Need For New Standards In Radiation Therapy
- From: J <nswex@nalid;no>
- Date: Mon, 03 Mar 2008 01:18:45 -0500
http://www.medicalnewstoday.com/articles/98708.php
Need For New Standards In Radiation Therapy
Radiology / Nuclear Medicine News
Article Date: 27 Feb 2008 - 2:00 PST
Modern radiation techniques result in substantial variation between the
prescribed dose and the actual dose of radiation delivered to the tumor,
according to a study published online February 26 in the Journal of the
National Cancer Institute. As a result of this newly uncovered trend, the
authors are calling for national guidelines for intensity-modulated
radiation therapy (IMRT).
IMRT systems are designed to deliver the prescribed dose of radiation to a
tumor while sparing surrounding tissues. IMRT does this by delivering many
small beams of radiation that are individually controlled. Because of the
complexity of the system, radiation oncologists and physicists rely on
special software and equipment to deliver the planned dose over the
treatment area.
In the current study, Indra J. Das, Ph.D., and colleagues at the
University of Pennsylvania in Philadelphia reviewed the data for 803
patients who were treated with IMRT for brain, prostate, or head and neck
cancer at one of five institutions between October 2004 and July 2006. The
researchers determined the minimum, maximum, and median radiation doses
delivered over the targeted region by using the planned dose for each
patient and measuring the actual amount of radiation in plastic or water
that radiologically resembles tissue.
By comparing the measured dose to the planned dose, the investigators
discovered that 369 patients (46 percent) received a maximum dose
delivered to some portion of the tissue that was more than 10 percent
above the prescribed dose. (Ten percent is the typically acceptable level
of variation.) Moreover, the minimum dose delivered to the tumor site in
506 patients (63 percent) was more than 10 percent below the prescribed
dose.
"We found that in IMRT the prescribed dose rarely corresponded to the
planned, or delivered, dose," the authors write. "Dosimetric variations
between the prescribed dose and the recorded dose could be reduced by
establishing international and/or national guidelines."
In an accompanying editorial, John Willins, Ph.D., and Lisa Kachnic, M.D.,
of the department of radiation oncology at Boston Medical Center and
Massachusetts General Hospital commend the authors for putting together an
important dataset that provides a new window into the clinical application
of IMRT.
The editorialists endorse the authors' call for guidelines in IMRT.
"Widespread use of IMRT planning standards would not only facilitate
multicenter clinical trials but would also provide clinicians with solid
guidance in their everyday practice on the question of what constitutes a
'good' IMRT plan," they write.
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Article adapted by Medical News Today from original press release.
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