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Dynalog Import

David Kirkaldie
  • Updated

Topics covered in this article include:

SpeedSimple.gifSpeedComplex.gifRepeatability.gif

Introduction

Dynalog files are generated by the MLC controller during the delivery. The controller appends a new record in the dynalog every 50 ms. Two files are generated per treatment field, one per MLC bank. The data includes the beam status (on/off), the beam hold-off indicator, the segment number (time interval), the position of the jaws, the gantry angle, the expected and actual positions of each MLC leaf and the fractional dose delivered at the instant marked by the record. ¹

Dynalog files may be used to determine leaf accuracy, speed and repeatability. Individual leaves are identified to troubleshoot potential problems. In addition, maximum deviations by leaf are displayed for each bank.

Measurement Summary

The analysis displays the following test results:

  • Leaf Animation
  • Accuracy by Leaf
  • Leaf Accuracy Summary
  • Leaf Speed by Leaf
  • Leaf Speed Summary
  • Repeatability by Pattern and Repeat
  • Repeatability Summary

The measurements are completely automated, requiring the user only to drag and drop the file into the web-based software interface. A detailed report is created.

Instructions

The test requires two DLG files; one for each bank.  The file name should look like A*.dlg and  B*.dlg, case-insensitive, where the * portion of the name matches between the two files. Below is an example of selecting the image type in the upload widget:

dynalog004.png

When imaging QA tests are added to templates an upload control will appear in the scheduled QA's data entry screen allowing the user to upload images for automated analysis.

To add files to the upload queue simply drag them from a Windows Explorer folder to the drag and drop folder and release them. Alternatively, by clicking on the Add Files button to the lower right of the control a windows file selection dialog will open and files can be selected for upload. Under either method, multiple files may be selected for upload at once.

If the automatically upload checkbox is checked (the default) then file uploading will start immediately as files are added

hancock004.png

If the automatically upload button is turned to off the file upload process must be started manually clicking the Start upload button on the lower right of the control. To clear the upload queue click the Clear button.

dynalog005.png

Once file series have been uploaded they will be displayed below the upload control. To remove a series from the queue click the Cancel button beside the series. To start processing click the Start Processing button. A description for the image series can be added at this point. Click the Edit button next to the series. Type a description for the series into the text box that appears below Description and either click Save or press the enter key. The description can also be edited after the images have been processed. Descriptions will appear in the report with the analysis of the series. 

dynalog007.png

While files are being processed users may perform other tasks such as data entry.

Available Tests

Template Section Subsection Tests
Dynalog File Analysis Visualization
  • Leaf Animation
Accuracy
  • Accuracy by Leaf
  • Leaf Accuracy Summary
Speed
  • Leaf Speed by Leaf
  • Leaf Speed Summary
Repeatability
  • Repeatability by Pattern and Repeat
  • Repeatability Summary

 

Specifications to Create a Plan File

Please use your manufacturers recommended plan file where available. 

QA Settings

To obtain accurate results, the correct MLC must be selected in the QA settings. Navigate to Manage Schedule Configurations, click on the schedule, and ensure the correct MLC is selected:

dynalog003.png

Detailed Discussion of Measurements

For information on how the measurements were recorded in the log, please see the manufacturer's reference manual.

Leaf Animation

The leaf animation section displays a Graphics Interchange Format (.gif) file for each pair of files uploaded so that the leaf movement may be visualized. Bank B is on the left, while bank A is on the right. If the leaf widths do not match the model MLC, the QA settings should be checked to verify the correct model is selected (see the QA Settings section for full details).

Accuracy

All sequences, either step and repeat or continuous beam, will yield results for the accuracy test. The tables below are generated by the accuracy test.

AccuracyByLeaf.png

The table above provides the following measurements:

  • Leaf Pair - number of the leaf pair.
  • Max. Abs. Deviation Bank A - The maximum absolute deviation for the leaf pair measured for bank A.
  • Max. Abs. Deviation Bank B - The maximum absolute deviation for the leaf pair measured for bank B.
  • Total Deviation x Time Bank A - The maximum absolute deviation for the leaf pair measured for bank A multiplied by the time spent at deviance with the expected position. The helps identify leaves that have frequent deviations. A larger time spent at a deviation may be indicative of an issue. 
  • Total Deviation x Time Bank B - The maximum absolute deviation for the leaf pair measured for bank B multiplied by the time spent at deviance with the expected position. The helps identify leaves that have frequent deviations. A larger time spent at a deviation may be indicative of an issue. 

