IMRT – Intensity Modulated Radiation Therapy, Abroad

Intensity Modulated Radiation Therapy cost:
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It is one of the most advanced, automated, high precision procedures, available in external beam therapy. The biggest advantage of IMRT is that it helps protect and shield the healthy tissues and critical structures from the potentially damaging radiations. Unlike the conventional radiation therapy system which allows the field to be shaped in two dimensions, IMRT allows the field to be shaped in three dimensions (3D). This increases the precision in the management of tumors (which are thicker in some places and thinner in others).

Intensity Modulated Radiation Therapy provides radiation fields with optimized non-uniform spatial intensity distributions from different directions, to achieve the ideal dose distribution over the tumor with sparing of the nearby critical structures.

How does IMRT work?

• To begin with, a CT scan is performed on the afflicted site, in order to make an estimation of the exact contours and dimensions of the tumor, and the surrounding healthy structures. It is essential for the oncologist to understand the three dimensional shape and size of the tumor and identify the normal tissue surrounding it. Several other scanning procedures like MRI (Magnetic Resonance Imaging) or PET (Positron Emission Tomography) or insert radio-markers are done to estimate the exact location and size of the tumor. This is essential for determining the treatment plan for the patient.
• Accordingly, the dose of the radiation is decided.
• The patient is treated using a large equipment called the linear accelerator, which releases beams containing photons (something similar to X rays). These radiation beams are modulated to various levels of intensity and are conveyed from different directions using the computer controlled multi leaf collimator.
• The leaves of this multi-leaf collimator move in and out periodically, contouring the radiation beam to the shape and size of the tumor.
• The beams then target the tumor site from different angles, so as to maximize the dosage.

The sites that are most commonly treated with IMRT are: lung, spine, kidney, pancreas, liver, breast, larynx, tongue, prostate and sinus. The brain is treated with IMRT when one-session radio-surgery is inappropriate or is unavailable.

Various radiation therapies used to fight cancer:

1. The conventional method
2. IMRT
3. Stereo- tactic radiation therapy

The conventional method:

• This procedure involves the use of multiple radiation fields, choice of beam energies, and the weighting of different beams. It uses a linear accelerator to divert the beam.
• In addition, 2D blockers are used to protect the surrounding healthy tissues.
• This technique is predominantly based on trial and error. To site an example, a radiation oncologist will first and foremost plan the radiation treatment field and accordingly, calculate the required optimal dose. In case, the dosage is not acceptable, a new radiation field needs to be set up, other modifications need to be considered, and the entire procedure repeated, until the most favorable dosage and contouring is achieved. As a result, this method is a time consuming and a Herculean task.

How imrt has an edge over the conventional procedure?

1. IMRT delivers the highest radiation dosage to the target tumor (using the linear accelerator), through a 3D conformal radiation therapy. The radiation oncologist calculates the required optimal dose, and the tumor contours that are to be covered. The computer assisted mathematical optimization technique decides the optimal treatment field.
2. IMRT keeps the dose of radiation to the surrounding healthy and normal structures below the tolerance level, i.e., it limits the radiation to surrounding tissues lower than the selected threshold limit. Furthermore, the radiation oncologist can also delineate where he does not want the radiation to be deposited. Also, the need for blocks, wedges, and compensators is obviated.
3. IMRT is an individualized radiation technique, uniquely designed for each patient.
4. The number of treatment sessions is lesser than the conventional method.
5. IMRT reduces the side effects which in turn improves the quality of life of the patients.
6. The treatment delivery is also highly effective, since, there isn’t any need for different beam energies of photons, or mixed photons and electrons beams.
7. The multi-leaf collimator helps convey a relatively uniform distribution of the radiation dose over the target site.
8. IMRT assists in treating multiple targets of the same origin, at the same time. For example, in multiple brain metastases, the metastases can be managed and treated concurrently with a high dose radiation, while the other parts of the brain (healthy tissues) are avoided. This helps in diminishing treatment related toxicity to a very great extent.
9. IMRT helps treat multiple targets of different origin, at the same time. Two absolutely unrelated tumors can be treated simultaneously. Example, a pituitary adenoma and a chemodectoma can be managed at the same time.
10. Differential weighting, on both, the targeted tumor and the surrounding healthy tissue can be done. More often than not, the tumor is weighted more than the healthy tissue. However, in certain cases, such as, in an instance of brain tumor surrounding the optic chiasma, if the patient does not want to lose his eye sight (a treatment complication), then, the avoidance structure, in this case, the optic chiasma is weighted more than the tumor.
11. A sub-division of the IMRT is SMART, or simultaneous modulated accelerated radiation therapy. In this method, different targets are treated with different fraction sizes to different doses. Example, the primary target (the tumor) and the secondary target (sites of lymphatic drainage) are treated concurrently with a total dosage of 60 Gy and 50 Gy respectively. Their fraction doses would be 2.4 Gy and 2 Gy, respectively, daily. This therapy finishes in a shorter period of five weeks, hence called accelerated. Consequently, it is also, a cost effective procedure. But most importantly, this technique has a huge radio-biological advantage. It prevents the accelerated re-population of the clonogens, thereby, prevents a therapy failure and greatly improves prognosis.

