Radiation Therapy — Internal vs External

A nurse enters the room of a patient with a cervical implant and spends 45 minutes repositioning pillows. That nurse just violated the most critical radiation safety principle — and may not even realize it.

Radiation therapy delivers ionizing energy to destroy cancer cells by damaging DNA. External beam radiation (teletherapy) comes from a machine outside the body — the patient is NOT radioactive between treatments. Nursing care focuses on protecting the skin in the treatment field: no lotions unless facility-approved, no adhesive tape, and no sun exposure on marked areas; wash gently with lukewarm water and mild soap; assess for desquamation (dry then moist). Fatigue is cumulative and worsens over the treatment course. Internal radiation (brachytherapy) places a sealed or unsealed radioactive source inside or near the tumor. The patient IS radioactive while the source is in place. Nurses follow three cardinal safety principles: minimize TIME near the source (limit to 30 minutes per shift per caregiver), maximize DISTANCE (stay as far as practical, work efficiently at bedside), and use appropriate SHIELDING (lead apron, portable shields). Pregnant staff must not care for brachytherapy patients. Visitors are limited to 30 minutes per day, standing at least 6 feet away. If a sealed source becomes dislodged, NEVER pick it up with bare hands — use long-handled forceps, place it in a lead-lined container, and notify the radiation safety officer immediately. The patient on bedrest with a cervical implant must remain on strict bedrest with a low-residue diet to prevent source displacement.

Key Distinctions

Don't confuse external beam (patient is safe to be around between treatments) with brachytherapy (patient is radioactive while source is in place) — the safety precautions are completely different. Students mix up sealed sources (e.g., cervical cesium implant — body fluids are safe) with unsealed sources (e.g., oral I-131 for thyroid cancer — body fluids are radioactive and require private bathroom, double-flushing, and careful handling of linens and excreta). Skin care belongs to external radiation; radiation isolation belongs to internal.

Clinical Pearl

Time, Distance, Shielding — TDS. Think of it as your radiation safety seatbelt. Shortest time, longest distance, strongest shielding. Every second counts.