The CTP Lookup Table Editor

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This article describes how to update the DICOM Anonymizer lookup table to manually assign subject IDs in clinical trials. The intended audience of this article is clinical trial administrators and coordinators.

In some clinical trials, subject identifiers are manually assigned before images are acquired and processed. In such trials, the DICOM Anonymizer is configured to convert the text stored in the PatientID element of an image into a non-PHI subject ID. CTP provides a Lookup Table Editor web page for assigning the subject IDs. This page can be accessed by any user with the CTP admin privilege.

To access the page, log in as an admin user and click the Lookup Table Editor button on the home page. A page will load, listing all the anonymizers that have lookup tables in the configuration. Click on the desired lookup table. A new page will load, listing all the values currently in the table and providing a row to add a new value:

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Because the lookup table can be used for mapping many types of elements, each type of element is assigned a keytype by the administrator who configures the DICOM anonymizer script for the trial. The keytypes that appear in the anonymizer script are listed on the Lookup Table Editor page for convenience.

When adding a key to the table, enter the keytype, a forward slash, and the PHI value in the left field and the replacement value in the right field. If a DICOM anonymizer script only references a single keytype, it is not necessary to enter the keytype or the forward slash in the left column; the Lookup Table Editor will insert them automatically. After entering the two values, click the Save icon in the upper right corner of the window body.

In trials where subject IDs are preassigned, it is possible to enter the replacement values in advance. To enter a preassigned replacement value, enter the value in the left column preceded by two periods, and leave the right column blank. Then click the Save icon. Preassigned values appear in in the table like this:

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When inserting PHI values for preassigned replacement values, multiple values can be entered before clicking the Save icon.

The current contents of the lookup table are shown in the table under the entry fields. It is possible to update an entry by re-entering it.

For convenience, two icons on the right side of the pane allow the lookup table to be downloaded to or uploaded from a spreadsheet in CSV format. The recommended procedure is to download the lookup table, open it with the spreadsheet program, add as many subjects as desired, save the spreadsheet as a CSV file, and then upload it to the Lookup Table Editor. When adding rows in the spreadsheet program, column A contains KeyType/PHI values and column B contains replacement values. No title row is allowed.

Note: The lookup table is a properties file consisting of lines, one per property. Each property is a key=value pair, where the key is the concatenation of the keytype, the forward slash, and the replacement value. A simple lookup table properties file with a few preassigned replacement values might look like this:
#Wed Nov 20 12:50:03 CST 2013

IMPORTANT NOTE: The lookup table is used during the processing of DICOM images. After an image has been processed, subsequent changes in the table do not affect it. Therefore, it is not a good idea to modify entries that have already been used to process images. Doing so might assign the same subject ID to multiple subjects.