Understanding Radiation Therapy Types And Side Effects
Explore the different types of radiation therapy, including external and internal radiation. Learn about common side effects, how to manage them, and what to expect during treatment.
Written by Dr. M L Ezhilarasan
Reviewed by Dr. Dhankecha Mayank Dineshbhai MBBS
Last updated on 19th Sep, 2025
Introduction
A cancer diagnosis often comes with a whirlwind of new information and treatment options. Among the most common and effective tools in the fight against cancer is radiation therapy, used in over half of all cancer cases. But what exactly is it? If you or a loved one is beginning this journey, understanding what to expect can significantly reduce anxiety and empower you to be an active participant in your care. This guide will demystify radiation therapy, breaking down the different types—from advanced external beam techniques to internal brachytherapy. We'll walk you through the entire process, from the first consultation to the final session, and provide a comprehensive look at potential side effects, offering practical strategies for management. Our goal is to equip you with knowledge and confidence as you navigate this critical phase of treatment.
What is Radiation Therapy and How Does It Work?
Radiation therapy (also called radiotherapy) is a highly targeted treatment that uses high-energy particles or waves, such as X-rays, gamma rays, or protons, to destroy or damage cancer cells. The fundamental principle lies in its ability to damage the DNA inside these cells. Cancer cells are particularly vulnerable because they multiply much faster than most healthy cells. While radiation affects both, healthy cells are remarkably resilient and can often repair the damage much more effectively than cancer cells can.
Treatment is meticulously planned to maximize the dose to the tumor while minimizing exposure to surrounding healthy tissues. The intent of treatment can be:
- Curative: To eliminate the cancer entirely.
- Palliative: To shrink tumors, relieve pressure, or reduce pain caused by cancer, thereby improving quality of life, even if a cure isn't the primary goal.
The Radiation Oncology Team: Your Partners in Care
You are not alone in this process. A dedicated team of specialists will guide you every step of the way. This team is led by a radiation oncologist, a doctor who specializes in using radiation to treat cancer. They are supported by:
- Medical Physicists: Experts who ensure the equipment works correctly and delivers the precise dose calculated.
- Dosimetrists: Work with the oncologist and physicist to create the complex treatment plan.
- Radiation Therapists: Operate the machines and deliver your daily treatments.
- Radiation Oncology Nurses: Manage your care, educate you on side effects, and provide support throughout treatment.
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Major Types of Radiation Therapy
External Beam Radiation Therapy (EBRT)
This is the most common form, where radiation is delivered from a machine outside the body called a linear accelerator. Advanced imaging and computer software allow for extreme precision. Key techniques include:
- 3D-Conformal Radiation Therapy (3D-CRT): Uses CT scans to create a 3D model of the tumor, allowing beams to be shaped to match its contours.
- Intensity-Modulated Radiation Therapy (IMRT): An advanced form of 3D-CRT where the intensity of the radiation beams can be varied, allowing even more precise targeting and sparing of nearby healthy organs. This is a cornerstone of modern radiation oncology.
- Image-Guided Radiation Therapy (IGRT): Uses daily imaging (X-rays, CT scans) before each treatment to confirm the tumor's position, accounting for subtle movements like breathing or changes in bladder fullness.
- Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT): Delivers very high, precise doses of radiation to small tumors in a few sessions (sometimes just one). SRS is for brain tumors, while SBRT (or "CyberKnife") is for tumors elsewhere in the body.
- Proton Beam Therapy: A highly advanced type of EBRT that uses protons instead of X-rays. Protons can be controlled to deposit most of their energy directly in the tumor, with virtually no exit dose, making it excellent for treating cancers very close to critical structures.
Internal Radiation Therapy (Brachytherapy)
This involves placing a radioactive source directly inside or next to the tumor. It allows a high dose of radiation to be delivered to a very specific area with minimal reach to healthy tissues. Common uses include prostate, cervical, and uterine cancers.
- High-Dose Rate (HDR) Brachytherapy: A temporary, high-power source is placed for several minutes at a time through catheters, typically over a few sessions.
- Low-Dose Rate (LDR) Brachytherapy: A permanent or temporary low-power source is implanted. "Seed implants" for prostate cancer are a common example of permanent LDR brachytherapy.
Systemic Radiation Therapy: A Different Approach
Here, radioactive substances are given orally or intravenously. These substances travel through the bloodstream to seek out and destroy cancer cells. A common example is Radioactive Iodine (I-131) therapy for thyroid cancer.
The Radiation Therapy Process: From Simulation to Treatment
- Step 1: Consultation and Simulation: Your radiation oncologist will discuss your goals. This is followed by a "simulation" session where you are positioned exactly as you will be for treatment. You may receive tiny tattoo dots (freckle-sized) to ensure precise positioning every time.
- Step 2: Treatment Planning: Using the scans from simulation, your team spends days creating a custom plan. This complex process ensures the prescribed dose targets the tumor while respecting the "tolerance doses" of nearby organs.
- Step 3: Daily Treatment Sessions: Treatments are usually outpatient, Monday through Friday, for several weeks. Each session is painless and lasts only 10-20 minutes, though you may be in the room longer for setup. The therapists leave the room but can see and hear you at all times.
Common Side Effects of Radiation Therapy
Side effects are typically localized to the area being treated and are cumulative, often starting a few weeks into treatment.
Managing General Side Effects: Fatigue and Skin Changes
- Fatigue: This is very common. Combat it by listening to your body, pacing activities, light exercise like short walks, and ensuring good nutrition.
- Skin Changes: The skin in the treatment area may become red, irritated, dry, or peel, much like a sunburn. Use only gentle, fragrance-free soaps and moisturizers recommended by your care team. Avoid sun
- exposure completely on the treated area.
