Medical imaging is a branch of diagnostic technology that captures images of the human body for clinical and research purposes. The images are obtained through visual inspection or by using other techniques such as ultrasound, infrared imaging, computer tomography (CT), magnetic resonance imaging (MRI), etc.

Medical imaging equipment uses film to capture digital images in radiology, pathology, immunology, and endoscopy fields. The camera used in medical imaging systems has a film chamber that can be filled with one of the types of film depending on the type of image required. Let us take a look at all these types.

1. What is Wet Imaging Film?

Definition

Wet film processing, also known as liquid chemical film processing, has historically been the foundation of traditional film-based imaging. Wet film imaging is a process that uses emulsions to image biological matter. It is important to understand how wet processing is used in the medical field.

The wet imaging film consists of a flexible plastic base coated on one side with a layer of light-sensitive chemicals. The chemicals used in the wet film are silver halide, developed by the reaction between silver salt and halide salts. The development of the exposed film typically takes place in a dark room apart from the camera. This is because light will make the chemicals reactive, resulting in lost work.

Wet imaging films use a light-sensitive emulsion in a thin layer that consists of a mixture that includes gelatin, colloidal silica, plasticizers, solvents, etc. The emulsion is spread uniformly on a PET film (Polyethylene terephthalate), which is then dried.

Wet film processing is typically more expensive than other digital scanning options. It is often the first imaging modality of choice when performing certain procedures, such as chest x-ray and ultrasounds. However, the wet film can create high-quality images of tissue and fluids in all organ systems. It is often used in conjunction with various image analysis techniques. The technology is common within the radiography and ultrasound fields, but it is also commonly used in radiology, pathology, nephrology, endoscopy, and nuclear medicine.

1) What is X-ray film

X-ray film is a form of light-sensitive diagnostic media used in radiography. Medicine uses it to image internal organs, bones, and soft tissue structures.

X-ray film uses silver halide as its primary sensitizer, which means it is sensitive to X-rays that fall in the electromagnetic spectrum at 25 to 100 kiloelectron volts (keV). X-ray films are also known as “radiographic emulsions”. They are typically made of cellulose nitrate and acrylate plastic base coated with silver halide emulsion.

X-rays pass through an object and expose the X-ray film wrapped in a protective lead covering. The exposed film is processed to produce the picture. X-ray film is highly sensitive to light and requires a long exposure time. The typical exposure time for a radiograph on the X-ray plate is from 5 to 15 seconds. A plate must be scanned and transported in a closed, light-tight container or darkroom to prevent degradation of the image by ambient light or humidity.

Advantages of X-Ray Film

Offers sharp image quality: X-ray films provide sharp images. These films allow the radiologist to distinguish between normal and abnormal tissues.

X-ray films are compatible with most equipment: X-ray film is easily compatible with most X-ray equipment. It can be used in analog and digital radiography machines.

X-ray films are user friendly and environment friendly: X-ray films are environment friendly, and it is also light- and humidity-sensitive, so it is easy to handle. The X-ray film can be handled safely in hospitals, clinics, doctors’ offices, or other places.

FUJIFILM and AGFA x-ray film allows for rapid processing of fine images with high-quality resolution.

Disadvantages

The X-ray film is sensitive to both heat and cold. The film will be damaged if the X-ray image is exposed to high temperatures, such as during sterilization or autoclaving.

Summary

X-ray film has been used for more than 100 years. It is a common modality used in many types of medical imaging, including radiology, nuclear medicine, and radiography. In most of these fields, x-ray film is typically the first choice for creating images.

2) What is Analog film

Analog imaging film is a light-sensitive radiographic film that images the human body (or any other subject) with an X-ray tube. The term “analog imaging” refers to the fact that these films are sensitive to X-rays, unlike digital imaging technology.

The analog film consists of a base and emulsion coated on both sides. It generally has a thickness of 0.14 mil (0.0035 mm). The emulsion consists of silver halide and gelatin, which is sensitive to visible light but becomes sensitive to X-rays after processing and drying. When a charged particle, such as an X-ray, passes through the film, it deposits its energy in the silver halide grains forming a latent image. The film’s process is similar to when X-ray films are developed.

