Radiation therapy is one of the main treatment methods used in cancer care. This method of treatment can be used as a sole treatment for cancer or in combination with surgery, chemotherapy, and/or hormone therapy. UPMC Hillman Cancer Centre offers convenient access to a wide range of treatment options using a variety of photon and electron energies.
3D Conformal Radiation Therapy
3D conformal radiation therapy is a cancer treatment that shapes the radiation beams to match the shape of the tumour. In the past, radiation beams only matched the height and width of the tumour — exposing healthy tissue to radiation. Advances in imaging technology have made it possible to locate and treat the tumour more precisely.
Conformal radiation therapy uses the targeting information to focus precisely on the tumour, while minimising the amount of healthy tissue included in the treatment area. This more precise targeting makes it possible to use higher doses of radiation: these higher doses have proven to be more effective in shrinking and killing tumours. More radiation is more effective in shrinking and killing tumours.
Electron therapy, or electron beam therapy (EBT) is a kind of external beam radiotherapy where electrons are directed to a tumour site. This type of therapy is performed using a linear accelerator, which is a high-energy x-ray machine that directs radiation to the tumour.
Intensity Modulated Radiation Therapy (IMRT)
IMRT is a method of treatment planning and delivery that allows a very precise and customised radiation therapy plan to be created. The shape of the radiation beam coming from the treatment machine can be ‘modulated’ (adapted) to conform to the shape of the area that the consultant radiation oncologist wants to treat.
The main aim of IMRT is to maximise the dose of radiation that can be delivered to the target area (tumour site), while minimising the dose to the surrounding normal tissues. The ultimate aim of IMRT is to deliver a dose high enough to ensure tumour control whilst keeping the treatment side effects to a minimum.
RapidArc® Radiotherapy Technology
RapidArc® radiotherapy technology, developed by Varian Medical Systems, is an extremely fast and precise form of image-guided, intensity-modulated radiation therapy (IMRT). Image guidance improves tumour targeting and IMRT shapes the radiation dose so that it conforms closely to the 3D shape of the tumour. This means more dose to the tumour and potentially less to surrounding healthy tissue. RapidArc®’s image-guided treatment:
- Delivers a complete IMRT treatment with one or two rotations of the treatment machine around the patient
- Can treat the entire tumour volume with the radiation dose during one revolution of the machine
RapidArc® involves varying (or modulating) the intensity of the radiation (in this case, high-energy x-rays) being used as therapy for cancer.
What can I expect during RapidArc® treatment?
The radiosurgical team of oncologists and radiation physicists:
- Uses computer-generated images to develop a “custom-designed” treatment plan
- Delivers a precise, tightly focused radiation dose that conforms to the shape of the tumour, while limiting the amount of radiation that reaches surrounding healthy tissues
A significant benefit provided by RapidArc® is the speed of a treatment. A RapidArc® treatment is delivered with a single, 360-degree rotation of the linear accelerator, which takes less than two minutes.
Image Guided Radiation Therapy (IGRT)
As treatment planning and delivery techniques in radiation therapy have developed with the evolution of more advanced technology, the aim has become to maximise the dose to the tumour while minimising the dose to the surrounding healthy tissue.
However, tumours can move, both during a radiation treatment session and from one treatment session to another, as a result of normal internal organ function (digestion, elimination, and breathing) and small differences in the way the patient is positioned for treatment. If these changes in position move the tumour out of the planned treatment range, the tumour may not receive the full amount of radiation that it should, or normal tissues may receive more radiation than they can tolerate.
IGRT techniques are used to verify the tumour location each day. An On-Board Imager®, an automated system for delivering IGRT treatment, allows the radiation therapist to:
- Obtain high-resolution x-ray images to pinpoint tumour sites
- Adjust patient positioning when necessary
- Complete the treatment to an accuracy of less than two mm variance
IGRT enables the clinical team to locate the tumour while the patient is in the treatment position, and to minimise the volume of healthy tissue exposed to radiation during treatment.
