Radiation Safety in the Orthopaedic Theatre: The Invisible Hazard

Visual Element: An interactive "Scatter Map". A top-down view of an operating theatre with a C-arm. The user can move the surgeon and scrub nurse to different positions to see the relative radiation dose (Heatmap).

Orthopaedic surgeons are among the highest exposed medical professionals to ionizing radiation, second only to interventional cardiologists/radiologists. We use fluoroscopy (C-arm) daily for fractures, spine surgery, and injections.

Radiation is an invisible, odorless, silent hazard. Because the effects are often delayed by decades (cancer) or cumulative (cataracts), it is easy to become complacent. This guide brings the physics of safety into the theatre.

Part 1: The Biological Risk

Radiation damage comes in two flavors:

1. Deterministic Effects (Threshold Based)

These happen once you cross a specific dose threshold. Severity is proportional to dose.

• Skin Burns: Rare in orthopaedics, but possible in long spine cases.
• Cataracts: The lens is highly sensitive. Posterior subcapsular cataracts can occur with cumulative doses > 0.5 Gy.
  • Risk: Orthopaedic surgeons have a significantly higher rate of cataracts than controls.

2. Stochastic Effects (Chance Based)

There is no "safe" threshold. Every photon carries a probability of inducing a DNA mutation leading to cancer.

• Cancer: Thyroid, Breast, Leukemia, Brain (left-sided prevalence in interventionalists).
• Genetic: Mutations passed to offspring (theoretical).

Part 2: The Source of Exposure (Scatter)

You are not exposed to the direct beam (hopefully, unless your hands are in it). You are exposed to Scatter Radiation.

• The Patient is the Source: When the X-ray beam hits the patient, it bounces off (Compton Scattering).
• The Physics: The larger the patient (obesity), the more scatter is generated.

Part 3: The Principles of Protection (ALARA)

As Low As Reasonably Achievable.

1. Time (Minimize Beam-On)

• Pulse Mode: Use pulsed fluoroscopy (e.g., 12 pulses/sec) instead of continuous. This reduces dose by 50-75% with no loss of image quality for static bones.
• Last Image Hold: Look at the static image on the screen, don't stare at the live fluoro while thinking.
• The "Heavy Foot": Don't step on the pedal until you are ready.

2. Distance (The Inverse Square Law)

This is the most powerful tool. Intensity = 1 / Distance².

• Step Back: Taking one step (1 meter) back reduces your exposure by >90%.
• The Scrub Nurse: Should step away during shots.
• Hands Free: Use tools (forceps/clamps) to hold instruments, not your hands.

3. Shielding

• Lead Aprons: 0.5mm Lead Equivalent (PbEq). Wrap-around is best to protect the back.
• Thyroid Shield: Mandatory. Reduces thyroid dose by 20-fold.
• Lead Glasses: Mandatory. Regular glasses do not block X-rays.
• Mobile Shields: Use the lead screen hanging from the ceiling or the mobile lead wall.

Part 4: C-Arm Positioning (The "Inverted" C-Arm)

Visual Element: Comparison diagram of "Correct" vs "Incorrect" C-arm orientation.

Rule: X-ray Tube UNDER the table. Image Intensifier OVER the patient.

• Why?:
  • Tube Down: The source is under the table. Most scatter is directed back towards the floor (your feet). The table and patient absorb some energy.
  • Tube Up (Inverted): The source is at your head level. Scatter bounces off the patient directly into your eyes and thyroid. Dose to the surgeon's head is 10-100x higher.
• Lateral Shoot-Through: Stand on the side of the Image Intensifier (the "Bucket"). The source (Tube) shoots towards you, so the scatter bounces back towards the tube side.

Part 5: Pregnancy and Radiation

• The Limit: Fetal dose limit is 1 mSv over the entire pregnancy.
• Safety: With proper lead (double thickness or maternity apron) and a fetal dosimeter worn under the lead, orthopaedic surgery is safe during pregnancy.
• Policy: Declare pregnancy early to Safety Officer to get the second badge.

Conclusion

Radiation safety is a culture. It requires the surgeon to lead by example.

1. Wear your lead (and glasses).
2. Put the tube down.
3. Step back.
4. Pulse the beam.