Last Updated on December 7, 2023
C-arm image intensifier or x-ray image intensifier is an imaging component that converts X-rays into a visible image and is a commonly used gadget in orthopedic surgeries. It is also used in many other procedures like gastroendoscopy, vascular surgery, neurosurgery, etc.
C-arm machines are fluoroscopy machines and are commonly called as image intensifiers. Fluoroscopy is a procedure that produces live body images using X-rays.
There are two types of C-arm image intensifiers or fixed image intensifiers
- Fixed
- Mobile.
A mobile C-arm image intensifier system is used during surgery for image-guided interventions or minimally invasive procedures. The imaging system unit can perform a variety of movements that allow for use in a variety of surgical procedures such as cardiology, orthopedics, and urology.
In orthopedic surgery, it is specifically used in complicated cases such as repositioning dislocated bone fragments, placing pedicle screws in the spine or positioning osteosynthetic material. It aids in surgery by displaying the structure not visible otherwise and aids in the accurate placement of implants. Several surgeries are not possible to carry out unless aided by a C-arm.
How C-arm Image Intensifier Work?
C-arm image intensifiers convert low-energy X-rays into visible light images. These use several thousand times less radiation and can produce visible images despite being based on X-rays.
On exposure, the X-ray beam strikes the patient’s part to be observed and emerges out. This enters the input window of the image intensifier and is partially absorbed by the fluorescent input screen to create several light photons. Due to the photoelectric effect [release of electrons on being struck by photons (light particle)], electrons are produced. Simply put the process is reversed at the output which converts electric signals into images.
The imaging device then displays the images so formed.
Components of a C-arm System
The main components of the C-arm image intensifier system are discussed below.
X-ray Generator
The X-ray generator is contained in the frame where the C-arm is mounted and can be controlled by the workstation unit directly. It is typically located on one side of the “C” of C-arm.
Imaging System
Also called a detector or image intensifier, it is located on the opposite side of “C” and always maintains its relation with a generator despite the position of the “C”.
Workstation Unit
It is like a controller unit and can control the entire procedure of the C-arm image intensifier. The workstation unit contains various controls and switches to control the power supply and radiographic controls among others.
Most of orthopedic procedures require a radiolucent operating table for optimum utilization of the C-arm.
Uses of C-arm Image in Orthopedics
The c-arm system has revolutionized orthopedic surgery. Not only, does it help to reduce surgical exposure by allowing maneuvering through smaller incisions, it has also enabled orthopedic surgeons to perform closed fracture fixation which was not possible earlier. A closed fracture reduction and fixation means that the fracture site need not be exposed. This further reduces the healing time and the period spent in rehabilitation.
The real-time live images allow surgeons to visualize the fracture reduction as well as accurate implant placement.
Following surgeries commonly employ the use of a C-arm image intensifier (Most of them are like minimally invasive procedures when coupled with C-arm use.)
- Spinal Surgeries: Spinal instrumentation like pedicle screw system, plate, and screw system require the use of imaging during the surgery.
- Nailing of Long Bones: Closed intramedullary nailing is used in diaphyseal fractures of long bones, especially the femur, and tibia. Using the C-arm, the medullary cavity is accessed from the selected point, and using the steps of surgery fracture is reduced and the nail is inserted without ever opening the fracture site, and maneuvering while getting input from the C-arm. Softer nails of titanium such as TENS nails are used in pediatric long bone fractures.
- K-Wires: Used for short bone fractures such as hand bones and foot bones. The use of a C-arm image system allows closed treatment.
- Hip Surgeries: Hip fixation implants frequently require fluoroscopic control
- Metaphyseal fracture fixation: C-arm guides accurate placement of wires and screws while protecting joint breach.
Following is a short video of metatarsal fracture fixation using C-arm. No fracture incision was required.
Risks and Hazards
However, the C-arm uses much less X-rays, but it is still a source of radiation. The radiation is insignificant when a single surgery is considered. However, it could be risk-fraught when repeated exposure occurs to the surgeon and OT personnel. Hence, proper shields of protection should be worn by all the staff present in the theater.
In the case of surgeries of children and pregnant women, all the measures should be taken to reduce the exposure further
