Feature | August 28, 2013 | Raissa Rocha

The Latest in Prostate Radiotherapy

IMRT and image guidance technologies continue to lead the way for treatment of prostate cancer patients

In the past 20 years there have been considerable improvements in the treatment of prostate cancer. As it is across all radiation oncology, techniques have evolved from conventional external beam radiation therapy (EBRT), to more targeted therapies that are delivered in fewer visits. One of the latest notable trends in radiotherapy is the emergence of real-time image guidance for intensity-modulated radiation therapy (IMRT). For prostate cancer, radiotherapy is often deployed in conjunction with surgery (prostatectomy) or as curative therapy, depending on the stage of disease. As these new techniques emerge, it becomes more important for clinicians to identify which ones work most effectively and for which patients.

Types of Radiotherapy for Prostate Cancer 

Radiation therapy can be divided into two main types: external and internal. Both forms have shown to be effective in treating prostate cancer, though more research and long-term information is available on the former.1 For prostate cancer, EBRT remains the standard, with IMRT becoming the most commonly used. Other external treatment options for patients include the older 3-D conformal radiation therapy (3D-CRT); and proton therapy, which uses targeted beams of proton particles rather than X-rays.

Internal radiation therapy, or brachytherapy, typically involves the use of small radioactive sources that are inserted into the prostate gland for direct delivery. There are two types of prostate brachytherapy: permanent low-dose rate (LDR) and temporary high-dose rate (HDR). LDR brachytherapy involves the insertion of radioactive seeds through the skin and into the prostate using thin needles. The seeds are tiny enough to avoid discomfort, and are typically left in place after radiation delivery is complete. In HDR brachytherapy, needles are used to insert catheters into the prostate. The catheters then deliver the radioactive materials into the gland for about five to 15 minutes.[1] Depending on the stage of disease and/or the size of the prostate gland, brachytherapy can be deployed to minimize damage to healthy tissues surrounding the prostate.

Evolution of Techniques

Steve Eulau, M.D., medical director and radiation oncologist, Seattle Prostate Institute, has been treating prostate cancer for almost 20 years. He noted the remarkable evolution of treatments available for patients, calling the pace of change “breathtaking.” Where before the amount of radiation used to treat patients was so overwhelming that men were discontinuing treatment, now beams are “being delivered to conform in a rational way to the anatomy of the patient,” he stated.

3D-CRT is considered an “older” technique that uses 3-D images of the tumor to shape more precise beams of radiation for treatment. The beams are projected using a linear accelerator (linac) from different angles around the patient, who remains situated in the same position on the table throughout each course of treatment. Another form of conformal therapy involves the use of proton beams rather than X-ray beams, though proton therapy is not yet widely available and only a handful of sites in the United States offer it as treatment.

Advanced variations of 3-D therapy include the now-routinely used IMRT, image-guided radiation therapy (IGRT) and volumetric modulated arc therapy (VMAT). IMRT allows radiation oncologists to not only shape radiation beams, but to also vary the intensity of those beams within a given field, said Eulau. Another external technique projects radiation from a geometric arc around the patient, rather than from a set of predetermined orientations and angles. Similar to IMRT, the RapidArc system, a proprietary technology from Varian Medical Systems, can adjust the shape and intensity of the beams when projecting at the patient, explained Agam Sharda, senior manager of treatment solutions marketing for Varian’s oncology systems business.

Ultimately, radiotherapy techniques have been evolving to become more accurate, precise and efficient. “What that helps to do is deliver maximum dose to the target, while limiting dose to sections that are not the target,” Sharda said. “As a result we are, in some cases, witnessing better side effects than with earlier techniques.”

The Advent of Real-Time Image Guidance

For Eulau, the development of real-time image guidance and tracking for therapy treatments has been transformational for radiation oncologists. Where before a computed tomography (CT) scan was used for planning and tracking during treatments, radiofrequency (RF) guidance now allows clinicians to know where the prostate is and its exact size during the actual procedure. In clinical use for the past four or five years, RF guidance contrasts significantly with CT, which only showed the prostate during the moment the image was taken. “Before, we ran the risk of deluding ourselves that we knew exactly where these fragile tissues were within the body,” said Eulau. As a result, past radiation delivery may have affected more normal tissue than desired.

A user of Varian’s Calypso real-time tracking system, Eulau now uses three RF beacons that are placed into the prostate.  The beacons are activated from the console by clinicians, and the console detects wavelengths sent by the beacons to determine their locations. “It allows us to know exactly where we are with millimeter precision within the body, 10 times a second,” Eulau said.

Varian and other vendors are also using a variety of imaging modalities besides CT to develop guidance technologies. Varian’s Vitesse real-time planning solution uses ultrasound to guide and aid HDR brachytherapy treatments, and the first patient to be treated with the latest version of Vitesse was a prostate cancer patient in North Carolina. Earlier in 2013, Elekta and Philips Healthcare joined a research group that is developing a combination of magnetic resonance imaging (MRI) and radiation therapy for more precise cancer treatments.


