How Radiation Treatment Works

Radiation damages the DNA of cancer cells, preventing their division. Healthy tissues repair more effectively than tumors, which is why treatments are administered in small daily doses (fractions) over several weeks to balance efficacy and safety. Precision imaging guides beams to the target, and treatment plans consider breathing, organ motion, and past therapies.

Questions about the likelihood of cancer returning after radiation are common. Risk depends on cancer type, stage, biology, and whether radiation is combined with surgery or systemic therapy; your care team can provide statistics on how radiation impacts local control. Regarding proton therapy vs traditional radiation benefits, proton beams have a lower exit dose, potentially reducing exposure to nearby tissues in select cases near vital organs.

Types: External and Internal

Most patients undergo external beam radiation therapy (EBRT) using a machine called a linear accelerator. EBRT techniques include 3D conformal therapy, intensity-modulated radiation therapy (IMRT), image-guided radiation therapy (IGRT), stereotactic radiosurgery, and stereotactic body radiotherapy for targeted, brief treatments.

Internal radiation, or brachytherapy, involves placing radioactive sources inside or near the tumor for a high dose to the target and a quick dose falloff in normal tissue. Systemic radiation uses radiopharmaceuticals traveling through the bloodstream to specific cancer cells, like bone-seeking agents or targeted agents for certain neuroendocrine and prostate cancers.

Patients contemplating chemotherapy vs radiation therapy pros and cons should understand they serve distinct roles: radiation acts locally; chemotherapy and drugs have a systemic effect. In some cancers, they’re combined (chemoradiation) to improve cure rates or shrink tumors before surgery.

Planning, Targeting, and Sessions

The process begins with a “simulation.” For those wondering how to prepare for radiation simulation scans, wear comfortable clothing, avoid lotions on the treatment area, and bring previous imaging. The team might create a custom mask or body mold and place skin marks or tattoos to assist daily alignment. A planning CT, sometimes combined with MRI or PET, maps the tumor and nearby organs; physicists then design a plan that contours and modulates the dose around sensitive areas.

During radiation treatments, sessions usually last 10–30 minutes, primarily for positioning. The machine may rotate around you but doesn't make contact; you will not feel the radiation. Therapists monitor and communicate through an intercom; you breathe normally unless instructed to hold your breath for chest or breast treatments to protect the heart. After each session, normal activities can typically be resumed.

Benefits, Risks, and Recovery

Benefits include tumor control, symptom relief (like pain or bleeding), organ preservation, and a shorter recovery period than surgery for some patients. Side effects vary based on the treated area and dose. Common short-term reactions are fatigue, skin irritation, sore throat with head-and-neck therapy, and bowel changes with pelvic therapy; most resolve weeks post-treatment.

Questions about long-term effects of radiation therapy often arise. These effects can include stiffness or fibrosis, changes in bowel or bladder function, lymphedema, or, rarely, secondary cancers occurring years later; your team adjust the dose to minimize these risks. Practical measures include how to manage fatigue from radiation therapy, such as pacing activities, light exercise, maintaining good sleep hygiene, and checking for anemia or thyroid problems if fatigue persists. For skin care after radiation, use fragrance-free cleansers, moisturizing creams recommended by your clinic, avoid tight clothing and heat on the area, and protect healed skin with broad-spectrum SPF 30+. The best diet during radiation therapy emphasizes protein, hydration, and small frequent meals; a registered dietitian can provide tailored advice, especially for mouth, throat, or GI treatments.

Many Americans inquire about radiation therapy cost with Medicare. Outpatient EBRT is usually covered under Part B; you may be responsible for deductibles and coinsurance unless you have Medigap or a Medicare Advantage plan with different cost-sharing. Facility type and technique (e.g., proton centers) can affect out-of-pocket costs, so requesting an estimate from your clinic’s financial counselor is wise.

Combining Therapies and Advances

Radiation is coordinated with surgery to reduce tumors preoperatively or eliminate microscopic cells afterward. When combined with drugs, chemoradiation can enhance cure rates in cancers like rectal, cervical, and head-and-neck, though it may increase side effects; your team will explain the chemotherapy vs radiation therapy pros and cons and why a combined approach might be beneficial.

Precision continues to enhance. Adaptive radiation modifies plans mid-course as tumors shrink. MRI-guided linacs visualize soft tissue in real-time to refine margins. For selected patients and sites, proton therapy vs traditional radiation benefits include reducing the dose to organs like the heart or brain, potentially lowering some side effects while maintaining control. Researchers are studying ultra-fast “FLASH” delivery and new radiopharmaceuticals providing cell-killing radiation internally. Ask your radiation oncologist whether a clinical trial or an advanced technique is suitable for your diagnosis and goals.

Radiation Therapy for Cancer, Explained