scholarly journals Improved Patient Dosimetry at Radioiodine Therapy by Combining the ICRP Compartment Model and the EANM Pre-Therapeutic Standard Procedure for Benign Thyroid Diseases

2021 ◽  
Vol 12 ◽  
Author(s):  
Martin Andersson ◽  
Sören Mattsson
Keyword(s):  
Standard Procedure ◽  
Absorbed Dose ◽  
Compartment Model ◽  
Thyroid Diseases ◽  
The Body ◽  
Whole Body ◽  
Patient Specific ◽  
Transfer Coefficients ◽  
Thyroid Uptake ◽  
Benign Thyroid

Radioactive iodine is commonly used for the treatment of different thyroid conditions since the 1940s. The EANM has developed a standard pre-therapeutic procedure to estimate patient specific thyroid uptake at treatment of benign thyroid diseases. The procedure which models the time dependent fractional thyroid uptake is based on a two-compartment fitting system, one representing the thyroid and the other the blood. The absorbed dose is however only estimated for the thyroid and not for any other organ in the body. A more detailed biokinetic model for iodine is given by the ICRP and includes an iodide transport in the whole body. The ICRP model has 30 different compartments and 48 transfer coefficients to model the biokinetics of iodide and to model different transfer for inorganic iodide and organic iodine. The ICRP model is a recirculation iodine model, and the optimization is performed on the whole model and not exclusively on the thyroid as in the EANM procedure. Combining the EANM method and the ICRP model gives both patient specific estimations of thyroid uptake and retention and include most organs in the body. The new software gives both an improved patient specific dosimetry for the thyroid and an estimation of the absorbed dose to non-target organs and tissues like kidneys, urinary bladder, stomach wall, and uterus. Using the method described in this paper, the repercussions on the daily routines will be minimal.

Removal of Vancomycin during Plasmapheresis

1997 ◽  
Vol 31 (10) ◽  
pp. 1132-1136 ◽  
Author(s):  
Syble D McClellan ◽  
Charles H Whitaker ◽  
Richard C Friedberg
Keyword(s):  
Tertiary Care ◽  
Compartment Model ◽  
The Body ◽  
Patient Specific ◽  
Pharmacokinetic Parameters ◽  
Serum Concentrations ◽  
Total Clearance ◽  
Concentration Data ◽  
Vancomycin Concentration ◽  
Total Body

OBJECTIVE: To examine the removal of vancomycin during plasmapheresis, determine whether drug administration should be withheld prior to or a supplemental dose given after the procedure, and determine whether a redistribution phenomenon in vancomycin serum concentrations occurs after plasmapheresis. DESIGN: Prospective, cohort study. SETTING: An 800-bed, tertiary-care, teaching hospital. PATIENTS: Twelve patients receiving vancomycin as prescribed who were also undergoing therapeutic plasmapheresis. METHODS: Blood samples for determination of vancomycin concentrations were obtained from each patient immediately before, during, immediately after, and 2 hours after plasmapheresis. Vancomycin concentration in plasma removed by plasmapheresis and volume of plasma removed were measured. Patient-specific pharmacokinetic parameters were determined for each patient using serum concentration data and a one-compartment model. Percent of drug removed by plasmapheresis and percent increase in vancomycin total clearance secondary to plasmapheresis were calculated. RESULTS: A mean of 6.3% of the total body store of vancomycin was removed by plasmapheresis. Vancomycin clearance during plasmapheresis averaged 1.6 L/h, which was an average increase of 285% in the total clearance of vancomycin from the body. Nine of 10 patients had a higher observed vancomycin concentration 2 hours after plasmapheresis than that predicted by degrading the concentration observed immediately after the procedure, suggesting that redistribution in serum concentrations occurs after the procedure. CONCLUSIONS: A single one-volume plasmapheresis does not remove a clinically important amount of vancomycin; therefore, supplemental dosing after the procedure is not necessary. A redistribution phenomenon in vancomycin concentrations appears to exist after plasmapheresis. Further study is needed to determine how long the redistribution phase lasts and when vancomycin concentrations should be measured after plasmapheresis.

