Introduction: DICOM Image Customization

DICOM image customization involves modifying both metadata and the byte array in a DICOM file. This includes adjusting tag elements, padding, and offsets to align with specific requirements. Below is an overview of the procedure used to customize a DICOM image.

Procedure Overview

The customization process consists of the following steps:

• sortTags – Organizes DICOM tags in ascending order based on offset.

• preProcessByteArray – Ensures proper padding for Value Representations (VRs).

• customizeByteArray – Evaluates shifts in the byte array.

• changeOffsets – Updates lengths and offsets in the dataset and metadata objects.

sortTags: Sorting Tags and Custom Tags by Offset

Purpose: Sorts standard and custom DICOM tags in ascending order based on their offset positions, ensuring sequential processing.

Steps:

• Organize both standard and custom tags based on offset.

• Identify the minimum offset in the custom tags to serve as the starting shift point.

• Add necessary padding to custom tags to maintain alignment.

preProcessByteArray: Checking and Adjusting Padding

Purpose: Ensures that certain Value Representations (VRs) maintain a consistent structure by enforcing even-length values.

Steps:

• Identify odd-length tag values and pad them with a space (ASCII 32) if needed.

Example: A tag value of "TEST1" (length = 5) will be padded to "TEST1 " (length = 6) to maintain even-length formatting.

customizeByteArray: Evaluating Byte Array Shifts

Purpose: Calculates necessary shifts in the byte array caused by tag modifications, ensuring proper alignment.

Steps:

• Identify changes in tag lengths and compute how these modifications affect subsequent tag positions.

• Apply the necessary shifts to adjust the dataset structure.

Example: A tag at offset 10 changes from length 5 to 3, shifting subsequent tags backward by 2 bytes.

• Update shifts for all consecutive tags to maintain consistency.

changeOffsets: Updating Dataset and Metadata

Purpose: Ensures that all tag offsets and lengths are accurately updated in both the dataset and metadata objects.

Steps:

• Adjust tag lengths and offsets according to the shifts determined in customizeByteArray.

• Verify that all tags are properly aligned in the dataset.

• Ensure metadata consistency by checking that tag values are correctly mapped in the updated structure.

API Reference

customizeByteArray

Generates a customized version of the DICOM series by modifying its metadata and byte array based on specified custom tags.

Syntax

customizeByteArray (
series: Series,
customTags: MetaData
): Series

Parameters

Parameter	Type	Description
series	Series	Series to customize
customTags	MetaData	The customized tags/metadata to set

Returns

Series – The customized series with updated metadata and byte array.

How to save the customized series

To save the newly modified series as a DICOM file, use the following approach:

var blob = new Blob(
  [
    series.instances[
      series.imageIds[
        parseInt(document.getElementById("downloadInput").value, 10)
      ]
    ].dataSet.byteArray
  ],
  {
    type: "application/dicom"
  }
);

This code creates a Blob object from the byte array of a selected instance in the series, allowing it to be saved as a valid DICOM file.