Types of X-Rays: Residency Radiology

Conventional/ Film Screen Radiography

It utilizes X-ray film, which is made up of an emulsion of silver halide. The film’s maximum component is Silver Bromide. It may be single- or double-sided coated. General X-rays are coated on both sides, and mammography X-rays are coated on a single side. The screen intensifies the effect of X-rays and increases the amplitude. These films are also sensitive to light. Hence, X-rays are taken in dark rooms. The film development takes about 45 minutes.

CR (Computed Radiography)

In Computed Radiography, the X-ray is sent to a computer for printing. Film is not used; instead, a Photostimulable Phosphate plate(PSP)  is used. A scanner is used in CR, which reads PSP and gives images on a computer.  There are many advantages of computed radiography over conventional Radiography. The Advantages of CR over Conventional radiography are:

• Photostimulable Phosphate plate(PSP) can be reused.
• The image is editable on the computer.
• A retake of an X-ray is not needed.
• It can be shared online easily.
• PACS compatible.

DR (Digital Radiography)

X-rays are emitted from X-ray tubes in Digital Radiography. Selenium or Cesium iodide is used as a detector in digital radiography. The image is available on the computer, the same as Computed Radiography. The Advantages of DR-

• Photostimulable Phosphate plate(PSP)  is not required.
• Very quick method of radiography
• PACS compatible

Position of an X-ray

If the patient is standing in front, then the doctor’s right side becomes the patient's left side, and vice versa. This is important because it allows us to read the X-Ray properly.

Black and White Principle in X-rays

X-rays passing through less dense areas (air) have maximum penetration. The image produced will be black. X-rays passing through more dense areas (water or bones) have minimum penetration. The image will be white. Bones cause the maximum attenuation of X-rays. Simply put, increased penetration produces a black color on X-ray, while decreased penetration produces white.

On X-ray, Pneumothorax (air) is Black, Pleural effusion (water) is Grey/White, and Calcification (bones) is  White. On the other hand, in a Computed tomography scan (CT scan), which is a 3D X-ray, Pneumothorax (air) is Black, Pleural effusion (water) is White, and Calcification (bones) is White

Fluoroscopy

A video, movie, or cine X-ray is known as fluoroscopy. It is used for moving structures such as Blood-DSA (Digital Subtraction Angiography), GIT peristalsis- Barium- motility, Cardiology, Diaphragmatic palsy- Paradoxical movement of the diaphragm, C-arm in ortho OT and ERCP. Radiation exposure is high in Fluoroscopy compared to X-ray. Fluoroscopy causes high radiation and leads to sterilization. Image intensifiers are used in Fluoroscopy to convert images into video on the screen. The image can be white or inverted (white structures on X-ray may appear black on Fluoroscopy). The patient is given a Barium swallow. It is real-time X-ray imaging. There is a High radiation exposure.

Mammography

It has compression plates. The breasts are placed on them. X-rays penetrate breasts vertically and enter a detector. Compression is a must to make better penetration and uniformity of breasts. Mammography is contraindicated in acutely painful conditions like Mastitis and Breast abscess. Mammography helps in the early detection of breast cancer. It is used more because of its benefits than a chest x-ray. Mammography in young females gives a white image; they have dense breasts. Most of the time, two perpendicular views are taken, the Craniocaudal and MLO views. When the axillary lymph nodes are also seen, it gives a 3D orientation of the pathology. For example, AP and lateral views are taken for clarity in a fracture.

Xeromammographiy/Xeroradiography. Xero (dry) radiograph is taken for breasts. It uses a silicon plate. No film development or chemicals are used.

Mammography vs Chest X-ray

Mammography needs compression between the plates for better penetration of the rays. It can detect Microcalcifications (0.5mm) and malignant cases. Contrast must be high, and Kvp should be low in mammography. The Anode in mammography is made of molybdenum or rhodium (in young females). The Filter is made of molybdenum in mammography; in X-rays, it is aluminum and copper. The window is made up of beryllium in mammography and glass in chest x-ray.

Frequently asked questions

Q. Which is the safe color in dark rooms?

Ans: X-ray film is the least sensitive to red light; thus, red is the safest color.

Q. PACS is an acronym for?

1. Portal Archiving & Common System
2. Planning Archiving & Communication System
3. Picture Archiving & Communication System
4. Photo Archiving & Computerized System

Ans: C, Picture Archiving & Communication System

Q. In what format is PACS saved in the system?

Ans: DICOM (Digital Imaging & Communication in Medicine) format

Q. Which work on the same modalities? (FMGE)

1. USG, CT
2. USG, MRI
3. Radiograph, CT 

Ans: C, Radiograph and CT scan 

Q. What is the investigation of choice in breast abscess?

Ans: USG 

Q. Do mammograms have radiation exposure?

Ans: Yes.

Q. Is mammography radiation less or more harmful than chest X-rays?

Ans: More harmful, as one mammography equals 20-25 chest x-rays. One chest x-ray has 0.02msV exposure. One mammography has 0.4msV exposure. The benefits are far greater than the risk of radiation exposure.

Hope you found this blog helpful for your Systemic and General Radiology preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.