1. Overview

Image-Guided Radiation Therapy (IGRT) is an advanced technique that uses imaging during each treatment session to improve accuracy. It allows doctors to see the exact position of the tumor and adjust for any movement before delivering radiation.

Tumors can shift slightly due to breathing, digestion, weight changes, or daily positioning. IGRT helps correct these shifts in real time. It is not a standalone radiation type but is usually combined with other modalities like IMRT, VMAT, SBRT, or 3D-CRT.

Common imaging tools include cone-beam CT (CBCT), X-rays, MRI, or ultrasound. These images are taken right before or during treatment to ensure the radiation beams hit the cancer precisely while protecting healthy tissues.

IGRT has become a standard part of modern radiation therapy for many cancer types.

Read also: How Does 3D Conformal Radiation Therapy (3D-CRT) Work?

2. Why is it done, and when is it chosen over other modalities

Doctors use IGRT to increase treatment accuracy and reduce side effects. It helps deliver the planned radiation dose exactly where it is needed.

Main reasons for IGRT:

• Tumors located near critical organs (prostate, lung, pancreas, liver, spine)
• Areas affected by organ motion (breathing or bladder/bowel filling)
• When very tight margins around the tumor are required
• For re-treatment or dose escalation (higher doses)
• In complex cases where precision is critical

When IGRT is chosen:

• For prostate cancer (to account for daily prostate movement)
• Lung tumors (to manage breathing motion)
• Abdominal or pelvic tumors
• Head and neck cancers
• When using advanced techniques like IMRT or SBRT that demand high accuracy

Comparison with other modalities:

• Without IGRT: Relies on skin marks or bony landmarks, which are less precise.
• Vs. Non-image-guided radiation: IGRT reduces the risk of missing the tumor and lowers radiation to healthy tissues.
• Often paired with IMRT/VMAT or SBRT to make them safer and more effective.

Image-Guided Radiation Therapy (IGRT) is selected whenever daily or real-time verification can improve outcomes and safety.

3. Side effects of treatment

Side effects of IGRT depend more on the main radiation technique (IMRT, SBRT, etc.) and the treatment area than on the imaging itself. The improved accuracy of IGRT often helps reduce side effects.

Early side effects (during or shortly after treatment):

• Fatigue
• Skin irritation or redness
• Site-specific symptoms, such as:
  • Urinary or bowel changes (pelvis)
  • Cough or shortness of breath (lung)
  • Difficulty swallowing (head and neck)

Late side effects (months to years later):

• Scarring or fibrosis in treated areas
• Changes in organ function (bladder, bowel, lung)
• Dry mouth or taste changes (head and neck)
• Secondary cancers (rare)

Because Image-Guided Radiation Therapy (IGRT) allows smaller safety margins, it often results in fewer or milder side effects compared to older methods. Your team will promptly monitor and manage any issues.

4. How to prepare before the treatment

Patient Segment

• Attend the simulation session and follow positioning instructions carefully
• Follow specific preparation rules (empty bladder, full bladder, or fasting) as directed for your cancer site
• Maintain consistent daily habits (same diet, bowel routine) to reduce positioning changes
• Inform the team about any discomfort or difficulty lying still
• Continue prescribed medications unless told otherwise
• Ask questions about the imaging process to reduce anxiety

Doctor / Medical Team Segment

• Perform detailed planning CT and sometimes MRI or PET scans
• Create custom immobilization devices (masks, cushions, or vacuum molds)
• Place fiducial markers (tiny gold seeds) in or near the tumor when needed
• Develop a treatment plan with safety margins
• Set up daily imaging protocols and correction thresholds
• Perform quality checks on imaging and radiation equipment

Proper preparation ensures consistent and accurate daily treatments.

5. What to expect

Before treatment

You will have a simulation visit where scans are taken in the exact treatment position. The team may give you instructions for bladder or bowel preparation. Small skin marks or tattoos are often placed for alignment.

During treatment

• You lie on the treatment table in the same position each day.
• The team takes quick images (usually 1–2 minutes) before radiation.
• They review the images and make small adjustments to your position if needed.
• Radiation is then delivered (typically 10–30 minutes depending on the technique).
• The full session usually lasts 15 to 45 minutes.

Number of sessions: IGRT is used across the full course of treatment. This can range from 3–5 sessions (with SBRT) to 20–40 sessions (with standard IMRT/VMAT), given daily over several weeks.

After treatment

You can usually go home immediately and continue normal daily activities. Some fatigue may build up over the course of treatment.

6. Expected results of the procedure

Image-Guided Radiation Therapy improves the overall effectiveness and safety of radiation treatment.

• Better tumor targeting leads to higher local control rates.
• Reduced radiation to healthy tissues often means fewer side effects.
• Allows safer delivery of higher doses when needed.
• Excellent outcomes when combined with IMRT or SBRT for prostate, lung, and other cancers.

Studies show IGRT helps achieve strong cancer control while maintaining good quality of life. Results vary depending on cancer type, stage, and the specific radiation technique used with it. (Cancer Research UK)

7. Call to Action

If you are considering radiation therapy, Image-Guided Radiation Therapy (IGRT) can make your treatment more precise and safer.

Book an appointment with a radiation oncologist to discuss whether IGRT combined with other techniques is appropriate for your condition.

For more personalized information and to review your imaging and treatment options, contact our radiation oncology team today. Expert guidance will help you choose the best approach for your care.