A breakthrough technology for delivering image-guided radiotherapy is now available in Houston at Houston Metro Urology Diagnostic and Cancer Treatment Center offering new hope to people who are battling cancer.

Houston Metro Urology recently installed a Clinac iX™ medical linear accelerator from Varian Medical Systems, for treating cancer with Dynamic Targeting™ image-guided radiotherapy (IGRT). This new robotic and automated technology combines a state-of-the-art treatment machine with sophisticated digital imaging, tracking and monitoring tools, enabling doctors to deliver the most accurate treatments possible, even when treating tumors that move as the patient breathes.

The new system at Houston Metro Urology incorporates a high-quality imaging device that enables clinicians to position patients very precisely and to deliver the radiation dose directly to a targeted area with submillimeter accuracy, guided by three-dimensional images of the patient’s anatomy.  The system’s versatility makes it appropriate for treating a wide range of abnormalities, from small metastases to larger tumors, even in cases where the tumor is close to critical structures like the spinal cord or the optic nerve.  A “respiratory gating” tool compensates for normal respiratory motion during treatment.  Taken together, these tools deliver extremely precise treatments with the potential for better outcomes and fewer side effects. 

The Clinac iX, with its On-Board Imager™ device, is visually compelling.  Housed in a treatment vault visible through glass windows or via closed-circuit television, the machine stands approximately nine feet tall and rotates 360 degrees around the patient to deliver radiation beams from almost any angle.  The On-Board imager is attached to the machine on a pair of robotic arms that extend out on either side of the patient to generate anatomical images that will guide the treatment.  Sophisticated image-matching software shows patient anatomy on computer monitors in a futuristic control console outside the treatment room.

SmartBeam IMRT involves varying (or modulating) the intensity of the radiation (in this case, X-rays), being used as therapy for cancer.  It is a new form of radiation therapy that uses computer-generated images to plan and then deliver more tightly focused radiation beams to cancerous tumors than is possible with conventional radiotherapy. With this capability, clinicians can deliver a precise radiation dose that conforms to the shape of the tumor, while significantly reducing the amount of radiation to surrounding healthy tissues. Consequently, the technique can increase the rate of tumor control while significantly reducing adverse side effects.

Consultation
The IMRT treatment process generally consists of several steps, including consultation, positioning, imaging, treatment planning, plan verification, and treatment delivery.  A dedicated team of medical professionals will guide you and work with you every step of the way.

The first step is to meet with your radiation oncologist, who will review your medical history pathology reports, conduct a physical examination and set an appointment for you to begin the positioning and imaging process.

Treatment Preparation
Most cases require a treatment preparation session.  Special molded devices that help the patient maintain the same position every day are developed at this point.  Colored, semi-permanent ink may be used to mark the patient’s skin, to assist in positioning the patient for treatment by aligning the radiation equipment with the targeted area.  A special CT scan in the treatment position is sometimes taken, for use as a reference image later on in the process.  The treatment preparation session might take from thirty minutes to an hour and the CT scan might take an additional 15-30 minutes.

Following the CT scan, the radiotherapy treatment planning process usually takes several days.  When the plan is complete, the patient is given an appointment to begin radiation treatments.

Treatment Planning
Using the information gathered in positioning and imaging, the radiation oncologist, radiation physicist, and dosimetrist (a person specially trained to calculate and plan radiation doses) work together to design the best IMRT treatment plan for your situation.  As part of the treatment planning, your medical team conducts extensive quality assurance testing with the treatment equipment to be sure that your planned treatment can be accurately and easily carried out.

The first IGRT treatment session is sometimes longer than subsequent ones so that additional X-ray films and checks can be done.  A typical IMRT treatment session lasts about 15 minutes.

In the treatment room, the radiation therapist uses the marks on the patient’s skin to locate the treatment area. The patient is positioned on a treatment table. Sometimes, special molded devices are used to help with rough positioning.

The radiation therapist leaves the treatment room and remotely controls a digital On-Board Imager™ device to fine-tune the patient’s position and move the treatment couch into final position.  The On-Board Imager rotates around the patient to take digital images of the targeted area.  Usually two or more images are taken from different angles.  A complete rotation of the machine may be used to generate a three-dimensional image.  These images are then used to guide the final adjustments of the treatment couch.

Although the patient is alone in the treatment room, he or she can be seen on a television screen or through a window in the control room.  The therapist can talk with the patient through an intercom.  Patients do not see or hear the radiation and usually do not feel anything.

Treatment Delivery

Radiation therapy usually is given five days a week for six or seven weeks. When radiation is used for palliative care, the course of treatment lasts for two to three weeks. For each radiation therapy session, the patient is in the treatment room for about 15 to 30 minutes.  These types of schedules, which use small amounts of daily radiation rather than a few large doses, help protect normal body tissues in the treatment area. Weekend rest breaks allow normal cells to recover. The total dose of radiation and the number of treatments a patient needs depend on the size and location of the cancer, the type of tumor, the patient’s general health and other factors.

The daily treatment sessions usually last about fifteen to thirty minutes.  Most of this time is used by the radiation therapist to ensure accurate positioning of your treatment area.  You may notice laser lights in the room; these help the therapist make sure that you are level and straight on the treatment table.

Dose delivery itself may take only a few minutes.  The treatment radiation given by the linear accelerator is invisible and you will not feel it, just as you do not feel an X-ray.  The accelerator emits a buzz as it produces the radiation beams.  You may also hear the quiet, high-pitched sound of the MLC and see the leaves move.  It is important to lie as still as possible during this time, so that the radiation dose is delivered to the exact same treatment area each time.

The accelerator will move around you to the first treatment angle specified in your treatment plan, administer radiation, then move to the next specified angle to administer radiation.  The number of angles depends upon your treatment. 

When your course of treatment is completed, you will have a series of follow-up visits in which your doctor will monitor your condition and the effects of the treatment.  Your doctor may request blood tests, X-rays, and/or scans at these appointments.  Discuss with your doctor how to stay healthy after treatment.  Ask about nutrition, exercise, and environmental changes that could help you maintain a healthy lifestyle.  Equally as important, find out about support groups for cancer patients and survivors, so that you can connect with others who have had similar experiences.