On Some Methodological Issues of Studying Cytogenetic Effects in Cancer Patients Treated with Neutron Therapy Using U-120 Cyclotron

2018 ◽  
Vol 63 (2) ◽  
pp. 47-54
Author(s):  
В. Лисин ◽  
V. Lisin
Keyword(s):  
Radiation Field ◽  
Chromosome Aberrations ◽  
Absorbed Dose ◽  
Neutron Radiation ◽  
The Body ◽  
Beam Intensity ◽  
Whole Body ◽  
Γ Radiation ◽  
Cytogenetic Effect ◽  
Tissue Equivalent

Purpose: To study dosimetric characteristics of neutron radiation field, to determine their role in the formation of the total cytogenetic effect in the patient’s body and to assess the cytogenetic dosimetry capabilities in improving the quality of NT. Material and methods: A therapeutic beam with the average neutron energy of ~6.3 MeV was obtained from the V-120 cyclotron. The radiation field of the beam was investigated with the help of two ionization chambers with different sensitivity to neutrons. Chamber with high and low sensitivities were made of polyethylene and graphite, respectively. To exclude the uncertainty associated with the change in beam intensity in time, a dosimeter monitor operating in the integral mode was used. Results: The dependence of the monitor factor on the irradiated area was measured. The distributions of the absorbed dose of neutrons and γ-radiation over the depth of the tissue-equivalent medium were found. The contribution of γ-radiation to the neutron dose was increased from ~10 % at the entry to the medium to ~30 % at a depth of 16 cm. Dose distributions of scattered neutron and γ-radiation in the plane of the end face of the forming device were obtained. The contribution of these radiations to the dose received by the patient’s body was estimated. This contribution was shown to be comparable with that from the therapeutic beam. The analysis of the influence of NT on the estimation of the frequency of chromosome aberrations in the blood of patients was carried out. Conclusion: The frequency of chromosome aberrations in the blood of patients was determined by the whole-body dose, including dose due to scattered radiation. When using equal focal doses, the cytogenetic effect was found to be dependent on the area of the irradiated field and the depth of the tumor in the patient’s body. The differences in the RBE of neutrons and γ-radiation as well as the instability of the therapeutic neutron beam intensity create uncertainties that do not allow for the necessary control over the doses using the cytogenetic dosimetry. Therefore, cytogenetic dosimetry should be combined with an effective instrument dosimetry method. The use of biodosimetry based on the assessment of the frequency of chromosome aberrations is promising for controlling the average whole-body dose, on which the overall radiation response of the body depends.

Estimation of [177Lu]PSMA-617 tumor uptake based on voxel-wise 3D Monte Carlo tumor dosimetry in patients with metastasized castration resistant prostate cancer

2020 ◽  
Vol 59 (05) ◽  
pp. 365-374
Author(s):  
Theresa Ida Götz ◽  
Elmar Wolfgang Lang ◽  
Olaf Prante ◽  
Michael Cordes ◽  
Torsten Kuwert ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Monte Carlo ◽  
Three Dimensional ◽  
Absorbed Dose ◽  
Whole Body ◽  
Patient Specific ◽  
Average Dose ◽  
Castration Resistant Prostate Cancer ◽  
Castration Resistant ◽  
Before And After

Abstract Objective Patients with advanced prostate cancer are suitable candidates for [177Lu]PSMA-617 therapy. Integrated SPECT/CT systems have the potential to improve the accuracy of patient-specific tumor dosimetry. We present a novel patient-specific Monte Carlo based voxel-wise dosimetry approach to determine organ and total tumor doses (TTD). Methods 13 patients with histologically confirmed metastasized castration-resistant prostate cancer were treated with a total of 18 cycles of [177Lu]PSMA-617 therapy. In each patient, dosimetry was performed after the first cycle of [177Lu]PSMA-617 therapy. Regions of interest were defined manually on the SPECT/CT images for the kidneys, spleen and all 295 PSMA-positive tumor lesions in the field of view. The absorbed dose to normal organs and to all tumor lesions were calculated by a three dimensional dosimetry method based on Monte Carlo Simulations. Results The average dose values yielded the following results: 2.59 ± 0.63 Gy (1.67–3.92 Gy) for the kidneys, 0.79 ± 0.46 Gy (0.31–1.90 Gy) for the spleen and 11.00 ± 11.97 Gy (1.28–49.10 Gy) for all tracer-positive tumor lesions. A trend towards higher TTD was observed in patients with Gleason Scores > 8 compared to Gleason Scores ≤ 8 and in lymph node metastases compared to bone metastases. A significant correlation was determined between the serum-PSA level before RLT and the TTD (r = –0.57, p < 0.05), as well as between the TTD with the percentage change of serum-PSA levels before and after therapy was observed (r = –0.57, p < 0.05). Patients with higher total tumor volumes of PSMA-positive lesions demonstrated significantly lower kidney average dose values (r = –0.58, p < 0.05). Conclusion The presented novel Monte Carlo based voxel-wise dosimetry calculates a patient specific whole-body dose distribution, thus taking into account individual anatomies and tissue compositions showing promising results for the estimation of radiation doses of normal organs and PSMA-positive tumor lesions.

