1. In digital radiography, the patient will be positioned according to the specific examination being performed. This may involve lying down, standing up, or sitting in a particular position. The goal is to ensure that the area of interest is properly aligned with the X-ray beam to obtain the desired image.
2. Correct body part selection is crucial in digital radiography to accurately diagnose and treat patients. By selecting the correct body part, the radiographer ensures that the image obtained corresponds to the area of interest. This helps in avoiding misdiagnosis or unnecessary exposure to radiation.
3. Collimation refers to the process of restricting the X-ray beam to the desired area. Proper collimation helps in reducing scatter radiation and improving image quality. It also helps in reducing patient dose as the exposure is limited to the intended area.
4. A radiographic image with a complementary metal oxide silicon (CMOS) detector is formed through a series of steps. Firstly, the X-ray photons interact with the detector, generating electrical charges. These charges are then converted into digital signals by the CMOS detector. Finally, the digital signals are processed and reconstructed to form the radiographic image.
5. The process of digitalization by an analog-to-digital converter (ADC) involves converting the analog X-ray signal into a digital format. The ADC samples the analog signal at regular intervals and assigns a digital value to each sample. This digital representation allows the image to be stored, manipulated, and displayed digitally.
6. Image extraction with photostimulable phosphor (PSP) plates involves the use of a laser scanner. After exposure to X-rays, the PSP plate retains the energy in the form of trapped electrons. When scanned by a laser, these trapped electrons are released, producing light. The emitted light is then converted into a digital image through photodetectors and signal processing.
7. In charge-coupled device (CCD) radiography, the image is formed by the conversion of X-ray photons into electrical charges. The CCD detector consists of an array of pixels that convert the incoming X-ray photons into electrical signals. These signals are then digitized and processed to form the final image.
8. A histogram is a graphical representation of the distribution of pixel intensities in an image. It shows the frequency of occurrence of each intensity level. The histogram can provide valuable information about the image's overall contrast and brightness.
9. Automatic rescaling is a feature in digital radiography systems that adjusts the image's brightness and contrast automatically. It ensures that the image is displayed with optimal visibility, even if the exposure factors were not ideal. This helps in maintaining consistent image quality.
10. Look-up-table (LUT) is a function used in digital radiography to modify the appearance of an image. It maps the original pixel values to new values, allowing adjustments in contrast and brightness. LUTs can be used to enhance specific anatomical structures or highlight certain abnormalities.
11. Contrast manipulation in digital radiography involves adjusting the difference in pixel intensities between structures of interest. Parameters that control image contrast and density include window width, which determines the range of pixel values displayed as shades of gray, and window level, which sets the midpoint of the gray scale.
12. Spatial frequency resolution in digital radiography refers to the ability to detect fine details in an image. It can be controlled by adjusting the spatial frequency filtering. Spatial frequency filtering involves enhancing or suppressing specific frequencies in the image. This can be done using different types of filters.
13. The two main types of spatial frequency filtering in digital radiography are high-pass filtering and low-pass filtering. High-pass filtering enhances high-frequency details, such as fine structures, while suppressing low-frequency components. Low-pass filtering, on the other hand, enhances low-frequency components while suppressing high-frequency details.
14. Window level and window width are parameters used to adjust the display of pixel values in a digital radiographic image. Window level sets the midpoint or average pixel value displayed as gray, while window width determines the range of pixel values displayed. Adjusting these parameters can alter the image's contrast and brightness.
15. High-pass filtering occurs when frequencies above a certain cutoff value are enhanced in an image. This can be useful in highlighting fine details or edges. High-pass filtering is commonly used in image processing techniques to enhance image sharpness.
