1. Introduction to Mammography

1.1 Definition

Mammography is a specialized radiographic imaging technique used to examine the breast using low-energy X-rays. It is primarily used for the early detection, diagnosis, and evaluation of breast diseases, particularly breast cancer.

Mammography produces high-resolution images of breast tissue, allowing radiologists to identify abnormalities that may not be palpable during a clinical breast examination.

It is an important diagnostic tool for detecting:

• Breast masses and lumps.                                 
  
  
  
• Microcalcifications and macrocalcifications.
• Architectural distortion.
• Asymmetrical breast densities.
• Skin and nipple abnormalities.
• Changes associated with benign and malignant breast diseases.

Mammography can identify some breast cancers before symptoms develop, making it an important component of breast cancer screening programs.

1.2 Principle of Mammography

Mammography works on the principle of differential attenuation of low-energy X-rays by different breast tissues.

The breast consists mainly of:

1. Adipose tissue: Fatty tissue that generally appears relatively dark on a mammogram.
2. Fibroglandular tissue: Glandular and connective tissues that generally appear white.
3. Calcifications: Calcium deposits that appear as bright, white areas.
4. Masses and other lesions: Their appearance depends on their composition, density, shape, margins, and surrounding tissue.

1.3 Objectives of Mammography

The major objectives of mammography are:

• Early detection of breast cancer.
• Screening asymptomatic individuals according to age and risk.
• Investigation of breast symptoms, such as a lump, nipple discharge, or skin changes.
• Characterization of breast lesions.
• Assessment of suspicious calcifications.
• Evaluation of abnormalities detected by clinical examination or other imaging methods.
• Localization of non-palpable lesions for image-guided biopsy or surgery.
• Monitoring the response to treatment and detecting recurrence when clinically indicated.

1.4 Types of Mammography

Mammography can be classified into the following types.

1. Screening mammography

Screening mammography is performed in individuals without breast symptoms to detect cancer at an early stage.

It generally includes two standard projections of each breast:

• Craniocaudal (CC) view.
• Mediolateral oblique (MLO) view.

2. Diagnostic mammography

Diagnostic mammography is performed to investigate a breast abnormality or clarify a finding detected during screening.

It may include:

• Additional mammographic projections.
• Spot-compression views.
• Magnification views.
• Implant-displacement views.
• Digital breast tomosynthesis.
• Targeted breast ultrasound when indicated.

3. Digital mammography

Digital mammography uses electronic detectors to capture the X-ray image and display it on a computer workstation.

It allows image processing, electronic storage, transmission, and comparison with previous examinations.

4. Digital breast tomosynthesis

Digital breast tomosynthesis is an advanced mammographic technique that acquires multiple low-dose projection images at different X-ray tube angles and reconstructs them into thin image sections.

It helps reduce the masking effect caused by overlapping breast tissues.

5. Contrast-enhanced mammography

Contrast-enhanced mammography uses intravenous iodinated contrast material and specialized low- and high-energy X-ray acquisitions to demonstrate areas of contrast uptake in the breast.

It may be used in selected diagnostic situations, depending on clinical indications and local protocols.

2. Historical Developments of Mammography

The development of mammography represents a major advancement in diagnostic radiology. Improvements in X-ray equipment, breast compression, imaging detectors, and computer-based reconstruction have significantly enhanced breast imaging.

2.1 Discovery of X-rays: 1895

In 1895, Wilhelm Conrad Röntgen discovered X-rays.

This discovery established the foundation of diagnostic radiography and subsequently enabled the development of specialized breast imaging techniques.

2.2 Early Breast Radiography: 1913

In 1913, German surgeon Albert Salomon conducted early radiographic investigations of surgically removed mastectomy specimens.

He used X-rays to study breast tumors and their relationship to surrounding tissues.

His work demonstrated that radiography could reveal structural abnormalities within the breast.

However, these early examinations were performed on excised specimens rather than being established as routine imaging of the living breast.

2.3 Development of Clinical Mammography: 1920s–1930s

During the 1920s and 1930s, researchers investigated techniques for obtaining better radiographic images of the breast.

Early mammographic examinations faced several technical challenges:

• Low image contrast.
• Poor spatial resolution.
• High radiation exposure relative to image quality.
• Difficulty distinguishing normal and abnormal breast tissues.
• Limitations of conventional X-ray equipment.

These limitations restricted the widespread clinical application of mammography.

2.4 Contributions of Stafford L. Warren: 1930s

Stafford L. Warren investigated the use of radiography to examine the breast and identify abnormalities.

