scholarly journals Human biodistribution and internal dosimetry of 4-[ 18F]fluorobenzyl-dexetimide: a PET radiopharmaceutical for imaging muscarinic acetylcholine receptors in the brain and heart

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Cameron D. Pain ◽  
Graeme J. O’Keefe ◽  
Uwe Ackermann ◽  
Vincent Dore ◽  
Victor L. Villemagne ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Effective Dose ◽  
Muscarinic Receptors ◽  
Left Ventricular ◽  
Whole Body ◽  
Myocardial Uptake ◽  
Parasympathetic Innervation ◽  
Time Activity ◽  
The Brain

Abstract Background 4-[18F] fluorobenzyl dexetimide (F-DEX) is the first non-subtype selective fluorine-18 labelled tracer for muscarinic receptors (mAChR) used in humans. A recent first-in-human study found high regional brain uptake with low variation in normal subjects. Disturbance of mAChR has been reported in Alzheimer’s and Parkinson’s disease, schizophrenia and depression and various cardiac diseases. The following work assesses the biodistribution, organ tracer kinetics and radiation dose associated with F-DEX. Method Dose calculations were based on activity uptake derived from multiple time point whole body PET CT imaging and the organ-specific dosimetric S-factors derived from the ICRP 133 standard man and woman mathematical phantoms. Effective doses were calculated using the latest ICRP tissue weighting factors. Results Serial images and time activity curves demonstrate high brain and left ventricular myocardial uptake (5% and 0.65% of injected activity, respectively) with greater retention in brain than myocardium. The mean effective dose was in concordance with other 18F labelled tracers at 19.70 ± 2.27 μSv/MBq. The largest absorbed doses were in the liver (52.91 ± 1.46 μGy/MBq) and heart wall (43.94 ± 12.88 μGy/MBq) for standard man and the liver (61.66 ± 13.61 μGy/MBq) and lungs (40.93 ± 3.11 μGy/MBq) for standard woman. The absorbed dose to all organs, most notably, the red bone marrow (20.03 ± 2.89 μGy/MBq) was sufficiently low to ensure no toxicity after numerous follow-up procedures. Conclusions The radiation dose associated with an administration of F-DEX is comparable to that of other 18F labelled tracers such as FDG (19.0 μSv/MBq) and lower than tracers used for SPECT imaging of muscarinic receptors (I-DEX 28.5 μSv/MBq). Clinical use would likely result in an effective dose less than 4 mSv for the ICRP 133 standard phantoms after dose optimisation allowing justification for numerous follow-up procedures. Recent results from first in-human studies and a comparatively low radiation dose make F-DEX an attractive option for future applications of imaging muscarinic receptors in the brain. Further investigation of the potential of F-DEX for imaging parasympathetic innervation of the heart may be warranted.

scholarly journals Is Biological Effective Dose (BED) Predictive of Outcomes After Radiosurgery for Cerebral Arteriovenous Malformations?

Neurosurgery ◽  
2019 ◽  
Vol 66 (Supplement_1) ◽  
Author(s):  
Cody L Nesvick ◽  
Christopher S Graffeo ◽  
Michael J Link ◽  
Bruce E Pollock
Keyword(s):  
Radiation Dose ◽  
Effective Dose ◽  
Arteriovenous Malformations ◽  
Cox Regression ◽  
Treatment Time ◽  
Continuous Variable ◽  
Biological Effective Dose ◽  
Excellent Outcome

