feature: Optional OCR-Assisted Draft Pre-Fill

2026-06-28 01:28:54 +08:00
parent 5039dbb979
commit c160c5f912
42 changed files with 3592 additions and 33 deletions
@@ -0,0 +1,90 @@
+using System.Text.RegularExpressions;
+using Microsoft.Extensions.Options;
+using Tesseract;
+
+public class TesseractOcrService : IOcrService
+{
+    private static readonly (Regex Pattern, string FieldName)[] ClinicalPatterns =
+    [
+        (new Regex(@"(?:Patient\s+)?Name[:\s]+(.+)", RegexOptions.IgnoreCase | RegexOptions.Multiline), "patient.fullName"),
+        (new Regex(@"DOB[:\s]+(\d{1,2}[/-]\d{1,2}[/-]\d{2,4})", RegexOptions.IgnoreCase), "patient.dateOfBirth"),
+        (new Regex(@"(?:Date of Birth|Birth Date)[:\s]+(\d{1,2}[/-]\d{1,2}[/-]\d{2,4})", RegexOptions.IgnoreCase), "patient.dateOfBirth"),
+        (new Regex(@"(?:Sex|Gender)[:\s]+(\S+)", RegexOptions.IgnoreCase), "patient.sex"),
+        (new Regex(@"(?:Admission Date|Admitted)[:\s]+(\d{1,2}[/-]\d{1,2}[/-]\d{2,4})", RegexOptions.IgnoreCase), "encounter.admissionDate"),
+        (new Regex(@"(?:Department|Ward|Unit)[:\s]+(.+)", RegexOptions.IgnoreCase | RegexOptions.Multiline), "encounter.department"),
+        (new Regex(@"(?:Room(?:/Bed)?|Bed)[:\s]+(.+)", RegexOptions.IgnoreCase | RegexOptions.Multiline), "encounter.roomBed"),
+        (new Regex(@"HR[:\s]+(\d+(?:\.\d+)?)", RegexOptions.IgnoreCase), "observation.HEART_RATE.value"),
+        (new Regex(@"(?:Heart Rate|Pulse)[:\s]+(\d+(?:\.\d+)?)", RegexOptions.IgnoreCase), "observation.HEART_RATE.value"),
+        (new Regex(@"(?:Temp|Temperature)[:\s]+(\d+(?:\.\d+)?)", RegexOptions.IgnoreCase), "observation.TEMP_C.value"),
+        (new Regex(@"(?:BP Sys|Systolic)[:\s]+(\d+(?:\.\d+)?)", RegexOptions.IgnoreCase), "observation.BP_SYSTOLIC.value"),
+        (new Regex(@"(?:BP Dia|Diastolic)[:\s]+(\d+(?:\.\d+)?)", RegexOptions.IgnoreCase), "observation.BP_DIASTOLIC.value"),
+        (new Regex(@"(?:RR|Resp(?:iratory)?\s*Rate)[:\s]+(\d+(?:\.\d+)?)", RegexOptions.IgnoreCase), "observation.RESP_RATE.value"),
+        (new Regex(@"(?:SpO2|O2 Sat)[:\s]+(\d+(?:\.\d+)?)", RegexOptions.IgnoreCase), "observation.SPO2.value"),
+    ];
+
+    private readonly TesseractOcrOptions _options;
+    private readonly ImagePreprocessor _preprocessor;
+    private readonly ILogger<TesseractOcrService> _logger;
+
+    public TesseractOcrService(
+        IOptions<OcrOptions> options,
+        ImagePreprocessor preprocessor,
+        ILogger<TesseractOcrService> logger)
+    {
+        _options = options.Value.Tesseract;
+        _preprocessor = preprocessor;
+        _logger = logger;
+    }
+
+    public async Task<OcrExtractionResult> ExtractAsync(
+        Stream documentStream, string contentType)
+    {
+        var sw = System.Diagnostics.Stopwatch.StartNew();
+
+        using var preprocessed = _preprocessor.Preprocess(documentStream, contentType);
+        using var memStream = new MemoryStream();
+        await preprocessed.CopyToAsync(memStream);
+        var imageBytes = memStream.ToArray();
+
+        using var engine = new TesseractEngine(
+            _options.DataPath, _options.Language, EngineMode.Default);
+        using var pix = Pix.LoadFromMemory(imageBytes);
+        using var page = engine.Process(pix);
+
+        var rawText = page.GetText();
+        var meanConfidence = page.GetMeanConfidence();
+        var fields = ParseClinicalText(rawText, meanConfidence);
+
+        sw.Stop();
+        return new OcrExtractionResult(fields, rawText, (int)sw.ElapsedMilliseconds);
+    }
+
+    private static List<OcrExtractedField> ParseClinicalText(string text, float meanConfidence)
+    {
+        var fields = new List<OcrExtractedField>();
+        if (string.IsNullOrWhiteSpace(text))
+            return fields;
+
+        var baseConfidence = Math.Clamp(meanConfidence / 100f, 0.0, 1.0);
+        var matchedFields = new HashSet<string>(StringComparer.Ordinal);
+
+        foreach (var (pattern, fieldName) in ClinicalPatterns)
+        {
+            if (matchedFields.Contains(fieldName))
+                continue;
+
+            var match = pattern.Match(text);
+            if (!match.Success)
+                continue;
+
+            var value = match.Groups[1].Value.Trim();
+            if (value.Length == 0)
+                continue;
+
+            fields.Add(new OcrExtractedField(fieldName, value, baseConfidence));
+            matchedFields.Add(fieldName);
+        }
+
+        return fields;
+    }
+}