Tissue Perfusion Rate Determined from the Decay of Oxygen-15 Activity After Photon Activation in Situ

Hughes, Walter L.; Nussbaum, Gilbert H.; Connolly, Raymond J.; Emami, Bahman; Reilly, Paul E.B.

doi:10.1126/science.451567

Cited by 17 publications

(8 citation statements)

References 9 publications

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“…3-D imaging of activity is recon-structed from the detection data of the planar detector by using maximum likelihood algorithm, taking into consideration the attenuation coefficient of 511 keV gamma rays in the patient's body calculated by the patient's CT image data. In the experiment using a 22 Na point source, position resolution of measured activity with the distance between detector heads of 50 cm was about 2 mm of the full width at half maximum at isocenter in the FOV. The change of the position resolution depending on the increase of the distance between detector heads is about 1 mm.…”

Section: Iib Beam On-line Pet System Mounted On a Rotating Gantry Pmentioning

confidence: 99%

“…And there are some reports that research washout effect of 15 O activity generated by photonuclear reaction using high-energy x-ray irradiation. 22,23 Our previous study mentioned the washout effect of liver of patient in proton therapy. 15 One of the deterioration of images obtained from the measured activity using BOLPs-RGp will be for the washout effect.…”

Section: Iiia Measured Activity Distributionsmentioning

confidence: 99%

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Measurement and verification of positron emitter nuclei generated at each treatment site by target nuclear fragment reactions in proton therapy

et al. 2010

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Section: Iib Beam On-line Pet System Mounted On a Rotating Gantry Pmentioning

confidence: 99%

Section: Iiia Measured Activity Distributionsmentioning

confidence: 99%

Measurement and verification of positron emitter nuclei generated at each treatment site by target nuclear fragment reactions in proton therapy

et al. 2010

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“…Tissue activation was first discussed in detail by Tobias in 1949 7 and was first reported in gamma-ray experiments by Mayneord et al later that year. 8 Since then the radioactivity induced in tissues by photon, [8][9][10] proton, 11,12 neutron, 13 pion, [14][15][16] and heavy-ion radiotherapy beams [17][18][19] has been investigated. This induced activity has been studied as a source of patient dose, 11,20,21 as a means of determining elemental tissue composition, 10,11,13 and for determining dose distributions.…”

Section: Introductionmentioning

confidence: 99%

On‐line monitoring of radiotherapy beams: Experimental results with proton beams

et al. 1999

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Proton radiotherapy is a powerful tool in the local control of cancer. The advantages of proton radiotherapy over gamma-ray therapy arise from the phenomenon known as the Bragg peak. This phenomenon enables large doses to be delivered to well-defined volumes while sparing surrounding healthy tissue. To fully realize the potential of this technique the location of the high-dose volume must be controlled very accurately. An imaging system was designed and tested to monitor the positron-emitting activity created by the beam as a means of verifying the beam's range, monitoring dose, and determining tissue composition. The prototype imaging system consists of 12 pairs of cylindrical BGO detectors shielded in lead. Each crystal was 1.9 cm in diameter, 5.0 cm long, and separated by 0.5 cm from other detectors in the row. These are arranged in two rows, 60 cm apart, with the proton beam and tissue phantoms half-way between and parallel to the detector rows. Experiments were conducted with 150 MeV continuous and macro-pulsed proton beams which had beam currents ranging from 0.14 nA to 1.75 nA. The production and decay of short-lived isotopes, 15O and 14O, was studied using 1 min irradiations with a continuous beam. These isotopes provide a significant signal on short time scales, making on-line imaging possible. Macro-pulsed beams, having a period of 10 s, were used to study on-line imaging and the production and decay of long-lived isotopes, 13N, 11C, and 18F. Decay data were acquired and on-line images were obtained between beam pulses and indicate that range verification is possible, for a 150 MeV beam, after one beam pulse, to within the 1.2 cm resolution limit of the imaging system. The dose delivered to the patient may also be monitored by observing the increase in the number of coincidence events detected between successive beam pulses. Over 80% of the initial positron-emitting activity is from 15O while the remainder is primarily 11C, 13N, 14O with traces of 18F, and 10C. Radioisotopic imaging may also be performed along the beam path by fitting decay data collected after the treatment is complete. Using this technique, it is shown that variations in elemental composition in inhomogenous treatment volumes may be identified and used to locate anatomic landmarks. Radioisotopic imaging also reveals that 14O is created well beyond the Bragg peak, apparently by secondary neutrons.

