Radiation Dosimetry

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Radiation dosimetry of florbetapir F 18

Radiation dosimetry of florbetapir F 18

The present study was designed to provide the bio- distribution and radiation dosimetry of florbetapir. Our study has resulted in an ED estimate of 18.6 ± 4.26 μSv/ MBq or 6.88 mSv for 370 MBq for PET. We found that florbetapir is rapidly distributed throughout the body shortly following I.V. administration. The gallbladder was the organ that received the highest absorbed dose, with an average value of 143.0 ± 80.20 μSv/MBq across nine healthy volunteers. Variability in gallbladder activ- ity was observed, which is possibly related to differences in the individual kinetics of gallbladder emptying or dif- ferences across subjects in the timing of food consump- tion or diet. Images over time show that elimination occurs primarily by way of clearance from the liver and excretion through the gallbladder into the GI tract. Some accumulation is also observed in the urinary bladder. Modeling urinary bladder voiding at 90 min post-injection did not substantially change the radi- ation dosimetry results.
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Tissue Equivalent Gellan Gum Gel Materials for Clinical MRI and Radiation Dosimetry

Tissue Equivalent Gellan Gum Gel Materials for Clinical MRI and Radiation Dosimetry

Gellan gum gels preparation followed similar protocol as the previous publication of gellan gum gels used as tissue equivalent materials for radiation dosimetry [2]. As a biopolymer, gellan gum is susceptible to bacterial growth, so methyl 4-hydroxybenzoate (methylparaben) and propylene glycol were utilized as preservatives instead of the more common sodium azide which is undesirable due to its human toxicity [3]. Methyl 4-hydroxybenzoate is an antiseptic used in pharmaceuticals, and a preservative in the food industry [4] and propylene glycol also exhibits antibacterial properties [5] while aiding in the homogeneity and stability of the gel. To prepare the gels (per 100 mL): 1.25 g gellan gum powder (Alfa Aesar, USA) and 100 mg methyl 4- hydroxybenzoate (Sigma Aldrich, Canada) were added into 10.0 mL propylene glycol (Caledon Laboratories, Canada) to solvate the powders. Deionized water (52.5 mL) was then added with vigorous mixing at room temperature in order to disperse the powder. The resulting suspension was heated until complete dissolution. The transparent gel solution was cooled to 55 °C and mixed with the SPION solution and the metal salt solutions of gadolinium(III) chloride hexahydrate (GdCl 3 ·6H 2 O) (Alfa Aesar, USA) or manganese(II) chloride tetrahydrate (MnCl 2 ·4H 2 O) (Sigma
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Biological Tissue Modeling with Agar Gel Phantom for Radiation Dosimetry of 99mTc

Biological Tissue Modeling with Agar Gel Phantom for Radiation Dosimetry of 99mTc

The 99m Tc radiation dosimetry was performed using an agar gel cylindrical phantom with 4 cm diameter and 11.5 cm height, it was prepared with 18 MBq of 99m Tc to simulate the source region. A scintigraphy image series acquired at various time obtained with conjugate view technique was used to estimate cumulated activity A  and the absorbed dose (D) was estimated with the MIRD methodology. The source region was modeled with water and agar gel using the same geometry, volume and activity, to compare the activity (A(t)) and cumulated activity into both media. The source region was placed at 10 cm depth into a cylindrical water phantom with 24 cm diameter and 15 cm height and centered at its longitudinal axis. The Photopeak was centered at 140 keV. The activity at time t was estimated using the Equation (5),
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Safety, pharmacokinetics, metabolism and radiation dosimetry of 18F-tetrafluoroborate (18F-TFB) in healthy human subjects

Safety, pharmacokinetics, metabolism and radiation dosimetry of 18F-tetrafluoroborate (18F-TFB) in healthy human subjects

F-TFB was found to be well tolerated by the partici- pants in the study. The rapid pharmacokinetics, absence of metabolism, and specific biodistribution to NIS- expressing tissues of high-specific radioactivity 18 F-TFB in healthy human participants support its use as an iod- ide analog radiotracer for evaluation of thyroid and breast cancers and monitoring of gene therapies that employ the hNIS reporter gene. The radiation dosimetry estimates are on par with other 18 F-labeled radiophar- maceuticals with prominent renal excretion (e.g., 18 F- FDG) and are acceptable for clinical imaging purposes.
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Radiation dosimetry of [18F]-PSS232—a PET radioligand for imaging mGlu5 receptors in humans

