Get vector of header values for each DICOM slice for a header field

Get vector of header values for each DICOM slice for a header field

# S3 method for dicomdata
header_value(img_data, field)

Arguments

img_data	DICOM data returned by read_dicom
field	Header field keyword e.g. "PatientName"

Value

Vector of header values. Numeric values are converted to numbers.