patient position is now also extracted from the data

mu_map/data/prepare.py

@@ -22,6 +22,7 @@ headers.age = "age"
 headers.sex = "sex"
 headers.weight = "weight"
 headers.size = "size"
+headers.patient_position = "patient_position"
 headers.protocol = "protocol"
 headers.datetime_acquisition = "datetime_acquisition"
 headers.datetime_reconstruction = "datetime_reconstruction"
@@ -483,6 +484,7 @@ if __name__ == "__main__":
                     headers.sex: projection.PatientSex,
                     headers.weight: float(projection.PatientWeight),
                     headers.size: float(projection.PatientSize),
+                    headers.patient_position: projection.PatientPosition,
                     headers.protocol: protocol,
                     headers.datetime_acquisition: DICOMTime.Series.to_datetime(
                         projection