His work contributed to the development of clinical breast radiography and demonstrated the potential of mammography in detecting breast lesions.

2.5 Contributions of Raúl Leborgne: 1940s

Uruguayan radiologist Raúl Leborgne made important contributions to mammographic technique.

He emphasized the importance of breast compression and the identification of small calcifications.

His work improved the recognition of mammographic abnormalities associated with breast cancer.

2.6 Development of Dedicated Mammography Equipment: 1950s–1960s

During this period, Charles M. Egan helped advance mammographic technique through improvements in exposure factors, image quality, and the use of dedicated radiographic methods.

The development of more suitable equipment and exposure techniques improved the visibility of breast lesions.

Dedicated mammography systems increasingly incorporated:

• Lower-energy X-ray beams.
• Improved image contrast.
• More suitable target and filter combinations.
• Better positioning methods.
• Breast compression devices.

These developments helped establish mammography as a more reliable diagnostic procedure.

2.7 Development of Screen-Film Mammography: 1970s–1980s

Screen-film mammography became widely established during the latter part of the twentieth century.

Specialized mammographic film-screen combinations provided high spatial resolution and improved visualization of small breast abnormalities.

Important developments included:

• Improved film-screen systems.
• Dedicated mammography units.
• More effective breast compression.
• Improved automatic exposure control.
• Standardized positioning techniques.
• Better radiation protection and quality assurance.

These improvements helped establish mammography as an important method for breast cancer detection.

2.8 Introduction of Digital Mammography: 1990s–2000s

Digital mammography gradually replaced screen-film systems in many healthcare institutions.

Instead of recording the image directly on radiographic film, digital systems use electronic detectors.

Advantages include:

• Digital image processing.
• Wide dynamic range.
• Electronic image storage.
• Easy comparison with previous studies.
• Electronic transmission of images.
• Improved workflow and integration with hospital information systems.

Digital mammography also provided a foundation for advanced applications such as computer-aided detection and tomosynthesis.

2.9 Development of Digital Breast Tomosynthesis: 2000s–2010s

Digital breast tomosynthesis was developed to address one of the major limitations of conventional mammography: the superimposition of breast tissues.

In tomosynthesis, multiple projection images are acquired at different angles and reconstructed into thin sections.

This technique can improve lesion conspicuity and reduce the effect of overlapping structures.

Clinical adoption increased during the 2010s, and tomosynthesis became an important component of breast imaging in many healthcare facilities.

2.10 Modern Developments: 2010s to Present

Modern mammography incorporates advances in digital imaging, reconstruction algorithms, and image analysis.

Major developments include:

• Digital breast tomosynthesis.
• Contrast-enhanced mammography.
• Improved detector technology.
• Automated breast density assessment.
• Computer-aided detection.
• Artificial intelligence-assisted image analysis.
• Integration with picture archiving and communication systems (PACS).
• Improved dose monitoring and quality assurance.

These technologies support more efficient breast imaging, although their clinical usefulness depends on the indication, equipment, and individual patient characteristics.

3. Mammography Equipment

A dedicated mammography unit is designed to produce high-quality images of breast tissue using appropriately controlled low-energy X-rays.

3.1 Main Components

A. X-ray tube

The X-ray tube generates the radiation required for breast imaging.

Mammography tubes are designed to produce a suitable low-energy X-ray spectrum.

Common target materials include:

• Molybdenum.
• Rhodium.
• Tungsten.

The target and filter combination depends on the equipment design, breast thickness, breast composition, and selected imaging protocol.

B. Filtration system

The filtration system removes unwanted low-energy photons that contribute to patient dose without significantly improving the image.

Common filter materials in mammography include molybdenum, rhodium, and silver, depending on the system.

Modern systems may use different target-filter combinations to optimize image quality and dose.

C. Compression paddle

The compression paddle applies controlled compression to the breast during imaging.

Importance of breast compression:

• Reduces breast thickness.
• Reduces tissue superimposition.
• Improves image contrast and sharpness.
• Reduces motion blur.
• Helps produce a more uniform image.
• Can reduce the radiation dose required for an adequate image.

Compression may cause temporary discomfort, but proper communication and positioning help improve patient cooperation.

D. Breast support and image receptor

The breast support platform holds the breast in the correct position.

The image receptor may be:

• A digital detector.
• A screen-film receptor in older systems.

The receptor records the transmitted X-rays and produces the mammographic image.

E. Automatic exposure control

Automatic exposure control (AEC) helps regulate exposure according to the imaging conditions.

