DICOM PS3.16 2019b - Content Mapping Resource

TID 10013 CT Irradiation Event Data

This Template conveys the dose and equipment parameters of a single irradiation event.

A CT irradiation event is the loading of X-Ray equipment caused by a single continuous actuation of the equipment's irradiation switch, from the start of the loading time of the first pulse until the loading time trailing edge of the final pulse. Any on-off switching of the radiation source during the event shall not be treated as separate events; rather the event includes the time between start and stop of radiation as triggered by the user, e.g., a single sequence of scanning comprised of multiple slices acquired with successive tube rotations and table increments shall be treated as a single irradiation event. Depending on the examination workflow and the anatomical target region the CT irradiation event data may split into multiple instances of this Template for better dose estimation. The irradiation event is the "smallest" information entity to be recorded in the realm of Radiation Dose reporting. Individual Irradiation Events are described by a set of accompanying physical parameters that are sufficient to understand the "quality" of irradiation that is being applied. This set of parameters may be different for the various types of equipment that are able to create irradiation events.

Type:

Extensible

Order:

Significant

Root:

No

Table TID 10013. CT Irradiation Event Data

NL

Rel with Parent

VT

Concept Name

VM

Req Type

Condition

Value Set Constraint

1

CONTAINER

EV (113819, DCM, "CT Acquisition")

1

M

2

>

CONTAINS

TEXT

EV (125203, DCM, "Acquisition Protocol")

1

U

3

>

CONTAINS

CODE

EV (123014, DCM, "Target Region")

1

M

DCID 4030 “CT, MR and PET Anatomy Imaged”

4

>

CONTAINS

CODE

EV (113820, DCM, "CT Acquisition Type")

1

M

DCID 10013 “CT Acquisition Type”

4b

>>

HAS PROPERTIES

CODE

EV (113961, DCM, "Reconstruction Algorithm")

1-n

U

DCID 10033 “CT Reconstruction Algorithm”

5

>

CONTAINS

CODE

EV (408730004, SCT, "Procedure Context")

1

U

DCID 10014 “Contrast Imaging Technique”

6

>

CONTAINS

UIDREF

EV (113769, DCM, "Irradiation Event UID")

1

M

6b

>

CONTAINS

TEXT

EV (113605, DCM, "Irradiation Event Label")

1

U

6c

>>

HAS CONCEPT MOD

CODE

EV (113606, DCM, "Label Type")

1

MC

IF the value of Row 6b is the value of an Attribute in the images.

DCID 10022 “Label Types”

6d

>

CONTAINS

CODE

EV (128551, DCM, "Is Repeated Acquisition")

1

U

DCID 230 “Yes-No”

6e

>>

HAS CONCEPT MOD

CODE

EV (128552, DCM, "Reason for Repeating Acquisition")

1

M

DCID 10034 “Reason for Repeating Acquisition”

6f

>

CONTAINS

DATETIME

EV (111526, DCM, "DateTime Started")

1

U

7

>

CONTAINS

CONTAINER

EV (113822, DCM, "CT Acquisition Parameters")

1

M

8

>>

CONTAINS

NUM

EV (113824, DCM, "Exposure Time")

1

M

UNITS = EV (s, UCUM, "s")

9

>>

CONTAINS

INCLUDE

DTID 10014 “Scanning Length”

1

M

10

>>

CONTAINS

NUM

EV (113826, DCM, "Nominal Single Collimation Width")

1

M

UNITS = EV (mm, UCUM, "mm")

11

>>

CONTAINS

NUM

EV (113827, DCM, "Nominal Total Collimation Width")

1

M

UNITS = EV (mm, UCUM, "mm")

12

>>

CONTAINS

NUM

EV (113828, DCM, "Pitch Factor")

1

MC

IF row 4 equals (116152004, SCT, "Spiral Acquisition") or equals (113804, DCM, "Sequenced Acquisition")

UNITS = EV ({ratio}, UCUM, "ratio")

13

>>

CONTAINS

NUM

EV (113823, DCM, "Number of X-Ray Sources")

1

M

UNITS = EV ({X-Ray sources}, UCUM, "X-Ray sources")

14

>>

CONTAINS

CONTAINER

EV (113831, DCM, "CT X-Ray Source Parameters")

1-n

M

15

>>>

CONTAINS

TEXT

EV (113832, DCM, "Identification of the X-Ray Source")

1

M

16

>>>

CONTAINS

NUM

EV (113733, DCM, "KVP")

1

M

UNITS = EV (kV, UCUM, "kV")

17

>>>

CONTAINS

NUM

EV (113833, DCM, "Maximum X-Ray Tube Current")

1

M

UNITS = EV (mA, UCUM, "mA")

