Integrating PACS, CR and DR into Radiology Department

ABSTRACT

This research paper gives a thorough description of the Picture Archival and Communication System (PACS), Computed Radiography (CR) and Digital Radiography (DR). Various advantages of integrating these technologies in the Radiology Department are highlighted. The method of analysis includes taking into consideration the pros and cons of having these systems and it provides reputed information from various medical journals published within the recent years. The disadvantages of these systems are also explored also using excerpts. Recommendations to standardize exposure technique charts were suggested, as well as suggestions to provide individual training. To conclude, this paper clearly states that the advantages outweigh the disadvantages, and the integration of these three systems in any institution would be very beneficial.

INTRODUCTION

X-ray imaging involves the generation of x-radiation by utilizing the ability of high frequency of electromagnetic waves, and the capture of these x-rays after they have passed through the patient. With the use of conventional radiography, images are captured on film, whereas Digital Radiography (DR) is a filmless procedure where the images are displayed on a computer monitor. DR can be divided into cassette-based (Computed Radiography-CR) or cassette-less image capture. A Picture Archiving and Communication System (PACS) is a computerized means of replacing the role of conventional radiographic film. The use of CR/DR alongside PACS allows us to acquire, store, transmit and display radiographic images digitally. The transition of the Radiology Department from conventional radiography to these technologies comes with many benefits. The introduction of PACS, CR and DR has brought many positive changes in the Radiology Department such as improved patient care, efficiency in the workflow and improved image quality when compared to conventional radiography.

OBJECTIVES

The aim of this paper includes discussing these technologies in detail and how their integration into the Radiology Department has brought about positive changes. The intention of this paper is to discuss the advantages of each of these technologies (CR/DR and PACS) as compared to conventional radiography.

APPROACH

For this paper, various online medical journals as well as reputed medical websites were used. Focus was made on the most recent journals such as “PACS: Taking Radiology into the 21st Century.” This is a research journal of the Radiological Society of Pakistan and was published by the Pakistan Journal of Radiology in 2016. This journal discusses the impact upon patient care due to the transitioning of a full PACS system with digital images as opposed to film-based images. Another recent journal in which this paper is based on is “Transitioning to Digital Radiography,” by W. T. Drost. This journal was published by the Journal of Veterinary Emergency and Critical Care, San Antonio in 2011. This paper explores the different forms of DR and compares the workflow for each of these technologies. Finally, a publication entitled “Buyer’s Guide to Digital Radiography” discusses the issues that healthcare providers need to evaluate, such as digital technology costs, maintenance fees, and potential impact of this technology on staff.

FINDINGS AND DISCUSSION

X-ray imaging involves the generation of X-rays and the capture of these X-rays after they have passed through the patient. With the use of conventional radiography, images are captured on film. With this film-based radiography, cassettes contain the film and the image that is produced on this film is known as the latent image. These cassettes, with exposed film, are transported to the darkroom. In the darkroom, the film is taken out of the cassette. It is then developed and fixed to transform the latent image into a radiograph, and the cassette is then reloaded with an unexposed film. This manual processing takes a long time, as opposed to the automatic processing of a digital system that takes 60-90 seconds. One downside to these film-based radiographs is that it can only be at one location at a time and they are generally stored in a dark film room when not in use.

 Computed radiography (CR) is one form of Digital Radiography (DR), which employs the use of CR cassettes. An imaging plate that is coated with photostimulable phosphors is contained within these cassettes, and when exposed to x-rays, their electrons become excited to a higher energy state. The electrons become trapped in the phosphor. These trapped phosphors form a latent image, similar to that on an x-ray film in conventional radiography. The imaging plate must be processed rapidly because the electrons forming the latent image may only be stable or stored on the plate for minutes. The cassette containing the latent image is processed in the CR plate reader by removing the imaging plate from within the cassette, where it is then scanned by a laser which frees the trapped electrons, returning them to a lower level energy state. This laser scanning causes the material to emit light, and this light is captured and amplified using photomultiplier tubes, and then sent to an analog-to-digital (AD) converter.