Its purpose is to provide adequate image quality while avoiding unnecessary radiation exposure.

The radiographer must ensure correct positioning and appropriate AEC chamber selection, according to the manufacturer's instructions and departmental protocol.

F. Control console

The control console allows the radiographer to select and adjust exposure parameters, such as:

• Tube voltage (kVp).
• Tube current and exposure time.
• Target-filter combination.
• AEC settings.
• Magnification or tomosynthesis mode, where available.

G. Image processing workstation

The workstation displays and processes acquired images.

It supports:

• Image review.
• Adjustment of display settings.
• Comparison with previous mammograms.
• Image labeling.
• Electronic transmission.
• Storage in PACS.

H. Quality control equipment

Quality control equipment is used to assess system performance.

Depending on the equipment and protocol, quality control may include:

• Image quality assessment using a suitable phantom.
• Detector uniformity checks.
• Automatic exposure control evaluation.
• Compression force assessment.
• Artifact evaluation.
• Radiation output and dose assessment.

Quality assurance is essential to maintain consistent image quality and radiation safety.

4. Method of Mammographic Examination

Mammography requires appropriate patient preparation, accurate positioning, suitable exposure selection, and careful evaluation of image quality.

The examination should be performed by trained personnel according to departmental protocols and applicable radiation safety standards.

4.1 Patient Preparation

Before beginning the examination, the radiographer should:

1. Confirm the patient's identity using approved identifiers.
2. Verify the clinical indication and examination request.
3. Ask about breast symptoms, including lumps, pain, nipple discharge, or skin changes.
4. Ask about previous breast surgery, biopsy, implants, and relevant medical history.
5. Review previous mammograms or breast imaging, if available.
6. Ask about the possibility of pregnancy when relevant to the examination.
7. Explain the procedure and the need for temporary breast compression.
8. Obtain consent according to institutional policy.
9. Ask the patient to remove clothing from the waist upward and provide appropriate privacy.
10. Ask the patient to remove deodorant, talcum powder, creams, or other products from the breast and underarm region.

Some products may produce artifacts that resemble calcifications.

Important history to obtain

The radiographer should establish:

• Whether the examination is for screening or diagnosis.
• The location and duration of any symptoms.
• Whether the patient has undergone previous breast surgery.
• Whether breast implants are present.
• Whether there is a history of breast cancer or biopsy.
• Whether previous images are available for comparison.

The radiographer should document relevant information according to departmental policy.

4.2 Positioning Principles

Correct positioning is one of the most important factors in mammography.

The aim is to include as much breast tissue as possible while minimizing motion and tissue folding.

The radiographer should:

• Position the patient comfortably.
• Adjust the height and angle of the unit.
• Bring the breast forward onto the image receptor.
• Ensure the breast is not twisted or folded.
• Apply compression gradually.
• Explain when the exposure will occur.
• Instruct the patient to remain still during exposure.

Correct positioning improves diagnostic accuracy and may reduce the need for repeat imaging.

4.3 Standard Mammographic Views

The two standard mammographic projections are the craniocaudal and mediolateral oblique views.

A. Craniocaudal (CC) view

The CC view is obtained with the X-ray beam directed from the cranial aspect toward the caudal aspect of the breast.

Positioning procedure:

1. Position the patient facing the mammography unit. 
   
   
   
2. Adjust the detector to a suitable height.
3. Place the breast on the image receptor.
4. Pull the breast forward to include posterior breast tissue.
5. Position the nipple as close as possible to a true lateral profile when achievable.
6. Apply compression to immobilize the breast.
7. Ensure the breast is not folded.
8. Make the exposure during suspended movement according to the system protocol.

Structures and tissue demonstrated:

The CC view demonstrates a large proportion of the breast, including medial and lateral tissue.

It is useful for identifying masses, calcifications, asymmetries, and other abnormalities.

Image evaluation criteria:

• Adequate inclusion of medial and lateral breast tissue.
• Minimal motion blur.
• Appropriate exposure and contrast.
• No significant skin folds.
• Suitable nipple positioning.
• Adequate posterior tissue inclusion.

B. Mediolateral oblique (MLO) view

The MLO view is an oblique projection designed to include a large amount of breast tissue, including the upper outer breast and the axillary tail.

Positioning procedure:

1. Adjust the detector angle according to the patient's body habitus and equipment design.
2. Position the patient beside the mammography unit. 
   
