General-DICOM

TCP limitations in DICOM

DICOM uses TCP (transmission control protocol) as its underlying network transport layer, and despite its widespread and generally successful use around the world for most Internet use, TCP does have some significant limitations. In practice, these limitations are extremely rarely encountered in real life, but they can sometimes be seen in stress test scenarios, and it is then important to to be able to distinguish between those failures which are due to the DICOM application being tested, and those which are intrinsic to TCP itself.

How to Specify the Cine Display Rate

There are multiple ways of specifying Cine Rate (Multi-Frame Display Speed) in DICOM, in two categories:

The actual acquisition times of the frames

There are two ways of specifying this, equally spaced or arbitrary, and the choice is defined by attribute Frame Increment Pointer (0028,0009), which will point at one or other of the following attributes:

Creating Secondary Capture Images

Any 'valid' Dicom Image is a conglomeration of Pixel data and several mandatory data attributes. To generate a Secondary Capture (SC) Image from existing non-Dicom image then all that is required is to load the required image into a DicomImage using the import function and then adding on the appropriate attributes. Dicom Objects will automatically take care of all the attributes relating to the pixel data (Group 0x0028).

Patient Orientation

Description Value in (0020,0020) Image
Original R\P
Rotated 90° A\R
Rotated 180° L\A
Rotated 270° P\L

UID Rules

There are several rules to be followed when making UIDs, and this page is a useful summary

Hounsfield Units


Hounsfield Units (HU) are used in CT images it is a measure of radio-density, calibrated to distilled water and free air.

HUs can be calculated from the pixel data with a Dicom Image vir two methods.

The first (and harder) method involves using the Slope and intercept value from the Dicom image and applying it to a target pixel.

HU = m * P + b

where: m is the Dicom attribute (0028,1053) "Rescale slope" b is the Dicom attribute (0028,1052) "Rescale intercept" P is the value of that particular pixel in the pixels array.

Get Patient Info from DICOM Print

Is it possible to get patient information from DICOM Print?

Some developers, faced by systems with DICOM Print and no DICOM C-STORE have wondered whether that "DICOM output" could be used to capture images to store in a PACS.

Hierarchical SOP Instance

While DicomObjects can not create a Dicom Hierarchical SOP Instance dataset collection directly, however it can do much of the work for you. A Hierarchical SOP Instance Dataset collection are similar in structure to a DicomDir which DicomObjects can create automatically. Hierarchical SOP Instances are primarily used in the creation of Key Note Objects. The Structure of the Hierarchical SOP Instance is Study - Series - Instance (NO PATIENT)

DICOM

Digital Imaging & Communication in Medicine

DICOM is the main standard used in medical imaging, and is the main purpose of DicomObjects

HISTORY

UIDs

UIDs are fundamental to DICOM and have many uses, including there being a unique one for each SOP_Class and for each Composite_Instance and each Normalised_Instance.

There are several rules for how a UID is constructed:

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