Introduction to Digital Radiography

Introduction to Digital Radiography

• Digital radiography (DR) involves using electronic detectors instead of film to capture x-ray images.
• Images are stored digitally, enabling easier manipulation and sharing.
• DR offers advantages, but also concerns such as higher upfront costs and possible sensor damage.

Objectives of the Lecture

• Students should be able to differentiate analog and digital images.
• Students should be able to describe various digital radiographic (DR) systems.
• Students should compare various DR systems (e.g., PSP, CCD, CMOS).
• Students should be able to list applications of DR in dentistry.

Image Receptors

• Dental images are created when an object is exposed to x-radiation.
• Attenuated beams are received by image receptors.
• Image receptors include films (analog), sensors/detectors, and image plates (filmless digital).

What is a Digital Image?

• A digital image is saved in a computer's memory.
• It's a representation of a real image as a set of numbers.
• Images are composed of pixels arranged in a matrix.
• Each pixel has a gray shade (color) and a specific position.

Digitization

• Digitization is any modality or method that creates an image viewable and storable on a computer.

Analog vs. Digital Images

• Analog images use dental films, showing continuous gray shades between black and white.
• Digital images use sensors, producing discrete gray shades (pixels).
• Digital images are numeric and discrete unlike analog images that use continuous tone.

Intraoral Digital Imaging

• Analog images are captured and displayed on conventional dental film.
• Digital images are captured by sensors and displayed on a computer monitor.

Advantages of Digitization

• Digital image enhancement is possible.
• Images can be shared with other specialists (teleradiography).
• Processing is faster.

Disadvantages of Digitization

• Longer processing times may still exist in some cases.
• Films are still used in combination with DR.
• No reduction in overall radiation dose in all DR systems.

DR Systems

• DR systems include direct (CCD, CMOS, CID) and indirect (PSP) systems.
• Direct systems convert x-ray energy directly to an electronic signal.
• Indirect systems use a photostimulable phosphor plate to store x-ray energy, converting it to light then an electronic signal.

Indirect Digital Radiography

• Indirect DR systems digitize analog images using scanners or cameras.
• The scanned analog image is converted to a digital image.

Direct Digital Radiography

• Direct digital radiography uses sensors that convert x-rays directly into digital signals.
• This approach typically provides immediate image viewing and eliminates the step of processing.

CCD and CMOS

• CCD (Charged Coupled Device): faster and better image resolution than PSP.
• CMOS (Complementary Metal-Oxide-Semiconductor): less expensive and less bulky than CCD.

PSP (Photostimulable Phosphor)

• PSP plates store x-ray energy electronically, releasing it as light for digitization.
• PSP plates are re-usable.
• PSP systems typically involve a scanning process.

Digora PSP System

• Digora is a common type of PSP system.
• It uses a reusable photostimulable phosphor imaging plate.
• The plates contain a layer of barium fluorohalide phosphor, which captures the x-ray energy.

Methods of Scanning Phosphor Plates

• Rotating plate scanning
• Stationary plate scanning

Pros & Facilities of Digital Radiography

• Time-saving compared to conventional imaging methods.
• Reduced exposure times (lower radiation dose).
• Enhanced image presentation and understanding to improve patient education.
• Digital Storage, Archiving, and Recall (SAR).
• Image compression for storage space efficiency.

Teleradiography

• Transmission of images (x-rays, CT, MRI) for consultation and sharing among specialists.

Environmental Friendliness

• No use of chemicals; reusable sensors; less space requirements (no darkrooms).

Fewer Files Cluttering

• Digital storage reduces the physical volume of radiographic files.

Sensor Sizes

• Sensors are available in various sizes to accommodate diverse imaging needs.

Image Enhancement

• Software can enhance image quality by adjusting brightness and contrast, sharpening, and pseudo-coloring.

Image Manipulation

• Software enables zooming, measuring, and magnification functionality.
• Software tools aid analysis and problem identification.

Combining Intraoral Radiographic Data

• Integration of intraoral and radiographic data for comprehensive analysis.

Pseudo 3D

Subtraction

• Using sequential radiographic images to analyze changes over time.
• Subtracting the first image from the second highlights changes (such as bone loss).

Quantitative and Qualitative Analysis

• Quantitative analysis produces numeric results for bone changes.
• Qualitative analysis visualizes areas of change on the image.

Geometric Standardization and Exposure Parameters

• Geometric parameters are crucial for accurate radiographic analysis.

Cons & Limitations

• High initial investment: digital systems are more expensive than traditional systems.
• Sensor Thickness: Some patients find direct sensors thicker and uncomfortable.
• Sensor Damage: Cables can be damaged; sensors often cannot be sterilized.
• Resolution: Some digital systems have lower resolution than film systems.
• Software needs: Advanced software is essential for efficient use.

Clinical Application of Digital Radiography in Dentistry

• Digital radiography is applicable to various dental specializations, improving diagnostic accuracy and image handling.

Dental radiographic use of DR in specializations like Prosthodontics, Implantology, and TMJ

• Digital radiography is used for these specific areas in dentistry to enhance the quality and accuracy of information gathering

Radiometric Measurements (Bone Density)

• Using the area tool for analysis; produces mean gray values after surgical intervention for bone density.

Digital Tomography for TMJ and Orthodontics

• Using digital tomography for analyzing temporomandibular joint (TMJ) conditions and other specific areas of the mouth.