Radiation therapy (RT) is one of the most effective and commonly used ways to treat cancer. Understanding the science, process, benefits, and potential side effects of this treatment can help promote clarity and confidence, whether you are a patient who has just been diagnosed or a loved one supporting someone through treatment.
This guide provides a detailed overview of the mechanism, planning process, and clinical goals of radiotherapy.
What is Radiation Therapy (Radiotherapy)?
Radiotherapy is a cancer treatment modality that uses high-energy radiation (such as X-rays, gamma rays, or particles) to target and destroy cancer cells or shrink tumors. Unlike chemotherapy, which typically acts systemically throughout the body, radiation therapy is a localized treatment that only affects the treated area [1].
The two primary methods of delivery are:
- External Beam Radiation Therapy (EBRT):
This is the most common type. A machine outside the body (a linear accelerator) directs focused radiation beams to the tumor site.
- Internal Radiation Therapy (Brachytherapy):
This method involves placing a radioactive source (like seeds, wires, or pellets) directly inside the body, close to the cancer cells, to deliver a high, localized dose.
Also Read : Different Types Of Radiation Therapy Used In Cancer Treatment
The Mechanism of Action: Targeting Cancer DNA
Radiation works by damaging the DNA within the cancer cells. This damage prevents the cells from successfully growing and dividing, eventually leading to cell death [2]. A key principle is that cancer cells are often less efficient at repairing this DNA damage than normal, healthy cells.
Treatment is typically delivered in small daily doses (fractions). This fractionation allows the healthy cells time to repair any incidental damage between sessions, while the cancer cells, which have poor repair mechanisms, accumulate lethal damage over the course of the treatment [3].
The Process of Receiving Radiation Therapy
A course of radiation treatment is a meticulous, multi-step process, overseen by a specialized team including a Radiation Oncologist, Medical Physicist, and Dosimetrist.
1. Consultation and Evaluation
The first step is a thorough consultation with a radiation oncologist. They will review your entire medical history, current health status, imaging scans, and pathology reports to determine if radiation therapy is appropriate for your specific cancer type and stage.
2. Simulation and Planning
This is the critical step for precision.
- Simulation:
You will undergo a CT scan, often combined with an MRI or PET scan, to create a highly accurate, three-dimensional map of your tumor’s exact location. Immobilization devices, such as customized molds or casts, are often created to ensure you are in the exact same position for every treatment session [4].
- Dose Planning:
The medical physics team uses specialized software to calculate the precise angle, shape, and intensity of the radiation beams. This plan is customized to maximize the dose delivered to the tumor while meticulously sparing nearby critical organs (Organs At Risk).
The choice of imaging centre and scan type should always be guided by your treating doctor or radiation oncologist. Availability of services may vary by location.
PET/CT Scan Centers |
| Pet/CT Scan in Satara |
| PET/CT Scan – Chiplun |
| Pet/CT Scan in Talegaon |
| Pet/CT Scan in Pune |
3. Treatment Delivery
Sessions are typically scheduled daily, five days a week (Monday through Friday), and can last anywhere from 2 to 8 weeks, depending on the treatment goal. Each session itself is short, often lasting only 10 to 20 minutes. Modern techniques like Volumetric Modulated Arc Therapy (VMAT) and Stereotactic Body Radiation Therapy (SBRT) use advanced technology, such as Image-Guided Radiation Therapy (IGRT), to confirm tumor position before and sometimes during treatment, ensuring high accuracy [4].
4. Follow-Up and Monitoring
Regular follow-up appointments and imaging scans are scheduled after the completion of treatment to monitor the tumor’s response and help you manage any potential late-onset side effects.
Clinical Goals of Radiation Treatment
Radiation therapy is used for various purposes in the cancer care pathway:
- Curative Intent:
Used either alone (for early-stage tumors) or in combination with surgery or chemotherapy to eliminate the cancer completely [1].
- Neoadjuvant Therapy:
Given before surgery to shrink the tumor, potentially making a large surgery more manageable or reducing the extent of tissue removal required.
- Adjuvant Therapy:
Given after surgery to destroy any microscopic cancer cells that may remain, thereby lowering the risk of local cancer recurrence.
- Palliative Care:
Used to ease symptoms in the advanced stages of cancer, such as reducing pain from bone metastases or relieving pressure from a large tumor [5].
Common cancers treated with RT include breast, prostate, head and neck, cervical, brain, and lung cancer.
What Are the Side Effects of Radiation Therapy?
While generally well-tolerated, side effects are common because the radiation affects some healthy cells along with the cancer cells. It is critical to note that side effects are localized to the treatment area.
- Systemic Side Effects:
The most common is fatigue, which often builds up during the course of treatment and slowly improves afterward [5].
