What is radiation therapy? Radiation therapy, or radiotherapy, uses ionizing radiation produced by a linear accelerator (linac) to kill cancer cells and shrink tumors. The radiation passes through the body and delivers dose to the affected area while minimizing dose to the skin and tissue it passes through.
Although the radiation affects both cancer and normal cells, it has a greater effect on the cancer cells, damaging their genetic material and making it impossible for these cells to continue to grow and divide. Treatment aimed at cure will give the highest possible dose of radiation to the cancer area (within safe limits) to attempt to kill all the cancer cells. Sometimes smaller
doses are used, where the aim is to reduce the size of a tumor and/or relieve symptoms.
Electrons are used to treat skin cancers and other superficial lesions, as they are absorbed by the first few centimeters of skin, leaving very little dose to pass into the body. Radiation therapy is used to both cure disease and alleviate the symptoms of cancer. There also are several non-malignant conditions treated using radiation therapy.
What happens during radiation therapy?
Here are the steps you’ll go through at 1st Line Oncology
Visit with the Radiation Oncologist
The radiation oncologist may ask for diagnostic procedures to be undertaken, either at 1st Line Oncology or at a general hospital. These can include X-rays, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET) scans, biopsies and blood tests. Once the nature of the disease has been established, a treatment regime will be planned and prescribed.
Imaging
MRI, CT or PET scanning is required to determine the exact size, shape and position of the area to be treated within the body, known as the treatment site. These images are then used to plan the patients’ treatment.
Treatment Planning
Once your images have been taken, your physician develops a treatment plan. The treatment plan is created using treatment planning software, which calculates the position, dose and frequency of the treatment. Before treatment commences the treatment may be simulated i.e., performed on a non-treating machine, to ensure the correct treatment will be delivered later.
Treatment
The patient usually receives the same treatment each day for a course of treatment, which can last up to six weeks. Treatment is monitored regularly and may be adjusted if the patient suffers from adverse side effects or loses weight.
To receive the radiation therapy, you will lie on a couch under the machine, and be asked to remain still during the actual treatment. The treatment is completely painless. Radiation cannot be seen or felt while it is being given.
Verification
During treatment a process of verification takes place. By using iViewGTTM on a digital linear accelerator or XVI imaging on Elekta Synergy®, images are taken of the treatment site. These images are used to verify both the patient position and the accuracy of the treatment beam.
Follow-up
When the treatment is completed, the patient attends follow-up clinics for up to five years. These are held to assist the patient in managing any post treatment side effects and to monitor the disease regression or progression. Initially the patient attends the Radiotherapy Center. Annual follow-ups may then be conducted at a hospital closer to the patient.
Radiation Therapy with a Linear Accelerator
The linear accelerator produces a radiation beam of either electrons or high energy X-rays. The beam is shaped to match the tumor shape and the patient is positioned to ensure that the beam is directed at the tumor.
In the majority of cases, radiation therapy is given as fractionated treatment, meaning that patients receive a daily dose of radiation five days a week for six to seven weeks. At each daily treatment, the radiation beam from the head of the linear accelerator is rotated around the patient at different angles so that the entire tumor receives an optimal radiation dose.
The geometry and intensity of the radiation field is adjusted to the tumor’s size and shape and also to the type of cancer that is treated. The treatment beam is shaped with a multileaf collimator (MLC) that functions much like the aperture on a camera.
IMRT Process
A key ongoing development in radiation therapy is intensity modulated radiation therapy (IMRT). This is a further development from conformal radiation therapy, a three-dimensional technique using multiple fixed beams of radiation or sequential multiple arc rotational beams to limit the dose to critical organs and healthy tissue. With the IMRT technique, the beam intensity is also varied (modulated) across the treatment field. Rather than being treated with a single, large uniform beam, the patient is treated with many very small beams; each of which can have a different intensity.
1st Line Oncology has implemented the Elekta Precise Treatment SystemTM to ensure that the performance parameters for a wide range of radiation therapy techniques and advanced applications, such as IMRT, are easily achieved. The precision of beam delivery, combined with the accuracy of patient positioning, provides speed, accuracy and high resolution. Elekta Precise Treatment SystemTM is a robust and reliable system designed for high intensity day-to-day clinical use.
IGRT Process
Today’s advanced methods in radiation therapy make it possible to deliver conformal and intensity modulated radiation fields. This in turn, makes it increasingly important to address the uncertainties arising from the motion of internal organs and daily patient set-up. With patients first imaged at one time and place, then moved and treated at a different time and place, the ability to achieve highly accurate dosage delivery has until recently been limited.
1st Line Oncology’s Image guided radiation therapy, or IGRT, now allows integration of high-resolution imaging on the linear accelerator that allows clinicians to both image and treat patients, at the same time, in the same location. The result is unmatched clinical confidence, enabling more aggressive treatment of tumors while minimizing damage to surrounding healthy tissue.
For patients, use of IGRT will mean:
Higher, more effective doses of radiation are delivered safely
Tumors that were previously untreatable, because of their proximity to organs or the spinal cord, now receive treatment
In some cases, overall treatment time can be shortened
Radiation side effects are often reduced, improving quality of life
By directly addressing the challenges of organ motion and set-up errors, 1st Line Oncology revolutionizes the way radiation therapy is implemented.
Stereotactic Radiation Therapy / Stereotactic Radiosurgery (*RT/SRS) Process
To expand the use of stereotactic radiation treatment, either in one single fraction through stereotactic radiosurgery (SRS) or as multiple-fraction stereotactic radiation therapy (SRT), demands greater accuracy in targeting and limitation of organ motion. Localization and immobilization devices, together with image guidance systems, play a key role. Once the target has been accurately localized the delivery of the radiation must be highly precise. Stereotactic radiation therapy therefore integrates high-resolution beam-shaping, stereotactic target localization, organ motion limitation and a unique image guided registration system based on 3D volumetric imaging, integrated and optimized for stereotactic radiation therapy.
1st Line Oncology’s advanced digital linear accelerator, integrates a 3D imaging system that enables us to obtain “cone beam CT” images of patients just before treatment. This capability allows us to visualize tumors at the point of treatment and more precisely target them with radiation beams. The advanced digital linear accelerator also includes a precise, high-resolution beam modulator, a device that conforms the radiation beam to the tumor – matching the beam’s shape to the tumor’s shape. Elekta’s Stereotactic Body Frame® enables the coordinates of a target to be localized during planning and treatment. More accurate localization enables conformal treatments such as IMRT to be performed with greater precision and provides the necessary conditions for dose escalation and hypofractionation. The linear accelerator’s Active Breathing CorrdinatorTM addresses the localization challenges associated with breathing motion and provides a stable and reproducible target position. It has particular application for precision treatment in the thorax or upper abdomen.
