Advances in Radiation Oncology
The field of radiation oncology is a steadfast contender in the fight against cancer. Technological advancements in imaging, treatment planning and treatment delivery are tremendously improving patient outcomes. More targeted radiotherapy is letting patients of all ages live a more normal life during and after the course of treatment and most importantly, improving outcomes. Last June, the nation's leading cancer organizations - the American Cancer Society, the Centers for Disease Control and Prevention, the National Cancer Institute, and the North American Association of Central Cancer Registries - released its "Annual Report to the Nation on the Status of Cancer, 1975 - 2001" that brought good news. It said Americans' risk of getting and dying from cancer continues to decline and survival rates for many cancers continue to improve. "The new data reflects progress in prevention, early detection and treatment," the report stated.
To better understand "progress" in the fight against cancer, still the second leading cause of death in the United States, examine a segment of oncology that physicians have utilized for more than 100 years to treat cancer: radiation therapy. Today, when utilized alone or in combination with other therapies, radiotherapy is used to treat more than 60 percent of all cancer patients.
Radiation therapy has undergone a number of technological advancements in the past decade, namely in its ability to better target cancer and avoid surrounding healthy tissue. Intensity modulated radiation therapy (IMRT) is seen as state of the art and advancements in image guidance techniques are complementing both IMRT and 3D conformal radiation therapy (3D-CRT). Multi-modality cancer centers are redefining treatment plans with smaller margins. And informatics is paving the way for filmless/paperless environments where staff members can utilize PCs and mobile computing devices to enter and access critical patient data at the point of care.
As the NCI works to achieve its goal to eliminate suffering and death due to cancer by 2015, researchers and physicians are dedicated to furthering the clinical spheres of radiation oncology - from screening and diagnosis, through treatment and follow-up.
IMRT: More than hope
IMRT's precision offers patients the ability to lead a more normal life during and after the course of treatment.
The IMRT buzz began in the early 1990s when early implementers used it to treat prostate and head and neck cancers. Current statistics show that 38 percent of radiation oncology sites offer IMRT, up from 4 percent in 1998, according to a 2003 IMV census. Disease sites now targeted include the central nervous system, gastrointestinal malignancies, lung cancer and brain tumors, particularly in children.
The hallmark of IMRT is its ability to allow a higher dose of radiation to permeate the tumor while avoiding sensitive structures, thus reducing side-effects. The technology combines computer-generated images and inverse treatment planning software to deliver a tightly focused radiation beam that matches the 3D shape of the tumor. Oncologists modulate the intensity of pencil-thin beams of radiation to combat the toughest of cancers, usually those adjacent to - and tightly intertwined with - complicated structures.
A pediatric brain tumor called a medulloblastoma can be treated with radiation. IMRT can prevent severe hearing loss, which has been a common complication of treatment. A patient with reoccurring cancer in and around the spine that already underwent some form of prior radiation can be treated with IMRT, too. For incidences of cancer in a woman's left breast, radiation can be aimed away from the heart and lung.
Varian Medical Systems, North American Scientific, Elekta and Siemens Medical Solutions are leaders in IMRT technology. The University of Nebraska Medical Center (UNMC) in Omaha, Neb., uses IMRT technology from Siemens to treat prostate and head and neck cancers. Forward-planning IMRT is used for the treatment of lymphomas and breast cancer. "In treatment of the prostate, certainly IMRT has allowed us to give radiation doses that are much more likely to be curative in the long run, but also decrease side effects," says Charles Enke, MD, chairman and professor for UNMC's department of radiation oncology.
The department operates a total of four linacs: three for IMRT and one for 3D-CRT, Enke says. One of the four rooms is equipped with a Novalis Shaped Beam Surgery system to perform whole-body stereotactic radiosurgery. The center's arsenal of radiotherapy systems treats up to 900 new patients annually. An average of 60 IMRT patients are treated daily.
The imaging impact
Improvements in imaging technologies assist physicians in uncovering illness at earlier stages. The better patients can be imaged, the better diseases can be treated.