 Drost (2015), in the article entitled “Transitioning to Digital”, stated that “The digital image is formed based on the location (x and y coordinates) and the intensity (z coordinate) of the light emitted during the laser scanning. The brightness of each pixel in the image relates to the amount of x-ray attenuation of the structure imaged.” After it is sent to the AD converter, the imaging plate is exposed to a high intensity fluorescent light, which eliminates any remaining electrons, allowing it to be reused. It is then put back into the cassette and ejected from the reader. CR cassettes are the same size as conventional X-ray cassettes and are also used in similar manner. One similarity is that a separate cassette must be used for each radiographic projection and a couple advantages of CR over conventional radiography is that a CR plate reader does not have to be located in a darkroom and processing of imaging plates takes 60–90 seconds. However, we can immediately see that conventional radiography, which uses darkroom, is more expensive from the constant purchases of film developer and fixer solutions, film holders, and the film itself. There are also costs associated with disposal of the chemical waste generated by processing the film. The elimination of these chemicals that are associated with conventional radiography, as well as the reduction in the use of radiation, are cost savings which can be reaped from DR.

Digital Radiography (DR) involves cassette-less imaging and comes in two forms; one that directly converts x-rays to an electrical signal (direct DR) and another that converts x-rays to light, and then to an electrical signal (indirect DR). Instead using a cassette, a piece of equipment called a flat panel detector is used. Direct DR detectors have a photoconductive layer that converts x-rays into an electric signal. This photoconductive layer is linked to a thin film transistor array that is spread across the detector, creating a matrix that maps the x and y coordinates of the signal. The intensity of the signal (z coordinate) is related to the x-ray attenuation of the patient, and is displayed as brightness. For indirect DR, the photoconductive layer is replaced by a scintillator, which is usually made of cesium iodide crystals. The scintillator converts x-rays to light, and a diode layer converts the light to an electrical signal that is linked to the thin film transistor. In both systems, the flat panel fits into the existing x-ray table and is connected to a computer via a cable.

 The workflow associated with DR is faster than that off analog radiography and CR. The computer in the DR is used to input patient data and to preview the images. The patient is placed on the x-ray table and the density of the body part being radiographed is measured. The settings for the x-ray machine are based on the technique chart. However, the technique chart varies from the one used for conventional radiography. Once an exposure is made, the radiograph is displayed on the computer within seconds (DentsiryIQ, 2015).

 One of the essential differences between conventional and CR/DR radiography is that film-based images cannot be altered once they are processed. The exposure conditions and the developing procedure for conventional radiography determines the final result; that is, the density and contrast are fixed (Drost, 2011). Whereas, digital images can be altered after they have been produced. The radiographer can apply different mathematical operations to alter the pixel values, which can change certain characteristics of the image. This operation is called “image processing” and can be used to correct overexposure or underexposure, amongst many other things. Once the study is complete, images are sent to a workstation or an image server.

 For conventional radiography, view boxes are required. Digital images however, are viewed on a monitor at one or multiple workstations. If clients request a copy of their digital images, CDs or DVDs should be able to burn at least at one workstation. A DR is a rectangular pixel matrix and each pixel contains information about x-ray attenuation of the structure in the x-ray beam. Film-based radiographs have a narrow range of exposure techniques that produce a diagnostic quality radiograph. DR systems have a wide dynamic range and are more ‘forgiving’ to the errors of radiographic technique (Strickland, 2000). A better contrast resolution is produced with a wide dynamic range than film-based radiographs. Detective quantum efficiency (DQE) describes the performance of an imaging system as a function of the system’s ability to process signal and noise. In general, digital systems with a high DQE have higher spatial and contrast resolution and therefore higher image quality. DR systems achieve a high DQE using lower radiographic techniques. This should mean fewer repeated radiographs based on the radiographic technique compared to conventional radiography. We can again see the benefits of CR/DR as compared to conventional radiography and transitioning our Radiology Department to include these technologies will cause it to benefit greatly.

 A Picture Archiving and Communication System (PACS) is a “computerized means of replacing the roles of conventional radiological film; images are acquired, stored, transmitted and displayed digitally,” (Strickland, 2000). PACS can be a single desktop personal computer which receives, stores and retrieves the images or it can be a country wide system with hundreds of health care facilities linked to each other by a high bandwidth network, having many servers and data centers. The kind of hardware required broadly consists of computers to store the images, workstations to review and retrieve them and a network to connect all the components (uz Zaman, 2016). When such a system is installed throughout the hospital, a filmless clinical environment becomes the result.