You can develop the analog film in a darkroom or an automatic cleaner that removes dust and debris from the emulsion and base coat before it is put through the automatic developer.

Advantages of Analog Film

• Analog film is highly sensitive even to low levels of radiation and thus is very useful for taking X-ray images. Since we have both positive and negative films in the market, it makes them more versatile compared to other types of X-ray films.
• Analog films are relatively inexpensive compared to other types of X-ray films.

Disadvantages of Analog Film

• Analog films are susceptible to damage from light, humidity, physical manipulation, and most chemicals.
• They are not as durable as other types of films.
• They are can’t be processed at home because of its sensitivity to light and heat.

Summary

X-ray film it’s a kind of analog film used in medicine that belongs to medical wet imaging film. It is processed by liquid chemicals in a dark room, green-sensitive and blue-sensitive. Analog films were the only form of imaging available before digital imaging. Some physicians and nurses still use them and may remain in use longer than digital images.

The most famous brands are FUJIFILM and AGFA.

2. What is a Medical Dry Imaging Film?

Dry imaging film is a type of film that doesn’t require any chemicals or water to develop an image. Instead, it uses heat and powdered chemicals to create an image on the film. The image on the film is then transferred to a printing plate, usually made of aluminum.

Dry imaging film consists of silver halide in a dry emulsion mixed with gelatin and plasticizers that must be developed by heat. After exposure, the film is developed using a heated drum or between two heated rollers. In some cases, the heat from the dry chemicals is enough to develop an image on the film, but in other cases, it needs to be put through an entirely dry process. The process makes it possible for the film to be developed in the darkroom, but it is not common practice. The dry film is then transferred to a printing plate that can be used in a photographic press.

There are 3 types of medical dry imaging films, medical thermal film, medical laser film and medical inkjet film, they are all medical digital film.

1) What is Digital Imaging Film?

Digital imaging film is a recent development in radiography, which uses X-ray film for diagnostic purposes using digital imaging technology. Digital imaging films offer medical professionals an alternative to analog films, giving them higher resolution images, broader image processing applications, and flexibility in quickly obtaining digital images rather than printed film.

Digital imaging films are made of an emulsion coated on both sides. One side is sensitive to visible light, which converts the visible light into the energy required to produce a latent image in the silver halide grains on the other side. Once the image has been created, it is developed using a process similar to analog films. However, it is sent through a processor, where it is digitized and stored on a computer storage drive. The digitized image can be manipulated by software and printed out as a hard copy.

Digital imaging films offer greater flexibility in manipulating radiographic images to improve archived more easily than analog images, allowing more efficient storage and retrieval.

Advantages

• Digital imaging films can be used in the computerized tomography (CT) scan, which produces detailed cross-sectional images of internal organs.
• Digital imaging films are currently the most widely used form of X-ray film commercially available. They have replaced analog films for many uses because of their capabilities for processing and archiving more digital information than analog images.
• Although digital imaging film does not produce a hard copy, it can be scanned at home by placing it through an automatic cleaner and then sent to a printer, where it will produce a printout. The images are stored and viewed using a computer.
• Digital images can also be combined with other types of imaging, such as computer tomography scans, ultrasound and magnetic resonance imaging (MRIs). This benefit is referred to as cine-radiography.
• The digitized image may need to be sent or printed at another location where it can be manipulated further, which may take extra time when ordering a diagnostic test
• Digital imaging films can be used in the computerized tomography (CT) scan, which produces detailed cross-sectional images of internal organs.

Disadvantages

• Digital films are not as sensitive to X-rays as other types of films, making them more resistant to damage from X-rays.
• Digital films are sensitive to physical damage and temperature, making them less versatile than other imaging methods.

2) What is medical thermal film

It is a medical imaging film (medical digital film) used in X-ray technology. The medical dry thermal film has a blue PET base or clear PET base. The film has a thickness of about 180 microns and can last up to two years of shelf life.

This film is used with medical thermal imagers to scan the body and patient. These images are X-ray machines that radiate a beam of invisible light (ultraviolet or infrared light) through the patient, which is then “read” with a special camera and processed by software. The thermal film is fed into these images along with an analog loop or full-plate film holder, which allows the thermal film to move between two heated drum runners and be exposed by light emitted from a radiographic tube that moves back and forth beneath it.