Radiation oncology centers around the globe are using state-of-the-art imaging equipment and IT systems to toughen their fight against cancer and improve outcomes. More centers are reducing their dependence on film by going digital. Vendors are complementing these modalities with oncology-specific image management systems that store and transmit large volumes of data associated with each patient. DICOM-RT, another advancement, allows the movement of data to exist between linear accelerators, record and verify systems and imaging modalities.
Computed tomography (CT) is the gold standard for 3D treatment planning. Its image clarity helps oncologists identify tumors and surrounding critical structures. A growing number of radiation oncology departments operate their own CT scanner today, as well as manage images from CT simulation. Industry analysts suggest that large volumes of cancer cases and the mounting use of advanced techniques such as IMRT increases the time needed to plan the delivery of patient treatments; thus impacting the desire to implement dedicated CT scanners.
Treatment plans are being supplemented with additional imaging information - such as magnetic resonance imaging (MRI) and positron emission tomography (PET) - to better define target volumes, especially with early stage and metastatic disease. When creating treatment plans, radiation oncologists will fuse CT images with MR and PET data. MRI is helpful in brain, head, neck and central nervous system tumors. PET images identify potential lesions by highlighting hyper-metabolic cellular activity.
While PET scans alone do not give enough anatomical information to accurately define the tumor volume, fused PET/CT datasets enable clinicians to identify where a tumor is in the body, to understand the metabolic activity and define the size of the tumor by mapping its boundaries. Clinical studies show that combined PET/CT information defines better treatment options.
A March study in the American Society for Therapeutic Radiology and Oncology's International Journal of Radiation Oncology*Biology*Physics said that PET/CT reduces the amount of radiation exposure to normal tissue in some lung cancer patients. The study, conducted on 21 patients with non-small cell lung cancer, created two 3D-CRT treatment plans, one with CT-based planning and the second with a combination of PET and CT-based planning. The researchers found that the size of the radiation fields could be decreased by using PET scan information, which means less radiation exposure to healthy lung tissue and the esophagus.
Delivering target treatments
"Radiation oncology as a specialty has evolved tremendously," says Ian Crocker, MD, professor of radiation oncology at Emory University School of Medicine in Atlanta. "When I came into radiation oncology, we just started using CT scanners to help plan treatments for structures in the chest and deep in the abdomen. What we found was that when we imaged those patients, we were missing part of the tumor 30 to 40 percent of the time because we had an incomplete understanding of the extent of the tumor. We have since begun using additional imaging modalities, including MRI and PET/CT."
UNMC's Enke concurs, saying the combination of imaging technologies in treatment planning is important. "With prostate [cancer], we have routinely used both MRI and CT data in a fused form because with MRI you can actually define tumor volumes within the prostate," he says. "With IMRT, we will actually give those internal targets within the prostate a higher dose than we give the remainder of the prostate tissue. It's a way of improving your chances for cure without really necessarily increasing the chances for side effects."
Image fusion improves tumor outlines so that the radiation dose can be tailored to the patient's disease area. The radiation oncology department at Grossmont Hospital in San Diego, Calif., uses Philips Medical Systems' Pinnacle3 3D RT treatment system integrated with Syntegra multi-modality software to automatically fuse electronic imaging studies.
In the past, physicians had to use "good eyes" to overlay images utilized in treatment plans, describes Mark Young, MS, lead medical physicist and radiation safety officer at Grossmont Hospital. Now, clinicians use high-end workstations located throughout the radiation oncology department. "It provides a node in the network to have all different imaging modalities come together so that you can simultaneously view all the different imaging equipment that is used," says Young.
With the click of a button, the treatment planning team acquires radiology and radiation oncology images; superimposing the physiological data from PET with anatomic data from CT and MR. "It allows us to avoid critical structures in addition to improving the accuracy of our targeting," adds Young. "Avoidance is becoming a bigger part of the game."