18

>>>

CONTAINS

NUM

EV (113734, DCM, "X-Ray Tube Current")

1

M

UNITS = EV (mA, UCUM, "mA")

19

>>>

CONTAINS

NUM

EV (113834, DCM, "Exposure Time per Rotation")

1

MC

IF row 4 does not equal (113805, DCM, "Constant Angle Acquisition")

UNITS = EV (s, UCUM, "s")

20

>>>

CONTAINS

NUM

EV (113821, DCM, "X-Ray Filter Aluminum Equivalent")

1

U

UNITS = EV (mm, UCUM, "mm")

21

>

CONTAINS

CONTAINER

EV (113829, DCM, "CT Dose")

1

MC

IF row 4 does not equal (113805, DCM, "Constant Angle Acquisition")

22

>>

CONTAINS

NUM

EV (113830, DCM, "Mean CTDIvol")

1

M

UNITS = EV (mGy, UCUM, "mGy")

23

>>

CONTAINS

CODE

EV (113835, DCM, "CTDIw Phantom Type")

1

M

DCID 4052 “Phantom Devices”

24

>>

CONTAINS

NUM

EV (113836, DCM, "CTDIfreeair Calculation Factor")

1

U

UNITS = EV (mGy/mA.s, UCUM, "mGy/mA.s")

25

>>

CONTAINS

NUM

EV (113837, DCM, "Mean CTDIfreeair")

1

U

UNITS = EV (mGy, UCUM, "mGy")

26

>>

CONTAINS

NUM

EV (113838, DCM, "DLP")

1

M

UNITS = EV (mGy.cm, UCUM, "mGy.cm")

27

>>

CONTAINS

NUM

EV (113839, DCM, "Effective Dose")

1

U

UNITS = EV (mSv, UCUM, "mSv")

28

>>>

HAS CONCEPT MOD

CODE

EV (370129005, SCT, "Measurement Method")

1

MC

IF row 27 is present

DCID 10011 “Effective Dose Evaluation Method”

29

>>>>

HAS PROPERTIES

NUM

EV (113840, DCM, "Effective Dose Conversion Factor")

1

MC

IF row 28 is present and equals (113800, DCM, "DLP to E conversion via MC computation") or equals (113802, DCM, "DLP to E conversion via measurement")

UNITS = EV (mSv/mGy.cm, UCUM, "mSv/mGy.cm")

30

>>

CONTAINS

NUM

EV (113930, DCM, "Size Specific Dose Estimation")

1-n

U

UNITS = EV (mGy, UCUM, "mGy")

31

>>>

HAS CONCEPT MOD

CODE

EV (370129005, SCT, "Measurement Method")

1

M

DCID 10023 “Size Specific Dose Estimation Method for CT”

32

>>>>

INFERRED FROM

NUM

EV (113931, DCM, "Measured Lateral Dimension")

1

MC

IF row 31 equals (113934, DCM, "AAPM 204 Lateral Dimension") or (113936, DCM, "AAPM 204 Sum of Lateral and AP Dimension")

UNITS = EV (mm, UCUM, "mm")

33

>>>>

INFERRED FROM

NUM

EV (113932, DCM, "Measured AP Dimension")

1

MC

IF row 31 equals (113935, DCM, "AAPM 204 AP Dimension") or (113936, DCM, "AAPM 204 Sum of Lateral and AP Dimension")

UNITS = EV (mm, UCUM, "mm")

34

>>>>

INFERRED FROM

NUM

EV (113933, DCM, "Derived Effective Diameter")

1

MC

IF row 31 equals (113934, DCM, "AAPM 204 Lateral Dimension") or (113935, DCM, "AAPM 204 AP Dimension") or (113936, DCM, "AAPM 204 Sum of Lateral and AP Dimension") or (113937, DCM, "AAPM 204 Effective Diameter Estimated From Patient Age")

UNITS = EV (mm, UCUM, "mm")

34b

>>>>

INFERRED FROM

NUM

EV (113980, DCM, "Water Equivalent Diameter")

1

MC

IF row 31 equals (113981, DCM, "Water Equivalent Diameter Representative Value")

UNITS = EV (mm, UCUM, "mm")

34c

>>>>>

HAS CONCEPT MOD

CODE

EV EV (370129005, SCT, "Measurement Method")

1

M

DCID 10024 “Water Equivalent Diameter Method”

34d

>>>>

INFERRED FROM

UIDREF

EV (113985, DCM, "Series or Instance used for Water Equivalent Diameter estimation")

1-n

MC

IF row 31 equals (113982, DCM, "Water Equivalent Diameter Integrated Across Scan Range") or (113984, DCM, "Water Equivalent Diameter From Localizer") or (row 31 equals (113983, DCM, "Water Equivalent Diameter From Raw Data") and the Raw Data is encoded in DICOM).

