Author: Laura Gater
Published: Oct 9/08
State-of-the-art imaging technology is aiding in the screening, diagnosis, and treatment of the three biggest killers of men: lung, prostate, and colon cancers. According to the National Cancer Institute (NCI of Bethesda, MD), the death rate from lung cancer—the leading killer cancer—continues to decrease among white and black men. Prostate cancer death rates have been declining since 1994, according to the NCI, and colorectal cancer mortality rates have been in steep decline since the mid-1980s.
Modalities for Diagnosis
“CT is and has been the gold standard” for cancer diagnosis and follow up, due to its ease of use, access in the community, and excellent ability to view tumors, according to Sholom Ackelsberg, general manager of global CT and functional imaging research at GE Healthcare (Waukesha, WI).
The use of positron emission tomography (PET) is also very effective in diagnosing tumors. More than 90% of all PET/CT procedures are done for oncology, because PET/CT provides metabolic information, so the physician can begin treatment planning at once.
CT and PET/CT both are used in screening, diagnosis, and treatment of lung, prostate and colorectal cancer.
“CT tells us the anatomical characteristics of the structure—the volume and density of the tumor structure—and the anatomical information, [as in] what organs the tumor is attached to or if the tumor has encroached upon the capsule of the prostate. It helps the physician in deciding the course of treatment,” states Praveen P. Nadkarni, MD, marketing manager of cardiac and preventive care in the CT marketing division at Siemens Medical Solutions (Malvern, PA). “CT also can guide radiation therapy treatment by telling us exactly where to deliver the radiation dose, and it also can tell us if the treatment has been effective, using a follow-up CT
scan to evaluate the change in tumor size post-treatment.”
Higher resolution is possible by the latest advances in CT technology, and the newer diagnostic tools that are enabled and enhanced by CT also help improve tumor detection. The first 4-slice CT scanner was developed in 1998, and it had a resolution of 1 mm for routine applications. Today’s newest CT scanners have a 0.4-mm resolution. CT scanners have evolved rapidly, from 4 to 16 and now to 64 slices per rotation.
“Even a small sub-millimeter change in resolution can make quite a difference in terms of earlier diagnosis,” Nadkarni explains.
Just 5 years ago, a CT exam of the colon took up to 15 minutes; today, advances in CT acquisition mean that the same exam can be done in about 10 seconds. Nodules are characterized more easily, and fewer movements take place in the colon during the exam.
Many techniques in imaging today are used for diagnosing and treating prostate cancer, including intensity modulated radiation therapy (IMRT), ultrasound, and brachytherapy. IMRT is an advanced mode of high-precision radiotherapy that uses computer-controlled X-ray accelerators to deliver exact radiation doses to a malignant tumor or particular areas within the tumor. The radiation dose is designed to conform to the tumor shape by modulating the strength of the radiation beam to focus a higher dose to the tumor, all while minimizing exposure to surrounding tissues. Treatment is carefully planned using 3-D CT images of the patient, along with computerized dose calculations to determine the dose intensity pattern that will best conform to the tumor shape. Several intensity modulated fields coming from different beam directions combine to produce a radiation dose tailored to the patient that maximizes tumor dose and minimizes exposure to adjacent tissues.
According to Michael J. Zelefsky, chief of brachytherapy services at Memorial Sloan-Kettering, “3-D IMRT allows radiologists to deliver higher radiation doses, a substantial improvement in brachytherapy. Ultrasound is used during the brachytherapy procedure to place the seeds with precision. Now we have very sophisticated computer programs to capture needle coordinates where the seeds should be for best dose to the gland and minimal dose to the urethra and rectum. [The use of] 3-D IMRT has reduced side effects [of radiation therapy] and improved precision.”
Because the ratio of normal tissue dose to tumor dose is minimized with the IMRT approach, increased radiation doses can be targeted safely to tumors with fewer side effects, compared to conventional radiotherapy techniques. IMRT also has the potential to reduce treatment toxicity, even when doses are not increased. IMRT allows immediate verification of successful treatment. Currently, IMRT is being used to treat cancers of the prostate, head and neck, breast, thyroid, and lung as well as in gynecologic, liver and brain tumors, lymphomas, and sarcomas.
IMRT can provide a high radiation dose to the prostate gland while reducing the dosage that reaches the rectum and bladder. Because it is so accurate, a higher daily dosage is frequently used, compared to regular radiation techniques, so the treatment can be completed in fewer days. IMRT can be used as the sole treatment for prostate cancer, for 6–7 weeks; or 4 weeks of IMRT is combined with HDR brachytherapy for a state of the art treatment combination.
Three-dimensional imaging software is used in clinical diagnosis and therapy planning, enabling users to combine medical images created in different scanning modalities to form a single image with richer diagnostic information. The technology can fuse images from the same or different modalities (eg, CT, MR, and PET), from data sets acquired at different times, or from data sets generated on equipment from different manufacturers.
Software-based fusion technology can assess the movement of a patient examined using a combined scanner, such as PET/CT, and comparing images taken at different times, such as before and after treatment. The user can create 2-D and 3-D views of human anatomy and interactively navigate within these images to better visualize and understand internal structures and disease conditions.
Men: More Health Savvy
“Consumers are becoming more aware their own health,” says Nadkarni of Siemens. “Now they take their health in their own hands. The Internet, as an educational medium, has been partially responsible for this [transformation]. Also, there is better and more consumer-directed advertising today.
“Also, physicians now realize that newer technologies can play a role in earlier diagnosis,” he continues. “Earlier diagnosis could equal a reduction in the morbidity and mortality rate.”
Improved technology, coupled with a growth in patient education, is responsible for earlier cancer diagnosis and treatment among men.
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About the Author
Laura's writing specialties are medical, health and business topics.
Just a few of her published writings: Medical Imaging, 24x7, Podiatry Management, Strategic Healthcare Marketing, Advance for Imaging & Radiation Therapy Professionals, Podiatry Management, RT (Respiratory Therapy),Corrections Forum, Radiologic Technology, For the Record, Plastic Surgery Products, Orthodontic Products, Chiropractic Products, Podiatric Products, and The American Journal of Managed Care (supplement on NSAIDs).
Laura is also the temporary medical producer for several websites, writing news briefs. She has also done healthcare research and reports, provided public relations for several non-profit organizations and taught freelance writing classes.
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