Mammography
# **Mammographic X-ray Equipment – Construction & Working**
Mammography machines are specifically designed for breast imaging using
**low-energy X-rays** for high soft-tissue contrast
## **1. Construction of Mammographic X-ray Equipment**
The key components include:
A. X-ray Tube Assembly**
- **Anode Material:** Uses **Molybdenum (Mo), Rhodium (Rh), or
Tungsten (W)** as the anode target.
- **Cathode:** Emits electrons toward the anode to generate X-rays.
- **Filtration:** Mo or Rh filters selectively remove unwanted high-energy
photons.
B. Breast Compression System**
- **Compression Paddle:** Made of plastic, applies uniform pressure on the
breast to reduce thickness, minimize scatter radiation, and improve image
quality.
C. Anti-Scatter Grid**
- Improves contrast by reducing scattered radiation reaching the detector.
D. Image Detector System**
- **Film-Screen System (Older) →** Uses intensifying screens to expose
film.
- **Digital Mammography (Modern) →** Flat-panel detectors convert X-ray
photons into electronic signals.
- **Digital Breast Tomosynthesis (DBT) →** Creates 3D breast images by
acquiring multiple slices.
E. Automatic Exposure Control (AEC)**
- Adjusts radiation dose based on breast thickness to ensure optimal
exposure.
22501
22501
---
## **2. Working Principle of Mammographic X-ray Equipment**
**Step 1: Patient Positioning & Breast Compression**
- The patient stands in front of the mammography unit, and the breast is
placed on the detector plate.
- The compression paddle flattens the breast to reduce motion and improve
image sharpness.
**Step 2: X-ray Exposure & Image Acquisition**
- The **low-kVp X-ray beam** (20–35 kVp) is directed through the
compressed breast.
- **Photoelectric effect dominates**, providing excellent soft tissue contrast.
- The detector captures the transmitted X-rays and converts them into an
image.
**Step 3: Image Processing & Analysis**
- In **film-screen mammography**, the exposed film is processed
chemically.
- In **digital mammography**, the detector's signals are converted into a
digital image for viewing on a workstation.
- **Tomosynthesis (3D imaging)** takes multiple X-ray projections from
different angles, reconstructing a 3D image for better lesion detection.
---
## **3. X-ray Beams & Filters in Mammography**
**A. X-ray Beam Quality in Mammography**
- Uses **low-energy X-rays (20–35 kVp)** for better soft tissue
differentiation.
- The beam is **more monochromatic** compared to conventional X-rays,
reducing unnecessary radiation dose.
22501
**B. Filtration in Mammography**
- **Purpose:** Removes high-energy X-rays that do not contribute to image
contrast.
- **Common Filter Materials:**
- **Molybdenum (Mo) Filter (0.03 mm thick):** Used with Mo anodes,
optimal for **thin breasts**.
- **Rhodium (Rh) Filter (0.025 mm thick):** Allows slightly higher energy
X-rays, used for **denser breasts**.
- **Aluminum (Al) Filter (0.5 mm):** Used in tungsten-based systems for
spectral shaping.
- **Beryllium (Be) Window:** Minimizes beam attenuation, allowing
low-energy X-rays to pass efficiently.
---
### **Summary**
**Construction:**
● X-ray tube (Mo, Rh, W anode)
● Compression paddle
● Anti-scatter grid
● Detector.
**Working:** Low-kVp X-ray beam passes through compressed
breast, and the detector captures the image
.
**X-ray Beams:** Low-energy (20–35 kVp), high soft-tissue contrast.
**Filters:**
● Mo (thin breasts)
● Rh (dense breasts)
● Al (tungsten anodes).
22501
