Table 1.

Comparison of two standards-based approaches utilized for Image Exchange in Ontario (East Toronto and West Toronto). Both approaches utilize a centralized “diagnostic image repository (DIR)” to store a copy of the images generated in that Ontario region. But each DIR uses different methods to identify patients, discover images, and retrieve reports

Item	Diagnostic image repository #1 (DIR1) (uses DICOM query/retrieve) East Toronto	Diagnostic image repository #2 (DIR2) (uses XDS-I) West Toronto
Patient identification	Deterministic match based on provincial Ontario Health Card Number.	PIX lookup: probabilistic patient matching based on a scorecard of key demographics.
Image discovery	DICOM (C-Find, C-Move, etc.)	XDS registry query
Report retrieval	Report txt is available from a well formed URL. Edge device will scrape contents of URL and convert to ORU.	Reports stored in document repository in CDA format. Edge device will convert CDA to ORU or DICOM Secondary capture depending on site’s preference.
Number of contributing sites	98	29
Patient population	≈ 4.2 Million patients	≈ 4 Million patients
Number of unique PACS vendors connected	9	9
Annual exam	≈ 5 Million exams annually	≈ 3 Million exams annually