Salivary gland scintigraphy with partial volume effects quantification: A phantom feasibility study

Mpumelelo Nyathi, Mpho Enoch Sithole


Salivary gland scintigraphy gives functional information on irradiated glands. Upon irradiation, their size may become less than 2–3 times the resolution of the gamma camera hence underestimation of the regional distribution of administered activity due to partial volume effects (PVEs) which hinder accurate quantification of their function.

To accurately quantify planar images of spheres mimicking irradiated parotid and submandibular glands with view of implementing salivary gland scintigraphy that involves quantification of PVEs.

A hollow head and neck phantom was fitted with spheres (diameters: 20mm; 14mm; 12mm and 10mm) filled with technetium-99m solution of activity concentration of 300kBq/mL. The spheres mimicked irradiated parotid glands (right (RP) and left (LP)) and submandibular glands (right (RSM) and left (LSM)) respectively. The phantom was filled with technetium-99m solution of activity concentration 144kBq/mL.1 A planar image was acquired in 5 minutes using Siemens E-Cam dual head gamma camera detector positioned 5cm vertically above the phantom, on 128×128 matrix size following a thyroid protocol. The detector was fitted with low energy high resolution collimators. ImageJ software was used for quantification.

The image counts post PVEs quantification were: LP=252,690; LP=160,836; RSM=149,315; LSM=68,292. The percentage quantification errors were: 44 per cent, 48 per cent, 51 per cent and 75 per cent for the LP, RP, RSM and LSM glands respectively.

ImageJ software improved quantitative accuracy of sphere images hence it provides a robust quantification tool for irradiated salivary glands.
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