Radiation Therapy - IGRTBook an Appointment
One of the more exciting developments over the past decade at the Urology Centers of Alabama has been the addition of Radiotherapy to the treatment options offered to patients with prostate cancer and other malignancies.ﾠ The construction of the Radiation Oncology department - The Van Scott Cancer Center – at the Homewood office in 2007 was the culmination of much effort on the part of the Urologists and Dr. Brian Larson, a Radiation Oncologist. ﾠDr Larson has practiced in Birmingham since 1991, at BMC Montclair, Trinity Medical Center, Grandview Medical Center, and BMC Princeton, as well as Medical Center East. By bringing state of the art equipment, including the latest in computer planning and treatment techniques to the facility, we are able to provide treatment for prostate cancer that is second to none. Radiation treatment for prostate cancer is one of the major treatment options available for patients.ﾠ The advantages of radiation include avoidance of major surgery, including the required hospitalization, anesthesia, and post-operative recovery period of surgery.ﾠﾠ Radiation treatment for prostate cancer has been used successfully for decades, but recent advances in technology have allowed an increase in the safe radiation dose achievable to the prostate, while minimizing the radiation effects on the normal tissues, such as the bladder, rectum, and pelvic bones.ﾠ This allows an improvement in cancer control, while reducing the side effects of the radiation treatments.
Who will be involved in this procedure?
Our facility relies on a specially trained team for IMRT (Image Guided Radiation Therapy) delivery. This team includes the radiation oncologist, medical radiation physicist, medical dosimetrist, radiation therapists, and radiation therapy nurse.
The radiation oncologist, a specially trained physician who heads the treatment team, sets an individualized course of treatment with the help of the radiation physicist, who ensures the linear accelerator delivers the precise radiation dose and that computerized dose calculations are accurate. A Board Certified Medical Dosimetrist calculates the IMRT exposures and beam configurations necessary to deliver the dose prescribed by the radiation oncologist. Highly trained radiation therapists position the patient on the treatment table and operate the machine. The radiation therapy nurse provides the patient with information about the treatment and possible adverse reactions.
What equipment is used?
A linear accelerator generates the photons, or x-rays, used in IMRT. A Halcyon linear accelerator, the latest accelerator design, was installed in early 2018, the first of its kind in the Southeast US and the 16th installed in the US. The Halcyon linear accelerator was designed to simplify and enhance the delivery of radiation treatments, offering unmatched accuracy, speed, and patient convenience. The patient lies on the treatment table, while the linear accelerator delivers beams of radiation to the tumor from various directions over several minutes. The intensity of each beam's radiation dose is dynamically varied according to treatment plan.
The Halcyon linear accelerator has an enclosed gantry design, different from most other linear accelerators, which allows faster rotational speeds and increased patient safety. The Halcyon utilizes a patient centered approach, where the daily treatment has fewer steps, streamlining the treatment process. The Multileaf Collimator, which shapes the radiation beam during the treatment, has a new stacked and staggered design allowing for more conformal plans. This gives the planning team (physician, physicist, and dosimetrist) more options to devise the optimal plan to deliver the highest possible radiation dose to the cancer while minimizing the nearby normal tissues.
How does IMRT work?
Radiotherapy at UCA represents an evolution of radiation technology, from standard to 3D to IMRT, to the newest innovation, VMAT (Volumetric Modulated Arc Therapy). IMRT has evolved even further and is now more efficiently delivered via VMAT. VMAT is the delivery of radiation while the linear accelerator moves in an arc around the patient and continuously adjusts the intensity of the radiation delivery during the rotation of the machine. This evolution in technology allows the delivery of high radiation doses with improved precision, creating the possibility of better cure rates with fewer side effects. Studies consistently show that the higher the radiation dose is, the better the chance of curing prostate cancer.
In the past, standard radiation involved starting with plain x-rays of the pelvis. Lines were hand drawn on each x-ray film to make "radiation fields". Lead blocks were then created which matched the hand drawings. Usually, four radiation beams were used, entering the body from the front, back, and both sides.
