Archive for month: August, 2020

The diagnostic system used by many mental health practitioners in the United States

Amid increasing fear of overexposure to radiation from CT scans, a panel of experts has recommended more research on the health effects of medical imaging and ways to reduce unnecessary CT tests, as well as industry standardisation of CT machines.
The recommendations were developed at the Radiation Dose Summit, organised by the National Institute of Biomedical Imaging and Bioengineering (NIBIB). The summit included more than 100 medical physicists, radiologists, cardiologists, engineers, industry representatives and patient advocates. The proceedings, held in Bethesda, MD in early 2011, covered currently understood risks of radiation exposure from CT scans, set priorities for future research, and called for changes to industry practices.
‘The number of CT exams in the U.S. has increased by about 10 percent each year over the past decade,’ said John Boone, UC Davis professor of radiology and lead author of the Radiology article. ‘This trend underscores the importance of developing a better understanding of the health risks of radiation exposure versus the benefits of enhanced diagnosis.’
The experts conceded that despite widespread public concern about radiation risks, the biologic effects from medical imaging tests are not entirely understood. Most direct evidence comes from the effects of instantaneous, high-dose, whole-body exposures due to industrial accidents and from survivors of the atomic bombs in Hiroshima and Nagasaki, Japan. Whether these findings can be extrapolated to people exposed to occasional and much smaller dosages applied to only parts of the body is uncertain.
‘The standards regarding ‘safe levels’ of radiation were designed for workplace safety and are very conservative,’ said Boone. ‘We don’t know whether the established thresholds are really meaningful for exposure from medical testing.’
The experts pointed out that because there is a high background incidence of cancer world-wide, the small incremental increase in cancer that may be attributable to low doses of radiation from medical imaging is extremely difficult to ascertain. They stated that national and international registries that track cancers and patient exposures to medical radiation may one day make it possible to conduct large epidemiological studies that could help make such associations.
‘In reaction to media coverage of radiation overexposure cases, some patients refuse to undergo medical imaging procedures,’ said Boone. ‘Yet for almost all patients, the risks of foregoing a needed medical procedure far outweigh any potential radiation-associated risks.’
Even accurately recording patient exposures of radiation from medical imaging is extremely difficult, according to the authors. Although it is easy to ascertain how much radiation a machine administers during an imaging study, the amount actually received by a patient depends on various factors including body size. For example, because of differences in body mass, children and small adults can receive a dose of radiation two to three times that of larger people, even when the dose administered is the same.
Other factors, such as whether the patient lies on a moving or stationary table, also affect the radiation dose received. Federally sponsored research is needed to develop methods to more accurately measure patient exposures from different types of CT scans, the authors suggested. UC Davis Comprehensive Cancer Center

The population of the United States is getting older, due not only to ageing boomers but also to a four-year increase in life expectancy from 1990 to 2010. An ageing population means increased diagnosis of prostate cancer. Statistically, the older the patient at time of diagnosis, the more aggressive the disease

Most patients whose breast cancer has spread to their lymph nodes have most of the lymph nodes in their armpit area removed after chemotherapy to see if any cancer remains. A study conducted through the American College of Surgeons Oncology Group and led by Judy Boughey, M.D. a breast surgeon at Mayo Clinic shows that a less invasive procedure known as sentinel lymph node surgery successfully identified whether cancer remained in lymph nodes in 91 percent of patients with node-positive breast cancer who received chemotherapy before their surgery. In sentinel lymph node surgery, only a few lymph nodes, the ones most likely to contain cancer, are removed.

‘Since treatment with chemotherapy before surgery can eliminate cancer in the lymph nodes in some patients, we were interested in evaluating whether sentinel lymph node surgery could successfully identify whether cancer remained in the lymph nodes after chemotherapy,’ says Dr. Boughey. Removing only a few lymph nodes reduces the risk of surgical complications such as numbness and arm swelling, she says.

Researchers studied 756 women with node-positive breast cancer who received chemotherapy as an initial treatment. Of study participants, 637 patients had both sentinel lymph node and axillary lymph node surgery. Sentinel lymph node surgery correctly identified whether cancer lingered in 91 percent of patients, including 255 patients with node-negative breast cancer and 326 patients with continuing node-positive disease.

Researchers also found that 40 percent of the patients had complete eradication of the cancer from the lymph nodes. The study had a false-negative rate of 12.6 percent and the false negative rate was significantly lower with the use of dual tracers (blue dye and radiolabeled colloid) to identify the sentinel lymph nodes.

Dr. Boughey says that technical factors in surgery are important to help ensure correct staging, the process of determining how far cancer may have spread.