Recognizing Intrapulmonary Lymph Node (IPLN) and Lymph Node in Soft Tissue Image from Low Dose Computed Tomography (LDCT) and Standard Dose Computed Tomography (SDCT): Study Using CIRS Phantom

Abstract

Low Dose Computed Tomography (LDCT) is well-known for lung screening which administers low dose on the patient. In screening, intrapulmonary lymph node (IPLN) and lymph node in mediastinum (soft tissue) need special attention. In this research, nodule simulations with 36-85 Hounsfield units (HU) were made. IPLN was embedded inside lung simulation medium that was shaped as the module for 002LFC CIRS Thorax Phantom. The same method was also used for lymph node that was embedded in the soft tissue area. Image acquisition was conducted using LDCT and SDCT (Standard Dose Computed Tomography) methods with 100 kV and 120 kV exposure condition. The variations for mAs were 11, 25, 30, and 50 for LDCT and 70, 80, 90, 100 for SDCT. The result showed that IPLN image could be detected using LDCT method at 100 kV. Meanwhile, lymph node in soft tissue was not easily detected using LDCT because the noise in LDCT was relatively higher than in SDCT.