The following examples are provided to illustrate the usage of the Defined and Performed Procedure Protocol IODs. They do not represent recommended scanning practice. In some cases they have been influenced by published protocols, but the examples here may not fully encode those published protocols and no attempt has been made to keep them up-to-date.
The primary applications (use cases) considered during the development of the Procedure Protocol Storage IODs were the following:
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Managing protocols within a site for consistency and dose management (Using Defined Protocols)
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Recording protocol details for a performed study so the same or similar values can be used when performing followup or repeat studies, especially for oncology which does comparative measurements (Using Performed Protocols)
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Vendor troubleshooting image quality issues that may be due to poor protocol/technique (Using Performed Protocols, Defined Protocols)
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Distributing departmental, "best practice" or reference protocols (such as AAPM) to modality systems (Using Defined Protocols)
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Backing up protocols from a modality to PACS or removable media (e.g., during system upgrades or replacement); most vendors have a proprietary method for doing this which would essentially become redundant when Protocol Management is implemented (Using Defined Protocols)
Additional potential applications include:
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Making more detailed protocol information available to rendering or processing applications that would allow them to select processing that corresponds to the acquisition protocol, to select parameters appropriate to the acquisition characteristics, and to select the right series to process/display (Using Performed Protocols)
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Improving imaging consistency in terms of repeatable technique, performance, quality and image charateristics; would benefit from associated image quality metrics and other physics work (Using Defined Protocols and Performed Protocols)
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Distributing clinical trial protocols (general purpose or scanner model specific) to participating sites (Using Defined Protocols)
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Recording protocol details for a performed study to submit with clinical trial images for technique validation (Using Performed Protocols)
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Tracking/extracting details of Performed Protocol such as timestamps, execution sequence and technique for QA, data mining, etc. (Using Performed Protocols)
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Making more detailed protocol information available to radiologists reviewing a study and priors, or comparing similar studies of different patients (Using Performed Protocols)
Using non-Patient-specific Protocols
In most cases, the scanner uses any protocol details in the modality worklist item to present to the technologist a list of matching Defined Protocols on this scanner.
Preparing and executing Patient-specific Protocols
In the simplest form, this process could be driven with a combination of the Modality Worklist and Defined Protocols.
In special cases, the radiologist might attend the scan and modify the protocol directly on the console.
Note that the primary record of adjustments is the Performed Protocol object (which can be compared to the referenced Defined Protocol object).
A new Defined Protocol is not typically saved unless the intent is to have a new Defined Protocol available in the Library.
On the XA Modality, the operator modifies the protocols and their parameters directly on the console at tableside. XA procedures are not fully planned in advance, they are interactive because the operator's actions will depend on real-time information from the live images, and on how the patient reacts to the intervention.
Typically the operator changes acquisition modes (e.g. Fluoroscopy, DSA, Rotational) and acquisition parameters (e.g. Field of View, frame rate, IQ/Dose levels). During the procedure the operator may need to change the protocols to switch to low-dose programs or to potentially modify the anatomy being imaged. The patient position on the table may change depending on the patient's size and type of procedure.
In some cases, several XA multi-frame images of different protocols and anatomies are acquired with the same patient position and stored within the same Series. Different Series may be created as other Series attributes have changed during the procedure (e.g. Patient Position).
Several Performed Protocol Elements may be recorded for the same Defined Protocol Element used.