Abstract INTRODUCTION Reports have shown that radiation dose directly correlates with the chance of nidus obliteration after stereotactic radiosurgery (SRS) for arteriovenous malformations (AVMs). However, recent studies have shown that the rate of obliteration was greater in patients having SRS before 2000. As the effect of radiation on cell viability is both dose- and time-dependent, one explanation may be that contemporary SRS, which utilizes more isocenters of radiation to improve dose conformality, takes longer to deliver the same radiation dose, thereby reducing its effectiveness. Biological effective dose (BED) is a metric that incorporates both dose and treatment time and has been shown to correlate with enhanced cell kill in Vitro, as well as normal tissue toxicity in animal models. METHODS A retrospective study of patients having single-session AVM SRS between 1990 and 2009 with a minimum of 2 yr follow-up. Excluded were patients having prior radiation or embolization, as well as patients having volume-staged SRS. BED was calculated using the mono-exponential model described by Jones and Hopewell. The primary outcomes of the study were time to obliteration and chance of excellent outcome (nidus obliteration with no new deficits). RESULTS Three hundred twenty-one patients (328 AVMs) met inclusion criteria (median follow-up, 6.7 yr). BED was associated with both decreased time to obliteration and excellent outcome in univariate Cox regression analyses, both when treated as a dichotomous (P = .002, HR = 1.51 for obliteration; P = .001, HR = 1.61 for outcome) or continuous variable (P = .049, HR = 1.002 for obliteration; P = .01, HR = 1.00 for outcome). In multivariable analyses including dichotomized BED and modified Radiosurgery-Based Arteriovenous Malformation Score as covariates, BED remained significantly associated with both time to obliteration (P = .01, HR = 1.46) and excellent outcome (P = .04, HR = 1.40). CONCLUSION BED was predictive of outcomes after AVM SRS. Further study is warranted to determine whether BED optimization should be considered as well as a prescribed treatment dose for SRS treatment planning.

EFFECTS OF THE SCAN RANGE ON RADIATION DOSE IN THE COMPUTED TOMOGRAPHY COMPONENT OF ONCOLOGY POSITRON EMISSION TOMOGRAPHY/COMPUTED TOMOGRAPHY

2018 ◽  
Vol 185 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Yusuke Inoue ◽  
Kazunori Nagahara ◽  
Hiroko Kudo ◽  
Hiroyasu Itoh
Keyword(s):  
Computed Tomography ◽  
Positron Emission Tomography ◽  
Radiation Dose ◽  
Effective Dose ◽  
The Body ◽  
Emission Tomography ◽  
Whole Body ◽  
Computed Tomography Images ◽  
Positron Emission ◽  
Proximal Thigh

Abstract We performed phantom experiments to investigate radiation dose in the computed tomography component of oncology positron emission tomography/computed tomography in relation to the scan range. Computed tomography images of an anthropomorphic whole-body phantom were obtained from the head top to the feet, from the head top to the proximal thigh or from the skull base to the proximal thigh. Automatic exposure control using the posteroanterior and lateral scout images offered reasonable tube current modulation corresponding to the body thickness. However, when the posteroanterior scout alone was used, unexpectedly high current was applied in the head and upper chest. When effective dose was calculated on a region-by-region basis, it did not differ greatly irrespective of the scan range. In contrary, when effective dose was estimated simply by multiplying the scanner-derived dose-length product by a single conversion factor, estimates increased definitely with the scan range, indicating severe overestimation in whole-body imaging.

Tc-99m-Tetrofosmin Scintigraphy: An Alternative Scintigraphic Method for Following up Differentiated Thyroid Carcinoma

1996 ◽  
Vol 35 (06) ◽  
pp. 230-265 ◽  
Author(s):  
E. Kresnik ◽  
P. Mikosch ◽  
W. Pipam ◽  
Iris Gomez ◽  
P. Lind ◽  
...  
Keyword(s):  
Thyroid Carcinoma ◽  
Imaging Modality ◽  
Region Of Interest ◽  
Differentiated Thyroid Carcinoma ◽  
Whole Body ◽  
High Dose ◽  
Post Injection ◽  
Detection Rates ◽  
Time Activity