PET/CT is making inroads in simulation as well. "In radiation oncology, if you don't start with the right imaging, you are not going to get the results that you need," says Paul Schilling, MD, medical director at the Community Cancer Center of North Florida in Gainsville. The radiation oncology center uses a GE Healthcare Discovery LS PET/CT scanner for imaging patients receiving radiation or chemotherapy.
"We use it in staging to see how far the cancer has spread," explains Schilling. "We use it to outline the tumor in preparation for radiation therapy treatment planning. Based on the image, the tumor is outlined and the patient is prepared for treatment."
Surmounting obstacles
When patients are placed in precisely the same position for their daily radiation treatments, tumors can shift by as much as two to three centimeters over six to eight weeks of therapy.
Tumor motion and inaccurate patient set up are impediments to successful radiotherapy treatment. "When patients come for treatment, they might not be positioned exactly the same way as they were planned for treatment," explains Emory's Crocker. "As a result, the radiation dose pattern may not be centered exactly on the tumor. In an extreme situation, part of the tumor may be missed as a result of inaccuracy in patient set up. Or, you may deliver an increased dose to some normal dose surrounding the patient set up."
Larger target margins may be used to compensate for errors in localization. However, Crocker says a larger volume requires delivering a lower dose of radiation.
Image-guidance overcomes some of the obstacles posed by inaccurate patient set up and tumor motion. It is not a new concept - weekly port films have been a standard of care for decades. Over the past 10 years, treatment verification technologies have progressed from MV port films to electronic portal imaging devices, to in-room CT scanners and ultrasound-based systems. North American Scientific's BAT (B-mode acquisition and targeting) - used a lot in the treatment of prostate cancers - combines an ultrasound probe and a 3D tracking system with a touchscreen-based treatment room interface to pinpoint targets at the time of a radiation therapy treatment.
Recent IGRT (image guided radiation therapy) advancements include Varian's On-Board-Imager (OBI), which clinicians at Emory use to create plans with smaller margins. The device mounts to a linear accelerator via robotically controlled arms and operates along three axes of motion so that the imager can be positioned for the best possible view of the tumor and surrounding anatomy. High-resolution images are taken of the patient prior to treatment and compared with reference images from treatment planning.
"If there is deviation between those two sets of x-rays, software will calculate that deviation," says Crocker. "The patient can be moved into the right position."
Emory reported first clinically using the system in June, treating at that time seven patients, four with brain tumors and three with head and neck tumors who ranged in age from 29 to 63. Emory clinicians have not yet determined if IGRT is more suitable for certain cancers, says Crocker. However, they are analyzing the change in dose delivered to tumors when using the OBI, as well as calculating the benefits in terms of improving the chances of cure or reducing the complication rates by being more precise with the treatment.
Emory also uses Varian's Trilogy stereotactic system. Trilogy is a high-powered linear accelerator outfitted with an OBI that delivers external beam radiotherapy. It can be used stereotactically to treat non-invasive brain cancer and certain neurological conditions.
The first patient Emory's Trilogy treated was a 56-year-old woman, a 10-year survivor of small cell lung cancer, who underwent radiosurgery for two small metastases in the brain. "It has a dose rate module that allows us to deliver the dose twice as quickly," says Crocker. "It is about twice as accurate as a regular linac." This allows for a reduction in the treatment volume, thereby reducing the risk of complications.
Emory's Trilogy is primarily used to treat brain cancers - stereotactic radiosurgery, fractionated stereotactic radiotherapy and pediatric treatments. Crocker envisions that the system's ability to perform image guidance will play a particular role in radiosurgery in extracranial sites. "We will be able to do the same treatments in the body that we have only been doing in the brain up to this point in time," says Crocker. "Patients with small lung cancer, pancreatic cancer or even prostate cancer may be candidates for these high-dose single fraction treatments."
21st century treatment
Informatics improves the delivery of cancer care. Take for example, The University of Texas MD Anderson Cancer Center in Houston. MDACC's division of radiation oncology treats nearly 4,500 new patients a year. The department consists of six treatment facilities, operates 24 linacs and runs four different kinds of treatment planning software. "It is a multi-modality, multi-vendor, multi-site environment," says Erdal Sipahi, the radiation oncology division's manager of system analyst services at MDACC.
