Eye tracking system unique to Korea

An automatic tracking system to facilitate gating of the eye during treatment of orbital cancer has been developed by the National Cancer Center of Korea (NCC).

Patients are seated for treatment with the affected eye propped open, head and neck immobilized, facing a proton beam nozzle. A computer screen shows the eyeball, with an x-axis and y-axis indicating the optimal time to inject the beam into the tumor.

The eye can move at any time, but we cannot fix the eyeball. With our system, during patient treatment, a doctor can check eye movement”, says Se Byeong Lee, Ph.D, chief medical physicist, National Cancer Center of Korea. “During treatment of the eye for cancer, our camera detects eye movement, then our computer opens the beam gate when the eye is positioned properly to receive the proton beam.”

NCC is the only proton center that has this type of automatic eye tracking system, says Lee. A clinician has to manipulate the proton beam manually at other sites.

Monte Carlo simulation helps improve dosing

Researchers at the National Cancer Center of Korea are using the Monte Carlo method to achieve more precise dose calculation for patients treated with proton therapy.

Sometimes we cannot treat with our proton beam modality because our commercial treatment planning system cannot calculate dose distribution for complicated anatomy,” says Se Byeong Lee, Ph.D., chief medical physicist, National Cancer Center of Korea.

To overcome this shortcoming, the beam delivery system needed to be reconstructed in a virtual environment. The research team used a GEANT4 Monte Carlo toolkit to build a complex simulation environment. They also strived to mimic the dynamic behavior of real irradiation of the beam delivery system at NCC and to obtain proton dose distribution that was close to measured data.

The team also confirmed the feasibility of GEANT4 for a therapeutic proton beam simulation by showing that the simulated proton dose distributions were aligned closely with the measured data over treatment beam range.

The study concluded that the developed simulation software may confirm patient planning decisions, such as initial beam spot size and momentum spread, after further Monte Carlo validation study.

Cone Beam CT research under way

NCC Korea is helping advance the use of Cone Beam computed tomography (CT) to help more precisely position the proton beam for optimal effectiveness.

“Cone Beam CT will allow us to have 3-D patient imaging so we can calculate the proton beam very accurately,” says Se Byeong Lee, Ph.D., chief medical physicist, National Cancer Center of Korea (NCC).

The benefits of 3-D imaging include more detailed information on beam alignment, the ability to respond to patient anatomical changes and the ability to re-plan beam arrangements. Currently, NCC is using 2-D X-ray technology to determine patient setup prior to proton treatment.

“With 3-D imaging, we can position the patient very accurately,” says Lee. “We have developed a basic concept and a basic algorithm for a Cone Beam CT system.”

UFPTI explores hypofractionation

Proton therapy clinicians are exploring the benefits and risks of treating slow-growing cancers with higher individual proton doses over a more accelerated time frame, cutting the total treatment period by a third or more.

“If the same tumor control goal can be accomplished safely in a shorter time with fewer proton fractions, it could have a huge benefit on health outcomes,” says Nancy Mendenhall, M.D., Clinical Director of the University of Florida Proton Therapy Institute. “And it could reduce the cost of treating some of the common cancers.”

Practitioners at the Jacksonville, Florida facility are in the midst of their second clinical trial evaluating the use of fewer, larger-sized fractions of the total proton dose, called hypofractionated proton therapy, to treat prostate cancer. UF Proton Therapy Institute is also conducting a clinical trial to assess hypofractionated proton treatments for lung tumors.

For some cancers, hypofractionation may allow clinicians to more fully optimize the power of protons, Mendenhall says. “It’s possible that certain types of cancers will be better controlled with hypofractionated proton therapy as compared with standard fractionated proton therapy,” says Mendenhall.

Other clinical trials of hypofractionated proton therapy are under way at ProCure Proton Therapy Centers in Oklahoma City, Oklahoma, and in Warrenville, Illinois. Those trials, overseen by the nonprofit Proton Collaborative Group, target prostate cancer.

And the Roberts Proton Therapy Center at the University of Pennsylvania’s Abramson Cancer Center in Philadelphia, Pennsylvania, is conducting a clinical trial to evaluate breast cancer treatments using hypofractionated proton doses.

