MDHB News

Intensity Modulated Radiation Therapy (IMRT)

Radiation therapy is continually improving with research and advancements in technology. There are variations on the way in which radiation therapy treatment can be delivered. Factors such as the type, size, shape and position of the cancer will determine the best radiation therapy treatment for each individual. Intensity modulated radiation therapy (IMRT) is one of the most advanced forms of radiation therapy. The development of IMRT has meant that, for some people:

cancer control may be improved
side effects may be reduced
tumours that previously could not be treated may now be treated
treatment may be faster

Radiaton Therapist Planning Treatment

What is IMRT?

Intensity modulated radiation therapy (IMRT) is a complex treatment technique that allows healthy tissue to be spared whilst delivering an optimal radiation dose to the tumour. This centre was the first centre in New Zealand, to provide IMRT.

The aim with all radiation therapy treatment is to deliver a dose of radiation that will be effective in killing the cancerous cells while minimising the dose received by the surrounding healthy tissue. IMRT works on the same concept but is more advanced and complex.

Radiation therapy treatment will often be given from several different angles. The treatment machine moves around the patient, stopping at specific angles to deliver the treatment beam and then moving on to the next angle. Where conventional radiation therapy uses a single beam of radiation, IMRT uses several small beams (beamlets) within a beam. A conventional beam puts out a reasonably even dose of radiation across the beam. When many beamlets make up the beam, there is greater capability to control the dose across the beam, and therefore modulate / vary the intensity across the radiation beam. IMRT allows the radiation dose to closely match the three-dimensional shape of the tumour and provides greater control in avoiding parts of the body that do not require treatment. Varying the intensity of the radiation also gives the ability to deliver larger radiation doses to concentrated areas within the tumour, making this a very precise treatment.

When is IMRT used?

IMRT is more beneficial for some areas of the body than others. IMRT may be used when the area to be treated is against, or very close to, an organ that cannot tolerate the amount of radiation that is needed to treat the cancer. IMRT is frequently used for treatment to the head and neck area where body parts such as the eyes, optic chiasm and spinal cord need to be avoided as much as possible.

Experience in the planning and delivery of IMRT

The RCTS Radiation Oncology IMRT program was established in 2003. Our team is highly experienced in the planning and delivery of IMRT. We were the first Radiation Oncology treatment centre in Australasia to be accredited by the MD Anderson accreditation programme (Texas, USA) for the delivery of Intensity Modulated treatment of head and neck cancer.

RCTS Radiation Oncology also runs a comprehensive 3D Image Guided Radiation Therapy (IGRT) program, specialising in IGRT for prostate, head and neck and lung cancer. Image guidance with conebeam imaging ensures accurate delivery of treatments.

With robust implementation of IMRT and IGRT programs, RCTS Radiation Oncology has been recognised as a world-leading facility. Siemens, the providers of the cancer treatment machines (linacs) for Palmerston North, have sent staff from other radiation therapy centres around the world to the RCTS for training to help them establish their own IMRT treatment programs.