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Interactive Reports: Scatterplot Over Time

The Scatterplot Over Time report helps identify unusual patterns or outliers for DIR dose indices. You can plot either the maximum or total dose index for CTDIvol, Dose Length Product (DLP), or Size-Specific Dose Estimate (SSDE).

To access the Scatterplot Over Time report, click on the CT Standardized Dose Index report 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 within the past 30 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)

  • Use the Exam Dates From and To filters to refine the search time period. By default the filters are set to query data for the past 30 days.

  • 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

  • Age Group

  • 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

  • Scanner

  • Highlight selects the comparison statistics for the entire registry for display on the chart, for the age group with the most exams, as listed in the Facility Exam Count table. The default selection is None. 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.

    • There are too few exams for the entire registry (fewer than 100 exams or 10 facilities) for the RPID and age group.

    • 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.

Sample Scatterplot and Functionality

The following example illustrates different features and components of the scatterplot report using the following criteria.

  • DIR Measure: CTDIVol Max across Scans

  • Exam Dates From 1/1/20 To 2/28/20

  • Query by: RPID


  • Highlight: 75th Percentile

DIR Interactive Reports - Sample Scatterplot 1

The report plots each value of CTDIvol, in mGy, by date. The Facility Exam Count table lists the number of exams, by age group, and the Registry Statistics table lists the corresponding number of studies, the median, and the 75th percentile for the entire registry for the comparison time period. Because the Highlight parameter is set to 75th Percentile that statistic is highlighted on the chart, using data for the Adult (Over 18) age group because it has the most data of all age groups listed in the Facility Exam Counts table.  A total of 323 exams for the facility appear on the plot for two different scanners. The Scanner Statisticstable summarizes the number of observations and minimum, maximum, and median measure values, with color-coding to indicate the largest values within each column. The color-coding highlights 13.9 as the largest median across all scanners. Clicking on that row highlights it in the table and filters the scatterplot to show only the data points for that scanner, making it easier to see which exams from that scanner are higher than the DIR statistic (see image, below).

DIR SDIR - Sample Scatter Plot 2

To undo the filter, click on the highlighted row a second time, or click the Undo button, in the lower-left corner.  You can also highlight data by clicking on a scanner in the Scanner Legend. Although nearly all exams are for adult patients, there is one pediatric exam, as indicated by the age group distribution. Using the Age Group filter, you can restrict the plot to a single pediatric age group, e.g. 15 - 18y. Doing so also changes the highlighted registry statistic from 18.2 to 12.1, providing a more useful comparison for this data. You can also click on the 15-18y group in the Facility Exam Count table, which then filters the scatterplot and updates the highlighted 75th percentile.

DIR SDIR - Sample Scatter Plot 3

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