A minimal model for human whole body cholesterol metabolism

1993 ◽  
Vol 265 (3) ◽  
pp. E513-E520
Author(s):  
R. E. Ostlund
Keyword(s):  
Minimal Model ◽  
Cholesterol Metabolism ◽  
Specific Activity ◽  
Clinical Investigation ◽  
Plasma Cholesterol ◽  
Fractional Excretion ◽  
Compartment Model ◽  
The Body ◽  
Whole Body ◽  
Mean Values

Important work by others has shown that human whole body cholesterol metabolism can be described by a three-compartment model computed from plasma cholesterol specific activity after an intravenous infusion of labeled cholesterol. However, some parameters of that model cannot be estimated precisely [coefficient of variation (CV) 15-19% after 40 wk of follow-up], making its use in routine clinical investigation difficult. On the other hand, a simpler two-compartment model can be calculated with excellent precision from only 10 wk of data (CV 2-8%), but its parameters are inaccurate (for example, the size of the central pool is overestimated by 20%, and the rate constant for fractional excretion of cholesterol from the body is underestimated by 15%). Thus both three-compartment and two-compartment models of cholesterol turnover have important limitations. An alternative is provided by a minimal model that takes advantage of the increased precision expected in the solution of models with fewer parameters. A three-compartment structure is used, but only four (rather than 6 or more) parameters are calculated: the mass of the rapidly mixing central cholesterol compartment, the fractional rate of cholesterol elimination from the body, and the average forward and reverse rate constants for cholesterol transfer between the rapid compartment and both slower compartments. Each of these parameters can be determined unambiguously (without the need to use a minimum or maximum estimate), accurately (mean values within 2% of theory), and with precision (CV 3-13%).(ABSTRACT TRUNCATED AT 250 WORDS)

Operational Values of Radioactive Skin Contamination in the Case of Radiological Accident

2020 ◽  
Vol 65 (3) ◽  
pp. 20-26
Author(s):  
M. Grachev ◽  
Yu. Salenko ◽  
Yu. Abramov ◽  
G. Frolov ◽  
V. Klochkov ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Absorbed Dose ◽  
The Body ◽  
Surface Contamination ◽  
Radioactive Material ◽  
Whole Body ◽  
Laboratory Animals ◽  
Intact Skin ◽  
Radioactive Substances ◽  
Skin Contamination

Purpose: Development of recommendations on the use in medical practice of institutions under FMBA of Russia of operational values of radioactive skin contamination in the event of radiological accidents. Material and methods: The easily measured radiation parameters were used as operational values: ambient dose equivalent rate (ADER) of γ-radiation, density of skin contamination with γ-, β- and α-emitting radionuclides. Operational values ​​of skin contamination were estimated on the basis of experimental data described in the literature and models on the kinetics of radioactive substances transport in the body, accepted values ​​of dose criteria for deterministic and stochastic effects. The estimation of radioactive material resorption through the skin was based on the results of experimental studies in laboratory animals (mainly piglets) for a limited set of chemical compounds of radionuclides. Results: The values of γ-ADER of the main dose-forming radionuclides measured at a distance of 10 cm from the skin surface in the range of 10–1000 μSv/h and the possible health effects due to the skin exposure and the intake of radioactive substances into the body were presented. In the IAEA recommendations, the level of skin contamination at 1 µSv/h is considered as a significant operational value according to the criterion of radioactive substances intake through the mouth from the contaminated surface of the hands. However, in our opinion, this estimate is excessively conservative; therefore it is not included in the recommended operational values. If the skin is contaminated with γ-β-emitting radionuclide solutions at a surface contamination higher than 106 Bq/cm2 (ADER ≥1000 µSv/h), the out of turn emergency decontamination should be carried out. Obligatory indications for the whole body counter examination after thorough decontamination and conducting biophysical analysis of bioassay are the following operational values: γ-ADER from the skin > 10 µSv/h; surface contamination of intact skin with β-active radionuclides > 20 000 β-part./(cm2·min); surface contamination of intact skin with α-active radionuclides > 200 α-part./ (cm2·min). Conclusion: The recommended operational values allow preliminarily and promptly to assess the health risk not only in the case of external (contact) exposure of the skin and underlying tissues, but also due to the intake of soluble radioactive substances into the body through intact and damaged (injured) skin. Taking into account the high degree of uncertainty of the estimates obtained, the operational values ​​should be considered as strictly conservative. They should be used only to determinate of urgency of decontamination carrying out for the provision of medical care during the prehospital and early hospital periods with the obligatory follow-up dosimetry examination for the final assessment of absorbed dose.