Summary Aim: The usefulness of the myocardial perfusion agent, Tc-99m-tetrofosmin (Myoview®) in the follow-up of differentiated thyroid carcinoma was evaluated in a clinical study of 15 patients, primary treated with thyroidectomy and high-dose I-131-therapy (2960-3700 MBq), 12 with suspected recurrence and metastases and three patients without any suspicion and compared with other non-specific tracers like TI-201 and Tc-99m-sestamibi. Method: Twelve patients with elevated thyroglobulin (Tg) levels of more than 10 ng/ml (group A), four of these had negative I-131 scans, and three patients with Tg levels less than 10 ng/ml (group B) were examined under TSH suppressive L-Thyroxine treatment. Whole body scans were taken with TI-201 (74 MBq; 20 min post injection), Tc-99m-sestamibi (370 MBq; 20-60 min post injection) and Tc-99m-tetrofosmin (370 MBq; 20-60 min post injection). Tumor/background ratios and optional time/activity analyses (up to 150 min post injection) were evaluated using the region of interest approach. Results: Compared with TI-201 (T/BG: 1.59, ± 0.396), Tc-99m-tetrofosmin showed slightly but not significant better T/BG ratios and detection rates (T/BG: 1.76, ± 0.345).Tc-99m-sestamibi (1.51, ± 0.31 p = 0.05) showea significantly lower values than Tc-99m-tetrofosmin. Conclusion: In the light of these results, scintigraphy with Tc-99m-tetrofosmin seems to be a possibly sensitive imaging modality in the follow-up of DTC with possible advantages concerning T/Bg ratio, background clearance, detection rate and dosimetry compared with TI-201 and Tc-99m-sestamibi, especially in patients with elevated Tg level and no iodine uptake , but further investigations are needed to confirm our preliminary results.

Measurement of lower-leg volume change by quantitative computed tomography

2008 ◽  
Vol 49 (9) ◽  
pp. 1024-1030 ◽  
Author(s):  
J.-E. Angelhed ◽  
L. Strid ◽  
E. Bergelin ◽  
B. Fagerberg
Keyword(s):  
Computed Tomography ◽  
Adipose Tissue ◽  
Radiation Dose ◽  
Effective Dose ◽  
Background Radiation ◽  
Quantitative Computed Tomography ◽  
Lower Leg ◽  
Whole Body ◽  
Common Symptom ◽  
Effective Radiation Dose

Background: Lower-leg edema is a common symptom in many diseases. A precise method with low variability for measurement of edema is warranted in order to obtain optimal conditions for investigation of treatment effects. Purpose: To evaluate computed tomography for precise measurement of lower-leg muscle and adipose tissue volumes using a very low level of effective radiation dose. Material and Methods: Eleven volunteers were examined three times during 1 day, either as two consecutive examinations in the morning and one single examination in the afternoon, or as one examination in the morning and two in the afternoon. Eleven scans with computed tomography were made at each examination, and lower-leg volumes were calculated from automatically measured scan areas and interscan distances. Volumes for muscle, adipose tissue, and bone were calculated separately. Minimal radiation dose was used. Results: Mean difference between the repeated examinations was −0.1 ml for total volume, −1.4 ml for muscle, and 1.6 ml for adipose tissue volume. The corresponding 95% confidence intervals were −6.5 to 6.0 ml, −3.5 to 6.5 ml, and −7.0 to 4.0 ml, respectively. The resulting effective dose was 0.5 µSv to one leg. Conclusion: Computed tomography can be used as a precise quantitative method to measure small volume changes of the lower leg as a whole, and separately for muscle and adipose tissue. The results were obtained with a negligible effective dose, lower than that delivered by modern fan-beam dual-energy X-ray absorptiometry whole-body examinations and equal to a few hours of background radiation.

ESTIMATION OF RADIATION DOSE IN CT VENOGRAPHY OF THE LOWER EXTREMITIES: PHANTOM EXPERIMENTS USING DIFFERENT AUTOMATIC EXPOSURE CONTROL SETTINGS AND SCAN RANGES

2019 ◽  
Vol 188 (1) ◽  
pp. 109-116
Author(s):  
Yusuke Inoue ◽  
Hiroyasu Itoh ◽  
Kazunori Nagahara ◽  
Yuka Takahashi
Keyword(s):  
Radiation Dose ◽  
Effective Dose ◽  
Lower Extremities ◽  
Whole Body ◽  
Exposure Control ◽  
Automatic Exposure Control ◽  
Dose Length Product ◽  
Ct Venography ◽  
Tube Current ◽  
Phantom Experiments

