Posted  January 5th, 2019

What to consider when buying an x-ray machine?

When time comes to purchase an x-ray machine, many buyers with no related technical knowledge will get confused between different machines’ specification, and consequently might not be able to compare prices fairly.

To start, let’s all agree that an x-ray machine consists of two basic parts, the x-ray system for x-ray radiation and the acquisition system. The acquisition system is responsible for receiving and reconstructing the x-ray images. Calling the machine conventional or digital in todays’ market depends on whether the two parts are integrated or not.

• Digital x-ray machine = x-ray system + digital acquisition system
• Conventional x-ray machine = x-ray system or x-ray system + conventional screen film (SFR)

Here is a very basic explanation of the x-ray system and what features to consider when buying an x-ray machine.

       I.  X-ray System

The main component for an x-ray machine is the tube and how it is mounted (floor mounted, ceiling suspended or portable unit), everything else could be optional. We will start with the patient table and the common features you might need to think about.

  1-      Patient table (PT)

If you are a chiropractor, you wouldn’t need a patient table. If the x-ray machine is for a hospital or imaging centre, then PT would be a necessary part. Below are few features for PT to decide which one is more suitable for your business.

• 2-way floating table: It moves in two directions, can be considered if you are a vet clinic.
• 4-way floating table: It moves in four directions, and this is the common type for most diagnostic imaging practices
• Fixed or elevating table: Fixed is more convenient for limited budgets as you might need to invest 5k-8K more for motorized elevating tables.
• Automatic Exposure Control: AEC function controls and limits the amount of x-ray exposed to patients making operators’ exposure-errors less likely to happen.
• Rotating bucky: It makes it easier to rotate the cassette or detector without taking it out of the tray. It saves time and makes the operators more satisfied, but not a necessary feature.

2-      Wall Bucky Stand (WBS)

There are few types of WBS, basic WBS and more advanced ones. Below are optional features to consider.

• Automatic Exposure Control: AEC function as mentioned in the patient table
• Fixed grid: Wall bucky stand usually comes with moving grid but can always be replaced with fixed grid which is more expensive. The fixed grid doesn’t make noise as it doesn’t need to move during x-ray exposures. Fixed grids are better in removing scattered radiation also more durable as no communication required between grid and generator during exposure. 
• Motorized movement: Most of the wall bucky stands are counter balanced but there are optional features to have them motorised for even easier lifting
• WBS tilting: Tilting the detector is always an optional feature making life easier for operators and patients, but all comes with additional cost
• Remote control of the WBS movement: Mostly available in all brands and not offered unless asked for.
• Synchronization between tube movement and WBS is a feature that limit the double work for operators as they don’t need to adjust the two parts. They just adjust the tube and the WBS will get aligned automatically. Very nice feature if you have busy workflow and need to save time.

3-      X-Ray tube mounting designs 

There are mainly two options for tube/collimator mounting.

• Floor mounted/floor-ceiling mounted (No big differences, only depending on the room dimensions and set-up)
• Ceiling suspended: Provides more flexibility in tube handling and positioning. It is more convenient solution when scanning emergency or in-patients while they are on their transporting trolleys, without the need to carry them onto the patient table.

4-      Generator power rating:

There are different generator power specifications depending on manufacturers. Below ranges are just to give a closer idea.

• 30KW – 50KW systems: Ideal for VETS and Chiropractors
• 50KW- 80KW systems: More ideal for hospitals and medical imaging centres.
• 3KW-20KW systems: Ideal for mobile and portable x-ray systems, from small animals to humans.

       II. Acquisition Systems

In todays’ market, there are two types of acquisition systems available, cassette readers (CR) and flat panel detectors (FPD). We will tackle few main points to compare both solutions and their related cost, without going in deep technical details.

• Speed

  FPD takes 2-6 seconds to acquire and reconstruct an image. CR can take an average of a minute to get the one image processed depending on operators’ speed. The advantage of multiple scanning at the same time using detectors versus one by one using CR systems gives FPD superiority in speed.  

• Detector Panel handling

  Although most of the recent FPD are shock tolerant, they should always be handled with care as there is a possibility of getting damaged if dropped from a distance. CR cassettes are much safer to use and less likely to get damaged.

• Image quality against applied dosage

  One more advantage of using FPD is the image quality specially if you are using CSI detectors which can give a better image quality at less applied dosage (which is also good for prolonging the life time of your x-ray machine).

• Panel Size
  
  FPD comes in one size of your choice, the most common is the wireless 14’X17” but there are options of tethered or wired 12x 12 inch, 14 x 17 inch or 17 x 17 inch. For the CR you can easily have the 3 sizes available with every CR system.

• Cost of ownership: 

  When it comes to cost, CR systems win for the short-term, they can be a better choice for a new starting business or a business that has limited number of patients every day. However, FPD might still be your better long-term investment choice considering depreciation value, satisfaction of stuff, speed and quality of the work done .

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