34e

>>>>

INFERRED FROM

NUM

EV (113986, DCM, "Z value of location of Water Equivalent Diameter estimation")

1

MC

IF row 31 equals (113981, DCM, "Water Equivalent Diameter Representative Value")

UNITS = EV (mm, UCUM, "mm")

35

>>

CONTAINS

INCLUDE

DTID 10015 “CT Dose Check Details”

1

M

36

>

CONTAINS

TEXT

EV (113842, DCM, "X-Ray Modulation Type")

1

U

37

>

CONTAINS

TEXT

EV (121106, DCM, "Comment")

1

U

38

>

CONTAINS

INCLUDE

DTID 1020 “Person Participant”

1-n

U

$PersonProcedureRole = EV (113851, DCM, "Irradiation Administering")

39

>

CONTAINS

INCLUDE

DTID 1021 “Device Participant”

1

MC

Required if the irradiating device is not the recording device.

$DeviceProcedureRole = EV (113859, DCM, "Irradiating Device")


Content Item Descriptions

Row 2

User-defined type of clinical acquisition protocol for creating images or image-derived measurements. May be taken from Protocol Name (0018,1030) or from Performed Procedure Step Description (0040,0254).

Row 3

The target region is the anatomy exposed.

Row 4

Description of the method used during acquisition of this CT irradiation event, may be derived from Acquisition Type (0018,9302).

Row 4b

Though not a characteristic of the acquisition per se, the type of reconstruction intended has a bearing on the technique used. If multiple types of reconstruction are performed, multiple values can be listed. These values should correspond to the values of Reconstruction Algorithm (0018,9315) in the reconstructed images.

Row 5

The acquisition was performed with or without contrast medium application.

Row 6d, 6e

If an acquisition is a repeat because an earlier acquisition was unsatisfactory, this may be recorded along with a coded reason. This is intended to help with subsequent analysis by providing a priori information about why the study might be flagged as an outlier with higher dose exposure values than usual for the type of study.

Row 6f

The DateTime that the application of X-Rays started for this irradiation event. This shall correspond to the start of the first irradiation in the Irradiation Event, which defines the starting point for the calculation of the contents of the Row 21 "CT Dose" CONTAINER.

Row 8

Total time the patient has received X-Ray exposure during the irradiation event.

Row 10

The value of the nominal width (referenced to the location of the isocenter along the z axis) of a single collimated slice in mm.

Row 11

The value of the nominal width (referenced to the location of the isocenter along the z axis) of the nominal total collimation in mm over the area of active X-Ray detection (z-coverage).

Row 12

Pitch Factor: For Spiral Acquisition, the Pitch Factor is the ratio of the Table Feed per Rotation to the Nominal Total Collimation Width. For Sequenced Acquisition, the Pitch Factor is the ratio of the Table Feed per single sequenced scan to the Nominal Total Collimation Width.

Row 14

CT X-Ray source parameters related to the acquisition. For each X-Ray source an item must be present. For multi-energy acquisitions, multiple items may be present for each X-Ray source, each item describing one energy level.

Row 15

Identification of the X-Ray source. Identifies the particular X-Ray source (in a multi-source CT system) for which the set of X-Ray source parameter values is reported.

Row 16

KVP value as measured/recorded by system.

Row 18

Mean tube current as measured/recorded by system.

Row 19

Exposure time as measured/recorded by the system per rotation.

Row 20

Thickness of an equivalent filter constructed from aluminum, in case of multi-source CT systems AND if Row 4 is not present

Row 21

CT Dose for one acquisition

Row 22

"Mean CTDIvol" refers to the average value of the CTDIvol applied within this acquisition.

CTDIvol is the volume CTDIw, where CTDIw is the weighted computed tomography dose index 100 as defined in IEC 60601-2-44.

For Sequenced and Spiral scanning, CTDIvol = CTDIw / Pitch Factor.

For Stationary and Free scanning, CTDIvol = CTDIw ✕ Cumulative Exposure Time/ Exposure Time Per Rotation.

According to IEC 60601-2-44 Ed 3 for Constant Angle Acquisition may be calculated as CTDIvol = (CTDIw / Current Time Product (mAs)) ✕ X-Ray Tube Current (mA) x (Nominal Total Collimation Width (mm) / Table Speed (mm/s)).

Note

The ratio CTDIw / Current Time Product is evaluated independently of the Constant Angle Acquisition but with the same settings of tube voltage and Total Collimation Width as those of the Constant Angle Acquisition.

See also CTDIvol (0018,9345) and Spiral Pitch Factor (0018,9311) in the “Enhanced Computed Tomography Image IOD” in PS3.3 .