   
   
3. Place the breast on the detector.
4. Raise the arm on the examination side as required.
5. Ensure the shoulder is relaxed and the pectoral region is positioned appropriately.
6. Pull the breast forward and upward.
7. Apply compression.
8. Check that the breast is not folded and that the posterior tissue is included.
9. Make the exposure while the patient remains still.

Structures demonstrated:

• Upper and lower breast tissue.
• Upper outer quadrant.
• Axillary tail.
• Pectoral muscle, when adequately included.
• Deep posterior breast tissue.

Image evaluation criteria:

• Adequate visualization of the pectoral muscle, as appropriate.
• Inclusion of the inframammary angle.
• Adequate posterior tissue coverage.
• Absence of significant skin folds.
• Appropriate breast compression.
• No motion blur.

4.4 Additional Mammographic Views

Additional views may be obtained when the standard projections do not adequately characterize a finding.

A. Spot-compression view

Spot compression applies focused compression over a specific region of the breast.

Purpose:

• Reduces tissue superimposition.
• Helps determine whether an apparent mass persists.
• Improves visualization of lesion margins.
• Clarifies focal asymmetries.

B. Magnification view

Magnification views enlarge a specific region, often using a dedicated magnification platform.

They are particularly useful for assessing microcalcifications.

The radiologist evaluates:

• Number and distribution of calcifications.
• Shape and morphology.
• Variation in size and appearance.
• Associated masses or architectural distortion.

C. True lateral view

A true lateral view is obtained with the X-ray beam directed horizontally through the breast.

It can help localize an abnormality in the superior-inferior direction and assist in correlating findings across projections.

D. Cleavage view

A cleavage view is used to demonstrate medial breast tissue, particularly when it is not adequately included in the standard CC views.

E. Implant-displacement view

For patients with breast implants, implant-displacement techniques may be used to improve visualization of native breast tissue.

The implant is displaced posteriorly while the breast tissue is brought forward for imaging, when clinically appropriate and technically feasible.

The technique must be adapted to the implant type, patient anatomy, and departmental protocol.

4.5 Exposure Factors in Mammography

Exposure selection depends on:

• Breast thickness.
• Breast composition.
• Target-filter combination.
• Detector characteristics.
• Automatic exposure control.
• Imaging mode.
• Equipment-specific protocols.

Mammography generally uses lower tube voltages than conventional general radiography because breast imaging requires high soft-tissue contrast.

Modern systems automatically optimize some exposure parameters, but the radiographer remains responsible for selecting the correct examination and ensuring appropriate positioning.

Factors affecting image quality

1. Contrast

Contrast allows differences between breast tissues to be distinguished.

2. Spatial resolution

High spatial resolution is essential for demonstrating fine structures, including small calcifications.

3. Noise

Excessive image noise may obscure subtle abnormalities.

4. Motion

Patient movement can produce blurring and reduce diagnostic quality.

5. Tissue superimposition

Overlapping tissues can obscure lesions or create appearances that mimic abnormalities.

6. Artifacts

Artifacts may arise from clothing, cosmetics, detector problems, positioning errors, or image-processing issues.

4.6 Radiation Protection in Mammography

Mammography uses ionizing radiation, so radiation protection is an essential part of the examination.

The principles of justification and optimization should be followed.

Important measures include:

• Performing examinations only when clinically indicated or according to an appropriate screening program.
• Using equipment designed for mammography.
• Selecting suitable exposure parameters.
• Applying adequate compression.
• Avoiding unnecessary repeat exposures.
• Performing routine quality control.
• Monitoring radiation dose according to the equipment and applicable standards.
• Following institutional protocols for patients who may be pregnant.

The objective is to obtain diagnostically adequate images at an appropriately optimized radiation dose.

Note: Breast compression is an important method of improving image quality and may reduce the dose required for an adequate image. However, the actual dose depends on breast thickness, tissue composition, equipment, and exposure settings.

5. Examination of Milk Ducts: Ductography or Galactography

5.1 Introduction

Ductography, also called galactography, is a specialized breast imaging procedure used to investigate selected cases of abnormal nipple discharge.

The procedure involves introducing a small amount of contrast material into an identifiable milk duct through the nipple opening, followed by mammographic imaging.

Milk ducts carry milk from the glandular lobules toward the nipple.

Abnormalities involving the ducts may produce nipple discharge, which can sometimes be associated with benign conditions or, less commonly, malignancy.

Ductography was historically an important technique for evaluating selected cases of pathologic nipple discharge. Today, ultrasound, diagnostic mammography, and breast MRI are also used, and ductography is reserved for selected clinical situations.