MDACC implemented Impac Medical Systems' information management system that provides integrated clinical and administrative management software comprised of an image-enabled electronic medical record (EMR), treatment and planning device integration, IMRT treatment management and quality assurance functions, patient registration, scheduling and charge capture.
Staff members securely access patient records from terminals located throughout its treatment facilities whenever they need it. Time is no longer spent tracking down paper charts or film. This is a huge benefit, since the chart is something that everybody wants to look at, says Sipahi.
Computers are the gatekeepers to a central data repository that houses oncology-specific data and images, including identification and field set up photos, reference images, patient demographics, schedules, patient charge capture records, nursing assessments and patient notes. "Wherever a physician or a nurse is with a patient, there is a computer available, whether it is wired or wireless," explains Siphai.
A wireless network lets staff members enter and access data into the EMR in real-time from laptop computers and pen tablets at the point of care. The department uses wireless technology primarily for entering and reviewing charting data, but it may eventually be used by physicians to access and review medical images.
"The EMR is a point of reference where [physicians] can look up patient information - an alternative to the paper chart," says Siphai regarding workflow improvements. "Clinicians utilize the image-enabled EMR to make informed decisions regarding a patient's treatment. All of the patient's information is located in the electronic chart. Clinicians can walk up to any computer in the facility and immediately access a patient's information."
"Our facility is so spread out, it's almost impossible for us to carry paper stuff around for people to review and look at," continues Siphai. "The biggest benefit is having the ability of the information to all the clinicians who need it. In terms of efficiency, we are saving lots of intangible dollars by not having to carry charts from one place to another."
No Information Is an Island: Radiation Oncology Jumping on IHE
"The ultimate goal is not to create a little island where everything on the island talks seamlessly to each other, but rather to create an entire universe where the entire medical enterprise talks to each other," says Jay Cooper, MD, director of Maimonides Cancer Center and chairman of radiation oncology at Maimonides Medical Center in Brooklyn, N.Y.
Cooper is referring to the American Society for Therapeutic Radiology and Oncology recent involvement in IHE (Integrating the Healthcare Enterprise), an initiative that works to improve the way computer systems in healthcare share critical information. IHE is a multi-year effort sponsored by the Radiological Society of North America and the Healthcare Information and Management Systems Society. The American College of Cardiology began working with IHE last year to focus on the integration of information in the cardiology department.
Now ASTRO is getting on the IHE bandwagon
"There have been efforts made on the diagnostic radiology and cardiology side," says Cooper. "We are working on interfacing with those people, to take the information from the imaging piece into the therapy piece, working from the imaging through the planning, from the planning to the treatment delivery."
ASTRO's IHE-RO Task Force (which includes members from ASTRO, RSNA, the American Association of Physicists in Medicine, American College of Radiology and National Electrical Manufacturers Association) is thinking big, but starting small. First, Cooper says the group must deal with the system integration problems inherent in radiation oncology today.
"If the treatment planning unit cannot talk to the treatment delivery unit, we have a tremendously important, fundamental problem," poses Cooper.
IHE-RO has identified different steps in the radiation treatment process that require system communication. "Each one of the steps has to have a defined language because that is really what the protocols come down to," explains Cooper.
"For example, taking the information from any planning system and transmitting it to any delivery system so that you don't have to worry if you bought a treatment planning system from vendor A and a treatment delivery system from vendor B," elaborates Cooper. "We will hopefully come up with a language that all vendors speak so that all information will flow seamlessly. At present, there are too many different languages being spoken. You are limited if you have to buy or are locked into buying systems and software from one vendor."
The next phase will be tying the healthcare enterprise together
"The reason that IHE is so important to patients and the reason that ASTRO is so enthusiastic about supporting IHE in helping to bring the information from the imaging stage, through the planning and delivery stage, is that the better each one of these stages connects to the other, the better job we are going to be able to do in taking care of patients," says Cooper.