A presentation on CT scan for PG and UG

A ppt on CT scan

1. CT SCAN GUIDE : Dr. SRIHARI .S PROFESSOR AND HEAD DEPT. OF PG STUDIES IN KAUMARABHRITYA JSSAMC, MYSORE 1 ST YEAR PG SCHOLAR DEPT. OF PG STUDIES IN KAUMARABHRITYA JSSAMC, MYSORE

2. CONTENTS : 1. Introduction and definition of CT 2. History of CT 3. Principle of CT 4. Clinical Applications 5. Examples of abnormal CT images 6. Advantages and Drawbacks 7. Discussion 8. Conclusion

3. INTRODUCTION CT scan is referred as Computed Tomography CAT scan - Computed Axial Tomography Tomography is derived from Greek word Tomos- Slice Graphy - To write Computed tomography is a medical imaging technique that uses specialized x-ray equipment to create detailed cross-sectional images (slices) of the body

4. HISTORY The first commercially available CT scanner was created by British engineer Godfrey Hounsfield of EMI Laboratories in 1972 He co-invented the technology with physicist Dr. Allan Cormack Both researchers were later on jointly awarded with 1979 Nobel Prize in Physiology and Medicine. By 1981, Hounsfield was knighted and became Sir Godfrey Hounsfield

5. Parts of a CT scan machine 1.Gantry 3. Collimator 4. Filters 2.Patient’s table 3.Computer (operational control) 1. X-Ray tube 2. Detector Generates x-ray beams Detects the x-rays passing through the patient’s body Narrows the beams of x-rays These are used to filter some rays from entering the patient’s body that may be harmful

6. PRINICPLE OF CT The Internal Structure of an object can be reconstructed from multiple projections of that object

7. HOW IT WORKS? Provides high-resolution cross-sectional anatomical images Table moves through a circular opening in the CT scanner called the Gantry , While an x-ray tube emits x-rays as it spins 360 degrees inside the gantry A detector array measures the amount of x-rays that pass through the anatomical part and cross-sectional images are generated from data

8. 1 ST Generation CT 2 nd Generation CT

9. 3 RD Generation CT 4 TH Generation CT

10. CLINICAL APPLICATIONS OF CT DIAGNOSIS AND SCREENING : CT scans are widely used for diagnosing a variety of conditions, including cancers, cardiovascular diseases, Infectious diseases, and neurological disorders . They can detect abnormalities in organs, tissues, and bones with high resolution TRAUMA: CT is crucial in the evaluation of trauma patients, as it can quickly assess internal injuries such as bleeding, fractures, and organ damage, helping guide immediate treatment decisions ONCOLOGY : CT scans are essential for staging of cancers, monitoring tumor response to treatment, and detecting recurrence. They provide detailed images of tumors , their size, location, and involvement of nearby structures

11. CARDIOLOGY : CT angiography(CTA) is used to assess the coronary arteries and diagnose Coronary artery disease(CAD). It can detect blockages or narrowing of the arteries and evaluate the extent of cardiac diseases NEUROLOGY : CT scans of the brain are valuable for diagnosing strokes, hemorrhages , tumors and other neurological conditions. They help identify structural abnormalities and guide neurosurgical interventions PULMONOLOGY : CT is used to evaluate the lungs and diagnose the conditions such as Pneumonia, Pulmonary embolism, Lung cancer, and Interstitial lung diseases. High- resolution CT(HRCT) is particularly useful for assessing lung tissue

12. ABDOMINAL AND PELVIC IMAGING : CT scans are employed to evaluate abdominal organs (Liver, Pancreas, Kidneys, etc.) and pelvic structures (Bladder, Uterus, Prostate, etc.). They help diagnose conditions like Appendicitis, Diverticulitis, and Kidney stones ORTHOPEDICS : CT scans provide detailed images of bones and joints, aiding the diagnosis of fractures, Arthritis, and other Musculoskeletal disorders. They are also used in surgical planning for complex fractures GUIDANCE FOR PROCEDURES : CT is used to guide minimally invasive procedures such as Biopsies, Abscess drainage, and Catheter placements. It helps ensure accurate placement and reduces risks associated with invasive procedures PEDIATRICS : CT scans are sometimes used in pediatric patients for evaluating congenital abnormalities, injuries, and developmental disorders. Special considerations are taken to minimize radiation exposure in children