Some of the best manufacturers of medical dry thermal films are FUJIFILM and AGFA brands.

Advantages:

• High contrast and resolution
• Clear images with good details
• Accurate and fast image quality evaluations
• Good for radiographic examinations
• Good for high-resolutions, high-contrast and low dose for diagnostic images
• Has quick image processing, faster than other imaging modalities such as ultrasound or MRI
• Compatible with many thermal printers

Disadvantages

• It’s effected by high temperature, need to store in certain environment
• The cost is expensive than some other films eg.inkjet film.

3) What is medical laser film

It is a light-sensitive polyester-based medical imaging film made of PET thermoplastic with silver halide emulsion on both sides. The film has a thickness of 180 microns and usually comes in blue. This type of film can be used by medical laser imagers that radiate a beam of invisible light (ultraviolet or infrared) through the patient, which is then “read” with a special camera, processed by the software, and printed out as a hard copy. The laser film is fed into the imaging machine with a full-plate film holder. Some of the best manufacturers of medical dry laser films are Fujifilm, Carestream, Codonics, Konica, and Kodak.

Advantages:

• Laser imageries have high resolution and contrast imaging
• They have faster image quality evaluations
• Good for radiographic examinations
• Suitable for working with silk-screen positives.
• In-line stabilized: The laser imaging machines are equipped with an in-line stabilization system to help reduce motion artifacts.
• Works well with high and low power lasers systems
• Compatible with many laser printers

Disadvantages:

• Easy to explored in light, need to handle carefully.
• The cost is expensive than some other films eg.inkjet film.

4) What is medical inkjet film

It is a light-sensitive polyester-based medical imaging film made of PET thermoplastic with silver halide emulsion on both sides. A bluish PET resin-coated base material and silica and alumina coatings make up the majority of inkjet medical printing film. In the radiology department, it is only used to print standard X-ray medical images, including CR, DR, CT, MR, and DSA. Inkjet film ensures no environmental pollution because it does not release poison-causing chemicals into the environment. Medical inkjet films are commonly used to scan standard X-ray images. The film is fed into the imaging machine with a full-plate film holder, and it moves between two heated drum runners. Some of the best manufacturers of medical inkjet films are Fujifilm, Carestream, and Konica brands.

Advantages:

• Environmental friendly: Great for environmental protection, environmentally friendly and no poison emitted, which can cause serious illness
• Water resistant and instant drying: It is not easy to get water spots and can dry quickly after getting wet
• High-quality images: It has good resolution, and high contrast, which ensures the diagnostic value of examination can be increased
• Can change the color of original images: One can change the color of standard images by changing the color of printer toner: black, blue or red
• Has quick image processing, faster than other imaging modalities such as ultrasound or MRI.
• Contains no chemical gas: Medical imaging films do not contain any poisonous gasses, carcinogenic or mutagenic chemicals that can be released during film manufacture or processing. Medical imaging films are also free of toxic solvents and alcohols that have thousands of times the EPA’s maximum allowable levels. The film does not release any poisonous gasses during image processing because it is thermally fast. All medical imaging scanning processes are completely safe to use anytime.

Summary

The most important things to remember about medical imaging films are that they are much less expensive than other imaging modalities. There are many different kinds of medical imaging films, but they all do the same thing with slight differences in how they operate. In addition to medical imaging films, many hospitals and clinics also have other scanning equipment that can be used as diagnostic tools. High-speed ultrasound and MRI machines are two examples of these diagnostic tools. The lower cost makes it financially feasible for many smaller hospitals and clinics to purchase and use these systems.

Conclusion

Medical imaging films are a valuable source of information when diagnosing at various medical facilities. The films are used primarily to create X-ray images of the body but can also be used in other imaging machines such as CT, MRI, and ultrasonography. It is important to evaluate what factors best suit the application to choose the best film for a particular situation or scenario.

The proper choice for imaging film is based on various factors such as cost, availability, quality, resolution, and overall image quality. The most important factor when choosing imaging films is understanding the benefits and limitations of each type of film and how various films are sensitive to specific types of radiation.