## 25.3 CT Scan A normal X-ray produces a flat, shadow-like image of internal body structures. A **CT scan** (Computed Tomography scan) uses X-rays in a more advanced way by taking multiple "slice" pictures as a scanner rotates around the patient's body. A computer then combines these slices to build a detailed, three-dimensional map of organs and bones, revealing details that a single X-ray cannot show. ### Definition and Purpose **CT Scan (Computed Tomography scan)**: A medical imaging method that uses X-rays and computer processing to create detailed 3-D images of internal body parts. **Purpose**: Useful for imaging soft tissues, blood vessels, lungs, brain, abdomen, and bones. ### CT Scanner Components - **X-ray source**: Emits X-ray beams toward the patient's body. - **Detectors**: A large number of detectors record the X-ray images. - **Gantry**: The circular part of the CT machine where the X-ray source and detectors are mounted on a rotating ring (Figure 25.6). - **Couch**: A table where the patient lies, which slowly slides through the gantry. ### How a CT Scan Works 1. The patient lies on a couch that moves through the gantry. 2. X-ray beams are aimed at the body. 3. The X-ray source and detectors rotate around the patient, taking views from various directions. 4. This process generates 2-D cross-sectional images, also known as **tomographic images**. 5. The couch and patient are then moved along the axis of the machine, and another set of images is taken. 6. A computer combines these numerous 2-D images to construct a detailed 3-D image of the organs under investigation (Figure 25.7). ### Importance of CT Scan Over Normal X-ray Film - **Detailed View**: CT scans provide significantly more detailed views compared to normal X-ray films. - **Overcoming Limitations of X-ray**: Normal X-ray films provide limited information, acting like a shadow where fine details can be obscured if one organ lies in front of the region of interest. - **High-Quality Images**: CT scans produce high-quality images essential for critical diagnostic purposes, such as studying tumors in cancer patients. ### Tumor Detection Methods (Medical Physics and Technology) - **Imaging Tests**: X-rays, CT scans, MRI scans, PET scans, ultrasound. - **Biopsy**: Tissue sample analysis. - **Blood Tests**: Biomarker detection. - **Physical Examination**: Checking for lumps or skin changes. - **Future Outlook**: AI-assisted imaging analysis and diagnostics are expected to enhance tumor detection.