped-wedge cluster randomized controlled trial to explore variation in doses used for diagnostic CT by pooling radiation dose data across diverse healthcare delivery systems. To compare different strategies for lowering and optimizing dose and identify the barriers and facilitators to implementing successful dose optimization strategies and standardizing practice.
Detailed description
The investigators are using a stepped-wedge cluster randomized controlled trial, collecting radiation dose information on CT from across all collaborating health care facilities, and leading several different interventions to optimize dose across facilities. In addition to collecting the CT radiation dose data, and using these results to provide feedback to the collaborating health care facilities, they will be conducting surveys of several individuals at each site, including key informants, such as lead radiologists, technologists, and medical physicist, and radiology administrators. They will compare and identify facilitators and barriers (assessed through surveys of participating facilities) associated with successful and failed implementation of dose optimization.
Interventions
OTHERSimple Audit Report
The simple audit provides comparison and feedback on radiation doses.
The multi-component intervention gives tailored feedback on needed changes plus guidance using quality improvement methods that facilitate organizational change. Provides access to experts, detailed audit, collaborative calls, and site visits (as needed).
OTHERIn-Person Meeting
Collaborator meeting with an emphasis on quality improvement.
Sponsors
University of California, Davis
University Hospital, Basel, Switzerland
Center for Diagnostic Imaging
Community Health Network
Children's Mercy Hospital Kansas City
City of Hope Medical Center
Albert Einstein Healthcare Network
Universität Duisburg-Essen
East Texas Medical Center Regional Healthcare System
Emory University
Henry Ford Health System
Huntsville Hospital Health System
Nicklaus Children's Hospital f/k/a Miami Children's Hospital
Mount Sinai Hospital, New York
Maastricht University Medical Center
Olive View-UCLA Education & Research Institute
Oxford University Hospitals NHS Trust
San Francisco VA Health Care System
St. Joseph Hospital of Orange
St. Luke's International Hospital, Japan
University of Virginia
University of California, Irvine
University of California, San Diego
National Cancer Institute (NCI)
University of California, San Francisco
Study design
Allocation
RANDOMIZED
Intervention model
FACTORIAL
Primary purpose
HEALTH_SERVICES_RESEARCH
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
No minimum to 99 Years
Healthy volunteers
Yes
Inclusion criteria
* Diagnostic CT scans of the head, chest, and/or abdomen/pelvis performed within the study period
Exclusion criteria
* non-diagnostic scans that are not of the head, chest, and/or abdomen/pelvis
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Mean Effective Dose (ED) | Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81 | We will assess the change in the mean effective dose after the simple audit and multi-component interventions (MCI) in comparison to before the audit and multi-component interventions. The numbers given below reflect absolute change in mean dose (in millisieverts) relative to the baseline period. |
| Percentage of CT Scans With an Effective Dose Above Benchmark | Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81 | We will assess the change in the percentage of examinations with an effective dose above the benchmark after the simple audit and after multi-component intervention (MCI) in comparison to doses before the audit and MCI. The benchmark for each anatomic area is defined as the 75th percentile of the dose distribution during the pre-intervention (baseline) period. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Mean Volume Computed Tomography Dose Index (CTDIvol) | Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81 | We will assess the change in the mean volume CT dose index (CTDIvol) from before versus after the audit and MCI intervention. CTDIvol (in units of milligray, mGy) is a measure of radiation dose, reflecting the amount of radiation imparted per CT slice by the scanner. Higher CTDIvol signifies more radiation dose. In general, a reduction in CTDIvol would be a sign of quality improvement, minimizing excess radiation exposure to the patient. |
| Mean Dose Length Product | Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81 | We will assess the change in the dose length product after the audit and MCI in comparison to before the audit and MCI. |
| Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81 | We will assess the change in organ doses after the simple audit and multi-component interventions (MCI) in comparison to before the audit and multi-component interventions. The numbers given below reflect absolute change in mean dose (in millisieverts) relative to the baseline period. |
| Percentage of CT Scans With a CTDIvol Above Benchmark | Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81 | We will assess the change in the percentage of examinations with a CTDIvol above the benchmark after the audit and after multicomponent intervention in comparison to doses before the audit and multicomponent intervention. The benchmark for each anatomic area is defined as the 75th percentile of the dose distribution during the pre intervention period. |
| Proportion of CT Scans With a Dose Length Product Above Benchmark | Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81 | We will assess the change in the proportion of examinations with a dose length product above the benchmark after the audit and after the MCI in comparison to doses before the audit and MCI. The benchmark for each anatomic area is defined as the 75th percentile of the dose distribution during the pre intervention period. |
Participant flow
Pre-assignment details
Study subjects were passively enrolled in this study; we had a waiver of informed consent and there was no direct contact with subjects. We have listed the number of unique subjects enrolled into each track; however, ALL ANALYSES WERE PERFORMED AT THE LEVEL OF THE CT SCAN, not at the individual subject level.
