Principle and comparison of two dental digital imaging methods

Dental practices are moving to digital imaging. Martin Pybus discusses digital imaging and explains the advantages and drawbacks of various systems. He also explains how the transition from film to digital imaging impacts practices and the work as a dental nurse.

Digital radiography was previously only used in hospitals and practices that were at the forefront of technology. It is now the most common method of imaging in dental surgery.

It can be daunting for those who are not familiar with the technology. We will be discussing the various technologies and the benefits that digital radiography can offer a dental practice. Also, how it can help the life of a dental nurse.

Before we get into digital radiography, let's take a look at radiation and its use in dentistry.

X-rays, which are also part of the electromagnetic spectrum, are similar to visible light. It may be helpful to think of x-rays as a beam of light coming from a torch.

Visible light cannot pass through objects like the human body. X-rays, which have a higher energy level than light, can pass through objects. The x-ray energy is higher than light and can therefore pass through more material.

The tubehead is the main part of an xray machine that produces X-rays. The tubehead uses electricity to heat the filament, just like a lightbulb. The heating creates electrons around the filament. These electrons are then accelerated towards a target made from tungsten by using a high voltage. When electrons strike the tungsten, they produce x-rays.

All of these components are housed in a vacuum within a glass chamber. This is similar to a lightbulb.

Some x-rays will not pass through the body to reach the film or digital detector. The body will stop some lower-energy xrays (also known as soft xrays). Only high-energy xrays (known to be hard xrays) can pass through the body. X-rays which hit the body but don't produce images are not recommended and should be avoided.

An AC or DC tubehead is available for X-ray machines. AC tubeheads produce softer x-rays, and they have longer exposure times. DC tubeheads produce nearly all of their xrays as hard and have a shorter exposure time. This reduces the dose for the patient and lowers the risk of the patient moving during exposure.

I get many inquiries like this: "Hello, I want to buy one of your digital radiograph machines." It quickly becomes clear that they want an intraoral xray machine, which is a source of xrays and not a detector. There are neither analogue nor digital x-rays. X-rays can be described as light, and x-rays are light.

Methods of detection

There was only one way to detect x-rays or produce the image-film. This was until the mid-to-late 1990s. Digital technology is now dominating.

Digital radiography involves detecting x-rays on a computer and then converting them to a digital radiographic image. Images can be stored and modified once they are inside the computer.

There are two types: the direct digital (Dental Xray Sensor) and the indirect digital (Dental PSP scanner).

Direct digital (Dental Xray Sensor)

This is because the image is transmitted directly from the detector into the computer.

An intraoral system uses a sensor to replace film. The signal is sent to the computer by a cable that runs from the sensor. It then passes through an electronic box which converts the signal into digital.

The computer converts it into an picture.

New intraoral sensors integrate electronics into the sensor body. This means that the entire system is made up of a sensor at one end and a USB plug on the other.

Wireless systems are possible, but they have disadvantages such as being bulkier and more difficult to use, requiring batteries, and being susceptible to interference.

Direct digital systems need specific positioning systems. Standard film holders can't be used.

Speed is the main advantage of a digital direct system. It takes just seconds to get the image onto the screen from pushing the exposure button. Direct systems may have a higher resolution depending on the product.

Indirect digital (Dental PSP Scanner)

An indirect system uses a medium that detects x-rays but is not directly connected to the computer. Indirect systems use a photostimulablephosphor plate (PSP) to detect x-rays, and then capture the image. The image is then scanned in a PSP scanner, Figure 4.

Here's how it works. The image plate is made from flexible plastic with phosphor on the one side. The phosphor absorbs energy when x-rays strike it. The higher the energy received by xrays, the greater the amount of energy that is stored.

The plate is placed in the scanner and scanned using a red laser. It works a lot like a CD player. The phosphor releases its stored energy as blue light when the red light hits it. The scanner measures the blue light and converts it into a digital signal, before sending it to the computer.

Exposure to bright light then removes the plate.

Direct digital systems don't require any specific positioning systems. Standard film holders can also be used.