DICOM PS3.3 2019a - Information Object Definitions

C.8.8 Radiotherapy Modules

This Section describes Radiotherapy-specific Modules.

Modules defined here make reference to "IEC" coordinate systems and standards. These standards are defined in IEC Standard 61217, "Radiotherapy Equipment - Coordinates, Movements and Scales" (Reference CEI/IEC 61217: 1996).


IEC document 62C/269/CDV "Amendment to IEC 61217: Radiotherapy Equipment - Coordinates, movements and scales" also defines a Patient-Based Coordinate System, and specifies the relationship between the DICOM Patient-Based Coordinate System (see Section C. and the IEC PATIENT Coordinate System. Rotating the IEC PATIENT Coordinate System described in IEC 62C/269/CDV (1999) by 90 degrees counter-clockwise (in the negative direction) about the x-axis yields the DICOM Patient-Based Coordinate System, i.e., (XDICOM, YDICOM, ZDICOM) = (XIEC, -ZIEC, YIEC). Refer to the latest IEC documentation for the current definition of the IEC PATIENT Coordinate System.

Many of the dosimetry concepts referred to in this document can be found in [ICRU Report 50].

C.8.8.1 RT Series Module

There exist significant differences in the manner in which RT objects as compared to diagnostic objects. An RT object can be one of several types, and a series of a given object type may be created over a temporal span of several weeks. The RT Series Module has been created to satisfy the requirements of the standard DICOM Query/Retrieve model while including only those Attributes relevant to the identification and selection of radiotherapy objects.

Table C.8-37. RT Series Module Attributes

Attribute Name



Attribute Description




Type of equipment that originally acquired the data.

Enumerated Values:


RT Image


RT Dose


RT Structure Set


RT Plan


RT Treatment Record

See Section C.

Series Instance UID



Unique identifier of the Series.

Series Number



A number that identifies this Series.

Series Date



Date the Series started.

Series Time



Time the Series started.

Series Description



Description of the Series.

Series Description Code Sequence



A coded description of the Series.

Only a single Item is permitted in this Sequence.

>Include Table 8.8-1 “Code Sequence Macro Attributes”

No Baseline CID is defined.

Operators' Name



Name(s) of the operator(s) supporting the Series.

Operator Identification Sequence



Identification of the operator(s) supporting the Series. One or more Items may be present in this Sequence. If more than one Item, the number and order shall correspond to the value of Operators' Name (0008,1070), if present.

>Include Table 10-1 “Person Identification Macro Attributes Description”

Referenced Performed Procedure Step Sequence



Uniquely identifies the Performed Procedure Step SOP Instance to which the Series is related.

One or more Items are permitted in this Sequence.

>Include Table 10-11 “SOP Instance Reference Macro Attributes”

Request Attributes Sequence



Sequence that contains Attributes from the Imaging Service Request.

One or more Items are permitted in this Sequence.

>Include Table 10-9 “Request Attributes Macro Attributes”

No Baseline CID is defined.

Include Table 10-16 “Performed Procedure Step Summary Macro Attributes”

No Baseline CID is defined.

C. Modality

The Enumerated Value for Modality (0008,0060) shall determined by the IOD.

Enumerated Values if RT Image IOD:


Enumerated Values if RT Dose IOD:


Enumerated Values if RT Structure Set IOD:


Enumerated Values if RT Plan IOD or RT Ion Plan IOD:



DICOM specifies that a given Series shall contain objects of only one Modality, and shall be created by a single device (described in the General Equipment Module). However, in general there may be many Series defined for a given modality/device pair. Note that a radiotherapy Series is generally created over an extended time interval (unlike in radiology, where all images in an image Series are generally created together).

DICOM PS3.3 2019a - Information Object Definitions