5.2 Anatomy of the Milk Ducts

The breast contains glandular tissue organized into lobes.

Each lobe consists of smaller lobular structures containing milk-producing units.

The ductal system transports secretions toward the nipple.

The main anatomical components include:

1. Lobules: Contain the milk-producing glandular structures.
2. Small ducts: Carry secretions away from the lobules.
3. Larger collecting ducts: Transport secretions toward the nipple.
4. Nipple openings: Allow duct contents to reach the external surface.

Duct abnormalities may include:

• Duct ectasia.
• Intraductal papilloma.
• Ductal obstruction.
• Filling defects.
• Ductal irregularity.
• Intraductal malignancy.

Not every duct abnormality causes symptoms, and not every case of nipple discharge requires ductography.

5.3 Indications for Ductography

Features of pathologic nipple discharge include:

• Spontaneous discharge.            
• Discharge from a single duct.
• Unilateral discharge.
• Bloody or clear serous discharge.

Clinical assessment and conventional imaging generally precede consideration of ductography.

Possible indications include:

• Investigation of persistent, unexplained, single-duct nipple discharge.
• Localization of a suspected intraductal lesion.
• Demonstration of a ductal filling defect.
• Assistance with surgical planning in selected cases.

Ductography is not routinely indicated for typical bilateral, multiductal, non-spontaneous discharge that is clinically consistent with physiologic secretion.

5.4 Contraindications and Limitations

Ductography may not be appropriate when:

• The responsible duct opening cannot be identified.
• There is active infection or significant inflammation affecting the proposed procedure.
• The patient has a relevant allergy to the intended contrast agent.
• The patient cannot tolerate the procedure.
• The examination is unlikely to provide useful information beyond other available imaging methods.

The decision should be made by the responsible clinician and radiologist after considering the patient's history, imaging findings, and the availability of alternative investigations.

5.5 Equipment Required for Ductography

• A dedicated mammography unit.    
• Sterile cannulation instruments.
• Fine duct cannula or blunt-tipped catheter.
• Small syringes.
• Appropriate contrast medium.
• Sterile preparation materials.
• Gloves and other necessary protective equipment.

A water-soluble, iodinated contrast agent is commonly used according to institutional protocol.

The choice of contrast material and the injection technique must be determined by the responsible radiologist.

5.6 Method of Examination

Ductography is an invasive procedure and should be performed by trained personnel under the direction of an appropriately qualified clinician.

Step 1: Patient preparation

The patient is positioned comfortably, and the clinical history is reviewed.

The radiologist confirms the nature and location of the nipple discharge.

The patient is informed about the procedure, possible discomfort, and potential complications.

Consent is obtained according to institutional policy.

Step 2: Identification of the responsible duct

The nipple is examined to identify the duct producing the discharge.

Gentle pressure may be applied to the nipple or surrounding tissue to help identify the responsible duct.

The specific duct opening is selected for cannulation.

Step 3: Cleaning and aseptic preparation

The nipple and surrounding skin are prepared using an appropriate antiseptic technique.

Sterile instruments and materials are used to minimize the risk of infection.

Step 4: Cannulation of the duct

A fine cannula or suitable blunt-tipped catheter is gently introduced into the identified duct opening.

Cannulation must be performed carefully to avoid trauma to the duct.

Step 5: Administration of contrast material

A small quantity of suitable contrast material is introduced slowly into the duct.

The amount and injection pressure are determined by the radiologist and the institutional protocol.

Forceful injection must be avoided because it can cause duct injury or contrast extravasation.

Step 6: Mammographic imaging

After contrast administration, mammographic images are obtained using suitable projections.

The projections are selected to demonstrate the opacified ductal system and any suspected abnormality.

Careful positioning is required to avoid obscuring the ductal structures.

Step 7: Image evaluation

The radiologist examines the images for:

• Ductal dilatation.
• Filling defects.
• Ductal narrowing or obstruction.
• Irregular ductal contours.
• Contrast extravasation.
• Associated masses or other suspicious features.

Step 8: Completion and documentation

The cannula is removed, and the patient is observed as appropriate.

The procedure and any complications are documented.

Further imaging, clinical assessment, or tissue sampling may be recommended according to the findings.

5.7 Mammographic Appearances in Ductography

A. Normal ductal system

The contrast outlines the ductal lumen and its branches without a suspicious filling defect or significant irregularity.

B. Duct ectasia

Duct ectasia refers to dilatation of a breast duct.

It may be associated with nipple discharge or inflammation, although it can also be asymptomatic.

