Which one to Choose? IMRT or IGRT?

The mere mention of the word ‘cancer’ can evoke fear in individuals, and cancer presents numerous challenges that make it an exceptionally difficult disease to treat. However, thanks to advancements in medical science, victory over this formidable illness is possible through early diagnosis and timely treatment. Substantial progress is being made in cancer treatments, particularly in the field of radiation therapy.

One of the primary types of cancer treatment is radiation therapy, which can be administered alone or in conjunction with other treatments. Intensity-modulated radiation therapy (IMRT) and image-guided radiation therapy (IGRT) are two radiation techniques that have revolutionised cancer treatment and are proving to be highly advantageous for cancer patients. These methods have emerged as the preferred treatments for a wide range of prostate cancer patients. Beyond their versatility in addressing various prostate cancer conditions, IGRT/IMRT is acknowledged as a mature radiation therapy technology that is covered by nearly all insurance companies.

Although IGRT and IMRT might seem similar at first glance, they are fundamentally different, and understanding these differences is crucial. Let’s delve into both approaches to better distinguish between the two therapies.

Intensity-Modulated Radiation Therapy (IMRT)

Before the advent of IMRT, radiation therapy faced a significant limitation: it could be tailored to the general shape of a tumour, but not to its precise size and contours. Intensity-modulated radiation therapy (IMRT) represents an advanced form of conformal radiotherapy that overcomes this challenge by utilising linear accelerators to administer 3D conformal radiation.

The procedure involves creating a 3D image of the tumour, which is then used to determine its exact size and shape. Employing this computer-generated image, the high-precision radiotherapy mode employs computer-controlled linear accelerators to deliver exceptionally accurate radiation doses that conform precisely to the tumour’s dimensions, even to specific regions within the tumour. Additionally, by modulating the intensity of the radiation beam across numerous small volumes, the physician can minimise radiation exposure to healthy tissue and organs. This approach enables swift and effective tumour targeting while maximising the safety of surrounding bodily tissues and organs.

What types of cancer can be treated with IMRT?

IMRT is a type of treatment used to address various types of cancer, such as:

• Head and neck cancer
• Breast cancer
• Prostate cancer
• Brain tumour
• Gastrointestinal cancers

It is also employed in the treatment of paediatric cancers, as well as Sarcoma, Lymphoma, and Gynaecological cancers. IMRT demonstrates particular effectiveness in treating patients who have previously undergone radiation therapy. Some patients may require multiple IMRT sessions. Typically, IMRT is administered five days a week for several weeks. The duration of the treatment is determined by the type, size, and location of the cancer. Each IMRT session lasts between 10 and 30 minutes, and the procedure is painless.

Side effects of IMRT

Depending on the part of the body being treated and the number of treatments a patient undergoes, they might experience some of the following side effects:

• Skin issues, which may include heightened sensitivity, reddening, rashes, itching, irritation, swelling, blisters, peeling, or dryness.
• Soreness, redness, and swelling in and around the treated area, as well as possible numbness.
• Urinary and bladder problems.
• Tiredness, exhaustion, and general fatigue.
• Hair loss in the treatment area and surrounding vicinity.
• Sudden loss of appetite, difficulty eating, and digestive problems.

Depending on the treatment area, side effects may resurface months or years after treatment and often become permanent. Side effects that might recur after treatment include:

• Infertility
• Changes in the brain, spinal cord, lungs, kidneys, colon, and rectum.
• Radiation can lead to joint changes.
• Alterations in the oral cavity and digestive tract.

Image-Guided Radiation Therapy (IGRT)

Tumours can migrate between treatment sessions as a result of factors such as breathing activity and alterations in organ absorption. The higher doses of concentrated radiation require the physician to know precisely where the radiation is aimed. In the past, radiation oncologists used external beam radiation therapy, such as IMRT, relying on mathematically calculated locations without the ability to visualise the tumour accurately.

To address this challenge, an advanced technology has emerged: Image-Guided Radiation Therapy (IGRT). IGRT is a form of radiation therapy that utilises Cone-Beam CT images to monitor the tumour’s location, enabling a more precise targeting of the radiation dose. Apart from the advantages mentioned above for IMRT, image-guided radiation therapy empowers radiation oncologists to administer radiation more accurately, effectively, and safely compared to many other radiation techniques. IGRT is commonly used in conjunction with IMRT to deliver focused radiation to cancerous tumours.

What types of cancer can be treated with IGRT?

IGRT works by targeting tumours that are located near or on sensitive tissues and organs that move due to everyday activities such as breathing, urinating, and defecating. It is used to treat the following types of cancer:

• Spine cancer
• Prostate cancer
• Lung cancer
• Breast cancer
• Brain cancer
• Liver cancer
• Bone cancer
• Bladder cancer
• Esophageal cancer

IGRT usually involves multiple sessions. Due to the time required for acquiring and analysing images, the duration of IGRT treatment sessions may be longer compared to other radiation treatments. Patients typically undergo IGRT treatments for a couple of weeks, usually five days per week. The number of treatments needed depends on factors such as the type of cancer, as well as the size and location of the tumour. Before and during the IGRT procedure, the radiologist will employ imaging techniques such as PET, MRI, and CT scans to more accurately pinpoint the cancer’s location.

Side effects of IGRT

As less radiation penetrates the surrounding tissues and organs, the potential side effects associated with this treatment are likely to be fewer than those linked with other radiation therapies. Nevertheless, it is essential to be aware of the potential side effects of radiation therapy so that one can inform their healthcare provider if necessary. Some potential side effects include:

• Sudden loss of appetite and difficulty chewing, swallowing, and digesting food.
• Dry mouth, eyes, and throat.
• Headache, nausea, and vomiting.

In addition to these, there are additional adverse reactions that may occur during IGRT treatment:

• Patients may experience soreness, discomfort, and numbness in or around the treated area.
• If the treated area is around the face, such as the neck, light sensitivity may occur.
• Diarrhoea and bladder problems.
• Hair loss in the treated area and its surroundings.

Which one to Choose – IMRT or IGRT?

After going through all the steps of both procedures, one can decide which one is best suited for their case. In the present day, hospitals typically offer only minimal IMRT techniques, with a few exceptions for specific cases. Patients who seek to benefit from the most advanced technology can choose IGRT. There is no need to worry about not choosing IGRT, as both IMRT and IGRT are accepted according to the guidelines. Nevertheless, it is essential to consider selecting IGRT for the treatment of:

• Prostate Cancer
• Selected cases of large volume radiation
• Situations where a rapid response to cancer is expected.

IMRT is particularly beneficial for individuals who have previously undergone radiation therapy.

It is important to note that patients will be under the direct care and supervision of an experienced medical team at Apollo Hospitals, Karnataka, who will provide support throughout the procedure. Apollo’s technology and state-of-the-art equipment can be compared to those found in the world’s leading centres. The hospital offers the broadest range of technologies for personalised patient treatment, delivering exceptional healthcare.