Participants by arm
| Arm | Count |
|---|---|
| Baseline Period Reflects CT scans analyzed during a baseline period of usual care (before intervention). The duration of this period differed by randomization Track (A, B, or C). | 0 |
| Baseline Period Reflects CT scans analyzed during a baseline period of usual care (before intervention). The duration of this period differed by randomization Track (A, B, or C). | 526,439 |
| Simple Audit Intervention Period Reflects CT scans analyzed after receiving the simple audit report intervention. The duration of this period differed by randomization Track (A, B, or C). | 0 |
| Simple Audit Intervention Period Reflects CT scans analyzed after receiving the simple audit report intervention. The duration of this period differed by randomization Track (A, B, or C). | 251,409 |
| Multi-component Intervention Period Reflects CT scans analyzed after receiving the multi-component intervention. The duration of this period differed by randomization Track (A, B, or C). | 0 |
| Multi-component Intervention Period Reflects CT scans analyzed after receiving the multi-component intervention. The duration of this period differed by randomization Track (A, B, or C). | 207,576 |
| Total | 985,424 |
Baseline characteristics
| Characteristic | Simple Audit Intervention Period | Multi-component Intervention Period | Total | Baseline Period |
|---|---|---|---|---|
| Age, by type of scan Abdomen | 56.3 Years STANDARD_DEVIATION 18.3 | 56.4 Years STANDARD_DEVIATION 18.3 | 56.2 Years STANDARD_DEVIATION 18.3 | 56.0 Years STANDARD_DEVIATION 18.2 |
| Age, by type of scan Chest | 62.1 Years STANDARD_DEVIATION 15.2 | 62.0 Years STANDARD_DEVIATION 15.2 | 61.8 Years STANDARD_DEVIATION 15.2 | 61.6 Years STANDARD_DEVIATION 15.3 |
| Age, by type of scan Combined abdomen and chest | 62.8 Years STANDARD_DEVIATION 15.5 | 63.4 Years STANDARD_DEVIATION 15.4 | 62.8 Years STANDARD_DEVIATION 15.4 | 62.5 Years STANDARD_DEVIATION 15.3 |
| Age, by type of scan Head | 60.7 Years STANDARD_DEVIATION 19.9 | 60.6 Years STANDARD_DEVIATION 19.9 | 60.4 Years STANDARD_DEVIATION 19.9 | 60.1 Years STANDARD_DEVIATION 19.9 |
| Age, Customized 18-29 years | 18468 CT scans | 15391 CT scans | 73881 CT scans | 40022 CT scans |
| Age, Customized 30-39 years | 21198 CT scans | 17615 CT scans | 84693 CT scans | 45880 CT scans |
| Age, Customized 40-49 years | 29492 CT scans | 24351 CT scans | 118142 CT scans | 64299 CT scans |
| Age, Customized 50-59 years | 46589 CT scans | 37951 CT scans | 182997 CT scans | 98457 CT scans |
| Age, Customized 60-69 years | 54155 CT scans | 44102 CT scans | 212418 CT scans | 114161 CT scans |
| Age, Customized 70-79 years | 45969 CT scans | 39073 CT scans | 177416 CT scans | 92374 CT scans |
| Age, Customized 80 years and older | 35538 CT scans | 29093 CT scans | 135877 CT scans | 71246 CT scans |
| Ethnicity (NIH/OMB) Hispanic or Latino | NA CT scans | NA CT scans | NA CT scans | NA CT scans |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | NA CT scans | NA CT scans | NA CT scans | NA CT scans |
| Ethnicity (NIH/OMB) Unknown or Not Reported | NA CT scans | NA CT scans | NA CT scans | NA CT scans |