Abstract We performed phantom experiments to assess radiation dose in computed tomography (CT) venography of the lower extremities. CT images of a whole-body phantom were acquired using different automatic exposure control settings and scan ranges, simulating CT venography. Tube current decreased in the lower extremities compared to the trunk. The scout direction and dose modulation strength affected tube current, dose length product (DLP) and effective dose. The middle and distal portions of the lower extremities contributed substantially to DLP but not to effective dose. When effective dose was estimated by multiplying DLP by a single conversion factor, overestimation was evident; this became more pronounced as the scan range narrowed. In CT venography of the lower extremities, the scout direction and modulation strength affect radiation dose. Use of DLP severely overestimates radiation dose and underestimates effects of scan range narrowing.

scholarly journals Cumulative radiation dose estimation from recurrent CT scan in adult patients with history of cancer in AL Dywanyia city.

2018 ◽  
Vol 9 (SPL1) ◽  
Author(s):  
Amjaad Majeed ◽  
Dergham Majeed Hameed
Keyword(s):  
Radiation Dose ◽  
Ct Scan ◽  
Effective Dose ◽  
Mri Imaging ◽  
Biological Effective Dose ◽  
Risk Of Malignancy ◽  
Cumulative Radiation Dose ◽  
Radiation Worker ◽  
History Of

Radiation dose from diagnostic imaging techniquesis not monitoring in patients undergorecurrent exposure to radio-diagnosis imaging like X-ray, computed tomography (CT scan) & angiography. Evidence suggest an increased lifetime risk of malignancy of 1% per 100 milisevert (mSv),the recommendation in BEIR 7 report (Seventh Biologic Effect of Ionizing Radiation ) are to restrict healthcare and radiation worker to maximum dose of 20 mSv per year or to 100 mSv over three years period. To estimate the biological effective dose, cumulative radiation dose & risk of malignancy in patients with cancerwho expose to recurrent CT scan for tumor follow up. A prospective studyfrom January 2015 –January 2018 was performed at about 50 patients who have history of malignancy,calculating the biological effective dose in mSv from data obtainedfrom CT software (patient protocol ), than calculating cumulative dose & summationof dose over three years From 50 patients 37of them werefemale & 26% of them were male. Age range 23- 80yr& age mean 55yr,22 (44%) of patients exposed to more than 100mSv in three years, & 29 (58% ) of them are within category 3 b which mean they exposed to the maximum allowed dose level according to (BEIR 7) report, 4% of them are within 3a classification,30% within 2b (have moderate level of risk)& 8% within 2a (intermediate level of riskfor oncologist: balancethe importance of the diagnosis againstpatient cumulativedose exposure should be done in each patient before CT is requested,recordingthe no. type & time of exposed to radiation imaging techniques.For radiologist & radiographer : close follow up & recording ofthe biological radiation dose for each patients who have frequent CT Scan. In machine design: No. of approach should be done in patients who have repeated exposed to CT scan includedtechnical development Special care should be pay to the patient who previously exposed to radiation & are likely to be frequently image in futures. In some case,we can replaced CT scan by MRI imaging for tumor follow up.

scholarly journals Biodistribution and radiation dosimetry of the positron emission tomography probe for AMPA receptor, [11C]K-2, in healthy human subjects

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mai Hatano ◽  
Tomoyuki Miyazaki ◽  
Yoshinobu Ishiwata ◽  
Waki Nakajima ◽  
Tetsu Arisawa ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Effective Dose ◽  
Human Subjects ◽  
Whole Body ◽  
Single Subject ◽  
Radiation Doses ◽  
Healthy Human ◽  
Positron Emission ◽  
Healthy Human Subjects ◽  
Human Brains