13. Hounsfield Unit : Hounsfield scale is used to measure the Radiodensity It is expressed in Hounsfield Unit (HU) This density measurements are essential to differentiate between cyst, tumor , haematoma etc

14. BASICS OF CT: CT findings are always described on the basis of Densities : Isodence Hypodence Hyperdence Higher the density = Whiter is the appearance Lower the density = Darker the appearance

15. Brain is the reference density Anything of the density of Brain = Isodence Higher density than Brain = Hyperdence ( Skull) Anything darker (lower density) than Brain = Hypodense (CSF and Air)

16. TYPES PLAIN CT ( NON- CONTRAST CT) A plain CT scan is performed without the use of any contrast agent. It relies solely on X-rays to produce detailed images of the body part being scanned. Plain CT scans are commonly used to evaluate conditions where contrast is unnecessary or may not provide additional diagnostic benefit. For example, plain CT scans of the head are often used to detect skull fractures, hemorrhages, and other structural abnormalities without the need for contrast dye. CONTRAST-ENHANCED CT Involves the administration of a contrast agent (usually iodine-based contrast material) into a vein (intravenously) during the scan. This contrast dye helps highlight blood vessels and certain tissues, making them more visible on the CT images. They are particularly useful for evaluating blood vessels, tumors, inflammation, infection, and other conditions where enhanced visualization of specific structures or abnormalities is needed. Examples: CT angiography (CTA) for assessing blood vessels or CT abdomen/pelvis with contrast for evaluating organs and blood flow dynamics.

17. Pediatric CT scans require special considerations: 1. Radiation dose reduction 2. Sedation or anesthesia (if needed) 3. Child-friendly environment 4. Trained pediatric radiologists

18. ADVANTAGES OF CT SCAN : Detailed Imaging : CT scans provide detailed cross-sectional images of the body's internal structures, including bones, soft tissues, blood vessels, and organs. This level of detail helps in identifying abnormalities such as tumors, fractures, infections, and other conditions. Speed : CT scans are relatively quick compared to other imaging modalities like MRI. Wide Applicability : CT scans can be used to image almost any part of the body, making them versatile in diagnosing a wide range of medical conditions. Non-invasive : CT scans are non-invasive, They do not require incisions or the insertion of instruments into the body. This reduces the risk of complications and allows for repeated imaging when necessary.

19. High Resolution : Modern CT scanners offer high-resolution images, allowing for detailed visualization of small structures and abnormalities. This is particularly important in detecting small tumors or assessing subtle changes in organs. Compatibility with Other Imaging Modalities : CT scans can be easily combined with other imaging techniques such as PET scans (PET-CT) to provide both anatomical and functional information in a single exam. This hybrid imaging approach enhances diagnostic accuracy and helps in treatment planning. Accessibility : CT scanners are widely available in hospitals and imaging centers, making them accessible for routine diagnostic procedures as well as for urgent and emergency cases.

20. HAEMORRHAGE TUMOUR

21. Hydrocephalus

22. Periventricular ischemic encephalopathy

23. Bilateral periventricular leukomalisia

24. DRAWBACKS OF CT SCAN : Exposure to Ionizing Radiation : CT scans use X-rays to create detailed images, which expose patients to ionizing radiation. Although the radiation dose is relatively low, repeated CT scans over time can accumulate radiation exposure, potentially increasing the risk of cancer, particularly in children and young adults. Contrast Agent Risk : In Contrast-enhanced CT, there are risks of allergic reactions, ranging from mild itching and hives to severe reactions like anaphylaxis. There is also a risk of contrast-induced nephropathy (CIN) Cost : CT scans can be expensive, especially when contrast agents are used.

25. Patient Discomfort : Some patients may experience claustrophobia or anxiety during the scan, particularly with longer scan times or if contrast dye injection is involved. Limited Soft Tissue Differentiation : Compared to MRI, CT scans have limitations in distinguishing between certain types of soft tissues, which may affect the accuracy of diagnoses in some cases.

26. CONCLUSION : In conclusion, CT scans play a crucial role in modern medicine by providing detailed functional information that complements the anatomical information provided by other imaging modalities. They are widely used in clinical practice for diagnosing and monitoring a variety of conditions, from cancer to neurological disorders and cardiac diseases.