RT Journal Article SR Electronic T1 Letter To The Editor: Dacryocystography: Incompatibility of the “Reversed Pinhole Insert” in Some Collimator Designs JF Journal of Nuclear Medicine Technology JO J. Nucl. Med. Technol. FD Society of Nuclear Medicine SP 44 OP 45 VO 17 IS 1 A1 Cowan, Robert J. A1 Williams, Rodney C. A1 Ball, James D. A1 Phillips, David C. A1 Sievers, Carole C. YR 1989 UL http://tech.snmjournals.org/content/17/1/44.abstract AB