Absorbed-Dose Specification in Nuclear Medicine: Abstract

2002 ◽  
Vol 2 (1) ◽  
pp. 9-9 ◽  
Author(s):  
S. J. Adelstein ◽  
A. J. Green ◽  
R. W. Howell ◽  
J. L. Humm ◽  
P. K. Leichner ◽  
...  
Keyword(s):  
Nuclear Medicine ◽  
Absorbed Dose ◽  
The Body ◽  
Patient Specific ◽  
Dose Rates ◽  
Uniform Distributions ◽  
Medical Internal Radiation Dose ◽  
Medical Dosimetry ◽  
Dose Responses ◽  
Selection Of

A number of reasons have led to a reappraisal of dose specification for nuclear medicine. These include an appreciation of non-uniformities in the distribution of radioactivity in the body, at all levels, for even the most common diagnostic and therapeutic agents; an increasing need to deal with the complexities of varying dose rates; the imperative to provide individual rather than standardised dose estimates as targeted radionuclide therapy becomes more sophisticated; as well as improvements in technology. This Report deals first with biological considerations that inform the rational use of radionuclide dosimetry. Radiobiological factors in the selection of radionuclides and tumour and normal-tissue dose-responses are discussed. Then, the MIRD (medical internal radiation dose) approach to nuclear medical dosimetry, a robust method that has proven its clinical utility, is described. Following on is an elaboration of non-uniform distributions of radioactivity and of varying dose rates. Lastly, the Report deals with techniques and procedures for measuring time variant activity distributions, image fusion, patient specific dose computations, smallscale dosimetry, and the comparison of calculated and measured doses.

Influence of stable iodine on the uptake of the thyroid – model vs. experiment

2001 ◽  
Vol 40 (01) ◽  
pp. 31-37 ◽  
Author(s):  
U. Wellner ◽  
E. Voth ◽  
H. Schicha ◽  
K. Weber
Keyword(s):  
Time Course ◽  
Compartment Model ◽  
The Body ◽  
Iodine Uptake ◽  
Model Calculations ◽  
Physiological Conditions ◽  
Iodine Supply ◽  
Predicted Values ◽  
The Individual ◽  
Stable Iodine

Summary Aim: The influence of physiological and pharmacological amounts of iodine on the uptake of radioiodine in the thyroid was examined in a 4-compartment model. This model allows equations to be derived describing the distribution of tracer iodine as a function of time. The aim of the study was to compare the predictions of the model with experimental data. Methods: Five euthyroid persons received stable iodine (200 μg, 10 mg). 1-123-uptake into the thyroid was measured with the Nal (Tl)-detector of a body counter under physiological conditions and after application of each dose of additional iodine. Actual measurements and predicted values were compared, taking into account the individual iodine supply as estimated from the thyroid uptake under physiological conditions and data from the literature. Results: Thyroid iodine uptake decreased from 80% under physiological conditions to 50% in individuals with very low iodine supply (15 μg/d) (n = 2). The uptake calculated from the model was 36%. Iodine uptake into the thyroid did not decrease in individuals with typical iodine supply, i.e. for Cologne 65-85 μg/d (n = 3). After application of 10 mg of stable iodine, uptake into the thyroid decreased in all individuals to about 5%, in accordance with the model calculations. Conclusion: Comparison of theoretical predictions with the measured values demonstrated that the model tested is well suited for describing the time course of iodine distribution and uptake within the body. It can now be used to study aspects of iodine metabolism relevant to the pharmacological administration of iodine which cannot be investigated experimentally in humans for ethical and technical reasons.

