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Clinical application of in vivo treatment delivery verification based on PET/CT imaging of positron activity induced at high energy photon therapy
Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI). Stockholm University, Faculty of Science, Department of Physics. (Medicinsk Strålningsfysik)
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(English)In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560Article in journal (Other academic) Submitted
National Category
Radiology, Nuclear Medicine and Medical Imaging Cancer and Oncology Other Medical Sciences not elsewhere specified Medical Engineering
URN: urn:nbn:se:su:diva-72554OAI: diva2:502066
Available from: 2012-02-14 Created: 2012-02-14 Last updated: 2012-02-16Bibliographically approved
In thesis
1. Verification of high energy photon therapy based on PET/CT imaging of photonuclear reactions
Open this publication in new window or tab >>Verification of high energy photon therapy based on PET/CT imaging of photonuclear reactions
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

For classical and intensity modulated radiation therapy of deep-seated tumors, high-energy photons are the optimal radiation modality from an integral dose point of view. By using narrow scanned beams the treatment outcome can be improved substantially by delivering biologically optimized intensity modulated distributions often with sharp dose gradients. This requires using photons with energies well above 15 MV enabling verification of the treatment delivery in vivo by PET/CT imaging in a manner not previously possible. This new technique is based on the production of positron emitting radionuclides when the incoming high-energy photons interact through photonuclear reactions with the body tissues. The produced radionuclides, commonly 11C, 15O and 13N can then be monitored by PET and the distribution of activated nuclei show exactly where the radiation has penetrated the patient. In the subcutaneous fat, present in all humans, a high induced activity produces a perfect visualization of the location and even the intensity modulation of the incident beams. The reason for this is the high carbon content in combination with a low biological perfusion in fat tissues. Errors in the patient positioning such as setup errors or misplacement of the beams will thus show up in the PET images as a deviation from the actual radiation treatment plan. Interestingly, the imaged activity distribution from the subcutaneous fat also visualizes how the dose delivery can be deformed when the patient is erroneously positioned on the treatment couch as seen on the cover figure. Furthermore, the different half-lives of the produced radionuclides (20 min, 2 min, and 10 min, for 11C, 15O and 13N, respectively) allows for analysis of the dynamic behavior of tissue activity with the possibility of retrieving information such as tissue composition, biological and physical half-lives. The present thesis shows that considerable clinical information regarding the treatment delivery with high-energy photon beams can be obtained using PET/CT imaging. Although the study is based on the use of 50 MV photons the method may apply for beams with energies > 20 MV at higher doses.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2012. 49 p.
Photonuclear reactions, PET/CT treatment verification, High-energy photon therapy
National Category
Natural Sciences
Research subject
Medical Radiation Physics
urn:nbn:se:su:diva-72385 (URN)978-91-7447-461-9 (ISBN)
Public defence
2012-03-09, föreläsningssalen, Radiumhemmet, Karolinska universitetssjukhuset, Solna, 10:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Submitted. Paper: Manuscript.Available from: 2012-02-16 Created: 2012-02-09 Last updated: 2012-02-16Bibliographically approved

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Janek Strååt, Sara
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Medical Radiation Physics (together with KI)Department of Physics
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Radiology, Nuclear Medicine and Medical ImagingCancer and OncologyOther Medical Sciences not elsewhere specifiedMedical Engineering

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