LEARNING OBJECTIVES

1. 1 describe ultrasound imaging

2. 2 describe basic x-ray imaging

3. 3 describe CT scanners and identify how they differ from basic x-ray devices

4. 4 describe DICOM and PACS

5. 5 describe and characterize MRI

6. 6 describe and characterize nuclear medicine – both imaging and treatment

7. 7 describe and characterize PET scans

Introduction

The technology involved in imaging the inside of the human body is tremendous and amazingly broad. There are a vast array of unique devices, but this chapter will deal with general categories (based on the technique or source of image) of imaging devices.

Ultrasound

Ultrasound uses sound waves to image anatomy and anatomical function. Ultrasound can also be used to detect blood flow, anatomic movement (heart valves, for example), and, most commonly, anatomical structures. It is frequently chosen as an imaging modality because it does not use radiation and carries less risk to the patient. Ultrasound uses high-frequency sound waves (1–20 MHz) that are projected into the body. The waves hit an object, bounce back, and are detected with a piezoelectric crystal sensor. The distance from the transmitter probe and the anatomical structure can be calculated, and this data is used to produce an image. Computers can manipulate the transducer data to present three-dimensional or moving images.

Transducer probes, which contain both the transmitter and the sensor, come in many shapes and sizes. Some are designed to enter body cavities such as the esophagus and the vagina for better imaging quality.