Digital Radiography: Advantages and Disadvantages

This article discusses the advantages and disadvantages of using digital radiography in clinical diagnoses. It covers the benefits and drawbacks associated with this modern imaging technique.

Introduction

X-rays are absorbed by the human body based on the specific density and atomic number of the tissues they pass through. These differences in absorption are recorded by an image receptor or detector. Radiography imaging systems utilize X-rays, gamma rays, or similar non-ionizing radiation to visualize the internal structures of the human body. Traditional radiography relied on X-ray films to store images.

What is Digital Radiography?

Nowadays, two popular types of radiography systems exist: Computed Radiography (CR) and Digital Radiography (DR). Both are digital imaging techniques where acquired images can be viewed and manipulated on a computer.

• Computed Radiography (CR): Employs a CR cassette and imaging plate to record the image. A reader is needed to extract the image from the cassette or plate using a laser.

• Digital Radiography (DR): Cassetteless systems can be categorized into direct and indirect conversion systems.

  • Direct Conversion: X-ray photons directly bombard a photoconductor, such as amorphous selenium. These photons are converted directly into electronic signals, which are then amplified and digitized. Direct conversion systems don’t require a scintillator.
  • Indirect Conversion: A scintillator layer converts X-ray photons into photons of visible light. These visible light photons are subsequently converted into an electrical charge using amorphous silicon as a photodiode. Indirect systems are further divided into two types based on the use of either Thin Film Transistors (TFTs) or Charge-Coupled Devices (CCDs).

The information captured by both direct and indirect detectors is read by TFTs (thin film transistors).

Figure 1: X-Ray Imaging System Block Diagram

The figure above illustrates the basic working principle of an X-ray imaging system, including its key components: an X-ray generator, an X-ray detector (or image receptor), and a computer. The image receptor detects and records X-ray images. It’s positioned below or behind the patient, allowing X-rays that have passed through the patient to fall upon it. Different types of image recorders are used in clinical radiography for diagnostic purposes, including photographic film, storage phosphor screens, and direct digital readout devices.

Figure 2: Digital Radiography System (Image Courtesy: Carestream Health, Inc.)

The image above shows the DRX-Evolution Plus system from Carestream Health Inc., which includes a wireless detector, a patient table, an X-ray overhead tube (motorized), and an operator console. The wireless detector is particularly useful for patients who are unable to walk but require X-ray imaging.

Benefits or Advantages of Digital Radiography

The following are the benefits or advantages of digital radiography for clinical diagnosis:

• Lower Radiation Dose: Digital images can be captured with a lower dose of radiation compared to conventional radiography.
• Image Manipulation: It is possible to adjust or modify the contrast, color, and size of images to improve the visibility of body parts.
• Automated Image Analysis: Modern data processing algorithms allow for automated image analysis.
• Elimination of Film Processing: Digital radiography eliminates film processing errors and the hazards associated with handling chemical solutions, as used in conventional radiography.
• Real-Time Acquisition: Digital radiographs are acquired immediately and in real time.
• Long-Term Storage: Digital radiographs can be stored for long periods on various digital storage media, as required by legal regulations in many countries.
• Easy and Quick Transfer: Digital images can be transferred quickly and easily between offices or institutions. This facilitates immediate and fast treatment for patients and avoids the need for additional radiation exposure.

Drawbacks or Disadvantages of Digital Radiography

The following are the drawbacks or disadvantages of digital radiography:

• High Initial Cost: Digital radiography systems are very expensive, requiring computers, servers, storage devices, etc.
• Storage Requirements: It demands more storage space depending on the image sizes.
• Potential for Manipulation: Digital images are prone to intentional manipulation for misuse.
• Lower Resolution: Most storage phosphor systems offer lower optimal resolution compared to radiographic film.
• Training Requirements: Radiologists need to learn and adopt new machinery, technology, and positioning techniques.