The Chennai-based Dr Kamakshi Memorial Hospital would shortly install a state-of-the art Intensity Modulated Radio Therapy (IGRT) unit for the benefit of cancer community to make their Radiation treatment a cake-walk.

"The IGRT has the potential to achieve both unparalleled tumour control and normal tissue sparing," said Dr V. Srinivasan, the Consultant Clinical Oncologist of the Hospital. "The use of conventional radiotherapy is not possible to achieve dose intensification in a variety of cancers because of the normal tissue complications."

The concept of 3D CRT (3-D Conformal Radio Therapy) and IMRT (Intensity Modulated Radio Therapy) was introduced as dose intensification is essential for improving the results with radiotherapy.

This has resulted in sparing of the normal critical structures and the complications have come down with the higher radiation dose. However, due to the organ motion during the treatment (inter-fraction) and in between two fractions (intra-fraction), clinicians tend to take a large margin around the tumour in order to avoid a geographic miss due to this motion. This gave birth to Image Guided Radiation Therapy (IGRT).

If IMRT improves the radiation delivery precision, IGRT improves the radiation delivery accuracy. Hence; IGRT is by far the most advanced form of radiotherapy today, he explained.

4D imaging is now part of IGRT. The crucial element of the gating system is that it is a non invasive form of gating that works via room mounted cameras and a detector device that is placed on patients' body. It records the patient's breathing pattern during the scan. An analysis of the data with regard to target motion during the different phases of the breathing cycle by the oncologist determines the minimum movement and leads to therapeutic window defined by a lower and an upper threshold.

"By gating the treatment beam we are able to deliver a more precise dose to the tumour and avoid more of surrounding healthy tissues," Dr Srinivasan told Pharmabiz.

This provides a direct comparison of the planned dose distributions based on the planning CT, to the actual patient anatomy, moments before dose delivery.

Verification of target and normal tissue location is crucial for 3D-conformal radiation therapy and IMRT because higher positioning uncertainty leads to larger planning target volume margin for tumour coverage, which in turn increases normal tissue complications and hinders dose escalation efforts.

While briefing the process, Dr Srinivasan said, "CT Scans are the initial part of the planning process. Present technology has the capacity to treat irregularly shaped targets with highly conformal process. Because the dose distributions achieved with IMRT have very sharp gradients and the Planning Target Volume safety margins are becoming smaller, it is important to identify and understand the consequences of motion during treatment and between treatments across the entire planned prescription of radiation therapy. Frequent imaging in the treatment room during patient set up with therapy delivery decisions being based on the images acquired, is known as Image Guided Radiation Therapy or IGRT."

The department of Radiation Oncology of Kamakshi Hospital has one of the most active Brach therapy programs in the world. In addition to intra-cavitary and intraluminal treatments, the clinic has developed many novel approaches to brachytherapy also.