Kira Grogg1, Nathaniel M Alpert1, Xuping Zhu1, Chul Hee Min2, Mauro Testa3, Brian Winey3, Marc D Normandin1, Helen A Shih3, Harald Paganetti3, Thomas Bortfeld3, Georges El Fakhri4. 1. Center for Advanced Radiological Sciences, Nuclear Medicine and Molecular Imaging, Radiology Department, Massachusetts General Hospital, Boston, Massachusetts. 2. Department of Radiological Science, College of Health Science, Yonsei University, Wonju, Kangwon, Korea. 3. Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. 4. Center for Advanced Radiological Sciences, Nuclear Medicine and Molecular Imaging, Radiology Department, Massachusetts General Hospital, Boston, Massachusetts. Electronic address: elfakhri@pet.mgh.harvard.edu.
Abstract
PURPOSE: This work was a proof-of-principle study for the evaluation of oxygen-15 ((15)O) production as an imaging target through the use of positron emission tomography (PET), to improve verification of proton treatment plans and to study the effects of perfusion. METHODS AND MATERIALS: Dynamic PET measurements of irradiation-produced isotopes were made for a phantom and rabbit thigh muscles. The rabbit muscle was irradiated and imaged under both live and dead conditions. A differential equation was fitted to phantom and in vivo data, yielding estimates of (15)O production and clearance rates, which were compared to live versus dead rates for the rabbit and to Monte Carlo predictions. RESULTS: PET clearance rates agreed with decay constants of the dominant radionuclide species in 3 different phantom materials. In 2 oxygen-rich materials, the ratio of (15)O production rates agreed with the expected ratio. In the dead rabbit thighs, the dynamic PET concentration histories were accurately described using (15)O decay constant, whereas the live thigh activity decayed faster. Most importantly, the (15)O production rates agreed within 2% (P>.5) between conditions. CONCLUSIONS: We developed a new method for quantitative measurement of (15)O production and clearance rates in the period immediately following proton therapy. Measurements in the phantom and rabbits were well described in terms of (15)O production and clearance rates, plus a correction for other isotopes. These proof-of-principle results support the feasibility of detailed verification of proton therapy treatment delivery. In addition, (15)O clearance rates may be useful in monitoring permeability changes due to therapy.
PURPOSE: This work was a proof-of-principle study for the evaluation of oxygen-15 ((15)O) production as an imaging target through the use of positron emission tomography (PET), to improve verification of proton treatment plans and to study the effects of perfusion. METHODS AND MATERIALS: Dynamic PET measurements of irradiation-produced isotopes were made for a phantom and rabbit thigh muscles. The rabbit muscle was irradiated and imaged under both live and dead conditions. A differential equation was fitted to phantom and in vivo data, yielding estimates of (15)O production and clearance rates, which were compared to live versus dead rates for the rabbit and to Monte Carlo predictions. RESULTS: PET clearance rates agreed with decay constants of the dominant radionuclide species in 3 different phantom materials. In 2 oxygen-rich materials, the ratio of (15)O production rates agreed with the expected ratio. In the dead rabbit thighs, the dynamic PET concentration histories were accurately described using (15)O decay constant, whereas the live thigh activity decayed faster. Most importantly, the (15)O production rates agreed within 2% (P>.5) between conditions. CONCLUSIONS: We developed a new method for quantitative measurement of (15)O production and clearance rates in the period immediately following proton therapy. Measurements in the phantom and rabbits were well described in terms of (15)O production and clearance rates, plus a correction for other isotopes. These proof-of-principle results support the feasibility of detailed verification of proton therapy treatment delivery. In addition, (15)O clearance rates may be useful in monitoring permeability changes due to therapy.
Authors: Xuping Zhu; Samuel España; Juliane Daartz; Norbert Liebsch; Jinsong Ouyang; Harald Paganetti; Thomas R Bortfeld; Georges El Fakhri Journal: Phys Med Biol Date: 2011-06-15 Impact factor: 3.609
Authors: H Mizuno; T Tomitani; M Kanazawa; A Kitagawa; J Pawelke; Y Iseki; E Urakabe; M Suda; A Kawano; R Iritani; S Matsushita; T Inaniwa; T Nishio; S Furukawa; K Ando; Y K Nakamura; T Kanai; K Ishii Journal: Phys Med Biol Date: 2003-08-07 Impact factor: 3.609
Authors: Srilalan Krishnamoorthy; Boon-Keng K Teo; Wei Zou; James McDonough; Joel S Karp; Suleman Surti Journal: IEEE Trans Radiat Plasma Med Sci Date: 2020-12-14