Row 23

The type of phantom used for CTDI measurement according to IEC 60601-2-44(e.g., Head 16 cm diameter PMMA, Body 32 cm diameter PMMA).

Row 24

The CTDIfree air Calculation Factor is the CTDIfree air per mAs, expressed in units of mGy/mAs. The CTDIfree air Calculation Factor may be used in one method calculating Dose. For example, for this acquisition, Effective Dose = Mean X-Ray Tube Current ✕ Cumulative Exposure Time ✕ CTDIfree air Calculation Factor ✕ (Effective Dose/ CTDIfree air).

Row 25

MeanCTDIfree air is the mean CTDI for this acquisition, evaluated free-in-air according to IEC 60601-2-44. MeanCTDIfree air = Mean X-Ray Tube Current ✕ Cumulative Exposure Time ✕ CTDIfree air Calculation Factor. The CTDIfree air may be used in one method of calculating Effective Dose.

Row 26

For Spiral scanning, DLP = CTDIvol ✕ Scanning Length. For Sequenced scanning, DLP = CTDIvol ✕ Nominal Total Collimation Width ✕ Cumulative Exposure Time / Exposure Time per Rotation. For Stationary and Free scanning, DLP = CTDIvol ✕ Nominal Total Collimation Width (according to IEC 60601-2-44).

Row 27

Effective Dose in mSv of the single continuous time-frame of the irradiation computed as described in TID 10012 “CT Accumulated Dose Data”.

Row 29

The Effective Dose Conversion Factor is the ratio of the Effective Dose to the DLP, expressed in units of mSv/mGy.cm, and it is used as a factor in one method of estimating Effective Dose. Monte Carlo Simulations (or dosimetric measurements in an anthropomorphic phantom, e.g., the Alderson-Rando phantom) may be used as a basis for the evaluation of Effective Dose Conversion Factors.

Row 30

More than one Size Specific Dose Estimation may be included, for example if different computation methods are used.

Row 31

The methods of [AAPM Report 204] are listed in CID 10023 “Size Specific Dose Estimation Method for CT”; other methods may be used.

The phantom size (16cm or 32cm) used for the calculation is available from the phantom type defined in Row 23.

Row 32

The condition specifies inclusion of the Measured Lateral Dimension if it was used in the calculation.

Row 33

The condition specifies inclusion of the Measured AP Dimension if it was used in the calculation.

Row 34

The Derived Effective Diameter is conditionally included, whether it was derived from measurements or estimated from age, but may not be used for other (non-AAPM Report 204) methods.

Row 34b

A single value for Water Equivalent Diameter is encoded in Row 34b if the method uses a single value. It is required if the method uses a representative slice, but may also be present if the method used a Localizer or Raw Data at a single location rather than the entire scan range.

Row 34c

The modifier is intended to specify the family of methods and not the specific technique (e.g., for AAPM 220 (113987, DCM, "AAPM 220") is used, not (113981, DCM, "Water Equivalent Diameter Representative Value"), etc.).

Row 34d

If the method uses multiple slices across the scan range, the reconstructed image Series or (list of) Instances used is referenced; the values for Water Equivalent Diameter may or may not be recorded in the CT Image Module or CT Exposure Macro of those images. More than one Series may be referenced if the reconstructed images for this acquisition used for Water Equivalent Diameter estimation span multiple series.

If the Water Equivalent Diameter was computed from raw views rather than reconstructed images, then the Raw Data is referenced, if it was encoded in DICOM (it is not required to be).

Row 34e

This location is patient (not table or gantry) relative, to allow it to be defined in the Patient Coordinate System and hence related to the Image Position (Patient) in the reconstructed images (see TID 10014 “Scanning Length”, included at Row 9). It is required if the method uses a representative slice, but may also be present if the method used a Localizer or Raw Data at a single location rather than the entire scan range.

Row 35

Record of details associated with using the NEMA Dose Check Standard (NEMA XR-25-2010).

Row 36

The type of exposure modulation. May use the value of Exposure Modulation Type (0018,9323) from CT Exposure Macro or from CT Image Module.

Row 38

People responsible for the administration of the radiation reported in the irradiation event. May include values that would appear in Performing Physicians' Name (0008,1050), Performing Physician Identification Sequence (0008,1052), Operators' Name (0008,1070) and/or Operator Identification Sequence (0008,1072).

Row 39

The device that produced the irradiation in this Irradiation Event. I.e., the CT scanner. This is not required to be present if the information is the same as that already recorded in the TID 1004 “Device Observer Identifying Attributes” encoded via the inclusion of TID 1002 “Observer Context” in TID 10011 “CT Radiation Dose” Row 4, which in turn may be absent if identical to the content in the Enhanced General Equipment Module.

DICOM PS3.16 2019b - Content Mapping Resource