Transfer Syntax
A transfer syntax is the set of encoding rules — byte ordering, explicit or implicit value representation, and any compression — that a DICOM object is written in, and it is negotiated between two devices before they exchange data.
What Transfer Syntax means in practice
Each transfer syntax has its own unique identifier, so a sending device can offer several and let the receiver pick one both support. That negotiation is why a study can be sent compressed to one destination and uncompressed to another without changing the images. A receiver that supports only Implicit VR Little Endian will still work, because every DICOM implementation is required to support it.
Source
This definition follows NEMA PS3.5 §10 and Annex A — Transfer Syntaxes, published by NEMA as part of the DICOM standard.
Related terms
Lossless compression (DICOM)
Lossless compression reduces the size of DICOM Pixel Data while allowing the exact original pixel values to be reconstructed, unlike lossy compression, which permanently discards image information to achieve a smaller file.
Pixel Data
Pixel Data is the DICOM data element, tag (7FE0,0010), that holds the actual image content of an instance, encoded according to the file's transfer syntax.
C-STORE
C-STORE is the DICOM network service used to transfer a composite object — an image or similar instance — from one device to another, and it is the operation behind "sending a study" to a PACS.
Storage SCP
A Storage SCP is the role a device plays when it accepts incoming DICOM images, listening for C-STORE requests and storing what it receives — the role a PACS or an archiving viewer performs.
Related on this site: Transfer syntaxes SoftDicom reads.