A comparative effectiveness study, published online in May by JAMA Internal Medicine, evaluated the long-term outcomes of patients who received radiation treatments following surgery, comparing CRT against the newer and more expensive IMRT.[2] The study, led by researchers from the University of North Carolina, compared outcomes using Medicare data of IMRT and CRT patients treated between 2002 and 2007. The researchers found no significant difference between IMRT and CRT patients in rates of long-term gastrointestinal morbidity, urinary incontinent morbidity, urinary incontinence or erectile dysfunction.

Lead author Ronald Chen, M.D., MPH, assistant professor of radiation oncology, University of North Carolina at Chapel Hill School of Medicine (UNC), cites the study as showing the possible long-term benefits of radiation treatment for patients who have had a prostatectomy. “For patients who have had a prostatectomy already, and subsequently need radiation treatment, this study shows that IMRT and CRT seemed to have similar outcomes,” he said in the release.

The study came at a time when leading urological and radiation oncology organizations announced a new guideline regarding radiation therapy after
3] Released jointly by the American Society for Radiation Oncology (ASTRO) and the American Urological Association (AUA) in May, the guideline provides recommendations about the benefits and risks of additional treatment after prostate removal. The “Adjuvant and Salvage Radiotherapy After Prostatectomy: ASTRO/AUA Guideline” was published in the August 2013 issues of the official journals of both ASTRO and AUA.


www.cancer.org/cancer/prostatecancer/detailedguide/prostate- cancer-treating-radiation-therapy, accessed July 1, 2013

http://archinte.jamanetwork.com/article.aspx?articleid=1689975, accessed July 1, 2013

www.newswise.com/articles/view/602678/?sc=sphr&xy=10009115, accessed July 1, 2013

Related Content

Videos | Radiation Therapy | May 21, 2019
This is a walk through of the ViewRay MRIdian MRI-guided radiotherapy system installed at ...
Partial Breast Irradiation Effective, Convenient Treatment Option for Low-Risk Breast Cancer
News | Radiation Therapy | May 20, 2019
Partial breast irradiation produces similar long-term survival rates and risk for recurrence compared with whole breast...
New Method Improves Ability to Measure and Maximize Radiation Therapy Dose
News | Radiation Therapy | May 14, 2019
Delivering just the right dose of radiation for cancer patients is a delicate balance in their treatment regime....
Blue Earth Diagnostics Expands Access to Axumin in Europe
News | Radiopharmaceuticals and Tracers | May 13, 2019
Blue Earth Diagnostics announced expanded access to the Axumin (fluciclovine (18F)) imaging agent in Europe. The first...
Sponsored Content | Videos | Radiation Oncology | May 13, 2019
At ASTRO 2018, Accuray showcased new patient-fi
Radiotherapy After Chemo May Improve Survival in Advanced Hodgkin's Lymphoma Patients
News | Radiation Therapy | May 10, 2019
Patients with advanced Hodgkin's lymphoma who have large tumors at the time of diagnosis may benefit from radiotherapy...
A CyberHeart cardiac ablation radiotherapy treatment plan showing where the radiation beam will ablate for a noninvasive pulmonary vein isolation procedure. Varian acquires, buys, purchases Cyberheart.

A CyberHeart cardiac ablation radiotherapy treatment plan showing where the radiation beams will ablate for a noninvasive pulmonary vein isolation procedure to treat an arrhythmia.

Feature | Radiation Therapy | May 10, 2019
May 10, 2019 — Radiation oncology vendor Varian announced it acquired the start-up company CyberHeart, which has deve
Artificial intelligence (AI) was again the hottest topic in radiology, with 11 of the top 20 pieces of content this month relating to AI. These images are a few of the AI technologies highlighted in ITN Editor's Choice video of the most innovative AI technologies highlighted at RSNA 2018.

Artificial intelligence (AI) was again the hottest topic in radiology, with 11 of the top 20 pieces of content this month relating to AI. These images are a few of the AI technologies highlighted in ITN Editor's Choice video of the most innovative AI technologies highlighted at RSNA 2018. 

Feature | May 01, 2019
May 1, 2019 — Here is the list of the most popular content on the Imaging Technology New (ITN) magazine webs
Pencil Beam Scanning Better Protects Children With Brain Tumors
News | Proton Therapy | May 01, 2019
A comparison of three types of radiotherapy for children's brain tumors suggests a type of proton therapy called pencil...
Researchers Identify Ways to Predict and Avoid Radiotherapy Side Effects
News | Radiation Therapy | April 30, 2019
New research has shown a combination of biological markers and certain genetic changes can predict radiation...