---
sidebar_position: 4
sidebar_label: SOP Class Handler
title: SOP Class Handler Module
summary: Documentation for OHIF SOP Class Handler Module, which processes specific DICOM SOP classes into displayable sets, supporting various medical imaging formats and defining how different types of DICOM data are prepared for viewing.
---
# Module: SOP Class Handler

## Overview
This module defines how a specific DICOM SOP class should be processed to make a list of `DisplaySet`, things which can be hung in a viewport. An extension can register a [SOP Class][sop-class-link] Handler Module by defining a `getSopClassHandlerModule` method. The [SOP Class][sop-class-link].

The mode chooses what SOPClassHandlers to use, so you could process a series in a different way depending on mode within the same application.

SOPClassHandler is a bit different from the other modules, as it doesn't provide a `1:1`
schema for UI or provide its own components. It instead defines:

- `sopClassUIDs`: an array of string SOP Class UIDs that the
  `getDisplaySetFromSeries` method should be applied to.
- `getDisplaySetFromSeries`: a method that maps series and study metadata to a
  display set

A `displaySet` has the following shape:

```js
return {
  Modality: 'MR',
  displaySetInstanceUIDD
  SeriesDate,
  SeriesTime,
  SeriesInstanceUID,
  StudyInstanceUID,
  SeriesNumber,
  FrameRate,
  SeriesDescription,
  isMultiFrame,
  numImageFrames,
  SOPClassHandlerId,
  madeInClient,
}
```

## Example SOP Class Handler Module

```js
import ImageSet from '@ohif/core/src/classes/ImageSet';


const sopClassDictionary = {
  CTImageStorage: "1.2.840.10008.5.1.4.1.1.2",
  MRImageStorage: "1.2.840.10008.5.1.4.1.1.4",
};


// It is important to note that the used SOPClassUIDs in the modes are in the order that is specified in the array.
const sopClassUids = [
  sopClassDictionary.CTImageStorage,
  sopClassDictionary.MRImageStorage,
];

function addInstances(instances)  {
   // Add instances to this display set, and return the display set updated.
}

const makeDisplaySet = (instances) => {
  const instance = instances[0];
  const imageSet = new ImageSet(instances);

  imageSet.setAttributes({
    displaySetInstanceUID: imageSet.uid,
    SeriesDate: instance.SeriesDate,
    SeriesTime: instance.SeriesTime,
    SeriesInstanceUID: instance.SeriesInstanceUID,
    StudyInstanceUID: instance.StudyInstanceUID,
    SeriesNumber: instance.SeriesNumber,
    FrameRate: instance.FrameTime,
    SeriesDescription: instance.SeriesDescription,
    Modality: instance.Modality,
    isMultiFrame: isMultiFrame(instance),
    numImageFrames: instances.length,
    SOPClassHandlerId: `${id}.sopClassHandlerModule.${sopClassHandlerName}`,
    addInstances,
  });

  // Note returns an array now
  return [imageSet];
};

getSopClassHandlerModule = () => {
  return [
    {
      name: 'stack,
      sopClassUids,
      getDisplaySetsFromSeries: makeDisplaySet,
    },
  ];
};

```

### addInstances
In order to allow new SOP instances to be received and added to an existing display
set, the addInstances method can be added to a display set.  It is called
on the display set to be updated, and returns it when it has added at least one
of the instances to the display set.

### More examples :
You can find another example for this mapping between raw metadata and displaySet for
`DICOM-SR` extension.

## `@ohif/app` usage

We use the `sopClassHandlerModule`s in `DisplaySetService` where we
transform instances from the raw metadata format to a OHIF displaySet format.
You can read more about DisplaySetService here.

<!-- prettier-ignore-start -->
[sop-class-link]: http://dicom.nema.org/dicom/2013/output/chtml/part04/sect_B.5.html
[dicom-html-sop]: https://github.com/OHIF/Viewers/blob/master/extensions/dicom-html/src/OHIFDicomHtmlSopClassHandler.js#L4-L12
[dicom-pdf-sop]: https://github.com/OHIF/Viewers/blob/master/extensions/dicom-pdf/src/OHIFDicomPDFSopClassHandler.js#L4-L6
[dicom-micro-sop]: https://github.com/OHIF/Viewers/blob/master/extensions/dicom-microscopy/src/DicomMicroscopySopClassHandler.js#L5-L7
[dicom-seg-sop]: https://github.com/OHIF/Viewers/blob/master/extensions/dicom-segmentation/src/OHIFDicomSegSopClassHandler.js#L5-L7
<!-- prettier-ignore-end -->