Radiation dosimetry of [18F]-PSS232—a PET radioligand for imaging mGlu5 receptors in humans

Purpose: (E)-3-(pyridin-2-ylethynyl)cyclohex-2-enone O-(3-(2-[ 18 F]-fluoroethoxy)propyl) oxime ([ 18 F]-PSS232) is a new PET tracer for imaging of metabotropic glutamate receptor subtype 5 (mGlu5), and has shown promising results in rodents and humans. The aim of this study was to estimate the radiation dosimetry and biodistribution in humans, to assess dose-limiting organs, and to demonstrate safety and tolerability of [ 18 F]-PSS232 in healthy volunteers. Methods: PET/CT scans of six healthy male volunteers (mean age 23.5 ± 1.7; 21 – 26 years) were obtained after intravenous administration of 243 ± 3 MBq of [ 18 F]-PSS232. Serial whole-body (vertex to mid-thigh) PET scans were assessed at ten time points, up to 90 min after tracer injection. Calculation of tracer kinetics and cumulated organ activities were performed using PMOD 3.7 software. Dosimetry estimates were calculated using the OLINDA/EXM software.
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Toxicity and radiation dosimetry studies of the serotonin transporter radioligand [18 F]AFM in rats and monkeys

Toxicity and radiation dosimetry studies of the serotonin transporter radioligand [18 F]AFM in rats and monkeys

Background: [ 18 F]AFM is a potent and promising PET imaging agent for the serotonin transporter. We carried out an acute toxicity study in rats and radiation dosimetry in monkeys before the translation of the tracer to humans. Methods: Single- and multiple-dose toxicity studies were conducted in Sprague – Dawley rats. Male and female rats were injected intravenously with AFM tartrate as a single dose of 98.7 or 987 μ g/kg (592 or 5,920 μ g/m 2 , 100× or 1,000× the proposed human dose of 8 μ g, respectively) on day 1 or as five consecutive daily doses of 98.7 μ g/kg/day (592 μ g /m 2 /day, 100× human dose, total dose 493.5 μ g/kg). PET/CT scans were performed in four Formosan rock monkeys (two males and two females, each monkey scanned twice) using a Siemens BIOGRAPH scanner. After injection of [ 18 F]AFM (88.5 ± 20.3 MBq), a low-dose CT scan and a series of eight whole-body PET scans in 3-D mode were performed. Time-activity data of source organs were used to calculate the residence times and estimate the absorbed radiation dose using the OLINDA/EXM software.
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External and Environmental Radiation Dosimetry with Optically Stimulated Luminescent Detection Device Developed at the SCK CEN

External and Environmental Radiation Dosimetry with Optically Stimulated Luminescent Detection Device Developed at the SCK CEN

ESA programs related to bacterial experiments in space: research program MESSAGE (Microbial Experiments in the Space Station About Gene Expression) studied the ef- fect of space conditions on micro-organisms in general us- ing some well-known bacteria. During another experiment, MESSAGE 2, the samples and detectors stayed in space for ten days, of which eight were in the service module of the ISS. This dosimetry experiment was a collaboration between different institutes (School of Cosmic Physics, Institute for Advanced Studies, Dublin, Ireland, Johnson Space Centre Houston, USA, Department of Radiation Dosimetry, National Physics Institute, Czech Republic De- partment of Physics, Oklahoma State University, Still- water, USA and SCK-CEN, Mol, Belgium), so that the doses could be estimated by different techniques. For the high LET doses (>10 keV/μm), two types of track etch detectors were flown. The low LET part of the spectrum was measured by three types of thermoluminescent de- tectors ( 7 LiF:Mg,Ti; 7 LiF:Mg,Cu,P; Al
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The clinical safety, biodistribution and internal radiation dosimetry of [18F]AH113804 in healthy adult volunteers

The clinical safety, biodistribution and internal radiation dosimetry of [18F]AH113804 in healthy adult volunteers