C. Intraductal papilloma

An intraductal papilloma is a benign epithelial lesion arising within a duct.

On ductography, it may appear as a filling defect within the contrast-opacified duct.

Additional imaging or tissue diagnosis may be necessary.

D. Ductal obstruction

Obstruction may produce an abrupt interruption or failure of contrast to pass through a duct.

The appearance must be interpreted in light of the technical procedure, because incomplete cannulation or inadequate contrast delivery can mimic obstruction.

E. Irregular ductal narrowing

Irregular narrowing or distortion may be associated with a range of benign and malignant conditions.

The finding is not diagnostic of cancer by itself.

F. Contrast extravasation

Contrast extravasation occurs when contrast escapes outside the ductal lumen.

It may result from duct injury or incorrect cannula placement and can make the study difficult to interpret.

5.8 Advantages of Ductography

• Provides an outline of the ductal system.
• Can localize an abnormality within a duct.
• May assist with targeted clinical or surgical management.
• Can demonstrate filling defects that are not clearly characterized by conventional imaging.

5.9 Limitations of Ductography

• It is an invasive procedure.
• Successful examination depends on identifying and cannulating the responsible duct.
• It may cause discomfort.
• Duct injury and contrast extravasation can occur.
• It does not reliably distinguish benign from malignant lesions in every case.
• It may not demonstrate the full extent of disease.
• It does not replace tissue diagnosis when biopsy is indicated.

Complications

Possible complications include:

• Local discomfort.
• Minor bleeding.
• Duct injury.
• Infection.
• Contrast extravasation.
• Rare hypersensitivity reactions to contrast material.

The risk of complications should be discussed with the patient before the procedure.

5.10 Current Role of Ductography

Ductography is no longer the universal first-line imaging examination for nipple discharge.

The evaluation of pathologic nipple discharge commonly begins with clinical assessment and appropriate diagnostic breast imaging, often mammography and targeted ultrasound according to age and clinical circumstances.

Breast MRI may be considered when conventional imaging is negative or inconclusive and further investigation is warranted.

Ductography may be useful in selected cases when the responsible duct can be identified and the result is likely to guide management.

Important examination point: Ductography demonstrates the ductal lumen and its abnormalities, whereas conventional mammography evaluates the breast more broadly.

6. Breast Tomosynthesis

6.1 Definition

Digital breast tomosynthesis (DBT) is an advanced mammographic imaging technique that uses multiple low-dose X-ray projection images acquired at different angles to reconstruct thin sections of the breast.

It is often described as three-dimensional mammography, although it differs from conventional computed tomography.

In conventional two-dimensional mammography, structures throughout the compressed breast are superimposed in a single projection.

Tomosynthesis reduces the effect of this superimposition by reconstructing the acquired images into thin sections.

This may improve visualization of masses, architectural distortion, and other abnormalities.

6.2 Principle of Breast Tomosynthesis

Breast tomosynthesis is based on limited-angle X-ray acquisition and computational reconstruction.

During the examination, the X-ray tube moves through a limited angular range around the stationary, compressed breast.

Multiple projection images are acquired from different positions.

A computer then processes the projection data and reconstructs a series of thin image sections.

The reconstructed sections can be reviewed individually or as a cine sequence.

Basic principle

1. The breast is positioned and compressed.
2. The X-ray tube acquires projection images at multiple angles.
3. The detector records the transmitted X-rays.
4. The computer processes the acquired projection data.
5. Reconstruction algorithms generate thin image sections.
6. The radiologist reviews the reconstructed images.

The exact acquisition angle, number of projections, reconstruction method, and section thickness vary by manufacturer and protocol.

6.3 Equipment Used in Breast Tomosynthesis

A tomosynthesis system generally contains:

A. X-ray tube

The tube moves through a limited angular range to acquire multiple projection images.

B. Digital detector

The detector records the X-ray signal for each projection.

High detector performance is important for producing diagnostically useful reconstructed images.

C. Breast compression system

The breast remains compressed during acquisition to minimize movement.

D. Image reconstruction computer

The computer uses reconstruction algorithms to generate thin sections from the acquired projection images.

E. Diagnostic workstation

The workstation allows the radiologist to review:

• Individual reconstructed sections.
• The full image stack.
• Synthesized two-dimensional images, if available.
• Conventional mammographic images acquired during the examination.

F. Dose monitoring system

The system records or estimates radiation dose according to its design and applicable standards.

Dose monitoring helps ensure that imaging protocols remain optimized.

6.4 Method of Examination

The patient preparation and positioning principles are similar to those used in conventional digital mammography.