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“…However, as the sensitivity of the camera was very low and the output only analogous, no further such attempts were made (L Johansson, personal communication). Other early studies have shown the potential use of tissue activation for the analysis of tumor blood flow in animal studies [14-16]. More recently, by the study of biological washout processes of ion-beam-induced positron emitters, half-lives of various washout components could be measured in animals [10,11] and in patients [12,17].…”

Section: Resultsmentioning

confidence: 99%

Dynamic PET/CT measurements of induced positron activity in a prostate cancer patient after 50-MV photon radiation therapy

et al. 2013

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BackgroundThe purpose of this work was to reveal the research interest value of positron emission tomography (PET) imaging in visualizing the induced tissue activity post high-energy photon radiation treatment. More specifically, the focus was on the possibility of retrieving data such as tissue composition and physical half-lives from dynamic PET acquisitions, as positron-emitting radionuclides such as 15O, 11C, and 13N are produced in vivo during radiation treatment with high-energy photons (>15 MeV). The type, amount, and distribution of induced positron-emitting radionuclides depend on the irradiated tissue cross section, the photon spectrum, and the possible perfusion-driven washout.MethodsA 62-year-old man diagnosed with prostate cancer was referred for palliative radiation treatment of the pelvis minor. A total dose of 8 Gy was given using high-energy photon beams (50 MV) with a racetrack microtron, and 7 min after the end of irradiation, the patient was positioned in a PET/computed tomography (CT) camera, and a list-mode acquisition was performed for 30 min. Two volumes of interests (VOIs) were positioned on the dynamic PET/CT images, one in the urinary bladder and the other in the subcutaneous fat. Analysis of the measured relative count rate was performed in order to compute the tissue compositions and physical half-lives in the two regions.ResultsDynamic analysis from the two VOIs showed that the decay constants of activated oxygen and carbon could be deduced. Calculation of tissue composition from analyzing the VOI containing subcutaneous fat only moderately agreed with that of the tabulated International Commission on Radiation Units & Measurements (ICRU) data of the adipose tissue. However, the same analysis for the bladder showed a good agreement with that of the tabulated ICRU data.ConclusionsPET can be used in visualizing the induced activity post high-energy photon radiation treatment. Despite the very low count rate in this specific application, wherein 7 min after treatment was about 5% of that of a standard 18F-FDG PET scan, the distribution of activated tissue elements (15O and 11C) could be calculated from the dynamic PET data. One possible future application of this method could possibly be to measure and determine the tumor tissue composition in order to identify any hypoxic or necrotic region, which is information that can be used in the ongoing therapy planning process.Trial registrationThe official name of the trial committee of this study is ‘Regionala etikprövningsnämnden i Stockholm’ (FE 289, Stockholm, SE-17177, Sweden). The unique identifying number is 2011/1789-31/2.

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Tissue Perfusion Rate Determined from the Decay of Oxygen-15 Activity After Photon Activation in Situ

Cited by 17 publications

References 9 publications

Measurement and verification of positron emitter nuclei generated at each treatment site by target nuclear fragment reactions in proton therapy

Measurement and verification of positron emitter nuclei generated at each treatment site by target nuclear fragment reactions in proton therapy

On‐line monitoring of radiotherapy beams: Experimental results with proton beams

Dynamic PET/CT measurements of induced positron activity in a prostate cancer patient after 50-MV photon radiation therapy

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