Abstract[11C]K-2, a radiotracer exhibiting high affinity and selectivity for α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs), is suitable for the quantification of AMPARs in living human brains and potentially useful in the identification of epileptogenic foci in patients. This study aimed to estimate the radiation doses of [11C]K-2 in various organs and calculate the effective dose after injection of [11C]K-2 in healthy human subjects. Twelve healthy male subjects were registered and divided into two groups (370 or 555 MBq of [11C]K-2), followed by 2 h whole-body scans. We estimated the radiation dose of each organ and then calculated the effective dose for each subject. The highest uptake of [11C]K-2 was observed in the liver, while the brain also showed relatively high uptake. The urinary bladder exhibited the highest radiation dose. The kidneys and liver also showed high radiation doses after [11C]K-2 injections. The effective dose of [11C]K-2 ranged from 5.0 to 5.2 μSv/MBq. Our findings suggest that [11C]K-2 is safe in terms of the radiation dose and adverse effects. The injection of 370–555 MBq (10 to 15 mCi) for PET studies using this radiotracer is applicable in healthy human subjects and enables serial PET scans in a single subject.

Para-[123I]iodo-L-phenylalanine in patients with pancreatic adenocarcinoma

2008 ◽  
Vol 47 (05) ◽  
pp. 220-224 ◽  
Author(s):  
E. Gouverneur ◽  
A. Schaefer ◽  
J. Raedle ◽  
M. Menges ◽  
C.-M. Kirsch ◽  
...  
Keyword(s):  
Effective Dose ◽  
Brain Tumour ◽  
Pancreatic Adenocarcinoma ◽  
Bladder Wall ◽  
Whole Body ◽  
Residence Times ◽  
Tumour Imaging ◽  
Time Activity ◽  
Tumour Uptake ◽  
Absorbed Doses

SummaryRecently, p-[123I]iodo-L-phenylalanine (IPA) was clinically validated for brain tumour imaging. Preclinical studies demonstrated uptake of IPA into pancreatic adenocarcinoma suggesting its diagnostic application in patients with pancreatic tumours. The aim was to study the tumour uptake of IPA in patients with pancreatic adenocarcinoma and to analyse its biodistribution and dosimetry to assess the radiation dose resulting from its diagnostic use. Patients, methods: Seven patients with pancreatic adenocarcinoma underwent whole-body scintigraphies and SPECT up to 24 h after administration of 250 MBq of IPA. Tumour uptake of IPA was assessed visually. Time activity curves and the corresponding residence times were determined for whole-body, kidneys, liver, spleen, lung, heart content, brain, and testes. Mean absorbed doses for various organs and the effective dose were assessed based on the MIRD formalism using OLINDA/EXM. Results: IPA exhibited no accumulation in proven manifestations of pancreatic adenocarcinomas. IPA was exclusively eliminated by the urine and showed a delayed clearance from blood. Residence times were 0.26 ± 0.09 h for kidneys, 0.38 ± 0.19 h for liver, 0.15 ± 0.07 h for spleen, 0.51 ± 0.20 h for lungs, 0.22 ± 0.07 h for heart content, 0.11 ± 0.05 h for brain, 0.014 ± 0.005 h for testes and 6.4 ± 2.2 h for the remainder. The highest absorbed doses were determined in the urinary bladder wall and in the kidneys. According to the ICRP 60 the effective dose resulting from 250 MBq IPA was 3.6 ± 0.7 mSv. Conclusion: Para-[123I]iodo-L-phenylalanine can be used in diagnostic nuclear medicine with acceptable radiation doses. Besides its proven validity for brain tumour imaging, IPA does not appear to be suitable as tracer for pancreatic cancer.

scholarly journals Comparison of 111In Leakage from Labeled Endocardial and Epicardial Cells: Impact on Modeling Viability of Cells to Be Transplanted into Myocardium

2011 ◽  
Vol 2011 ◽  
pp. 1-8
Author(s):  
Kimberley J. Blackwood ◽  
Jane Sykes ◽  
Lela Deans ◽  
Gerald Wisenberg ◽  
Frank S. Prato
Keyword(s):  
Impulse Response Function ◽  
Whole Body ◽  
Parameter Estimates ◽  
Time Activity ◽  
Epicardial Cells ◽  
Injection Type ◽  
Indium 111 ◽  
Leakage Coefficient