Step 1: Patient preparation

Confirm the patient's identity, clinical indication, and relevant history.

Explain the procedure and obtain consent according to institutional policy.

Remove products that may create artifacts and ensure appropriate positioning.

Step 2: Positioning

Position the breast on the detector using the required projection, commonly CC or MLO.

Ensure adequate inclusion of breast tissue and avoid skin folds.

Step 3: Breast compression

Apply appropriate compression to immobilize the breast.

Compression remains important because movement can degrade the reconstructed images.

Step 4: Image acquisition

The X-ray tube moves through a limited angular range, acquiring a series of projection images.

The breast remains compressed during the acquisition.

The number and angular distribution of projections depend on the system.

Step 5: Image reconstruction

A computer reconstructs the projection images into thin sections through the breast.

The reconstructed sections reduce the superimposition of tissues located at different depths.

Step 6: Image review

The radiologist reviews the reconstructed image stack and any associated two-dimensional images.

The images are evaluated for:

• Masses.
• Architectural distortion.
• Asymmetries.
• Suspicious calcifications.
• Other abnormalities.

Additional diagnostic imaging or biopsy may be required depending on the findings.

6.5 Conventional Mammography Versus Breast Tomosynthesis

Important: Tomosynthesis does not eliminate tissue superimposition completely. Its ability to detect abnormalities depends on lesion characteristics, breast composition, image quality, and the imaging protocol.

6.6 Advantages of Breast Tomosynthesis

1. Reduced tissue superimposition

The principal advantage of tomosynthesis is that it reduces the masking effect caused by overlapping breast structures.

This may help distinguish a true mass from superimposed normal tissue.

2. Improved lesion conspicuity

Some masses and areas of architectural distortion may be more visible on reconstructed sections than on conventional two-dimensional images.

3. Improved assessment of breast abnormalities

Tomosynthesis may help the radiologist assess the shape, margins, and location of a lesion.

4. Potential improvement in screening performance

In some screening populations, tomosynthesis has been associated with increased cancer detection and reduced recall rates compared with conventional digital mammography alone.

The magnitude of benefit varies according to the population, screening program, equipment, and interpretation method.

5. Improved localization

Reviewing the reconstructed sections helps identify the depth at which an abnormality appears.

However, accurate localization and clinical management may require additional imaging.

6.7 Limitations of Breast Tomosynthesis

Despite its advantages, tomosynthesis has several limitations.

1. Radiation exposure

Tomosynthesis uses ionizing radiation.

The total dose depends on the system and protocol, including whether separate conventional 2D images are also acquired.

Some systems generate synthesized 2D images from tomosynthesis data, which can reduce the need for a separate 2D acquisition.

2. Longer interpretation time

Reviewing a stack of reconstructed sections may require more interpretation time than reviewing a small number of conventional mammographic images.

3. Equipment cost

Tomosynthesis equipment and associated infrastructure may require substantial investment.

4. Limited-angle acquisition

Tomosynthesis reconstructs images from projections acquired over a limited angular range. It does not provide the same complete volumetric information as conventional CT.

5. Persistent limitations in dense breasts

Although tomosynthesis reduces tissue superimposition, dense fibroglandular tissue can still obscure some cancers.

Additional imaging may be indicated according to clinical circumstances.

6. Microcalcification assessment

Tomosynthesis may demonstrate calcifications, but conventional magnification views or other diagnostic mammographic techniques may still be necessary for detailed characterization.

7. Not a replacement for biopsy

Suspicious lesions may require image-guided tissue sampling even when tomosynthesis provides clear visualization.

6.8 Clinical Applications of Breast Tomosynthesis

Breast tomosynthesis may be used for:

• Screening mammography.
• Diagnostic evaluation of breast masses.
• Investigation of focal asymmetries.
• Assessment of architectural distortion.
• Clarification of findings caused by overlapping tissues.
• Localization and characterization of selected breast abnormalities.
• Evaluation of selected cases of dense breast tissue.

Its use depends on local guidelines, equipment availability, clinical indication, and the patient's individual circumstances.

6.9 Radiation Dose in Tomosynthesis

Radiation dose is an important consideration in both conventional mammography and tomosynthesis.

Dose depends on:

• Breast thickness.
• Breast composition.
• Number of projections.
• Tube voltage and exposure settings.
• Detector efficiency.
• Whether separate two-dimensional images are acquired.
• Manufacturer-specific acquisition and reconstruction methods.

A tomosynthesis examination performed with a separate conventional 2D acquisition may involve a higher total dose than tomosynthesis alone.