An improvement over standard radiation was 3D-conformal radiation, which utilized CT scans in the planning process. The prostate, rectum, and bladder were circled on a computer screen showing the CT images. Any number of radiation beams could be used, and the computer shaped the beams to precisely match the contour of the prostate. Beams could be angled so that they missed most of the bladder and rectum, but passed through the prostate.
IMRT is even more computer intensive than 3D. Every beam is broken down into tiny "beamlets", and each beamlet can be given a different dose. This results in beams with different intensities across their surfaces. Multiple beams are used for each treatment. Although the beams are all different in shape and intensity profiles, once they all converge on the prostate you are left with a high dose covering the prostate gland, and a lower dose hitting the normal tissues, such as rectum and bladder.
VMAT is the newest, more efficiently delivered evolution of IMRT. This has enabled highly complex IMRT treatments to become safer and more precise. Some of the advantages of VMAT include highly conformal dose distributions with greater tumor coverage and less radiation dose to normal organ and tissues. In addition, VMAT on the Halcyon linear accelerator has greatly reduced treatment times so the patient requires less time on the treatment table each day.
IGRT - Image Guided Radiation Therapy
IGRT (Image Guided Radiation Therapy) has also been used at UCA along with IMRT to optimize the accuracy and precision of the radiation therapy. IGRT is an advanced technology that allows radiation to be delivered to tumors with more precision than was traditionally possible. One of the challenges encountered when radiation is delivered to a tumor is that the tumor can move based on the patient's day to day position on the treatment table, as well as internal organ motion. IGRT uses imaging technology with on-board imaging (OBI), the ability to obtain X-ray images or CT images (cone beam CT) with the linear accelerator prior to and during the radiation treatments. The OBI uses radiation beams to obtain the x-ray images and allow the radiation oncologist to visualize a patient's anatomy with organs such as the prostate, bladder and rectum, or implanted fiducial markers, with each radiation treatment. The patient’s position can be adjusted with millimeter accuracy using IGRT, assuring that the radiation treatment is delivered to the planned target by adjusting for internal organ movement. IGRT sets the stage for allowing the radiation oncologist to safely increase the radiation dose to tumors while minimizing side effects. IGRT is performed daily during the radiation treatment the radiation oncology facility
The Urology Centers of Alabama physicians use a special technique to insert fiducial markers into the prostate for Image Guided Radiation Therapy. IGRT is performed daily during the radiation treatment the radiation oncology facility.
This added accuracy allows radiation to be delivered to a tumor based on its location in the body at the precise moment of treatment. Thus IGRT allows the precise delivery of radiation to tumors in real time while allowing normal tissues to receive minimal radiation.
Normal tissue sparing
The primary goal of a radiation therapy course is the eradication of the cancer with the highest safe radiation dose. Another extremely important goal is to minimize normal organ exposure to the radiation to avoid all possible injury to the bladder and rectum, in the case of prostate cancer treatment. This is accomplished by emphasizing the importance of a full bladder during the radiation treatment daily to distend the majority of the bladder away from the prostate. The rectum is spared with several techniques. A rectal balloon is inserted daily in many patients to push the posterior rectum away from the prostate, reducing the dose to the majority of the rectum. Another option for some men with prostate cancer for sparing of the rectum is called the SpaceOAR, a hydrogel material inserted with a needle at the time of placement of the implanted fiducial markers. The Space OAR creates a space between the prostate and rectum to minimize the radiation dose to the rectum, and then the gel dissolves over several months following the radiation treatments.
The commitment of the physicians of the Urology Centers of Alabama to provide the best radiation treatment available is shown clearly by our tremendous staff and their insistence that the Van Scott Cancer Center have the latest, most advanced equipment available anywhere to assure patients and their families that we are able to offer state-of-the-art treatment in Birmingham comparable to treatment centers anywhere in the world.