Measurement of table feed speed in modern CT.

Atsushi Fukuda,Pei‐Jan P Lin,Tosiaki Miyati,Kosuke Matsubara

doi:10.1120/jacmp.v15i3.4703

Abstract

The purpose of this study was to develop and evaluate a noninvasive method to assess table feed speed (mm's) in modern commercial computed tomography (CT) systems. The table feed (mm/rotation) was measured at selected nominal table feed speeds, given as low (26.67 mm/s), intermediate (48.00 mm/s), and high (64.00 mm/s), by utilizing a computed radiography (CR) cassette installed with a photostimulable phosphor plate. The cassette was placed on the examination table to travel through the isocenter longitudinally, with a total scan length of over 430 mm. The distance travelled was employed to determine the total table feed length. To calculate the table feed speed, gantry rotation time was measured concurrently at a preselected nominal rotation time of 750 ms. Upon completion of data acquisition, the table feed and gantry rotation time were analyzed and used to calculate the actual table feed speed (mm/s). Under the low table feed speed setting, the table feed speed was found to be 26.67 mm/s. Similarly, under the intermediate and high table feed speed settings, the table feed speed was found to be 48.10 and 64.07 mm/s, respectively. Measurements of the table feed speed can be accomplished with a CR system and solid‐state detector, and the table feed speed results were in excellent agreement with the nominal preset values.PACS number: 87.57.Q‐

Highlights

On the basis of their investigation, we considered that a computed radiography (CR) system and solid-state detector would allow accurate measurement of the table feed speed
We believe that our technique is useful to physicists because 1) the table feed speed and gantry rotation time can be measured without a time-consuming process, and 2) the technique does not require complicated quality assurance (QA) tools or software as the CR system and solid-state detector are devices familiar to many departments of radiology
The measured values were in excellent agreement with nominal preset values, the results show that measured table feed speeds were faster than nominal settings

Summary

Introduction

While the table feed speed is an important scan parameter of any CT scanner, the accuracy and precision of the table feed speed are not necessarily known to medical physicists, whose responsibilities may include the QA of CT scanners. The American Association of Physicists in Medicine (AAPM) published two reports, Report 39(6) and Report 83,(7) on the QA of CT scanners which evaluate specifications and test procedures. Both reports included evaluation a Corresponding author: Atsushi Fukuda, Shiga Medical Center for Children, 5-7-30, Moriyama, Shiga prefecture, 276 Fukuda et al.: Measurement of table feed speed in CT of performance of electromechanical components such as table to gantry alignment, table vertical and longitudinal digital indicators, radiation dose profiles, and the X-ray-generator kVp accuracy. While the table feed speed was not explicitly included in these reports, the authors opine that verification of the table feed speed is essential for the proper assessment of a modern

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