An alternative approach is to produce a computed tomography (CT) image of the patient using the ‘cone beam’ technique. The linear accelerator rotates around the patient for a full arc allowing a full 3D volume to be imaged and analysed, with the patient’s position adjusted if necessary before treatment is delivered.
IGRT has allowed for the safe delivery of higher doses of radiation therapy to more precise targets within the body, improving the efficacy of treatment while sparing more healthy tissue.
4D Planning and Respiratory Gating
High-resolution conformal radiation therapy demands that consultant radiation oncologists accurately localise the tumour and define the tumour contour. They can then maximise the dose to the tumour while minimising the dose to the surrounding healthy tissue.
Unfortunately, physiological functions, such as normal respiration, can change the tumour position during treatment. Traditionally, this fact required the use of a larger treatment volume to compensate for tumour movement, with associated increases in the amount of normal, healthy tissue being irradiated.
4D planning and respiratory gating in radiation therapy allows us to monitor respiration quickly and easily, without sacrificing accuracy and patient comfort.
The system uses a sophisticated video monitor to characterise the patient’s breathing pattern. The pattern is obtained by tracking the motion of the lightweight marker box placed on the patient’s abdomen.
Through video image analysis and signal processing, the system identifies both the full range of chest wall motion during respiration and the normal pattern of that motion. By correlating this data with the motion of the tumour, we can create a treatment plan that ‘gates’ the treatment beam, meaning that the treatment machine switches on only when the tumour falls within the required positions.
This system allows the patient to breathe naturally and remain comfortable, although in some cases it may be necessary to coach the patient into a more even breathing pattern or have them hold their breath for short periods of time.
This method of treatment delivery is not necessary in all tumours, and is most helpful in body sites where breathing can potentially cause a large amount of motion of the internal organs. Often, a 4D planning scan is done to assess the breathing pattern and organ/tumour motion in such cases, but respiratory gating is not always required.
Cancers Treated by 4D Planning and Respiratory GatingLung Cancer
Deep Inspiration breath-hold techniques
Deep inspiration breath hold (DIBH) is a radiation therapy technique where patients take a deep breath during treatment, and hold this breath while the radiation is delivered. This technique was developed to reduce radiation exposure to the heart when treating cancer.
Treatment OptionsBreast Cancer
Brachytherapy is a technique for treating prostate cancer using tiny radioactive seeds (Iodine 125) that can be implanted into the prostate gland using needles.
‘Brachy’ is derived from the Greek word for ‘short’, and in this treatment the radioactive seeds are inserted directly into the prostate gland in contrast to conventional radiotherapy where it travels a distance through air and the body tissues before it reaches the prostate gland.
The latest techniques for brachytherapy were developed in the mid-1980s with the arrival of sophisticated ultrasound probes. These devices enable the accurate implantation of seeds into the prostate gland, thus allowing high doses of radiation to be delivered to the cancer.
There are now good long-term results from patients treated up to 20 years ago to show this form of treatment is highly effective in treating and curing patients with early prostate cancer. Brachytherapy appears as effective as other conventional treatments such as surgery (radical prostatectomy) or standard external beam radiotherapy.
Brachytherapy is not the only effective treatment for prostate cancer and some patients may be more suitably treated by other conventional treatments depending on their precise circumstances.
Cancers Treated by Prostate BrachytherapyProstate Cancer
Radium Ra 223 Dichloride (Xofigo®)
This treatment may be used in certain patients with metastatic prostate cancer that is unresponsive to medical or surgical treatment options. Depending on the results of certain tests, this treatment can be an option to treat bone pain caused by prostate cancer that has spread to bones anywhere in the body. At UPMC Hillman, Xofigo® is the name of the drug that is administered, which is an alpha particle-emitting radioactive therapeutic agent. It is given through a vein (intravenously), as a slow injection. The amount of Xofigo® received depends on many factors, including weight, general health and other health problems. Your doctor will determine your exact dosage and schedule.