X Ray Calcaneus Axial View Positioning

The axial view radiograph of the calcaneus, also known as the heel bone, is a crucial diagnostic tool in evaluating various foot pathologies. This specialized radiographic projection provides a comprehensive visualization of the calcaneus, enabling healthcare professionals to assess fractures, dislocations, bone spurs, and other abnormalities that may not be readily apparent on standard foot radiographs. Precise positioning and technique are key to obtaining high-quality images that accurately depict the anatomical structures and make easier accurate diagnosis.

Indications for Calcaneus Axial View

The calcaneus axial view is typically requested to evaluate the following conditions:

• Fractures: To identify and assess calcaneal fractures, which are often caused by high-impact trauma such as falls from height or motor vehicle accidents.
• Dislocations: To evaluate subtalar joint dislocations, where the calcaneus is displaced relative to the talus.
• Bone Spurs: To detect and assess the size and location of calcaneal bone spurs, which can cause heel pain and discomfort.
• Arthritis: To evaluate degenerative changes in the subtalar joint, such as osteoarthritis or rheumatoid arthritis.
• Tendonitis: To identify calcifications or other abnormalities associated with Achilles tendonitis or plantar fasciitis.
• Tumors: To evaluate bony lesions or tumors involving the calcaneus.
• Persistent Heel Pain: To investigate the underlying cause of chronic heel pain when other diagnostic modalities are inconclusive.

Contraindications

While the calcaneus axial view is a valuable diagnostic tool, there are certain situations where it may be contraindicated or require special considerations:

• Pregnancy: Radiography involves ionizing radiation, which can be harmful to the developing fetus. Because of this, pregnant women should avoid unnecessary X-ray examinations, especially during the first trimester. If the examination is deemed necessary, appropriate shielding should be used to minimize radiation exposure to the abdomen.
• Severe Trauma: In cases of severe trauma to the foot or ankle, the patient's condition may preclude proper positioning for the calcaneus axial view. Alternative imaging modalities, such as computed tomography (CT) or magnetic resonance imaging (MRI), may be more appropriate in these situations.
• Non-cooperative Patients: Patients who are unable to cooperate or maintain the required position due to pain, confusion, or other factors may not be suitable candidates for the calcaneus axial view. Sedation or alternative imaging techniques may be necessary.
• Open Wounds or Infections: The presence of open wounds or infections in the foot or ankle region may increase the risk of complications during the examination. In such cases, the healthcare provider should carefully weigh the benefits and risks before proceeding with the calcaneus axial view.

Equipment

The following equipment is required to perform the calcaneus axial view:

• X-ray Machine: A standard X-ray machine with a generator capable of producing the required kilovoltage (kV) and milliamperage (mA) settings.
• X-ray Table: A radiolucent X-ray table to support the patient during the examination.
• Image Receptor (IR): A digital radiography (DR) detector or computed radiography (CR) cassette to capture the X-ray image. The size of the IR should be appropriate to cover the entire calcaneus.
• Positioning Aids: Foam wedges, sandbags, or other positioning aids to help maintain the patient's foot in the correct position.
• Lead Shielding: Lead aprons and gonad shields to protect the patient from unnecessary radiation exposure.

Patient Preparation

Prior to performing the calcaneus axial view, the following steps should be taken to prepare the patient:

1. Explain the Procedure: Explain the purpose of the examination, the positioning requirements, and the importance of remaining still during the X-ray exposure. Answer any questions the patient may have and address any concerns they may express.
2. Remove Artifacts: Ask the patient to remove any metal objects, such as jewelry, watches, or piercings, from the foot and ankle region, as these can create artifacts on the X-ray image.
3. Provide Protective Shielding: Provide the patient with a lead apron to protect their torso and a gonad shield to protect their reproductive organs.
4. Ensure Patient Comfort: Make sure the patient is comfortable and properly supported on the X-ray table. Use positioning aids as needed to maintain the correct position and minimize discomfort.

Calcaneus Axial View Positioning: Step-by-Step Guide

The following steps outline the proper positioning technique for the calcaneus axial view:

1. Patient Position:
   • Position the patient in a seated or supine position on the X-ray table, with the affected leg extended.
   • check that the patient is comfortable and well-supported.
2. Foot Position:
   • Dorsiflex the foot as much as possible, bringing the toes towards the shin. This helps to elongate the calcaneus and improve visualization.
   • Maintain the foot in a neutral position, avoiding any rotation or inversion.
3. Image Receptor (IR) Placement:
   • Place the IR under the heel, ensuring that it is centered to the calcaneus.
   • Align the long axis of the IR with the long axis of the foot.
   • The IR should be large enough to include the entire calcaneus and surrounding soft tissues.
4. Central Ray (CR) Angulation and Direction:
   • Angle the central ray 40 degrees cephalad (towards the head).
   • Direct the central ray to enter the plantar surface of the foot at the base of the calcaneus, exiting at the posterior aspect of the ankle.
5. Collimation:
   • Collimate the X-ray beam to the area of interest, including the calcaneus and surrounding soft tissues.
   • Avoid unnecessary radiation exposure by limiting the field size to the anatomical region of interest.
6. Breathing Instructions:
   • Instruct the patient to hold their breath during the X-ray exposure to minimize motion artifact.
   • Provide clear and concise instructions to ensure patient cooperation.

