Procedure for unmasking localization information from ProstaScint scans for prostate radiation therapy treatment planning.
OBJECTIVE
To demonstrate a method to extract the meaningful biologic information from (111)In-radiolabeled capromab pendetide (ProstaScint) SPECT scans for use in radiation therapy treatment planning by removing that component of the (111)In SPECT images associated with normal structures.


METHODS
We examined 20 of more than 80 patients who underwent simultaneous (99m)Tc/(111)In SPECT scans, which were subsequently registered to the corresponding CT/MRI scans.A thresholding algorithm was used to identify (99m)Tc uptake associated with blood vessels and CT electron density associated with bone marrow. Corresponding voxels were removed from the (111)In image set.


RESULTS
No single threshold value was found to be associated with the (99m)Tc uptake that corresponded to the blood vessels. Intensity values were normalized to a global maximum and, as such, were dependent upon the quantity of (99m)Tc pooled in the bladder. The reduced ProstaScint volume sets were segmented by use of a thresholding feature of the planning system and superimposed on the CT/MRI scans.


CONCLUSIONS
ProstaScint images are now closer to becoming a biologically and therapeutically useful and accurate image set. After known sources of normal intensity are stripped away, the remaining areas that demonstrate uptake may be segmented and superimposed on the treatment-planning CT/MRI volume.
DeWyngaert
J Keith
JK
Department of Radiation Oncology, New York University Medical Center, New York, NY, USA. keith.dewyngaert@med.nyu.edu
Noz
Marilyn E
ME
Ellerin
Bruce
B
Kramer
Elissa L
EL
Maguire
Gerald Q
GQ
Zeleznik
Michael P
MP
D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal; D006801:Humans; D007205:Indium Radioisotopes; D008297:Male; D008875:Middle Aged; D011467:Prostate; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D016719:Radioimmunodetection / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D013667:Technetium; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D001743:Urinary Bladder / Q000000981:diagnostic imaging
D000911:Antibodies, Monoclonal; D007205:Indium Radioisotopes; D013667:Technetium; C101315:Capromab Pendetide