- Localized Side Effects:
These depend entirely on the site treated:
- Skin:
Redness, itching, dryness, or peeling in the treatment field (similar to a sunburn).
- Head/Neck:
Mouth sores (mucositis), difficulty swallowing (dysphagia), or dry mouth.
- Abdomen/Pelvis:
Nausea, vomiting, diarrhea, or urinary changes.
- Hair Loss:
Only occurs in the treated area (e.g., scalp hair loss from brain radiation).
- Skin:
Most acute side effects are temporary and typically resolve within a few weeks to months after treatment ends. Your oncology team will prescribe supportive care medications and provide nutritional and skin care advice to help manage these issues.
For patients considering advanced treatment options, consulting an experienced oncologist is essential for personalized guidance and monitoring.
Accessing Advanced Radiation Care
When seeking a radiation oncology center, focus on quality indicators:
- Accreditation:
Check for recognized accreditations (e.g., NABH in India) which attest to quality and safety standards.
- Expertise:
Look for radiation oncologists trained in major national or international centers who participate in multidisciplinary tumor board meetings.
- Technology:
Access to advanced technology (like IMRT, VMAT, and SBRT) is essential for precise treatment.
Financial Assistance:
In India, various Government Health Insurance Schemes are designed to improve access to cancer care. Programs like Ayushman Bharat (Pradhan Mantri Jan Arogya Yojana) and the Mahatma Jyotiba Phule Jan Arogya Yojana (MJPJAY) in Maharashtra provide financial coverage for radiation therapy and other cancer treatments for eligible beneficiaries, often making treatment essentially cashless (National Health Authority, 2024) [6]. Patients should consult with the hospital’s patient welfare or insurance desk for eligibility details.
Conclusion
Radiation therapy remains a fundamental and increasingly sophisticated pillar of modern cancer treatment. Through precision planning, advanced technology, and dedicated care, it offers thousands of patients the chance for a cure or significant symptom relief. Prompt consultation with a qualified radiation oncologist is the crucial first step in developing an effective, personalized treatment plan.
Disclaimer
The content of this blog is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. Radiation therapy planning and selection are complex and highly personalized medical decisions.
References
- National Cancer Institute. (2022). Radiation Therapy for Cancer. Contextual Link:
- Joiner, M. C., & van der Kogel, A. J. (2020). Basic Clinical Radiobiology (5th ed.). CRC Press. Contextual Link: (Note: This is a core textbook supporting the principle of DNA damage and fractionation.)
- Hall, E. J., & Giaccia, A. J. (2019). Radiobiology for the Radiobiologist (8th ed.). Lippincott Williams & Wilkins. Contextual Link: (Note: This is a core textbook supporting the radiobiological principles.)
- Gunderson, L. L., Tepper, J. E., & Haddock, M. G. (2012). Clinical Radiation Oncology (3rd ed.). Elsevier Health Sciences. Contextual Link: (Note: This is a core textbook supporting the procedures of simulation and IGRT.)
- American Society for Radiation Oncology (ASTRO). (2023). Understanding Radiation Therapy: A Guide for Patients and Families. Contextual Link:
- National Health Authority. (2024). Ayushman Bharat Pradhan Mantri Jan Arogya Yojana (AB PM-JAY). Contextual Link:
Frequently Asked Questions FAQ’s
Blog- A Comprehensive Guide to How Radiation Therapy Works
Is Radiation Therapy Painful During The Session?
No. Radiation therapy sessions are completely painless. You will not feel, see, or hear anything from the radiation beam itself. The most discomfort comes from having to lie still in the same position on the treatment couch for the 10-20 minutes it takes to deliver the dose.
Is There A Chance That The Radiation Can Harm My Baby If I Am Pregnant?
Yes. Radiation therapy is generally contraindicated (not recommended) during pregnancy as the radiation exposure can harm the developing fetus, especially if the treatment area is near the abdomen or pelvis. If you are pregnant or may be pregnant, you must inform your radiation oncologist immediately so the treatment plan can be safely modified or delayed.
Why Do I Need To Come For Daily Treatments (Fractions) Instead Of A Single High Dose?
Coming for daily fractions (smaller doses) over several weeks, known as fractionation, is a key strategy based on radiobiology. It achieves two goals:
- Maximizes Cancer Cell Kill: It takes advantage of the cancer cells' inability to repair themselves fully between treatments.
- Minimizes Normal Tissue Damage: It gives healthy cells time to recover and repair themselves, significantly reducing the severity of side effects and the risk of long-term damage.
Can I Transmit Radiation To Others After Treatment?
No. After receiving External Beam Radiation Therapy (EBRT), you are not radioactive and pose no risk of transmitting radiation to anyone, including children or pregnant women. Only certain types of Internal Radiation (Permanent Brachytherapy Seeds) require temporary precautions, which your doctor will clearly outline.