 The journal published by the Radiological Society of Pakistan (RSP) entitled “PACS: Taking over the 21 st Century,” discusses how PACS has revolutionized how images are stored, reported and distributed. The journal also states that PACS has forever changed the workflow in the Radiology Department as well as patient care. The efficiency resulting from handling data electronically is one of the main advantages of a PACS. That is, it cannot be stolen, lost or misfiled as compared to film-based images. Patients care is improved because it eliminates the physical need for the patient to carry the film wherever a consultation needs to be made, whether it is a private doctor or a public institute. They are also burdened with caring for their image records.

 Another advantage of PACS digital images over film-based images is the simultaneous viewing of the same image at multiple locations. Conventional film can only physically exist in one place at any one time. By introducing PACS in the Radiology Department, images are available at a fast rate for reviewing and reporting at various workstations, and there are no longer any delays due to the non-availability of images (Drost, 2011). Copying of film-based images, which would have been needed in such a case, were associated not only with additional cost but also lost in image quality. Furthermore, there is no loss of image quality over time with PACS images as compared to film-based images. The introduction of a PACS has undoubtedly brought about many positive changes in the Radiology Department.

 Although the introduction of PACS, CR and DR in our Radiology Department has many benefits, the cost factor in switching from conventional radiography to these technologies must be weighed, such as the cost of the digital equipment itself. In general, CR is the least expensive, followed by DR (uz Zaman, 2016). If the practice uses 2 or more x-ray tables simultaneously, CR cassettes can be used on either table, whereas for a DR system, a flat panel detector must be purchased for each x-ray table. Service contracts for the DR systems are recommended and the cost of these contracts is usually a percentage of the purchase price. Computer equipment, including monitors, is needed when the system is installed and the amount of computer equipment can be expanded at a later date if so desired. Regardless, factors that include maintenance and computer equipment, such as software upgrades, should be planned for. However, some benefits of DR may not be obvious initially. With the use of DR, the darkroom, x-ray film, processing chemicals and storage of recovered silver becomes obsolete (Van der Stelt, 2008). As DR becomes more popular in all phases of medicine, the demand for X-ray film will decrease, likely driving the price of film higher.

RECOMMENDATIONS

With the various advantages listed above, the overall upgrading of radiology departments worldwide to a digital system is strongly recommended and crucial. Digital systems can produce an increased radiation dose to patients, which has been noted, and as such, standardization of exposure values is very important. This can be done by developing exposure technique charts, identifying acceptable exposure ranges and also by ensuring that the technologist/radiographer receive proper training and integration with the use of a digital radiography system specifically.

CONCLUSION

The introduction of PACS, CR or DR into the Radiology Department has, without a doubt, generated numerous benefits. Some of the advantages that have been gathered from the literatures studied include improved workflow, better patient care, enhanced image quality, ease of use, faster completion of a study, fewer repeat radiographs, less physical storage space and the ability to easily send an image to another location. The various journals made particular note that even though there are a few disadvantages of switching to Digital Radiography, the advantages that exist with the use of DR are vast and overwhelms any disadvantages that exist. However, I believe that there should be some evidence to prove these claims, such as a case study within a named hospital. We can better appreciate the long-term investment in Digital Radiography if such a case study outlined initial cost of implementing and maintaining a conventional radiography system, then comparing these figures with the cost of transitioning to Digital Radiography.

REFERENCES

• Dentistryiq.com. (2015). Digital Radiographer: A change for the better. Retrieved 6 December 2019, from http://www.dentistryiq.com/articles/dem/print/volume-11/issue-3/equipment/digital-radiography-a-change-for-the-better.html
• Drost, W. T. (2011). Transitioning to digital radiography. Journal of Veterinary Emergency And Critical Care (San Antonio, Tex.: 2001), 21(2), 137-143. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1476-4431.2011.00611.x
• Strickland, N. H. (2000). Current topic: PACS (picture archiving and communication systems):
• Filmless radiology. Archives of Disease in Childhood, 83(1), 82-86. https://adc.bmj.com/content/archdischild/83/1/82.full.pdf
• uz Zaman, M., Sajjad, Z., & Fatima, N. (2016). PACS: TAKING RADIOLOGY INTO THE 21st CENTURY. PJR, 21(1).
• Van der Stelt, P. F. (2008). Better imaging: the advantages of digital radiography. The Journal of the American Dental Association, 139, S7-S13. https://www.sciencedirect.com/science/article/abs/pii/S0002817714634589