News | February 24, 2009

Researchers Work on PET with IMRT for "Dose Painting"

February 24, 2009 - Researchers are testing the use of positron emission tomography (PET) for dose painting, but have found the technique is limited by PET’s spatial resolution, according to researchers from the Catholic University of Louvain, Brussels, Belgium (Radiother. Oncol. doi: 10.1016/j.radonc.2008.11.014).

The theory is to use PET with a radiotherapy plan that takes account of tumor physiology, and to use PET to "paint" the dose to regions of intense activity or radiation resistance. PET is used in combination with intensity-modulated radiotherapy (IMRT) with an appropriate functional imaging modality.

The use of PET for dose painting relies on a perfect correlation between the observed PET signal and the underlying biology of interest. To test this, Nicolas Christian and colleagues imaged 15 tumor-bearing mice with PET following injection of the radiotracer 2-fluoro-2-deoxyglucose (18F-FDG). The mice were also imaged with MRI and then assessed using autoradiography.

The PET and autoradiography images however did not always match, particularly in tumor sub-volumes with high 18F-FDG-activity. This mismatch is significant because a biological image-guided IMRT plan would most likely increase the dose to these sites. The larger the tumor volume and the lower the activity threshold, then the better the match.

"Unfortunately, we do not yet have access to spatial image resolution that is good enough to be able to visualize what is going on at the microscopic level. We may make fairly large mistakes in the dose distribution by relying on what we see on the PET," said Vincent Grégoire, professor in radiation oncology at the Catholic University of Louvain and corresponding author for the paper.

Grégoire noted that if a PET system with a higher resolution were developed, the technique may be viable. The researchers are instead examining whether alternative radioisotope tracers could provide a better way of finding specific sites in the tumor where the dose should be increased, such as clusters of hypoxic cells. The researchers still want to investigate the concept of PET-based dose painting.

Source: Medical Physics Web

For more information: medicalphysicsweb.org

Related Content

Vinai Gondi, M.D., the Director of Research at the Northwestern Medicine Chicago Proton Center, Co-director of the Brain Tumor Center at Northwestern Medicine Cancer Center, Warrenville, and lead author of the NRG-BN001 abstract.

Vinai Gondi, M.D., director of research at the Northwestern Medicine Chicago Proton Center, co-director of the Brain Tumor Center at Northwestern Medicine Cancer Center, Warrenville, and lead author of the NRG-BN001 abstract.

News | Intensity Modulated Radiation Therapy (IMRT) | October 27, 2020
October 27, 2020 — A...
"Initial report of a randomized trial comparing conventional- vs conventional plus fluciclovine (18F) PET/CT imaging-guided post-prostatectomy radiotherapy for prostate cancer" was presented by Ashesh Jani, M.D., Winship Cancer Institute of Emory University, at ASTRO20
News | PET Imaging | October 26, 2020
October 26, 2020 — Adding the advanced PET radiotracer...
HABLE study prioritizes brain imaging and biomarker research among Mexican Americans.

Getty Images

News | PET Imaging | September 14, 2020
September 14, 2020 — To meet the pressing need to better understand the prevalence, progression, and clinical impact
a) Includes scintigraphy and PET with and without concomitant CT. b) Includes conventional radiography, dual-energy x-ray absorptiometry, fluoroscopy, and radiography performed during radiologic interventions. c) Includes general, cardiothoracic, maxillary, plastic, and orthopedic surgery and neurosurgery. d) Includes allergology, cardiology, geriatrics, general internal medicine, pulmonology, gastroenterology, and rheumatology

a) Includes scintigraphy and PET with and without concomitant CT. b) Includes conventional radiography, dual-energy x-ray absorptiometry, fluoroscopy, and radiography performed during radiologic interventions. c) Includes general, cardiothoracic, maxillary, plastic, and orthopedic surgery and neurosurgery. d) Includes allergology, cardiology, geriatrics, general internal medicine, pulmonology, gastroenterology, and rheumatology. Image courtesy of American Roentgen Ray Society (ARRS), American Journal of Roentgenology (AJR)

News | Radiology Imaging | August 14, 2020
August 14, 2020 — According to ARRS' ...
Tau (blue) and amyloid (orange) distribution patterns for super-agers, normal-agers and MCI patients, when compared to a group of younger, healthy, cognitively normal, amyloid-negative individuals. Brain projections are depicted at an uncorrected significance level of p < .0001. Color bars represent the respective t-statistic. Image courtesy of Merle C. Hoenig, Institute for Neuroscience and Medicine II - Molecular Organization of the Brain, Research Center Juelich, Juelich, Germany, and Department of Nucle

Tau (blue) and amyloid (orange) distribution patterns for super-agers, normal-agers and MCI patients, when compared to a group of younger, healthy, cognitively normal, amyloid-negative individuals. Brain projections are depicted at an uncorrected significance level of p < .0001. Color bars represent the respective t-statistic. Image courtesy of Merle C. Hoenig, Institute for Neuroscience and Medicine II - Molecular Organization of the Brain, Research Center Juelich, Juelich, Germany, and Department of Nuclear Medicine, University Hospital Cologne, Cologne, Germany.

News | PET Imaging | July 16, 2020
July 16, 2020 — Super-agers, or individuals whose cognitive skills are above the norm even at an advanced age, have b
PSMA PET/CT accurately detects recurrent prostate cancer in 67-year-old man. 18F-DCFPyL-PSMA PET/CT shows extensive, intensely PSMA-avid local recurrence in prostate (bottom row; solid arrow) in keeping with the known tumor recurrence in the prostate. Right: PET shows extensive, intensely PSMA-avid local recurrence in prostate (top row; solid arrow) and a solitary bone metastasis in left rib 2 (bottom row; dotted arrow). Image courtesy of Ur Metser, et al.

PSMA PET/CT accurately detects recurrent prostate cancer in 67-year-old man. 18F-DCFPyL-PSMA PET/CT shows extensive, intensely PSMA-avid local recurrence in prostate (bottom row; solid arrow) in keeping with the known tumor recurrence in the prostate. Right: PET shows extensive, intensely PSMA-avid local recurrence in prostate (top row; solid arrow) and a solitary bone metastasis in left rib 2 (bottom row; dotted arrow). Image courtesy of Ur Metser, et al.

News | PET-CT | July 16, 2020
July 16, 2020 — New research confirms the high impact of...