Guideline for radioiodine therapy for benign thyroid diseases (version 3)

2004 ◽  
Vol 43 (06) ◽  
pp. 217-220 ◽  
Author(s):  
J. Dressler ◽  
F. Grünwald ◽  
B. Leisner ◽  
E. Moser ◽  
Chr. Reiners ◽  
...  
Keyword(s):  
Radioiodine Therapy ◽  
Thyroid Volume ◽  
Thyroid Diseases ◽  
Antithyroid Drugs ◽  
Graves Disease ◽  
Co Morbidity ◽  
History Of ◽  
Individual Decisions ◽  
Prophylactic Use ◽  
Benign Thyroid

SummaryThe version 3 of the guideline for radioiodine therapy for benign thyroid diseases presents first of all a revision of the version 2. The chapter indication for radioiodine therapy, surgical treatment or antithyroid drugs bases on an interdisciplinary consensus. The manifold criteria for decision making consider the entity of thyroid disease (autonomy, Graves’ disease, goitre, goitre recurrence), the thyroid volume, suspicion of malignancy, cystic nodules, risk of surgery and co-morbidity, history of subtotal thyroidectomy, persistent or recurrent thyrotoxicosis caused by Graves’ disease including known risk factors for relapse, compression of the trachea caused by goitre, requirement of direct therapeutic effect as well as the patient’s preference. Because often some of these criteria are relevant, the guideline offers the necessary flexibility for individual decisions. Further topics are patients’ preparation, counseling, dosage concepts, procedural details, results, side effects and follow-up care. The prophylactic use of glucocorticoids during radioiodine therapy in patients without preexisting ophthalmopathy as well as dosage and duration of glucocorticoid medication in patients with preexisting ophthalmopathy need to be clarified in further studies. The pragmatic recommendations for the combined use of radioiodine and glucocorticoids remained unchanged in the 3rd version.

A Simple and Inexpensive Clinical Whole Body Counter

1976 ◽  
Vol 15 (05) ◽  
pp. 248-253
Author(s):  
A. K. Basu ◽  
S. K. Guha ◽  
B. N. Tandon ◽  
M. M. Gupta ◽  
M. ML. Rehani
Keyword(s):  
The Body ◽  
Whole Body ◽  
Vitro Assay ◽  
Body Counter ◽  
Optimum Parameters ◽  
Whole Body Counter ◽  
Single Detector ◽  
Background Index ◽  
Iodide Crystal

SummaryThe conventional radioisotope scanner has been used as a whole body counter. The background index of the system is 10.9 counts per minute per ml of sodium iodide crystal. The sensitivity and derived sensitivity parameters have been evaluated and found to be suitable for clinical studies. The optimum parameters for a single detector at two positions above the lying subject have been obtained. It has been found that for the case of 131I measurement it is possible to assay a source located at any point in the body with coefficient of variation less than 5%. To add to the versatility, a fixed geometry for in-vitro counting of large samples has been obtained. The retention values obtained by the whole body counter have been found to correlate with those obtained by in-vitro assay of urine and stool after intravenous administration of 51Cr-albumin.

Radioiodine treatment of feline hyperthyroidism in Germany

2002 ◽  
Vol 41 (06) ◽  
pp. 245-251 ◽  
Author(s):  
M. Knietsch ◽  
T. Spillmann ◽  
E.-G. Grünbaum ◽  
R. Bauer ◽  
M. Puille
Keyword(s):  
Radiation Exposure ◽  
Radiation Protection ◽  
Thyroid Function ◽  
Radioiodine Therapy ◽  
Whole Body ◽  
Radioiodine Treatment ◽  
Normal Thyroid ◽  
Normal Thyroid Function ◽  
Body Activity ◽  
Thyroid Uptake

SummaryAim: Establishment of radioiodine treatment of feline hyperthyroidism in veterinary routine in accordance with German radiation protection regulations. Patients and methods: 35 cats with proven hyperthyroidism were treated with 131I in a special ward. Thyroid uptake and effective halflife were determined using gammacamera dosimetry. Patients were released when measured whole body activity was below the limit defined in the German “Strahlenschutzverordnung”. Results: 17/20 cats treated with 150 MBq radioiodine and 15/15 cats treated with 250 MBq had normal thyroid function after therapy, normal values for FT3 and FT4 were reached after two and normal TSH levels after three weeks. In 14 cats normal thyroid function was confirmed by controls 3-6 months later. Thyroidal iodine uptake was 24 ± 10%, effective halflife 2.5 ± 0.7 days. Whole body activity <1 MBq was reached 13 ± 4 days after application of 131I. Radiation exposure of cat owners was estimated as 1.97 Sv/MBq for adults. Conclusion: Radioiodine therapy of feline hyper-thyroidism is highly effective and safe. It can easily be performed in accordance with German radiation protection regulations, although this requires hospitalisation for approximately two weeks. Practical considerations on radiation exposure of cat owners do not justify this long interval. Regulations for the veterinary use of radioactive substances similar to existing regulations for medical use in humans are higly desirable.

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