| Patient diameter Abdomen | 30.8 Centimeters (cm) STANDARD_DEVIATION 4.7 | 30.9 Centimeters (cm) STANDARD_DEVIATION 4.7 | 30.8 Centimeters (cm) STANDARD_DEVIATION 4.7 | 30.7 Centimeters (cm) STANDARD_DEVIATION 4.6 |
| Patient diameter Chest | 29.0 Centimeters (cm) STANDARD_DEVIATION 4.9 | 28.9 Centimeters (cm) STANDARD_DEVIATION 5.1 | 28.9 Centimeters (cm) STANDARD_DEVIATION 5 | 28.9 Centimeters (cm) STANDARD_DEVIATION 4.9 |
| Patient diameter Combined abdomen and chest | 29.5 Centimeters (cm) STANDARD_DEVIATION 4.2 | 29.7 Centimeters (cm) STANDARD_DEVIATION 4.2 | 29.7 Centimeters (cm) STANDARD_DEVIATION 4.2 | 29.7 Centimeters (cm) STANDARD_DEVIATION 4.1 |
| Patient diameter Head | 17.1 Centimeters (cm) STANDARD_DEVIATION 1.5 | 17.2 Centimeters (cm) STANDARD_DEVIATION 1.5 | 17.1 Centimeters (cm) STANDARD_DEVIATION 1.5 | 17.1 Centimeters (cm) STANDARD_DEVIATION 1.5 |
| Race (NIH/OMB) American Indian or Alaska Native | NA CT scans | NA CT scans | NA CT scans | NA CT scans |
| Race (NIH/OMB) Asian | NA CT scans | NA CT scans | NA CT scans | NA CT scans |
| Race (NIH/OMB) Black or African American | NA CT scans | NA CT scans | NA CT scans | NA CT scans |
| Race (NIH/OMB) More than one race | NA CT scans | NA CT scans | NA CT scans | NA CT scans |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | NA CT scans | NA CT scans | NA CT scans | NA CT scans |
| Race (NIH/OMB) Unknown or Not Reported | NA CT scans | NA CT scans | NA CT scans | NA CT scans |
| Race (NIH/OMB) White | NA CT scans | NA CT scans | NA CT scans | NA CT scans |
| Sex: Female, Male Female | 132772 CT scans | 110088 CT scans | 521701 CT scans | 278841 CT scans |
| Sex: Female, Male Male | 118637 CT scans | 97488 CT scans | 463723 CT scans | 247598 CT scans |
| Type of scan Abdomen | 87518 CT scans | 72084 CT scans | 345273 CT scans | 185671 CT scans |
| Type of scan Chest | 69678 CT scans | 56410 CT scans | 269208 CT scans | 143120 CT scans |
| Type of scan Combined abdomen and chest | 14784 CT scans | 14416 CT scans | 59889 CT scans | 30689 CT scans |
| Type of scan Head | 79429 CT scans | 64666 CT scans | 311054 CT scans | 166959 CT scans |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk |
|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 0 | 0 / 0 | 0 / 0 |
| other Total, other adverse events | 0 / 0 | 0 / 0 | 0 / 0 |
| serious Total, serious adverse events | 0 / 0 | 0 / 0 | 0 / 0 |
Outcome results
Primary
Change in Mean Effective Dose (ED)
We will assess the change in the mean effective dose after the simple audit and multi-component interventions (MCI) in comparison to before the audit and multi-component interventions. The numbers given below reflect absolute change in mean dose (in millisieverts) relative to the baseline period.
Time frame: Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81
Population: The unit of analysis is CT scans; there were no data collected at the participant level. We excluded scans obtained during transition (washout) periods immediately following each intervention. The numbers given below reflect absolute change in mean dose (in millisieverts) relative to the baseline period.
