Software parameters and standard DICOM Library

I am a new user of the NCIRF software and I want to match all of the software parameters with standard DICOM library for a retrospective study for patients that had chest x-rays and fluoroscopy. Any suggestions on which library to look at? For instance in the reference phantom it says "arms raised or lowered", what does this correspond to in a DICOM library? I noticed there is no place to input tube current? Also, I could not find HVL in the standard CR, X-Ray DICOM browser. Can Source Distance to Patient be used in place of Source Isocenter Distance?

Kindly find attached a pdf of my match so far.

Thank you. Parameters-and-Dicom-match.pdf

NCI Dose Team response

A good reference for the common DICOM tags by modality is here: https://dicom.innolitics.com/ciods. Also, each vendor should have a copy of their DICOM conformance statement freely available.

There is no DICOM tag for patient arm position, but there are for patient position and laterality (e.g., AP/PA, R/L). There is no DICOM tag for HVL in digital radiography and fluoroscopy, only added filtration (typically mm Cu). Currently, NCIRF has common kVps and HVLs that you can match with the HVL measured on the machine. Source to patient distance is only an estimate and we would use source to image distance = source to isocenter distance and place the reference point where the detector would be wrt the patient. Field size and collimation are available in the subset of DICOM tags in "Display Shutter" and DAP is tag (0018,115e) in dGy*cm^2.

While it may be easiest to use the DICOM header information for projection radiographs, for fluoroscopy, the radiation dose structured reports (RDSRs) are the best source for this information where there are multiple exposures, techniques, angulations and collimation. See attached excerpt from an RDSR. Hope that helps.

-Seth RDSR-example.pdf

Community reply

Thanks for the response. Just to follow up. Why is the display shutter used to approximate the field size at the isocenter instead of the field of view dimensions (0018,1149)? Also what of the Isocenter coordinate X,Y and Z, I don't see it in the CR DICOM either? Does the table positions in the RSDR correspond to the coordinates?

NCI Dose Team response

We believe that display shutter and field of view dimensions are interchangeable, with field of view dimension being used more for fluoroscopy than digital radiography. There are no isocenter coordinates for digital radiography (fixed table/wall bucky, variable SID), so you will need to know the anatomy being imaged and use the collimation and SID to translate to NCIRF sims. For fluoroscopy, the table positions (LONG, LAT, HEIGHT) are essentially the patient's position wrt isocenter or IRP.

Community reply

Is there any parameter in the NCIRF software that if left out would have little or no impact on the dose calculation?

NCI Dose Team response

Similar to NCICT, all input parameters in NCIRF are required to calculate organ doses. We haven't done the analysis of dose uncertainties yet for fluoroscopy but it should be interesting to evaluate them using NCIRF. Any other thoughts from the community would be appreciated.