Streaming video of "Smart Beam" IMRT:

Three-Dimensional Conformal Radiation Therapy
(3-D CRT)

Over the past decade, there have been tremendous advancements in the technology of computerized treatment planning and delivery systems that allow radiation oncologists to implement techniques that will allow for higher doses of cancer killing radiation to be delivered to tumors, while limiting the dose of potentially damaging radiation to the surrounding normal structures. The development of three-dimensional conformal radiation therapy (3D CRT) was a major advance in this technology. Specifically, 3-D CRT enables radiation oncologists to shape treatment fields more accurately than had been possible in the past using standard two-dimensional (2-D) treatment planning; thereby, allowing for higher doses of radiation to be delivered to the desired target (the tumor). 3D CRT is now widely, but not universally used at many radiation therapy clinics.

"Smart Beam"™ Intensity-Modulated
Radiation Therapy (IMRT)

Currently, the most advanced form of 3-D CRT, Intensity Modulated Radiation Therapy (IMRT), represents "cutting edge technology", which is yet a huge step beyond 3-D CRT. IMRT utilizes an advanced computer programming system that divides each of the radiation treatment beams into multiple rays, or "beamlets", and assigns different beam intensities or beam strength to the individual rays. Theoretically, IMRT technology should allow for the ability to deliver precisely targeted radiation to irregularly shaped tumors, and allow for improvement in the shielding or limiting the exposure of surrounding normal tissues from undesirably high levels of radiation. Undesirable side effects, therefore, should be reduced.

Does IMRT Improve Tumor Control and Cure Rate?

Multiple studies have demonstrated that the limitation of the ability to deliver higher doses of radiation to tumors can result in a significant increase in failure to prevent the growth of such tumors and, therefore, limit the chance of cure. Research into this situation has suggested that there are two primary reasons for limiting the possibility of curative radiation therapy.

1) Imperfect targeting of the tumor, and
2) Insufficient radiation dose.

Although radiation treatment has the ability to, and does, cure many patients of their cancer, some of the more aggressive and resistant cancers require more accurate targeting of the radiation beam and/or higher doses of radiation in order to be eradicated. In addition, the use of specific custom fabricated immobilization devices help to accurately position the patient and limit the amount of undesirable movement thereby improving the ability to "target the tumor". This improves the accuracy of the directing of the radiation beam, and increases the chances of delivering the highest possible safe radiation dose to the cancer area and provide a greater likelihood of cure with radiation therapy. Not all patients, however, need IMRT to treat their cancer.
Accuracy

Improvement in targeting includes the use of treatment planning CT scans (computerized axial tomography [CAT]) or treatment planning MRI scans (magnetic resonance image). These special imaging procedures are conducted with the patient placed in the identical position that he or she will be placed for the actual delivery of the radiation treatment. Although some facilities have CT scanners "on site" in the radiation therapy department, these scanners may have limited resolution and frequently do not produce the highest quality CT image, and thereby, limit the physician's ability to accurately identify the tumor boarders. Typically, most sophisticated and highest resolution CT scanners are located at diagnostic radiology centers. Carolina Radiation Medicine in cooperation with a local diagnostic radiology center in Greenville, is able to utilize the highest technology CT scanners available today for such treatment planning CT scans. The detailed information obtained from these superior quality CT images is then downloaded into the three-dimensional (IMRT) treatment planning computer system at the Carolina Radiation Medicine Cancer Treatment Center, where all of the treatment planning is performed by the physicist, dosimetrist, and radiation oncologist.

Not All MLC’s Are The Same

The MLC (Multi-Leaf Collimator) in use at the CRM Cancer Treatment Center on the Varian 2100 C/D Linear Accelerator contains 120 leaves (the Millennium 120 MLC). The small (5.0 mm) size of the central leaves of this MLC provides for the finest tuning and most accurate shaping of the radiation beam that is currently available on any linear accelerator in use in this area.

Older model MLCs contain as few as 52 or 80 leaves, and therefore, cannot provide the accuracy, nor the complexity, of beam shaping as the Millennium MLC, on the Varian linear accelerator. In addition, the Varian MLC and the associated computerized operating system is the only linear accelerator MLC available in the world that is capable of producing "dynamic MLC treatments". With dynamic MLC, or “Sliding Window”, all moveable parts of the accelerator, including the gantry and collimator can simultaneously be set into motion. This occurs while the MLC leaves move to provide for the ability to shape the treatment beam constantly from multiple directions, without the need to interrupt the radiation treatment. The need to move the treatment gantry and treatment couch on which the patient lies to specific positions before engaging the radiation beam is called "point and shoot", and requires some additional treatment time as a result. Dynamic MLC can be accomplished with the patient lying in the treatment position for a shorter period of time. Not all IMRT treatment plans, however, are best provided by the use of the dynamic MLC.

Why It Takes More Than A “Fancy Car”

The ability to provide accurate and safe IMRT treatment depends on the skills and experience of all the staff including the clinician (radiation oncologist), medical physicist, dosimetrist, and radiation therapists. All radiation oncologists, physicists and radiation therapists at the CRM CTC are board certified and have many years of experience in the specialty of radiation therapy. The utilization of sophisticated treatment planning systems, such as the MDS-Nordion Helax TMS-IMRT computer system, the IMPAC Multi-Access "record and verify system", (which double checks all treatment setup data), and the use of high quality imaging studies (treatment planning CT scans and MRI scans), ultimately results in the CRM staffs' ability to provide some of the most technologically advanced methods of radiation cancer treatment available today.

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Streaming video of "Smart Beam" IMRT:

Three-Dimensional Conformal Radiation Therapy (3-D CRT)

Three-Dimensional Conformal Radiation Therapy
(3-D CRT)