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Radiological Protection of Patients |
Digital radiology may represent the greatest technological advance in medical imaging over the last decade. The use of photographic films for X ray imaging will be obsolete in a few years. An appropriate analogy that is easy to understand is the replacement of typical film cameras with digital cameras. Images can be taken, immediately examined, deleted, corrected, and subsequently sent to a network of computers.
The benefits from digital radiology are enormous. It can make the facility filmless. The referring physician can view the requested image on a desktop personal computer, often with the report, just minutes after the examination was performed. The images are no longer held in a single location; they can be seen simultaneously by physicians who are kilometres apart. In addition, the patient can have all his or her X rays on a compact disk to take to another physician or hospital.
No. A darkroom is not required. If you need to print images, printers similar to computer printers will produce good images on radiographic film without chemicals.
Not necessarily. If you decide to use CR (computed radiography) you may continue using your X ray system after necessary modification.
No. The software to manage digital images is user-friendly and quite easy to use.
You will need some specific training to obtain the full advantages of digital radiology but not for the interpretation of X ray images.
CR means 'computed radiography' and this technique uses photo-stimulable phosphor plates to obtain the digital images. The great advantage is that you can still use your present X ray systems just by changing the cassettes. DR means 'digital radiography' and requires the use of newer X ray systems with a digital detector integrated. At the moment this last option is still more expensive but allows improving the workflow (it is no longer necessary to handle the cassettes).
This is not a good option. Angiography procedures require specifically designed X ray systems.
Yes, the most common solution is to use CR (computed radiography) with mobile systems, but there are already mobile X ray units with a digital detector (called 'flat detector' integrated on it) in the market. With these systems, the imaging tool is not a radiographic film but a phosphor plate. The digital detector receives the radiation going through the patient and converts it into a digital image that can be immediately visualized on a monitor.
Look for the image at the PACS with a similar name the day and time of the examination for the same modality. Try also to find the image by the identification number of the patient.
It is not easy to recognize the radiographic technique in digital imaging. If the modality used has been a flat panel detector, radiographic technique could be archived in the DICOM header.
It is not always possible to process the image or adjust the display so as to make it good for diagnosis. If some relevant areas of the image are saturated (the pixel content has the maximum value) the exposure must be repeated.
It is not easy to know it. Sometimes in the DICOM header a tag with the series number is archived. Another tag indicates the number of images acquired in every series. The only retrospective information that could be obtained is the number of series 'non archived' before the one existing in the PACS, e.g. if the archived series is the number 3, two other series were obtained before and not archived. It is not possible to know if other ulterior series were obtained.
Although digital imaging systems have potential for dose reduction, the experience shows that many facilities provide more doses to patients. The primary reason is that over-exposure goes undetected, unlike with film where the image turns dark or black. In digital imaging, in contrast, the image becomes better when it is over-exposed. Further, there is a tendency to take more images than necessary. In several hospitals, in-patient utilization (number of examinations per in-patient day) increased after transition to digital systems, while out-patient utilization (number of examinations per visit) also increased, although the number of examinations per visit nationally were decreased. It is very easy to delete images, and technologists tend to repeat exposure if the positioning is wrong or if there is motion blur. Such repeats normally go undetected. Thus digital imaging has the potential to increase the number of exposures and hence patient dose.
It is not easy to recognise these overexposures if the radiographic technical data or the dose values are not recorded by the X ray system or in the DICOM header. The wide dynamic range of digital detectors and the automatic post-processing create difficulty in recognising overexposures.
It is possible but one has to put some efforts. If obtained images are automatically sent to the PACS, a query to the images obtained the same day for the same patient could give the information. Other possibility is to look at the DICOM header. Sometimes a digit indicates if it is the first or subsequent exposure.