Estimation of radioactivity in single-photon emission computed tomography for sentinel lymph node biopsy in a torso phantom study. Issue 6 (June 2015)

• Record Type: Journal Article
• Authors: Kitamura, Hideaki; Kono, Yuzuru; Murano, Takeshi; Hiroi, Kenta; Ihara, Kanyu; Aso, Tomohiko; Inoue, Kazumasa; Fukushi, Masahiro
• Is Part Of: Nuclear medicine communications. Volume 36:Issue 6(2015:Jun.)
• Publication Date: 2015-06
• Subjects: quantification -- sentinel lymph node -- single-photon emission computed tomography -- total radioactivity; Nuclear medicine -- Periodicals; 616.07575
• DOI: 10.1097/MNM.0000000000000294
• Languages: English
• ISSNs: 0143-3636

Abstract

Abstract : Objective: The number of lymph nodes to be removed is determined from residual counts. Advance estimation of residual radioactivity in lymphatic nodes before a biopsy is useful for reducing surgical operation time. The purpose of this study was to estimate the total radioactivity of a small hotspot in single-photon emission computed tomography (SPECT) of a torso phantom. Methods: A cross-calibration study was performed to convert counts in SPECT images to radioactivity. A simulation study was performed to estimate the size of the volume of interest (VOI) covering a hotspot corrupted with full-width at half-maximum between 8 and 16 mm. The estimation of total radioactivity was validated in a torso phantom study using small sources. Results: True radioactivity was approximately equal to integrated values of hotspots using the VOI with a diameter of 40 mm in our simulation study. The difference was less than 18% in cases of more than 9.4 kBq. Conclusion: The total radioactivity in small sources simulating a typical sentinel node was estimated from SPECT images using a VOI of 40 mm in a torso phantom study. Because the difference from actual values was less than 10% on average when radioactivities were more than 9.4 kBq, the total radioactivity of a lymph node can be estimated in a clinical examination.