For each subject, key organs and tissues were delineated and analytical fits were made to the image data as functions of time to yield the normalised cumulated activities. These were input to an internal radiation dosimetry calculation based upon the Medical Internal Radiation Dose (MIRD) schema for the Cristy-Eckerman adult male or female phantom. The absorbed doses per unit administered activity to the 24 MIRD-specified target organs were evaluated for an assumed 3.5-h urinary bladder voiding interval using the Organ Level INternal Dose Assessment/ Exponential Modelling (OLINDA/EXM) code. The sex-specific absorbed doses were then averaged, and the effective dose per unit administered activity was calculated.
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Internal radiation dosimetry of a 152Tb-labeled antibody in tumor-bearing mice

Internal radiation dosimetry of a 152Tb-labeled antibody in tumor-bearing mice

The assessment of radiotracer biodistribution in preclin- ical animal models is an essential part of radiopharma- ceutical drug development. The standard method for obtaining biodistribution data has long been the ex vivo measurement of radioactivity concentration in organs of small mammals, dissected at given time points after ra- diopharmaceutical administration. In addition, there is a growing interest in generating radiation dosimetry data from preclinical studies, in order to better define the radiobiological implications of novel probes, with par- ticular regard to the toxicity and efficacy profiles of therapeutic radiopharmaceuticals [1, 2]. According to the RADAR formalism [3], two terms are required for the calculation of the absorbed dose to a target tissue: the dose factors (DFs) and the time-integrated activity. The DFs incorporate information on the physical prop- erties of the radionuclide, on the geometrical interplay between source and target organs, as well as on their structure. Thanks to the development of realistic small animal geometric phantoms and their implementation in commercial dosimetry software, an accurate calculation of DFs for small animals is now easily accessible [4–6].
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Human biodistribution and radiation dosimetry of the 5-HT2A receptor agonist Cimbi-36 labeled with carbon-11 in two positions

Human biodistribution and radiation dosimetry of the 5-HT2A receptor agonist Cimbi-36 labeled with carbon-11 in two positions

C-WAY- 100635; 14.1 μSv/MBq) [13, 23]. The estimated effect- ive dose for 11 C-Cimbi-36 in this study is also in ac- cordance with preclinical studies; effective dose was found to be 4.9 μSv/MBq and 7.7 μSv/MBq, when ex- trapolating from pig and rat dosimetry, respectively [11]. In the case of 11 C-Cimbi-36, studies in pigs thus proved to have a better translational value compared with rats, but differences across species cannot be predicted [13]. The decision of whether to undertake human radiation dosimetry studies of a new radioli- gand, when 11 C-labeled tracers show this limited vari- ability, should therefore be considered. Dosimetry studies are both costly and time-consuming, and ex- pose healthy individuals to radiation, with (perhaps) no added benefit compared with a conservative
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Radiation dosimetry of [18F]VAT in nonhuman primates

Radiation dosimetry of [18F]VAT in nonhuman primates

We used PET measures of radioactivity in organs and direct arterial blood sampling to calculate dosimetry exposure after the iv injection of [ 18 F]VAT in nonhuman primates. The liver was the critical organ with radiation dosimetry of 51.1 μ Gy/MBq for males and 65.4 μ Gy/ MBq for females. We calculated an effective dose of 16 and 19 μ Sv/MBq for male and female, respectively. Given the relatively low exposure to gonads and bone marrow (radiosensitive organs), we should be able to inject up to 764 MBq under the 21 CFR 361.1 guidelines (<50 mSv to any organ, <30 mSv to radiation sensitive organs).
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First evaluation of PET-based human biodistribution and radiation dosimetry of 11C-BU99008, a tracer for imaging the imidazoline2 binding site

First evaluation of PET-based human biodistribution and radiation dosimetry of 11C-BU99008, a tracer for imaging the imidazoline2 binding site

PET and CT image data were imported to MRIcroN [22] and volumes of interest drawn using the combin- ation of PET scan and/or CT that most clearly depicted organs relevant to radiation dosimetry (full list given in Table 2). Measured activity concentrations were trape- zoidally integrated over all five scans, with the activity in the final scan assumed to decay with no further re- distribution. The integrated activity concentrations per unit injected activity were multiplied by OLINDA/EXM 1.1 organ volume to derive organ residence times (equivalent time that unit activity spends in that organ per injected unit activity). These values were used as source organs for input to OLINDA/EXM 1.1 using both the mean residence times over all subjects, as well as for each subject individually. The residence times
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Radiation dosimetry and biodistribution in non-human primates of the sodium/iodide PET ligand [18F]-tetrafluoroborate

