TY - JOUR T1 - Evaluation of a <sup>153</sup>Gd flood source for anatomic shadowing in scintigraphy scans JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1864 LP - 1864 VL - 56 IS - supplement 3 AU - Frank DiFilippo Y1 - 2015/05/01 UR - http://jnm.snmjournals.org/content/56/supplement_3/1864.abstract N2 - 1864 Objectives In certain scintigraphy studies where anatomic reference is desired, a 57Co flood source often is introduced to acquire an anatomic shadow along with the emission image. The 136 keV photons from the 57Co source produce the shadow in the 140 keV 99mTc window. However this method is not ideal since crosstalk degrades lesion detection. A 153Gd flood source was investigated as an alternative, with the goal of improving lesion detection.Methods The 153Gd source emits 100 keV photons which do not appear in the 140 keV window; thus emission data and transmission data are acquired in separate windows. Phantoms with 99mTc point sources of various activities were imaged to quantify signal versus background counts using different flood sources (57Co, 153Gd, or none). Some crosstalk was observed with the 153Gd source and was attributed to simultaneous detection of 100 keV photons and x-ray photons (~40 keV) from 153Gd decay. Use of brass filters to suppress x-ray detection also was studied.Results Lesion signal-to-noise ratio (SNR) was significantly higher with the 153Gd flood source than with the 57Co flood source in all phantom configurations studied. Lesion SNR with the 153Gd flood source was improved slightly further when introducing filters to attenuate x-rays from 153Gd decay. Compared to the case of no flood source, lesion SNR with the 153Gd flood source was similar or slightly lower. Clinical images (breast lymphoscintigraphy and wholebody lymphedema scans) using the 153Gd source demonstrated the ability to visualize low-intensity lesions without significant background.Conclusions Using the 153Gd flood source, co-registered functional and anatomic images are produced for both anterior and posterior views. Lesion detection is improved compared to using a 57Co flood source for anatomic shadowing. ER -