Technical Factors

The following technical factors are typically used for the calcaneus axial view:

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• kVp (Kilovoltage Peak): 60-70 kVp
• mAs (Milliamperage-Seconds): 5-10 mAs
• Focal Spot Size: Small focal spot
• SID (Source-to-Image Receptor Distance): 40 inches (100 cm)
• Grid: Non-grid technique is typically used, unless the patient is very large or the calcaneus is particularly dense.

These technical factors may need to be adjusted based on the patient's size, bone density, and the specific equipment being used.

Image Evaluation Criteria

The following criteria should be used to evaluate the quality of the calcaneus axial view radiograph:

• Visualization of Calcaneus: The entire calcaneus should be clearly visualized, including the anterior, middle, and posterior facets, as well as the tuberosity and sustentaculum tali.
• Absence of Rotation: The calcaneus should be free of rotation, as evidenced by the symmetrical appearance of the medial and lateral aspects of the bone.
• Appropriate Density and Contrast: The image should have adequate density and contrast to allow for clear visualization of bony structures and soft tissues.
• Sharpness and Detail: The image should be sharp and well-detailed, with minimal motion artifact.
• Proper Collimation: The collimation should be appropriate, limiting the field size to the area of interest.
• Absence of Artifacts: The image should be free of artifacts caused by metal objects, patient motion, or other factors.

Common Errors and Solutions

• Rotation: Rotation of the foot can distort the appearance of the calcaneus and make it difficult to assess fractures or other abnormalities. see to it that the foot is in a neutral position, with the toes pointing straight up. Use positioning aids to maintain the correct position.
• Insufficient Dorsiflexion: Insufficient dorsiflexion of the foot can obscure the calcaneus and make it difficult to visualize the anterior and middle facets. Encourage the patient to dorsiflex the foot as much as possible. If necessary, use a foam wedge to support the foot in a dorsiflexed position.
• Incorrect Central Ray Angulation: Incorrect angulation of the central ray can result in a foreshortened or distorted image of the calcaneus. check that the central ray is angled 40 degrees cephalad. Use a goniometer to accurately measure the angle.
• Motion Artifact: Patient motion can blur the image and make it difficult to visualize fine details. Provide clear breathing instructions and confirm that the patient is comfortable and well-supported. Use a short exposure time to minimize motion artifact.
• Inadequate Collimation: Inadequate collimation can result in unnecessary radiation exposure to the patient. Collimate the X-ray beam to the area of interest, including the calcaneus and surrounding soft tissues.

Anatomical Considerations

The calcaneus is the largest of the tarsal bones and forms the heel. It articulates with the talus superiorly and the cuboid anteriorly. The calcaneus has several important anatomical landmarks, including:

• Tuberosity: The posterior portion of the calcaneus, which serves as the attachment site for the Achilles tendon.
• Sustentaculum Tali: A medial projection that supports the talus.
• Anterior, Middle, and Posterior Facets: Articular surfaces that articulate with the talus.
• Calcaneal Sulcus: A groove that runs along the superior surface of the calcaneus and forms the floor of the tarsal sinus.

Pathology

The calcaneus is susceptible to a variety of pathological conditions, including:

• Fractures: Calcaneal fractures are often caused by high-impact trauma and can be classified as intra-articular or extra-articular.
• Bone Spurs: Calcaneal bone spurs, also known as heel spurs, are bony projections that can develop on the plantar surface of the calcaneus.
• Plantar Fasciitis: Inflammation of the plantar fascia, a thick band of tissue that runs along the bottom of the foot.
• Achilles Tendonitis: Inflammation of the Achilles tendon, which connects the calf muscles to the calcaneus.
• Subtalar Joint Arthritis: Degenerative changes in the subtalar joint, which can cause pain, stiffness, and limited range of motion.

Radiation Safety

As with all radiographic examinations, Make sure you practice proper radiation safety principles when performing the calcaneus axial view. It matters. The following measures should be taken to minimize radiation exposure to the patient and healthcare personnel:

• Use the ALARA Principle: The ALARA (As Low As Reasonably Achievable) principle should be followed at all times. Use the lowest possible radiation dose that is necessary to obtain a diagnostic image.
• Collimate the X-ray Beam: Collimate the X-ray beam to the area of interest, avoiding unnecessary radiation exposure to surrounding tissues.
• Use Protective Shielding: Provide patients with lead aprons and gonad shields to protect their reproductive organs.
• Minimize Repeat Examinations: Avoid repeat examinations by ensuring that the patient is properly positioned and that the technical factors are optimized.
• Monitor Radiation Exposure: Healthcare personnel should wear radiation monitoring badges to track their cumulative radiation exposure.
• Maintain Equipment: Regularly inspect and maintain X-ray equipment to check that it is functioning properly and that radiation levels are within acceptable limits.

Conclusion

The calcaneus axial view is a valuable radiographic projection for evaluating various foot pathologies. Still, precise positioning and technique are essential to obtaining high-quality images that accurately depict the anatomical structures and help with accurate diagnosis. By following the guidelines outlined in this article, healthcare professionals can check that they are performing the calcaneus axial view safely and effectively, providing patients with the best possible diagnostic care.