Introduction

Students will scan the content of an opaque mystery box similar to the way a CT scan functions. For the laboratory exercise, the instructor and students will build a basic device using standard physics laboratory equipment, such as a photogate, a rotation sensor, and a rotation table with an affixed scan area.

Using a computer interface device (Vernier LabPro) the experimenters use LabVIEW to synchronize the sensory devices and the scan display. The LabVIEW program was invaluable to the project as it is completely customizable, allowing for interfacing in a straightforward manner with the hardware, and is equipped with an array of display tools. We used LabVIEW to read the Vernier photogate and rotary motion sensor data. The data is fully processed within LabVIEW using trigonometric equations. Finally, the data is displayed using the LabVIEW intensity graph tool. Students can adjust the color table within LabVIEW similar to the way a radiologist does it in a real CT scan.

This laboratory exercise is intended for high school seniors in a physics classroom. The students will learn the trigonometry involved in computing the position of objects being scanned—SOH CAH TOA and line equations. Additionally, students will learn how the absorption of x-rays is involved in the imaging process and how back projection is used to generate a CT scan image. The electromagnetic spectrum can be discussed in the lecture to explain how x-rays and infrared waves are absorbed by a medium, for example, tissues in the human body. These subjects can lead to a discussion on how such a device is used in a medical setting and why x-rays can be used for imaging.

Key Materials

Vernier Photogate
Vernier  Rotary Motion Sensor
Rotating Platform
Sample Enclosure
Ring Stand Clamps
Computer with LabVIEW
 
For a more complete parts list, download the Lab Materials.