Stereotactic radiation therapy:

• This therapy is an advanced form of the external beam radiation therapy, which provides greater precision and accuracy compared to the IMRT.
• It incorporates the use of focused radiation beams that target a well contoured tumor using extremely detailed scans.
• It can be used with great efficacy for all stages of malignancies (Stage I to Stage IV).
• The greatest advantage of Stereo-tactic radiation therapy is that unlike the conventional radiotherapy, which requires almost six to eleven weeks of treatment, it requires lesser and shorter sessions.

Hospitals, however, refer to this form of therapy depending up on the equipment manufacturer instead of using the term Stereo-tactic Radiation Therapy. The various brands include Cyber Knife, X-Knife, Gamma Knife, Novalis, and TomoTherapy. There are considerable differences between the various brands and also differences regarding, what is best managed by a particular equipment.

Cyber Knife: Primarily used for radiation therapy, it is effective in the management of tumors in the brain, vertebral column and a few other parts of the body. However it can be used to manage smaller tumor lesions with a size of about 3 to 4 centimeters. Cyber knife has the advantage of, having the constant ability to adapt to the displacement of the tumor due to movement of the surrounding organs. Also the treatment can be split into different sessions, if required for preserving the surrounding healthy tissue. However, for surgical management Cyber knife requires tumor markers inside the tumors to help irradiation. More over, Cyber knife doesn’t provide conventional doses but extremely high doses of radiations making it slightly less preferred. More aboutCyber Knife cancer treatment abroad.

Gamma Knife: Also used primarily for radiation therapy, its effectiveness is limited to the tumors of the brain. In addition, it requires a rigid frame to hold the body, while irradiation, to ensure accuracy and precision. It is also used to manage smaller tumor lesions and is not chosen for larger tumors

Tomo-therapy: Though it is not primarily used for radiation therapy, it can perform radio surgery. It can be used for the treatment of tumors anywhere in the body and can be used to manage tumors of larger sizes as well. It also has the advantages of the Cyber knife procedure like ability to adapt to the continual displacement of the tumor and splitting the treatment into different sessions to protect the surrounding healthy tissue.

Limitations of the intensity modulated radiation therapy:

1. Although the IMRT is superior to the conventional method in precision, it is not as accurate and specific as the Stereo tactic Radiation Therapy.
2. IMRT works well in the treatment of large tumors, about 4 centimeters and bigger, not for smaller tumors.
3. This therapy, is a relatively, newer approach. Hence, the tools, the equipment and the techniques are all in a preliminary stage of development. There are a few stumbling blocks which hamper its clinical use.

Conclusion:

Theoretical data and clinical studies have demonstrated the enormous benefits of the Intensity Modulated Radiation Therapy. It has special value in the reduction of treatment related toxicity. IMRT has resulted in the introduction of the novel concepts of inverse planning in contrast to the trial and error approach which was used by conventional radiotherapy. This therapy is of absolute significance and immense importance in the management of childhood cancers. Most of the symptoms are milder than conventional radiation therapy and the procedure in practically painless.

IMRT, is radio-biologically highly beneficial, and also offers the patients greater convenience. The upshot is better tumor control, lesser harm to healthy tissues, and neighboring structures, and a better quality of life for the patients.

Though IMRT is approved by the United States Food and Drug Administration, the availability of the technology across hospitals is very limited. However, most experts are of the opinion that the technology will be widely available across the globe in the next few years. This therapy holds great promise in radiation oncology.

Resources:

Cyberknife in India
Cyberknife at Anadolu Medical Center, Turkey
Chemotherapy Treatment (CHOP) Abroad
RCHOP Chemotherapy
Cyberknife Cancer Radiotherapy Overseas Radical Gastrectomy Surgery Abroad
Mastectomy Surgery Abroad
Total Pelvic Exenteration Abroad
Cervical Cancer Treatment Abroad
Chemotherapy Treatment Abroad

Medical Tourism Corporation facilitates Intensity Modulated Radiation Therapy(IMRT) in Europe (Turkey) and other overseas world-class oncology treatment destinations.