LeafAccuracySummary.png

The table above provides a summary of the leaves with the maximum absolute deviation. The table provides the following measurements:

  • Leaf Bank - the leaf bank, A or B.
  • Max. Abs. Deviation - The maximum absolute deviation measured for an individual leaf in the bank.
  • Max. Abs. Deviation Leaf - The leaf number where the maximum absolute deviation was measured.
  • Maximum Total Deviation x Time - The maximum absolute deviation measured for any leaf in the bank multiplied by the time spent at deviance with the expected position. The helps identify the leaf with the most frequent deviations. A larger time spent at a deviation may be indicative of an issue. 
  • Maximum Total Deviation x Time Leaf - The leaf number where the maximum total deviation x time was measured.

Note: if more than one leaf is found at the same maximum value, only the first will be reported.

Speed

Speed tests require the beam to be on during leaf movement sequences. The speed measures from the time the leaf reaches a steady speed until it reaches its destination. Here are examples of speed patterns:

 

SpeedSimple.gifSpeedComplex.gif

Below are the tables generated  by the speed tests.

LeafSpeedByLeaf.png

The table above provides the following measurements:

  • Leaf Pair - number of the leaf pair.
  • Mean Leaf Speed Bank A - mean leaf speed of the specified leaf in bank A.
  • Mean Leaf Speed Bank B - mean leaf speed of the specified leaf in bank B.

LeafSpeedSummary.png

The table above provides the following measurements:

  • Leaf Bank - the leaf bank, A or B.
  • Mean Leaf Speed - the mean leaf speed of all leaves in the bank.
  • Maximum - the maximum leaf speed of all leaves in the bank.
  • Maximum Leaf - the leaf where the maximum leaf speed was measured.
  • Minimum - the minimum leaf speed of all leaves in the bank.
  • Minimum Leaf - the leaf where the minimum leaf speed was measured.
  • Leaf Speed Standard Deviation - the standard deviation of all leaves in the bank.

Note: if more than one leaf is found at the same maximum value, only the first will be reported.

Repeatability

Repeatability tests require a step and repeat acquisition where the beam is off during leaf movement. The beam off time segments the patterns in the sequence. At least two distinct patterns must be used and each pattern must be repeated at least once. Here is an example:

Repeatability.gif

In the example above there are two patterns:

Reproducibility-pattern2.pngReproducibility-pattern1.png

The first pattern encountered is labeled pattern 1, the second pattern 2, and so on. Each pattern is repeated at least once. If the patterns were interspersed in a series of 1,2,1,2,1 each pattern would have its own table and the Pattern Repeat shows which number in the series is being compared to the first instance of the pattern:

Series Number Pattern Pattern Repeat
1 1 -
2 2 -
3 1 3
4 2 4
5 1 5

Below are the two tables produced by the image pattern above: 

Repeatability001.png

 Repeatability002.png

Results for bank a and b are given for each pattern and pattern repeat combination.

  • Maximum Absolute Deviation - displays the maximum absolute deviation for a leaf pair when comparing all of the pattern repeats against the first instance of the pattern. 
  • Maximum Absolute Deviation Leafs - displays the leaf pair number where the maximum absolute deviation occurred.
  • Value at Maximum Absolute Deviation - displays the maximum deviation and whether it was positive or negative.

Example Report

Below is an example of a report where a repeatability sequence was used. Note that the speed test is not generated for a repeatability sequence.

dynalog001.png

Citations

1. Rodriguez, M., Brualla, L. Treatment verification using Varian’s dynalog files in the Monte Carlo system PRIMO. Radiat Oncol 14, 67 (2019). https://doi.org/10.1186/s13014-019-1269-1

Example Files

Below are example files for use in testing: 

 

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