Site-Specific Side Effects: What to Expect Based on Treatment Area
- Head/Neck: Sore throat, difficulty swallowing, taste changes, dry mouth.
- Chest: Cough, shortness of breath, difficulty swallowing.
- Abdomen/Pelvis: Nausea, vomiting, diarrhea, urinary frequency.
- Pelvis (for women): Vaginal dryness, irritation.
- Pelvis (for men): Erectile dysfunction, urinary issues.
Your team will provide specific medications and advice to manage these side effects of radiation therapy.
Long-Term Side Effects and Late Effects
Some side effects, called "late effects," can develop months or years after treatment. These are rare but can include tissue scarring, infertility, or a very small increased risk of a second cancer later in life. Your oncologist will discuss your specific risks based on your treatment area and dose.
Life During and After Treatment: Tips for Coping and Recovery
Maintaining a balanced diet, staying hydrated, and getting moderate rest and exercise are crucial. Don't hesitate to ask for help from family and friends. Emotional support through counseling or support groups can be invaluable. After treatment ends, you will have regular follow-up appointments with your oncology team to monitor your recovery and long-term health. If you experience persistent or severe side effects after completing treatment, it's important to consult your doctor. For ongoing support, you can connect with a specialist online through Apollo24|7 for further evaluation and guidance.
Quick Takeaways / Key Points
- Radiation therapy is a localized, targeted treatment that damages cancer cell DNA.
- It can be used to cure cancer, control its growth, or relieve symptoms.
- The two main types are External Beam Radiation and Internal Brachytherapy.
- Side effects are usually limited to the treatment area and are manageable.
- Fatigue and skin irritation are the most common general side effects.
- A dedicated team of specialists will guide you through the entire process.
- Open communication with your healthcare team is key to managing side effects effectively.
Conclusion
Navigating radiation therapy can feel daunting, but understanding the process, the different types available, and the strategies to manage potential side effects can transform anxiety into empowerment. This treatment represents a powerful, precise weapon against cancer, constantly evolving with technologies like IMRT and proton therapy that better protect healthy tissues. Remember, your radiation oncology team is your greatest ally—lean on their expertise, communicate your symptoms openly, and follow their guidance for self-care. The journey through treatment is a significant step toward recovery, and with the right knowledge and support, you can focus on healing and looking forward to life after cancer. For any persistent concerns during your recovery, always consult your primary oncologist.
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Consult Top Specialists
Dr. Mohamed Azeem
General Physician/ Internal Medicine Specialist
2 Years • MBBS,MD(Internal Medicine) CCEBDM
Karaikudi
Apollo Hospitals Karaikudi, Karaikudi
Dr. Swathi Reddy Perugu
General Physician/ Internal Medicine Specialist
7 Years • MBBS, MD (General Medicine)
Hyderabad
Health plus, Hyderabad
Dr D M Karthik
General Practitioner
4 Years • MBBS, Fellowship in Diabetes Mellitus, Advance certificate in Diabetes Mellitus, Derma Nutrition Certification
Visakhapatnam
Apollo 24|7 Clinic - Andhra Pradesh, Visakhapatnam
Dr. Sandhya Chandel
General Physician/ Internal Medicine Specialist
16 Years • MBBS, MD (Int. Med.), IDCCM
Bilaspur
Apollo Hospitals Seepat Road, Bilaspur
(125+ Patients)
Dr. Ashita Kuruvilla
General Practitioner
6 Years • MBBS
Kolkata
KVC CLINIC, Kolkata
Consult Top Specialists
Dr. Mohamed Azeem
General Physician/ Internal Medicine Specialist
2 Years • MBBS,MD(Internal Medicine) CCEBDM
Karaikudi
Apollo Hospitals Karaikudi, Karaikudi
Dr. Swathi Reddy Perugu
General Physician/ Internal Medicine Specialist
7 Years • MBBS, MD (General Medicine)
Hyderabad
Health plus, Hyderabad
Dr D M Karthik
General Practitioner
4 Years • MBBS, Fellowship in Diabetes Mellitus, Advance certificate in Diabetes Mellitus, Derma Nutrition Certification
Visakhapatnam
Apollo 24|7 Clinic - Andhra Pradesh, Visakhapatnam
Dr. Sandhya Chandel
General Physician/ Internal Medicine Specialist
16 Years • MBBS, MD (Int. Med.), IDCCM
Bilaspur
Apollo Hospitals Seepat Road, Bilaspur
(125+ Patients)
Dr. Ashita Kuruvilla
General Practitioner
6 Years • MBBS
Kolkata
KVC CLINIC, Kolkata
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Frequently Asked Questions
Will I be radioactive after external beam radiation?
No. External beam radiation does not make you radioactive. The radiation passes through your body during treatment. You can safely interact with others, including children and pregnant women.
How long does a typical course of radiation therapy take?
A full course of conventional EBRT typically lasts 2 to 8 weeks, with treatments given once a day, Monday through Friday. Stereotactic treatments (SRS/SBRT) are much shorter, often completed in 1 to 5 sessions.
What does radiation therapy feel like?
The treatment itself is painless, much like getting a standard X-ray. You will not see, smell, or feel the radiation during the session.
Are the side effects of radiation therapy permanent?
Most common side effects like fatigue and skin irritation are temporary and gradually improve within weeks of finishing treatment. Some long-term or late effects can be permanent, but your doctor will discuss these risks with you beforehand.
Can I work during radiation treatment?
Many people continue to work, especially if their side effects are manageable. However, fatigue can be significant. It's best to discuss your schedule with your employer and consider flexible hours or taking time off if needed.