Radiation Therapy 101: How It Works & What to Expect | Apex Radiation Oncology, Jaipur

Radiation Therapy 101: How It Works and What to Expect

What is radiation therapy?

Radiation therapy (also called radiotherapy) is a medical treatment that uses high-energy radiation to destroy cancer cells or slow their growth. It is one of the three main pillars of cancer treatment—alongside surgery and systemic therapies such as chemotherapy and immunotherapy—and is used with curative, adjuvant, neoadjuvant, and palliative intent depending on the specific diagnosis. Radiation works by damaging the DNA inside cancer cells; when the damage is significant enough, the cells lose their ability to replicate and eventually die. Normal tissues can also be affected, but modern techniques aim to minimise this through precise targeting and careful planning.

Worldwide, roughly 50% of all people diagnosed with cancer will receive radiation therapy during their course of care, and radiotherapy contributes to about 40% of curative cancer treatments. In India and specifically in Rajasthan, access to advanced radiation oncology services in cities like Jaipur, Bikaner, Udaipur, and Sri Ganganagar has become a priority as cancer incidence rises and more patients seek high-quality, local care. At Apex Hospitals, our radiation oncology teams across Jaipur, Malviya Nagar, Mansarovar, Bikaner, Udaipur, Sawai Madhopur, Jhunjhunu, and Sri Ganganagar provide comprehensive radiotherapy services, from consultation to survivorship support.

Radiation therapy can be delivered in different ways depending on tumour type, location, stage, and patient health. The main categories include external beam radiotherapy (EBRT), brachytherapy (internal radiation), and systemic radiotherapy. Each method has specific indications and advantages which will be discussed in detail later. Patients often ask whether radiation therapy is painful — the treatment itself is painless; discomfort usually arises from positioning, skin reactions, or effects on nearby organs. Modern technology and expert supportive care keep those effects to a minimum.

How radiation therapy works: basics of biological effect and targeting

The primary goal of radiation therapy is to deliver a lethal dose of ionising radiation to cancer cells while sparing surrounding healthy tissue. At the cellular level, radiation causes breaks in DNA strands—single and double strand breaks. Cells can repair some damage, but when the damage is too extensive or the repair mechanisms fail (common in rapidly dividing tumour cells), cellular death follows either through apoptosis, mitotic catastrophe, or senescence.

Radiation oncologists use several strategies to maximise tumour control and limit toxicity:

• Fractionation: Radiation dose is divided into multiple small daily doses (fractions) to allow normal tissue to repair while still damaging cancer cells.
• Precision targeting: Advanced imaging (CT, MRI, PET) and planning software define the tumour volume and critical nearby organs, creating a customised dose distribution.
• Image guidance: Techniques such as IGRT (image-guided radiotherapy) monitor tumour position before and during treatment to adjust for movement (e.g., breathing).
• Modulated delivery: Methods like IMRT (intensity-modulated radiotherapy) shape the beam intensity to conform dose tightly to complex tumour shapes.

The balance between tumour control probability (TCP) and normal tissue complication probability (NTCP) guides planning decisions. For some cancers, higher dose per fraction delivered in fewer sessions is effective and convenient—this is the principle behind stereotactic treatments (SBRT or SRS). For others, conventional fractionation remains the safer option.

In practical terms, a patient’s treatment is not only about physics and biology but also about personalisation. Radiation oncologists at Apex Hospitals work closely with medical oncologists, surgical teams, and diagnostic radiology to create an integrated plan. This multidisciplinary coordination reduces delays, improves outcomes, and ensures that considerations such as combined chemo-radiation or timing relative to surgery are optimally addressed.

Types of radiation therapy and their differences

Understanding the different types of radiation therapy helps patients and families make informed decisions with their care teams. The most commonly used categories are external beam radiotherapy, brachytherapy, and systemic radiopharmaceuticals. Each modality offers unique advantages and is chosen based on tumour location, size, spread, and the patient’s overall health.

External beam radiotherapy (EBRT) is the most widely used method. It delivers radiation from a machine outside the body (linear accelerator). EBRT includes advanced forms such as IMRT, IGRT, and stereotactic radiotherapy (SBRT/SRS). Brachytherapy places radioactive sources inside or next to the tumour, commonly used for cervical, prostate, and certain head & neck cancers. Systemic radiotherapy uses radioactive drugs (e.g., radioactive iodine for thyroid cancer, radium-223 for bone metastases) to target disease throughout the body.

Apex Hospitals in Jaipur and other centres in Rajasthan offer many of these advanced modalities, including IMRT, IGRT, and stereotactic radiotherapy. While proton therapy and certain particle therapies are highly precise and reduce dose to normal tissues, they are less widely available in India and typically offered in specialised centres; we continuously evaluate and expand access to advanced options to ensure our patients receive the most appropriate technology for their needs.

Who needs radiation therapy? indications and common cancers treated

Radiation therapy is indicated across a broad spectrum of cancers and clinical scenarios. It may be used to:

• Attempt a cure as the primary treatment (e.g., localised prostate, head & neck, early lung cancers).
• Eradicate microscopic disease after surgery (adjuvant therapy) to reduce recurrence risk.
• Shrink tumours before surgery (neoadjuvant therapy) to make them operable.
• Provide symptom relief and improve quality of life for advanced disease (palliative radiation).
• Control tumour growth in metastatic sites such as bones or brain.