quaac 0.0.3

A package for reading and writing QuAAC files.

Intent

The Quality Assurance Archive & Communication (QuAAC) project is a standardization effort for the storage and exchange of routine quality assurance data that spans vendors and inter-clinical sites.

Rationale

The QuAAC project was born out of the need to store and exchange routine QA data in a vendor-neutral format. Clinics that move between commercial vendors of QA equipment and software are often faced with the challenge of converting their data from one paradigm to another, depending on the vendor. This can also happen when migrating from a in-house solution to a commercial solution. There currently exists no reasonable standard for the storage and exchange of this QA data. The QuAAC project aims to fill this gap.

Philosophy

1. The QuAAC project is a community effort.

2. The QuAAC project is a living standard and will evolve as use cases are identified and addressed.

3. QuAAC is meant to store both “interpreted” data as well as raw data.

4. Raw data is expected and encouraged to be linked with the interpreted data.

5. The QuAAC project is not a replacement for DICOM, but rather a complement.

6. Data should be stored in a format that is easily parsed by humans and machines.

7. QuAAC is not a QA platform.

8. QuAAC is not meant for patient data.

9. QuAAC is vendor-neutral.

Comparison with DICOM

The advent of the DICOM standard has been a boon to the medical imaging community. It has allowed for the exchange of medical images and metadata between vendors and clinical sites. However, QA data is a niche area that involves more than just images and metadata. There is often extra data associated with QA data that doesn’t fit into standard DICOM fields. Further, this project does not define a standard for the exchange of QA data. Per philosophy #6, any QuAACS archive is readable by humans and machines. By keeping the format simple, it is easy to parse and extract data from a QuAACS using commonly-available software tools.

Compared to DICOM, the scope is significantly smaller, both in terms of the addressed needs as well as the number of definitions. QA data is diverse, but DICOM has a much larger scope.

Why not use private DICOM tags?

Private DICOM tags are a great way to store extra data in a DICOM file. However, they are not standardized and are not guaranteed to be readable by other vendors. Further, parsing the data from a private DICOM tag is no easier than using simple file formats.

Examples of QA data

• Daily high-dose rate afterloader timing check

• Machine Performance Check MLC bank A max error

• Cone-beam CT uniformity

• Planar MV contrast

• An ion chamber reading

• Flatness and symmetry from a water tank profile scan

Important

These are individual data points, usually part of a larger dataset. A “daily QA” usually involves a number of these data points. Also note that these data points might be based on raw data, such as a profile scan or DICOM images.

QA data vs raw data

We make an important distinction between QA data and raw data. QA data is either raw or interpreted data, useful for the evaluation of a machine’s performance. Raw data is intermediate data that is used to generate QA data. For example, a profile scan is raw data, but the flatness and symmetry values are QA data. Although critical in many cases to generate the QA data, the raw data itself is not QA data.

Why use it?

Reasons to use QuAAC include:

• Standardization of QA data storage

• Easy to implement

• Vendor-neutral storage

• Easy to parse and read

• clinic-to-clinic communication compatibility

• Vendor switchover compatibility