| Arm | Measure | Group | Value (MEAN) |
|---|---|---|---|
| Simple Audit Intervention Period | Change in Mean Effective Dose (ED) | Combined abdomen and chest | -0.88 Millisieverts (mSv) |
| Simple Audit Intervention Period | Change in Mean Effective Dose (ED) | Abdomen | -0.13 Millisieverts (mSv) |
| Simple Audit Intervention Period | Change in Mean Effective Dose (ED) | Head | -0.01 Millisieverts (mSv) |
| Simple Audit Intervention Period | Change in Mean Effective Dose (ED) | Chest | -0.14 Millisieverts (mSv) |
| Multi-component Intervention Period | Change in Mean Effective Dose (ED) | Head | -0.05 Millisieverts (mSv) |
| Multi-component Intervention Period | Change in Mean Effective Dose (ED) | Chest | -0.26 Millisieverts (mSv) |
| Multi-component Intervention Period | Change in Mean Effective Dose (ED) | Abdomen | -0.81 Millisieverts (mSv) |
| Multi-component Intervention Period | Change in Mean Effective Dose (ED) | Combined abdomen and chest | -2.04 Millisieverts (mSv) |
Primary
Percentage of CT Scans With an Effective Dose Above Benchmark
We will assess the change in the percentage of examinations with an effective dose above the benchmark after the simple audit and after multi-component intervention (MCI) in comparison to doses before the audit and MCI. The benchmark for each anatomic area is defined as the 75th percentile of the dose distribution during the pre-intervention (baseline) period.
Time frame: Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81
Population: The unit of analysis is CT scans; there were no data collected at the participant level. We excluded scans obtained during transition (washout) periods immediately following each intervention.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Simple Audit Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Abdomen | 24.7 Percent of CT scans over benchmark |
| Simple Audit Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Chest | 26 Percent of CT scans over benchmark |
| Simple Audit Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Combined chest and abdomen | 26.7 Percent of CT scans over benchmark |
| Simple Audit Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Head | 26.2 Percent of CT scans over benchmark |
| Multi-component Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Head | 26 Percent of CT scans over benchmark |
| Multi-component Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Abdomen | 24.7 Percent of CT scans over benchmark |
| Multi-component Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Combined chest and abdomen | 23 Percent of CT scans over benchmark |
| Multi-component Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Chest | 25.5 Percent of CT scans over benchmark |
| Multi-component Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Head | 21.8 Percent of CT scans over benchmark |
| Multi-component Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Chest | 24.9 Percent of CT scans over benchmark |
| Multi-component Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Combined chest and abdomen | 18.8 Percent of CT scans over benchmark |
| Multi-component Intervention Period | Percentage of CT Scans With an Effective Dose Above Benchmark | Abdomen | 22.2 Percent of CT scans over benchmark |
Secondary
Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT
We will assess the change in organ doses after the simple audit and multi-component interventions (MCI) in comparison to before the audit and multi-component interventions. The numbers given below reflect absolute change in mean dose (in millisieverts) relative to the baseline period.
Time frame: Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81
Population: The unit of analysis is CT scans; there were no data collected at the participant level. We excluded scans obtained during transition (washout) periods immediately following each intervention. The numbers given below reflect absolute change in mean dose (in millisieverts) relative to the baseline period.
| Arm | Measure | Group | Value (MEAN) |
|---|---|---|---|
| Simple Audit Intervention Period | Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Chest (lung organ dose) | -2.1 Milligrays (mGy) |
| Simple Audit Intervention Period | Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Combined chest and abdomen (colon organ dose) | -13.0 Milligrays (mGy) |
| Simple Audit Intervention Period | Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Combined chest and abdomen (lung organ dose) | -16.0 Milligrays (mGy) |
| Simple Audit Intervention Period | Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Head (brain organ dose) | -2.9 Milligrays (mGy) |
| Simple Audit Intervention Period | Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Abdomen (colon organ dose) | -6.0 Milligrays (mGy) |
| Multi-component Intervention Period | Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Head (brain organ dose) | -7.5 Milligrays (mGy) |
| Multi-component Intervention Period | Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Abdomen (colon organ dose) | -12.2 Milligrays (mGy) |
| Multi-component Intervention Period | Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Chest (lung organ dose) | -3.7 Milligrays (mGy) |
| Multi-component Intervention Period | Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Combined chest and abdomen (lung organ dose) | -30.1 Milligrays (mGy) |
| Multi-component Intervention Period | Change in Mean Organ Doses: Brain Dose for Head CT; Lung Dose For Chest CT; Colon and Liver Dose for Abdomen CT | Combined chest and abdomen (colon organ dose) | -17.6 Milligrays (mGy) |
Secondary
Change in Mean Volume Computed Tomography Dose Index (CTDIvol)
We will assess the change in the mean volume CT dose index (CTDIvol) from before versus after the audit and MCI intervention. CTDIvol (in units of milligray, mGy) is a measure of radiation dose, reflecting the amount of radiation imparted per CT slice by the scanner. Higher CTDIvol signifies more radiation dose. In general, a reduction in CTDIvol would be a sign of quality improvement, minimizing excess radiation exposure to the patient.
