C.4.16 Radiation Dose

Table C.4-16 defines the Attributes that may be used to communicate information related to radiation dose values. The attributes are intended to enable the Information System to store Patient exposure to ionizing radiation for legal purposes. Though these attributes are not intended to be used to accurately calculate volume dose distribution, they may serve for some quality control purposes.

This module provides a means to communicate radiation dose values but DICOM does not define any requirements for the accuracy of these values, which may be defined in other professional, national or international standards.

The scope of the attributes contained in this module covers the entire acquisition that comprises the Modality Performed Procedure Step. Attributes that relate to single images, such as mAs or kVP, may be included in the Image IODs. It is beyond the scope of DICOM to define what attributes may be required to calculate or estimate area dose product values.

Note: The X-Ray Radiation Dose SR SOP Class provides a more comprehensive means of reporting radiation dose. Such a dose report may be referenced in the Image Acquisition Results Module.

Table C.4-16

RADIATION DOSE MODULE ATTRIBUTES

Attribute Name Tag Attribute Description
Anatomic Structure, Space or Region Sequence (0008,2229) Anatomic structure, space or region that has been exposed to ionizing radiation. Zero or one Item shall be included in this Sequence.
>Include ‘Code Sequence Macro’ Table 8.8-1 No Baseline Context ID is defined.
Total Time of Fluoroscopy (0040,0300) Total duration of X-Ray exposure during fluoroscopy in seconds (pedal time) during this Performed Procedure Step.
Total Number of Exposures (0040,0301) Total number of exposures made during this Performed Procedure Step. The number includes non-digital and digital exposures.
Distance Source to Detector (0018,1110) Distance in mm from the source to detector center. Note: This value is traditionally referred to as Source Image Receptor Distance (SID).
Distance Source to Entrance (0040,0306) Distance in mm from the source to the surface of the patient closest to the source during this Performed Procedure Step. Note: This may be an estimated value based on assumptions about the patient’s body size and habitus.
Entrance Dose (0040,0302) Average entrance dose value measured in dGy at the surface of the patient during this Performed Procedure Step. Note: This may be an estimated value based on assumptions about the patient’s body size and habitus.
Entrance Dose in mGy (0040,8302) Average entrance dose value measured in mGy at the surface of the patient during this Performed Procedure Step. Note: This may be an estimated value based on assumptions about the patient’s body size and habitus.
Exposed Area (0040,0303) Typical dimension of the exposed area at the detector plane. If Rectangular: row dimension followed by column; if Round: diameter. Measured in mm. Notes: 1. This may be an estimated value based on assumptions about the patient’s body size and habitus. 2. This attribute is used in the X-Ray Acquisition Dose Module with units in cm (see Section C 8.7.8 Table C.8-33).
Image and Fluoroscopy Area Dose Product (0018,115E) Total area-dose-product to which the patient was exposed, accumulated over the complete Performed Procedure Step and measured in dGy*cm*cm, including fluoroscopy. Notes: 1. The sum of the area dose product of all images of a Series or a Study may not result in the total area dose product to which the patient was exposed. 2. This may be an estimated value based on assumptions about the patient’s body size and habitus.
Comments on Radiation Dose (0040,0310) User-defined comments on any special conditions related to radiation dose encountered during this Performed Procedure Step.
Exposure Dose Sequence (0040,030E) Exposure Dose Sequence will contain Total Number of Exposures (0040,0301) items plus an item for each fluoroscopy episode not already counted as an exposure. Zero or more Items shall be included in this sequence.
>Radiation Mode (0018,115A) Specifies X-Ray radiation mode. Enumerated Values: CONTINUOUS PULSED
>KVp (0018,0060) Peak kilo voltage output of the x-ray generator used. An average in the case of fluoroscopy (continuous radiation mode).
>X-Ray Tube Current in µA (0018,8151) X-Ray Tube Current in µA. An average in the case of fluoroscopy (continuous radiation mode).
>Exposure Time (0018,1150) Time of x-ray exposure or fluoroscopy in msec.
>Filter Type (0018,1160) Type of filter(s) inserted into the X-Ray beam (e.g. wedges). See C.8.7.10 and C.8.15.3.9 (for enhanced CT) for Defined Terms.
>Filter Material (0018,7050) The X-Ray absorbing material used in the filter. May be multi-valued. See C.8.7.10 and C.8.15.3.9 (for enhanced CT) for Defined Terms.
>Comments on Radiation Dose (0040,0310) User-defined comments on any special conditions related to radiation dose encountered during during the episode described by this Exposure Dose Sequence Item.

Notes: 1. The Anatomic Region may be deduced from attribute values available within the Modality Worklist Management SOP Class, such as Reason for Service Request, Reasons for Requested Procedure, Scheduled Procedure Step Description and Scheduled Protocol Code Sequence.

2. The Image Area Dose Product should take into account collimator position and filters, and the value for the Exposed Area should also take into account collimator position. If the equipment does not provide the Entrance Dose, it may be calculated using Area Dose Product, Exposed Area, SID and an assumed body thickness.

3. The Distance Source to Detector (0018,1110) and Exposed Area (0040,0303) are only meaningful if they remain constant for all acquisitions during this Performed Procedure Step.