The Scatterplot Over Time report helps identify unusual patterns or outliers for DIR dose indices. You may elect to plot either the max or total dose index for CTDIvol, Dose Length Product (DLP), or size-specific dose estimate (SSDE).
To access the report, start by clicking CT Standardized Dose Index Reports from the Interactive Reports submenu, then click on the Scatterplot Over Time tab.
Select at least one Corporate Account and click Apply to create a scatterplot. By default, the report filters are set to retrieve exams for all facilities with study dates occurring within the past seven days for all RPIDs and scanners.
Use the report filters and parameters to refine the data in the scatterplot:
Facility lists all facilities associated with the selected corporate account(s)
DIR Measure selects the Dose Index type (CTDIvol, DLP, or SSDE) to be displayed using either the maximum value across scans or total for the exam
Note: Maximum and total values are the same for single-scan exams
There are two separate filters for study dates
Include Data From specifies the time period to include, relative to today. The default is the past seven days
Exam Date displays the range of exam dates actually available and can be used to narrow the time frame to a range within the Include Data From time period
Query by determines whether the RPID / Study Description filter displays standardized RPID exam names or the facility's Study Descriptions
Body Part restricts the RPID / Study Description filter to exams for the specified body part(s)
RPID / Study Description lists the available RPIDs or Study Descriptions, as determined by the Query by parameter setting
Registry Statistics selects the comparison statistics for the entire registry for display on the chart. The 75th percentile is selected by default. Only data for the oldest age group are used for highlighting. Registry statistics are not highlighted in the following cases
No registry statistics are available for the selected RPID
More than one RPID is selected in the RPID / Study Description filter
The Query by parameter is set to Study Description
Note: DIR statistics are available only for scatterplots when Query by is set to RPID because Study Descriptions are not standardized and cannot be aggregated and compared across DIR facilities.
The following example illustrates different features and components of the scatterplot report using the following criteria:
Dose Index Type: CTDIVol Max across Scans
Age Group: All
Include Data from: Last 3 Years
Exam Date Range: Aug. 22 - Dec. 31, 2016
RPIDs: CT ABD PELVIS W IVCON (RPID145)
Registry Statistics: 75th Percentile
The report plots each value of CTDIvol, in mGy, by date. The Registry Statistics table lists each age group and number of observations for the facility, and the median and 75th percentiles for the entire registry from the most recent DIR semiannual report. The 75th percentile for the oldest age group, Over 18, also appears in the chart with a red line and tan background to highlight values above the statistic.
A total of 650 exams for the facility appear on the plot for nine different scanners. The Scanner Statistics table summarizes the number of observations and minimum, maximum, and average measure values. The table is color coded with red indicating the largest values within each column. The color coding highlights 28.7 as the largest mean across all scanners. Clicking on that row highlights the data points for that scanner in the scatterplot, making it easier to see which exams from that scanner are higher than the DIR statistic.
Note: You can also highlight data by clicking on a scanner in the Scanner Legend.
Although the majority of exams are for adult patients, there are some pediatric exams, as indicated by the age group distribution. Using the Age Group filter, we can restrict the plot to a single pediatric age group, such as the 15-18 group. Doing so also changes the highlighted registry statistic from 18.3 to 12.2, providing a more useful comparison for these data points.