Time frame: Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81
Population: The unit of analysis is CT scans; there were no data collected at the participant level. We excluded scans obtained during transition (washout) periods immediately following each intervention. The numbers given below reflect absolute change in mean dose (in milligray, mGy) relative to the baseline period.
| Arm | Measure | Group | Value (MEAN) |
|---|---|---|---|
| Simple Audit Intervention Period | Change in Mean Volume Computed Tomography Dose Index (CTDIvol) | Abdomen | 0.09 Milligrays (mGy) |
| Simple Audit Intervention Period | Change in Mean Volume Computed Tomography Dose Index (CTDIvol) | Chest | 0.04 Milligrays (mGy) |
| Simple Audit Intervention Period | Change in Mean Volume Computed Tomography Dose Index (CTDIvol) | Combined abdomen and chest | -0.05 Milligrays (mGy) |
| Simple Audit Intervention Period | Change in Mean Volume Computed Tomography Dose Index (CTDIvol) | Head | 0.44 Milligrays (mGy) |
| Multi-component Intervention Period | Change in Mean Volume Computed Tomography Dose Index (CTDIvol) | Head | -0.56 Milligrays (mGy) |
| Multi-component Intervention Period | Change in Mean Volume Computed Tomography Dose Index (CTDIvol) | Abdomen | 0.03 Milligrays (mGy) |
| Multi-component Intervention Period | Change in Mean Volume Computed Tomography Dose Index (CTDIvol) | Combined abdomen and chest | -0.42 Milligrays (mGy) |
| Multi-component Intervention Period | Change in Mean Volume Computed Tomography Dose Index (CTDIvol) | Chest | -0.11 Milligrays (mGy) |
Secondary
Mean Dose Length Product
We will assess the change in the dose length product after the audit and MCI in comparison to before the audit and MCI.
Time frame: Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81
Population: Data were not collected.
Secondary
Percentage of CT Scans With a CTDIvol Above Benchmark
We will assess the change in the percentage of examinations with a CTDIvol above the benchmark after the audit and after multicomponent intervention in comparison to doses before the audit and multicomponent intervention. The benchmark for each anatomic area is defined as the 75th percentile of the dose distribution during the pre intervention period.
Time frame: Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81
Population: The unit of analysis is CT scans; there were no data collected at the participant level. We excluded scans obtained during transition (washout) periods immediately following each intervention.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Simple Audit Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Head | 24.4 Percentage of CT scans |
| Simple Audit Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Combined chest and abdomen | 23.6 Percentage of CT scans |
| Simple Audit Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Abdomen | 24.5 Percentage of CT scans |
| Simple Audit Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Chest | 26 Percentage of CT scans |
| Multi-component Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Abdomen | 24.9 Percentage of CT scans |
| Multi-component Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Chest | 25.8 Percentage of CT scans |
| Multi-component Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Head | 25.0 Percentage of CT scans |
| Multi-component Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Combined chest and abdomen | 22.7 Percentage of CT scans |
| Multi-component Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Abdomen | 24.1 Percentage of CT scans |
| Multi-component Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Head | 17.9 Percentage of CT scans |
| Multi-component Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Combined chest and abdomen | 19.9 Percentage of CT scans |
| Multi-component Intervention Period | Percentage of CT Scans With a CTDIvol Above Benchmark | Chest | 24.1 Percentage of CT scans |
Secondary
Proportion of CT Scans With a Dose Length Product Above Benchmark
We will assess the change in the proportion of examinations with a dose length product above the benchmark after the audit and after the MCI in comparison to doses before the audit and MCI. The benchmark for each anatomic area is defined as the 75th percentile of the dose distribution during the pre intervention period.
Time frame: Sites were randomized to 1 of 3 tracks, which determined the timing of intervention: Track A: audit at week 40, MCI at week 68 Track B: audit at week 44, MCI at week 74 Track C: audit at week 53, MCI at week 81
Population: Data were not collected.