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Introduction |
| Over the years, photographic film was the principal means of storing medical images. The challenges existed in emphasizing details or differences of images. The storage of images, retrieving from remote sites posed a great challenge for the medical community. With the advancement of PACS / DICOM standards, it has helped the community by providing a means of storing, processing, and transferring of medical images. Internet with standards for image communication has provided a new way for instant display of the patient information needed for diagnosis. |
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| Photographic, X-Ray, Ultrasounds etc are some of the imaging systems to be considered as Cameras. These images are limited to resolution, amplitude scale & noise content. |
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| Ex: X-Ray images are resolution – limited by the dimensions of X-Ray source & noise limited by the beam intensity. |
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| Ultrasound image is limited by the angular resolution of the transducer & it's ability to separate true signals from false signals & noise. |
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Information content / Properties of an image |
| Pixels |
| The information content of an image is the product of number of discrete picture elements (pixels) & the number of amplitude levels of each pixel. |
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| Noise |
| The parameter affecting the amplification permitted in a channel, originating from the photographic grain, electric charge or the statistical variations of the number of quanta (light, X-Ray, Gamma Ray). |
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| Signal to Noise ratio (SNR) |
| The ratio of the signals to noise is considered to be the number of amplitude steps within a channel. The noise figure of a channel is the ratio of theoretical or best possible SNR to the measured SNR. |
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| Spatial resolution |
| Spatial resolution is expressed in terms of lines pair per millimeter considering image as a surface of a given dimension. |
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| Image Noise |
| The combination of both the images and spatial resolution results in Image Noise. |
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| Modalities in Medical Imaging |
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X-Ray |
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Computed Radiography |
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Computed Tomography |
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Magnetic Resonance Imaging |
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Nuclear Medicine |
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Positron Emission Tomography |
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Single Photon – Emission Computed Tomography |
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Ultrasonography |
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| Medical Image diagnosis |
| This often requires examination of an entire high-resolution image followed by scrutiny of a portion of the image, the region of interest (ROI). The original image should have much higher resolution than the display monitor so that the magnified portion will not be compromised. |
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| Introduction to PACS |
| Image data are traditionally archived on films. With the advancement in Picture Archiving & Communication systems (PACS) the storage of images in digitized form and distributes them on demand over a high – speed network to a very high resolution graphics display monitors located hospitals, diagnostic centers, practices can be achieved. |
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| PACS works with the DICOM standard, thereby establishing a common communication standard for handling & transmission of medical images & data. These helps in enabling the exchange of information between workstation, modalities etc…PACS will have a built-in database for storage / archival functions. |
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| CareEMR's PACS product is mainly developed to aid the hospitals / diagnostic centers etc to enable image processing functions and as a storing & archiving system which also includes the below advantages:
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Replaces hard-copy films & providing more storage space.
Reducing the cost for acquiring & processing of hard-copy films |
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Timely access to images & Interpretation / Impression |
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Eliminating the dependency of patient carrying the hard-copy films |
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Centralized imaging system with no chances of misplacing the images |
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Image manipulation – Contrast, Bit slice, negative, Zoom, resolution, Color management etc… |
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Workforce Health maintenance by eliminating the film processing chemicals. |
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Conversion of image files – JPEG, BMP etc onto DICOM standard images. |
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