The full documentation that lists the DICOM Standards PS 3.3-2011, pp 388-389: Section C.7.3.1.1.1 http://medical.nema.org/Dicom/2011/11_03pu.pdf.
(Click table headers to sort)
Short Long CR Computed Radiography CT Computed Tomography MR Magnetic Resonance NM Nuclear Medicine US Ultrasound OT Other BI Biomagnetic imaging DG Diaphanography ES Endoscopy LS Laser surface scan PT Positron emission tomography (PET) RG Radiographic imaging (conventional film/screen) TG Thermography XA X-Ray Angiography RF Radio Fluoroscopy RTIMAGE Radiotherapy Image RTDOSE Radiotherapy Dose RTSTRUCT Radiotherapy Structure Set RTPLAN Radiotherapy Plan RTRECORD RT Treatment Record HC Hard Copy DX Digital Radiography MG Mammography IO Intra-oral Radiography PX Panoramic X-Ray GM General Microscopy SM Slide Microscopy XC External-camera Photography PR Presentation State AU Audio ECG Electrocardiography EPS Cardiac Electrophysiology HD Hemodynamic Waveform SR Structured Report Document IVUS Intravascular Ultrasound OP Ophthalmic Photography SMR Stereometric Relationship AR Autorefraction KER Keratometry VA Visual Acuity SRF Subjective Refraction OCT Optical Coherence Tomography (non-Ophthalmic) LEN Lensometry OPV Ophthalmic Visual Field OPM Ophthalmic Mapping OAM Ophthalmic Axial Measurements RESP Respiratory Waveform KO Key Object Selection SEG Segmentation REG Registration OPT Ophthalmic Tomography BDUS Bone Densitometry (ultrasound) BMD Bone Densitometry (X-Ray) DOC Document FID Fiducials PLAN Plan IOL Intraocular Lens Data IVOCT Intravascular Optical Coherence Tomography SC Secondary Capture modality for diagnostic use