Under conventional proton protocols, radiation oncologists may use a total proton dose of 70 to 80 gray-equivalents to treat certain cancers, Mendenhall explains. That total dose is divided into individual treatment doses, called fractions, of 1.8 to 2.0 gray-equivalents apiece. And each fraction is delivered to the patient regularly over an eight- to nine-week period of outpatient care.

“Historically, the whole reason for protracted radiation courses was to minimize the daily dosage to normal tissue and allow for repair of some sub-lethal damage,” says Mendenhall. But higher dose treatments using intensity-modulated radiation therapy demonstrated that hypofractionated photon treatments could be done fairly safely and effectively.

“If hypofractionation can be accomplished safely with x-rays, hypofractionation should be possible with protons — and possibly with less toxicity to healthy tissue since protons, unlike x-rays, have no exit dose and less entrance dose,” she adds.

Clinical application of hypofractionated proton beam therapy for common cancers was first delivered in the 1990s at Loma Linda University Medical Center in Loma Linda, California for early stage lung cancer, Mendenhall recalls.  “Results were excellent,” she says. “Since then, hypofractionated photon therapy has been used in lung, breast, and prostate cancer.  So far, hypofractionated proton therapy has been limited to clinical trials, particularly in prostate cancer.”

Two approaches to hypofractionated proton treatments are currently being pursued, mirroring ongoing photon studies.  The first is “moderate” hypofractionation, which reduces the total treatment period to about four to five-and-a-half weeks, Mendenhall continues, by increasing the fraction size to approximately 2.4 to 3.1 gray-equivalents.  The second is “extreme” hypofractionation, which dials each proton fraction up to a range of 4.7 to 8.0 gray-equivalents, reducing the treatment time to as few as two to two-and-a-half weeks.

Each approach has its advocates, says Mendenhall, and data ultimately will drive clinical application. “There’s a fair amount of emerging data that we’re watching involving extreme hypofractionation that may inform our next steps,” Mendenhall says, pointing to the ProCure clinical trials. And clinicians will need to be alert for unanticipated late-term effects of moderate and extreme hypofractionation, which may not appear for several years after treatment.

Researchers currently speculate that the best tumor candidates for hypofractionated proton treatments are small volume early-stage breast, prostate, and lung cancers.

Professional Sameer Keole identifies standout published papers on PT

As with all emerging technologies, the publication of peer-reviewed research papers supporting the validity and effectiveness of proton therapy began modestly. An online search of the literature revealed 818 citations in 1990. However, this is changing: By 2000, the list had grown to 2,496 studies and by 2010, to 6,200 studies.
Some proton therapy experts were asked to identify a recently published paper of noteworthy clinical significance. Here are summaries of three of the studies and brief commentaries from the experts.
Here is the paper selected by Sameer Keole, M.D. from the ProCure Proton Therapy Center in Oklahoma City, Oklahoma City, Oklahoma.

“Randomized trial comparing conventional-dose with high-dose conformal radiation therapy in early-stage adenocarcinoma of the prostate: long-term results from Proton Radiation Oncology Group/American College of Radiology 95-09.” by Zietman AL, Bae K, Slater JD, Shipley WU, Efstathiou JA, Coen JJ, Bush DA, Lunt M, Spiegel DY, Skowronski R, Jabola BR, Rossi CJ (J Clin Oncol. 2010; 28(7): 1106-11)

Study summary: Long-term results: prostate cancer

Early-stage prostate cancer patients (n=393) were treated with conformal photon therapy to a fixed dose of 50.4 Gy followed by a proton-beam boost dose of either 19.8 Gy (conventional dose) or 28.8 Gy (high dose). The median follow-up of patients was 8.9 years.

In this randomized trial, high-dose external proton beam radiation therapy provided better long-term cancer control than did conventional-dose proton beam radiation therapy in men with localized prostate cancer. Dose escalation to 79.2 Gy was safely achieved without an increase in late urinary or rectal morbidity. These findings show that patients receiving a high-dose boost following conformal photon therapy will more likely be free from an increasing PSA 10 years later and less likely to require additional cancer therapy.

