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Table 1 Energy spectra of a Ra-223 vial with MEGP and HEGP

From: Ra-223 SPECT for semi-quantitative analysis in comparison with Tc-99m HMDP SPECT: phantom study and initial clinical experience

Energy peak Relative detector sensitivity with HEGP to MEGP collimator Relative peak height to that at 84 keV with HEGP % decrease in sensitivity by attenuation medium
Attenuation medium (−) Attenuation medium (+)a Attenuation medium (−) Attenuation medium (+)a MEGP HEGP
84 99.5 98.3 NA NA 2.9 2.3
154 70.2 74.1 29.3 31.2 3.4 1.1
269 69.8 69.9 18.9 18.8 4.3 4.1
351 52.0 56.8 11.2 12.0 5.5 0.9
402 47.5 46.4 8.8 8.8 2.4 4.1
  1. aCT value of a chamber containing attenuation medium enclosing the vial was 350 HU
  2. NA not applicable, MEGP medium-energy general purpose, HEGP high-energy general purpose