Radiation dosimetry and biodistribution in non-human primates of the sodium/iodide PET ligand [18F]-tetrafluoroborate

The aims of this work were to perform PET imaging of a non-human primate and to estimate the human absorbed dose before clinical use of [ 18 F]-tetrafluoroborate in human PET studies. Monkeys are genetically closer to humans, so they are supposed to be the closest model of human metabolism. Some PET dosimetry studies with other radiotracers have compared the biodistribution and absorbed radiation dosimetry data obtained from humans and rodents or non-human primates [15, 17, 22, 23]. Des- pite biodistribution patterns being quite similar between species with all radiotracers, human effective dose using monkey data seems to be overestimated, with exposures to individual organs both over- and underestimated de- pending on the radiotracer. For example, Doss et al. [23] state that for the hypoxia marker 18 F-HX4, the effective dose estimated from monkey whole-body imaging is higher (42 mSv/MBq) in comparison with the result ob- tained from humans (27 mSv/MBq) However, as rodents show excretion patterns significantly different from those
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Evaluation of the biodistribution and radiation dosimetry of the 18F-labelled amyloid imaging probe [18F]FACT in humans

Evaluation of the biodistribution and radiation dosimetry of the 18F-labelled amyloid imaging probe [18F]FACT in humans

The Medical Internal Radiation Dose committee of the Society of Nuclear Medicine developed the algorithm to calculate absorbed dose D (the energy deposited per unit mass of medium (Gy)) in organs. The basic idea is that radiation energy from the radioisotope in the source organ is absorbed in the target organs, and the algorithm requires the net accumulated radioactivity in source or- gans as an input [15]. A PET scan contributes to quanti- tative knowledge on the whole-body distribution of radioisotope. In the present study, the accumulated ac- tivity in source organs was derived from PET measure- ments and the organ volumes of the reference male or female. The mean absorbed dose to the kth target organ is defined as follows:
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Biodistribution and radiation dosimetry of the novel hypoxia PET probe [18F]DiFA and comparison with [18F]FMISO

Biodistribution and radiation dosimetry of the novel hypoxia PET probe [18F]DiFA and comparison with [18F]FMISO

In this work, we first evaluated the safety and dosimetric data of [ 18 F]DiFA, a new [ 18 F]FMISO-based derivative with stronger hydrophilicity, in healthy volunteers for its potential use as a hypoxia PET tracer. We found that [ 18 F]DiFA caused no adverse effects after injection and had rapid clearance from the urine and reasonable biodis- tribution and dosimetry profiles in human subjects. In addition, in our comparison of the abilities of [ 18 F]DiFA and [ 18 F]FMISO to diagnose tumor hypoxia, we found that the diagnostic abilities were approximately equivalent, and good inter-observer reproducibility was observed even though there was a shorter time from the injection to the scan with the use of [ 18 F]DiFA.
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Biodistribution and radiation dosimetry of [64Cu]copper dichloride: first-in-human study in healthy volunteers

Biodistribution and radiation dosimetry of [64Cu]copper dichloride: first-in-human study in healthy volunteers

agent for the treatment of tumors; however, dosimetry estimations from human distribution data suggest that critical organs such as liver, kidney, pancreas, and intes- tines, would allow the administration of therapeutic ac- tivities of 64 Cu, on the order of several GBq (hundreds of mCi), without jeopardizing the function of these organs as shown in Table 4. The same applies to other radiosensitive organs and tissues such as gonads and red bone marrow. Note from Table 4 that the effective doses of [ 64 Cu]CuCl 2 are similar to those estimated for 177

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Radiation dosimetry of 18F-FDG PET/CT: incorporating exam-specific parameters in dose estimates