“The PROG 95-09 data certainly support the use of Proton Therapy for the treatment of prostate cancer. Of the six-dose escalation studies that have been published, it remains the only one that used a Proton Therapy component. Its inclusion allowed for safe dose escalation without an increase in rectal toxicity. It speaks volumes about the value of Proton Therapy”, says Sameer Keole, M.D. from the ProCure Proton Therapy Center in Oklahoma City, Oklahoma City, Oklahoma.

 

Professional Torunn Yock identifies standout published papers on Proton Therapy

As with all emerging technologies, the publication of peer-reviewed research papers supporting the validity and effectiveness of proton therapy began modestly. An online search of the literature revealed 818 citations in 1990. However, this is changing: By 2000, the list had grown to 2,496 studies and by 2010, to 6,200 studies.
Some proton therapy experts were asked to identify a recently published paper of noteworthy clinical significance. Here are summaries of three of the studies and brief commentaries from the experts. Here is the paper selected by Torunn I. Yock, M.D., M.C.H. of Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.

“Proton radiotherapy for pediatric bladder/prostate rhabdomyosarcoma: clinical outcomes and dosimetry compared to intensity-modulated radiation therapy.” by Cotter SE, Herrup DA, Friedmann A, Macdonald SM, Pieretti RV, Robinson G, Adams J, Tarbell NJ, Yock TI. (Int J Radiation Oncology Biol Phys. 2011; 81(5):1367–73.)

Study summary: Proton therapy: pediatrics

Proton therapy used to treat seven children with pediatric bladder/prostate rhabdomyosarcoma provided significant dose savings to normal structures, such as the bladder, femoral heads, growth plates and pelvic bones, compared to intensity-modulated radiation therapy.

Proton Therapy was well tolerated in these patients. Five of the seven children had intact bladders and were without evidence of disease at study completion. Although identifying the long-term impact of these reduced doses was beyond the scope of this retrospective study, the hope is that the decreased treatment toxicity associated with Proton Therapy will lead to fewer acute and late complications related to treatment.

“With a median follow-up of 27 months, the late-effect profile of this patient population looks promising to date. Further studies with extended follow-up and quality-of-life analyses are needed to confirm these early findings”, says Torunn I. Yock, M.D., M.C.H. of Department of Radiation Oncology, Massachusetts General Hospital [LINK: http://www.massgeneral.org/], Harvard Medical School, Boston, Massachusetts.

Professional Jacob B. Flanz identifies standout published papers on Proton Therapy

As with all emerging technologies, the publication of peer-reviewed research papers supporting the validity and effectiveness of proton therapy began modestly. An online search of the literature revealed 818 citations in 1990. However, this is changing: By 2000, the list had grown to 2,496 studies and by 2010, to 6,200 studies. Some proton therapy experts were asked to identify a recently published paper of noteworthy clinical significance. Here are summaries of three of the studies and brief commentaries from the experts.
Here is the paper selected by Jacob B. Flanz, Ph.D. of Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.

“A case study in proton pencil-beam scanning delivery”, by Kooy HM, Clasie BM, Hsiao-Ming L, Madden TM, Bentefour H, Depauw N, Adams JA, Trofimov AV, Demaret D, Delaney TF, Flanz JB. (Int J Radiation Oncology Biol Phys. 2009;76(2):624–30.)

Study summary: Scanned proton beams

The most conformal and efficient beam delivery is achieved with the beam scanning modality. Modulating the dose throughout the target volume creates an overall dose distribution that conforms to the target and minimizes the dose to tissues and organs outside the target. While a small pencil beam can exploit this potential for small tumors, the use of a larger scanned beam can also be extremely important for larger target volumes. It is, in fact, these larger volumes that, when treated with scattered proton beams, require highly complex treatment planning and costly patient-specific hardware — including brass apertures and range compensators — that cannot be reused. Treatment with scanned proton beams often eliminates that hardware, reduces the number of fields required and is much simpler to plan.

The case study of a 61-year-old man with a 21 x 12 cm retroperitoneal myxoid liposarcoma was presented. The patient was treated to 50.4 Gy relative biological effectiveness presurgery using a course of photons and protons to a clinical target volume, and a course of protons to the gross target volume. The use of beam scanning improved the dose distribution, reduced treatment time and lowered treatment costs.

