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 occurrence of irradiation being applied to a patient in single continuous time-frame between the start (release) and the stop (cease) of the irradiation. 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.

TID 10013 CT IRRADIATION EVENT DATA Type: Extensible Order: Significant

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 and MR Anatomy Imaged
4 > CONTAINS CODE EV (113820, DCM, “CT Acquisition Type”) 1 M DCID (10013) CT Acquisition Types
5 > CONTAINS CODE EV (G-C32C, SRT, “Procedure Context”) 1 U DCID (10014) Contrast Imaging Technique
6 > CONTAINS UIDREF EV (113769, DCM, “Irradiation Event UID”) 1 M
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 (P5-08001, SRT, “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/mAs, UCUM, “mGy/mAs”)
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 (G-C036, SRT, “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 INCLUDE DTID (10015) CT Dose Check Details 1 M
31 > CONTAINS TEXT EV (113842, DCM, “X-Ray Modulation Type”) 1 U
32 > CONTAINS TEXT EV (121106, DCM, “Comment”) 1 U
33 > CONTAINS INCLUDE DTID (1020) Person Participant 1-n U $PersonProcedureRole = EV (113851, DCM, “Irradiation Administering”)
34 > 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 5 The acquisition was performed with or without contrast medium application.
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 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 CT Information Object Description (PS 3.3).
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 Mean CTDIfree air is the mean CTDI for this acquisition, evaluated free-in-air according to IEC 60601-2-44. Mean CTDIfree 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.
Row 29 The Effective Dose Conversion Factor is the ratio of the Effective Dose to the DLP, expressed in units of mSv/mGycm, 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 Record of details associated with using the NEMA Dose Check Standard (NEMA XR-25-2010).
Row 31 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 33 People responsible for the administration of the radiation reported in the irradiation event. May include values which 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 34 The device which 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 Device Observer Context (TID 1004) encoded via the inclusion of Observer Context (TID 1002) in TID 10011 Row 4, which in turn may be absent if identical to the content in the Enhanced General Equipment Module.