Introduction. Previously we proposed a cellular imaging technique to determine the surviving fraction of transplanted cells in vivo. Epicardial kinetics using Indium-111 determined the Debris Impulse Response Function (DIRF) and leakage coefficient parameters. Convolution-based modeling which corrected for these signal contributions indicated that 111In activity was quantitative of cell viability with half-lives within 20 hrs to 37 days. We determine if the 37-day upper limit remains valid for endocardial injections by comparing previous epicardial cell leakage parameter estimates to those for endocardial cells. Methods. Normal canine myocardium was injected (111In-tropolone) epicardially (9 injections) or endocardially (10 injections). Continuous whole body and SPECT scans for 5 hours were acquired with three weekly follow-up imaging sessions up to 20–26 days. Time-activity curves evaluated each injection type. Results. The epicardial and endocardial kinetics were not significantly different (Epi: 1286±253; Endo: 1567±470 hours P=.62). Conclusion. The original epicardial estimate of leakage kinetics has been validated for use in endocardial injections.

Radiation dose and incidence of new metastasis in the anterior temporal lobe structures of radiosurgically treated patients

2010 ◽  
Vol 112 (1) ◽  
pp. 122-129 ◽  
Author(s):  
Bhuvaneswara R. Basina ◽  
Claire Olson ◽  
Dibyendu Kumar Roy ◽  
Chun-Po Yen ◽  
David Schlesinger ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Mr Imaging ◽  
Brain Tissue ◽  
Gamma Knife ◽  
Brain Lesions ◽  
Gamma Knife Surgery ◽  
Temporal Lobes ◽  
Temporal Structures ◽  
The Brain

Object Gamma Knife surgery (GKS) is frequently used to treat patients with metastasis to the brain. Radiosurgery seeks to limit radiation to the brain tissue surrounding the metastatic deposits. In patients with such lesions, a low radiation dose to the eloquent brain may help to prevent adverse effects. In this study the authors aimed to quantify the radiosurgical dose delivered to the anterior temporal structures in cases of metastatic brain lesions. They also evaluated the incidence and timing of new metastases in the anterior temporal lobes (ATLs) in patient cohorts that underwent GKS with or without whole-brain radiation therapy (WBRT). Methods The authors retrospectively analyzed 100 patients with metastatic brain lesions treated with GKS at the University of Virginia Health System. The anterior 5 cm of the temporal lobes and the hippocampi within the ATLs were contoured on the Gamma Knife planning station. Using the dose-volume histogram function in GammaPlan, treatment parameters for the metastases as well as radiation doses to the contoured ATLs and hippocampi were measured. Patients had clinical and MR imaging follow-ups at 3-month intervals. The ATLs and hippocampal regions were evaluated for the formation of new metastases on follow-up imaging. Results The demographic data—age, sex, Karnofsky Performance Scale score, number of temporal metastases at the time of GKS, total volume of metastatic tumors per patient, and number of intracranial metastatic deposits—were similar in the 2 cohorts. In patients without an ATL metastasis at the time of GKS, the mean maximum, 50% volume, and integral doses of radiation to the anterior temporal structures were very low: 2.6 Gy, 0.6 Gy, and 36.3 mJ in the GKS cohort and 2.1 Gy, 0.6 Gy, and 40.9 mJ in the GKS+WBRT cohort, respectively. Among the ATLs that had not shown a brain metastasis at the time of GKS, 8 of 92 temporal lobes in the GKS cohort and 10 of 89 in the GKS+WBRT cohort demonstrated a new anterior temporal lesion on follow-up MR imaging. Conclusions Gamma Knife surgery delivered a low dose of background radiation to the ATLs and hippocampi. The incidence of a new ATL metastasis in the GKS cohort was not higher than in the GKS+WBRT cohort. Gamma Knife surgery in the management of brain metastases limits the delivery of radiation to eloquent brain tissue without evidence of an appreciable propensity to develop new metastatic disease in the ATLs or hippocampi. This therapeutic approach may help to avoid unintended neurological dysfunction due to nonspecific delivery of radiation to eloquent brain tissues.

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