Radiation therapy uses high-energy rays, such as X-rays or proton beams, to damage the DNA within cancer cells, preventing them from growing and dividing. This precise, targeted approach aims to destroy malignant cells while sparing surrounding healthy tissue. The process involves a specialized team and multiple preparatory steps. Understanding the phases of treatment provides a helpful roadmap for patients.
Preparing for Your Treatment
The process begins with a planning phase known as simulation. Simulation uses imaging tools, typically a CT scan, to map the exact location, size, and shape of the tumor. This provides the anatomical data needed to define the radiation field and calculate the optimal dose.
Customized immobilization devices, such as body molds or masks, are created during simulation to ensure the patient is in the identical position for every session. These devices reduce movement and improve setup reproducibility. Small, permanent reference marks (tattoos) are placed on the skin, allowing therapists to align the treatment machine accurately before each daily session.
Following simulation, the treatment planning phase, known as dosimetry, begins and may take several days. Dosimetrists and physicists work with the radiation oncologist to design a customized plan. They calculate the angles and shapes of the radiation beams to ensure the prescribed dose is delivered effectively.
What Happens During Each Session
Radiation therapy is typically delivered five days a week for several weeks, a schedule known as fractionation. The daily visit usually lasts 15 to 30 minutes, though the radiation beam is only active for a few minutes. Treatment is delivered using a linear accelerator (Linac).
During the session, the patient lies on a treatment couch. Therapists use the skin marks and immobilization devices to align the body precisely before operating the machine from a control area. They maintain visual and audio contact. Patients must remain perfectly still during the treatment.
When the Linac delivers the radiation, there is no physical sensation, heat, or pain. The machine may make mechanical noises as it moves, but the radiation is invisible. If a patient feels uncomfortable, they can speak to the therapists, who can immediately stop the machine.
Acute Physical Reactions
Acute reactions occur during treatment or shortly after the final session, typically resolving within a few weeks to months. The most common systemic effect is fatigue, which often begins a few weeks into treatment and worsens. This exhaustion is caused by the body expending energy on repair and the daily stress of treatment.
Physical side effects are localized to the treated area. For all sites, the skin within the radiation field can develop a reaction similar to a sunburn, presenting as redness, dryness, itching, or peeling. These acute symptoms signal that the radiation is affecting rapidly dividing healthy cells, but these cells usually heal quickly.
Head and Neck
Common acute effects include inflammation of the mouth lining (mucositis), painful swallowing, dry mouth, and temporary changes in taste, which can make eating difficult.
Chest
Patients may experience a sore throat, difficulty swallowing, cough, and shortness of breath.
Pelvis or Abdomen
Radiation can irritate the gastrointestinal and urinary tracts, leading to diarrhea, nausea, vomiting, and bladder issues such as frequent or burning urination.
Practical Strategies for Managing Side Effects
Managing acute skin reactions involves gentle care. Patients should wash the skin using mild, unscented soap and lukewarm water, patting the area dry. Applying prescribed moisturizers or creams helps soothe dryness. Avoid applying heat or cold packs and protect the skin from sun exposure.
Dietary modifications address site-specific irritation. Head and neck patients should eat soft, pureed, or liquid foods and avoid spicy, acidic, crunchy, or very hot items. For diarrhea caused by pelvic or abdominal radiation, switch to a low-fiber diet, drink clear fluids, and avoid gas-producing foods. Nutritional counseling ensures patients maintain adequate calories.
Fatigue is best managed by balancing activity with rest. Light, regular activity, such as short walks, can help improve energy levels and mood. Patients should prioritize necessary tasks when they feel most energetic. Contact the medical team immediately if a fever of 100.4°F or higher, severe pain, or bleeding occurs, as these may indicate an infection.
Recovery and Long-Term Follow-Up
The period immediately following the final session marks the beginning of recovery, but side effects do not disappear instantly. Acute side effects may peak one to two weeks after treatment concludes. General side effects like fatigue and most localized acute reactions typically resolve within a few weeks to a couple of months.
Long-term effects persist or develop months to years after the course is completed. These effects are localized and result from subtle tissue damage, leading to a mild scarring process known as fibrosis. Examples include permanent changes in skin color or texture, localized hair loss, and reduced tissue elasticity.
Radiation to the chest may result in minor scarring visible on lung X-rays, while pelvic treatment can occasionally lead to increased bowel frequency or bladder sensitivity. Patients follow a schedule of post-treatment appointments and scans to monitor effectiveness and manage delayed issues, ensuring early identification of late effects.