Radiation dosimetry of 18F-FDG PET/CT: incorporating exam-specific parameters in dose estimates

diagnostic CT may be more or less than the radiation dose from a diagnostic PET/CT. Intuitively, a PET/CT with diagnostic technique compared to a standard PET/CT with separately acquired diagnostic CT may appear to be qualitatively equivalent but dosimetrically different be- cause the PET/CT with diagnostic technique CT can also be used for attenuation correction. CT dose from the standard PET/CT appears to be in addition to the dose from the separate diagnostic CT. However, differences in PET/CT and CT scanner hardware and software can cause the dose to be higher or lower. For example, the number of slices is typically different between dual- and single- modality units, and adaptive filtering may not available on PET/CT machines. Both hardware and software factors can cause the patient dose from a combined scan to be higher or lower than separately acquired scans and must be considered when evaluating the dose at a given clinic with reference or literature doses. Less variation is ob- served in reported PET dose that is estimated from a sin- gle source, such as ICRP 106. Even the standards at an imaging clinic for uptake time and acquisition time can affect dose by influencing injected activity. A busy clinic with a fixed injected activity per patient, for example, may administer relatively more activity to account for the inev- itable changes in scheduling that come with patient can- cellations, delays and other impacts on timing. There is evidence, however, that weight- or BMI-adjusted injected activity reduces patient dose and staff exposure without compromising image quality [44]. A busy clinic may also benefit from a relatively higher injected activity to shorten the acquisition time, as PET acquisition is based on total counts in a bed field and more activity results in the total counts achieved relatively sooner.
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THE METABOLISM OF GLYCINE 2 C14 IN MAN  III  THE URINARY EXCRETION OF C14 AND CUMULATIVE RADIATION DOSIMETRY

THE METABOLISM OF GLYCINE 2 C14 IN MAN III THE URINARY EXCRETION OF C14 AND CUMULATIVE RADIATION DOSIMETRY

the administration of 100 microcuries of carbon-14 the mean radiation dose falls by 40 days to 0.3 mrep/day which is an average "normal" dosage rate.. The data listed in Table II were in[r]

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Radiation Dosimetry By Tlds Inside Human Body Phantom While Using 192Ir HDR In Breast Brachytherapy

Radiation Dosimetry By Tlds Inside Human Body Phantom While Using 192Ir HDR In Breast Brachytherapy

Radiation describes electromagnetic waves, electrons, natural radioactivity, and x-rays. It refers to the atomic and subatomic particles and the whole of electromagnetic spectrum. There are two types of radiation; ionizing radiation can ionize a material it passes through and non ionizing radiation has a wavelength of 1 nm or longer, like radiowaves, visible light, microwaves, and ultraviolet light; the rest is ionizing radiations. Radiation emission is a release of any amount of energy by a system, the maximum energies calculated for alpha, beta, gamma, neutron, and heavy ions are 20, 10, 20, 15, and 100 MeV respectively, all radiation emissions obey quantum mechanics roles [1]. The first use of absorbed dose as the energy deposited per mass was 1950 by ICRU to provide appropriate metric to the biological effect of ionizing radiation in many applications; later, ICRU took into account the stochastic quantities to describe the energy depositions like lineal energy and energy imparted. Different types of radiations have different biological effects; radiation quality referred to the relative biological effectiveness (RBE) was used to describe the absorbed dose of gamma radiation or X rays as references to that of the used radiation at the same biological outcomes. ICRU introduced the quality factor which is a function of linear energy transfer (LET) of certain type of radiation, the choice of its values was depending on the RBE experimental ranges of biological objects and their endpoints [2].
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Method dependence, observer variability and kidney volumes in radiation dosimetry of 177Lu-DOTATATE therapy in patients with neuroendocrine tumours

Method dependence, observer variability and kidney volumes in radiation dosimetry of 177Lu-DOTATATE therapy in patients with neuroendocrine tumours

During the last decades, cancer survival in general has improved [1]. Several reports sug- gesting improved outcome in patients responding to PRRT have been published [2 – 4]. This is true for all treatment modalities including surgery, chemotherapy and radiation therapy. It has been shown that patients with somatostatin receptor positive neuroendo- crine tumours can be treated with good results using peptide receptor radionuclide therapy (PRRT) with 177 Lu-DOTA-D-Phe1-Tyr3-octreotate ( 177 Lu-DOTATATE) [3 – 7]. The thera- peutic effect is correlated to the delivered absorbed dose to the tumours for external beam radiation therapy (EBRT) and the same effect has been shown also for systemic treatment with ionizing radiation resulting from PRRT using 90 Y-[DOTA]-D-Phe1-Tyr3-octreotide ( 90 Y-DOTATOC) [8], and more recently in the case of pancreatic NETs using
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