Synthesized 2D images can reduce this additional exposure because they are generated computationally from the tomosynthesis data.

The appropriate approach is to use a validated imaging protocol that achieves diagnostic image quality while optimizing radiation exposure.

7. Role of the Radiographer in Mammography

The radiographer plays a central role in obtaining diagnostically adequate mammographic images while maintaining patient comfort and radiation safety.

7.1 Patient Communication

The radiographer should:

• Explain the procedure clearly.
• Describe the purpose of breast compression.
• Address patient concerns.
• Maintain privacy and dignity.
• Provide instructions before each exposure.

Good communication can improve patient cooperation and reduce motion-related image degradation.

7.2 Correct Positioning

The radiographer must ensure:

• Adequate breast tissue inclusion.
• Correct CC and MLO positioning.
• Appropriate positioning of the nipple and posterior breast tissue.
• Absence of significant skin folds.
• Appropriate breast compression.
• Minimal motion.

Positioning errors may obscure important tissue and necessitate repeat exposures.

7.3 Image Quality Assessment

Before completing the examination, the radiographer should assess the images for technical adequacy.

This includes checking:

• Positioning.
• Exposure and image quality.
• Motion blur.
• Artifacts.
• Adequate anatomical coverage.
• Correct image labeling.
• Appropriate laterality and projection identification.

Any technical problem should be addressed according to departmental protocol.

7.4 Radiation Protection

The radiographer should:

• Follow the principles of justification and optimization.
• Use appropriate exposure protocols.
• Avoid unnecessary repeat imaging.
• Follow equipment-specific procedures.
• Participate in quality assurance.
• Ensure proper equipment maintenance and dose monitoring.

7.5 Documentation and Image Management

The radiographer should ensure that:

• Patient identifiers are correct.
• The correct side and projection are labeled.
• The examination is documented.
• Relevant clinical history is recorded.
• Images are stored and transmitted correctly.
• Previous examinations are available for comparison when possible.

Accurate documentation supports clinical interpretation and continuity of care.

8. Comparison of Mammography, Ductography, and Breast Tomosynthesis

9. Important Examination Questions

The following questions are useful for radiography students preparing for university examinations, diploma examinations, and competitive examinations.

Short-answer questions

1. Define mammography.
2. State the principle of mammography.
3. List the main indications of mammography.
4. Name the two standard mammographic projections.
5. What is the purpose of breast compression?
6. Define ductography or galactography.
7. List the indications for ductography.
8. What is digital breast tomosynthesis?
9. State two advantages of tomosynthesis.
10. Mention two limitations of tomosynthesis.
11. What is a spot-compression view?
12. What is the purpose of a magnification view?
13. Name three materials used in mammography target-filter combinations.
14. What is the role of automatic exposure control in mammography?
15. Mention four image quality criteria for mammography.

Long-answer questions

1. Describe the introduction and historical development of mammography.
2. Explain the equipment used in mammography with the functions of its major components.
3. Describe the method of mammographic examination, including patient preparation and standard positioning.
4. Explain the anatomy of the milk ducts and describe the procedure of ductography.
5. Discuss the indications, advantages, limitations, and complications of ductography.
6. Define digital breast tomosynthesis and explain its principle, method of examination, advantages, and limitations.
7. Compare conventional digital mammography with digital breast tomosynthesis.
8. Discuss the role of the radiographer in mammography, including positioning, image quality, and radiation protection.

10. Conclusion

Mammography is a fundamental imaging technique in breast cancer screening and diagnosis. Its development from early specimen radiography to modern digital imaging has significantly improved the detection and characterization of breast abnormalities.

Correct patient preparation, positioning, compression, exposure selection, and image quality assessment are essential for obtaining diagnostically useful images.

Ductography provides specialized imaging of the milk ducts in selected cases of pathologic nipple discharge, although conventional breast imaging and other diagnostic methods generally play the primary role in initial assessment.

Digital breast tomosynthesis is an important advancement that reduces the effect of overlapping breast tissues by reconstructing multiple X-ray projections into thin image sections. It can improve the visibility of certain lesions, but it does not eliminate all limitations of mammography.

For radiographers, understanding the principles, equipment, procedures, indications, limitations, and radiation protection requirements of these techniques is essential for delivering safe and effective breast imaging services.

Key takeaway: Mammography remains central to breast imaging, ductography has a selective role in evaluating ductal abnormalities, and breast tomosynthesis improves the assessment of breast structures by reducing tissue superimposition.