Advance Radiation Therapy IGRT, IMRT, 3D-CRT – Introduction

Radiation therapy is a highly sought-after treatment module for cancer these days. Radiologists at the best hospitals for radiation therapy in India use beams of intense energy for killing cancer cells. They are globally renowned for the skillful and efficient use of the latest technology used for advanced radiation therapy. Radiation therapy is also used for treatment of some non-cancerous or benign tumors.

The ways in which radiotherapy is delivered has changed remarkably over the last few decades. The best radiologists for advanced radiation therapy in India have moved from using conventional radiotherapy with simple rectangular treatment fields to using progressively conformal radiotherapy techniques.

These changes in the way radiation therapy is delivered,are happening because of trials to improve the delivered dose to a patient’s tumour bearing tissues, and thus reduce irradiation of Organs At Risk (OARs). This drastically improves the therapeutic ratio of the radiation treatment. Radiation works by causing small breaks in the DNA inside cancer cells. These breaks stop cancer cells from growing further and dividing,thus causing them to die.

How can Radiation Therapy be used in Cancer Patients?

Your oncologist may advise radiation therapy as an option for your cancer treatment and for various reasons like –

• It can be the primary treatment module for your cancer.
• It can also be done before surgery in order to shrink the cancerous tumor (also known as neoadjuvant therapy).
• Radiotherapy can be advised after surgical removal of tumor in order to stop the growth of cancer cells that are left out (also known as adjuvant therapy)
• Along with other treatments like chemotherapy, forkilling remaining cancer cells
• In advanced stage cancers in order to relieve symptoms caused by the cancer

Types of Radiation Therapy

There are 2 main types of radiation therapy that doctors use for treating cancers –

• External Beam Radiation Therapy This is the most commonly used type of radiation therapy. The term External is self-explanatory. It means that the energy beams used during therapy come from a machine which is placed outside of your body. Your radiologist will aim the beams in a way that they penetrate your body to reach the cancer cells.
• Internal Beam Radiation Therapy The 2nd main type of radiation therapy is Internal Beam Radiation Therapy, also referred to as Brachytherapy. During this therapy, your radiologist who will be amongst the leading doctors for radiation therapy in India, will place an implant consisting of radiation in or near the cancer site of your body. The implants come in various shapes like – tube, seeds, capsule, wire, pellets, etc.

Types of External Beam Radiotherapy –

External Therapy can be further divided into below categories:

IGRT (Image-Guided Radiation Therapy)

• IGRT can be used during radiation therapy for any part of a patient’s body. However, doctors use it most commonly for those areas of the body that are prone to movement, such as your lungs or prostate, and also those positioned close to sensitive organs, like cancers of the head and neck area.
• By making use of techniques like IGRT, imaging experts are enhancing the cancer-destroying abilities of radiation therapy while simultaneously minimizing its effect on otherwise healthy and normal tissues and organs and also the side effects of this treatment itself.
• Machines that deliver radiation during IGRT, such as a linear accelerator or cyclotron, are equipped with special imaging technology that allows your doctor to image the tumor instantly before or even during the time when radiation is being delivered, while you are positioned on the treatment table.
• Using specific computer software, these images are then compared to the reference images that were taken during simulation.Simulation is use of a radiographic system or computer for planning your radiation therapy. Any desired adjustments will be made to your position and the radiation beams in order to target radiation more precisely at the tumor and hence avoid healthy nearby tissues.

IMRT(Intensity-Modulated Radiation Therapy)

• IMRT is mainly useful for tumors that are located nearby healthy organs which are sensitive to radiation therapy. This therapy can be an effective treatment for various types of cancers.
• During this therapy, the shielding which is made into the treatment machine moves while the radiation beam remains turned on. This lets the amount of radiation dose getting delivered from the treatment machine to be deliberately varied.
• By using several beams coming from various directions the radiation dose can be formed even more accurately in order to follow the shape of the tumor as closely as possible.
• The advantage of IMRT is that the high-dose area remains restricted to the tumor volume more precisely and fewer sections of the surrounding area receive high doses. This helps keep the surrounding organs more protected and the side effects of treatment can be significantly reduced.

3-D CRT

• 3D Conformal Radiation Therapy is that type of cancer treatment which shapes the radiation beams precisely to match the shape of the tumor.
• Earlier, the radiation beams could only match the height and width of the tumor, thus exposing nearby healthy tissue to radiation. The recent advances in imaging technology have made it possible now to exactly locate and treat the tumor more accurately.
• This therapy uses the targeting information for focusing exactly on the tumor, while avoiding the normal surrounding tissues.This precise targeting creates the possibility to use higher levels of radiation during treatment of cancer. More radiation is all the more effective for shrinking and destroying tumors.

Conclusion

The last two decades have seen noteworthy advancements with regards to technological progress in radiation delivery which has become much more precise using above methods. The results have significantly improved in sparing of healthy tissues and, hence, the possibility to improve cancer outcomes by the use of dose-escalation and altered fractionation.

Last, but not least, no advances in radiotherapy planning and delivery could have possibly happened without the presence of faster and highly powerful computer systems which enable the efficient running of the advanced software needed for planning and delivery.