“Much of the emphasis on the clinical use of beam scanning has been for small targets near critical structures; for example those in the head and neck area. This is due to the ability to use small (pencil sized) scanned beams to conform around concave shapes using multiple fields. The significant advantages of using scanned beams for larger targets seem to be less widely recognized. Large targets treated with scattered beams are difficult to plan, time consuming to treat, and require multiple fields with expensive patient-specific hardware. Using scanned beams (and they don’t even have to be so small) simplifies treatment planning and delivery and provides not only a better overall dose distribution, but also a more efficient and cost-effective treatment solution, even when compared with alternative modalities”, says Jacob B. Flanz, Ph.D. of Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.

 

Proton system installation begins in Italy

Installation of a cyclotron, a beam line and three state-of-the-art patient treatment rooms has begun in Trento, Italy, at the Agenzia Provinciale Per la Protonterapie (ATreP).

The proton beam system and the first patient treatment room are expected to be ready for commissioning by ATreP staff in Spring 2013. Commissioning is a monthlong process that includes confirming proton beam and dose accuracy, and integrating three-dimensional imaging into the proton targeting system. It is the final stage before clinicians at the facility can begin killing cancerous tumors with proton beams.

An IBA cyclotron arrived at the site in February and was hoisted to its concrete vault by a pair of heavy-lift cranes. Workers from the rigging firms of the Belgium-based Sarens Group and Italy-based Midolini Group moved the 220-ton cyclotron into place.

The facility has been designed in collaboration with Impresa di Costruzioni Ing. E. Mantovani S.P.A. of Venice, Italy.

ATreP was established by the autonomous Province of Trento in 2004. The three-story facility will be managed by the Provincial Health Service.

ATreP will house two gantry treatment rooms and a fixed-beam treatment room. Each of the treatment rooms will be equipped with the latest advance in IBA’s Universal Nozzle, the multi-mode proton beam delivery mechanism, which includes Pencil Beam Scanning.

Prague Proton Therapy Center

The Proton Therapy Center Czech s.r.o.  in Prague is well on its way to begin treating patients in September 2012. When fully operational in 2013, the center will be the first of its size in Central and Eastern Europe. The center is located on the campus of University Hospital na Bulovce.

The proton center will have five treatment rooms: three gantry rooms, one fixed-beam room and one eye treatment room. A full range of diagnostic equipment, including CT (computed tomography), MRI (magnetic resonance imaging) and a PET/CT scanner (an examination combining computed tomography and positron emission tomography), will also be available.

Over the last few months, the Prague Proton Therapy Center has achieved several milestones, including hiring key staff members, launching an interactive website, and developing partnerships with educational institutions, including the First Faculty of Medicine of Charles University and the Faculty of Nuclear Sciences and Physical Engineering of the Czech Technical University, both in Prague. The partnerships will support science and research, contributing to the development of radiation oncology and other oncological specializations.

Peter Vaněk, M.D., recently joined the center to serve as director of the health department and is excited to help develop the Proton Therapy practice. “I am honored to play a role in delivering this advanced form of cancer treatment to patients,” says Vaněk. “This is the highlight of my professional career, and I am very glad to be working with our talented team of radiation oncologists and physicists.”

The center has already demonstrated its leadership in proton therapy by hosting representatives from around Europe who are interested in learning about proton therapy and potentially partnering with the center or building their own.

New PT center in Seattle

The construction of  SCCA Proton Therapy in Washington, USA, began in 2011. In March 2012, a brand new cyclotron was installed at the facility.

This project results from a partnership between ProCure Treatment Centers, Inc. and the Seattle Cancer Care Alliance (SCCA). The footprint and silhouette of the center is similar to other ProCure buildings. The cyclotron is 18 feet across and 8 feet tall, but weighs as much as a Boeing 747 jetliner. It took four weeks for the proton accelerator to make the transoceanic voyage from the Port of Antwerp on the River Scheldt in Belgium to the Port of Tacoma on Commencement Bay on the northwest coast of Washington State.

Two 15-axle trailers carried each half of the cyclotron to the construction site on the Northwest Hospital & Medical Center campus. The 40-mile drive took two days to complete. As is customary with ProCure center designs, the cyclotron was installed through an opening at the side of the building, rather than from above.