Compartmental model of<sup>18</sup>F-choline

Janzen, Tilman; Tavola, Federico; Giussani, A.; Cantone, Maria Celeste; Uusijärvi, Helena; Mattsson, Sören; Zankl, M.; Petoussi-Henss, Nina; Hoeschen, Christoph

doi:10.1117/12.844219

Cited by 7 publications

(8 citation statements)

References 11 publications

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“…The study presented here represents 1 of the 2 different modeling approaches independently pursued within the project (11). Preliminary results on a smaller set of patients were presented at the 2010 meeting of the International Society for Optics and Photonics SPIE (12).…”

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confidence: 99%

A Compartmental Model for Biokinetics and Dosimetry of¹⁸F-Choline in Prostate Cancer Patients

Giussani

Janzen²,

Uusijärvi-Lizana³

et al. 2012

J Nucl Med

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PET with 18 F-choline ( 18 F-FCH) is used in the diagnosis of prostate cancer and its recurrences. In this work, biodistribution data from a recent study conducted at Skå ne University Hospital Malmö were used for the development of a biokinetic and dosimetric model. Methods: The biodistribution of 18 F-FCH was followed for 10 patients using PET up to 4 h after administration. Activity concentrations in blood and urine samples were also determined. A compartmental model structure was developed, and values of the model parameters were obtained for each single patient and for a reference patient using a population kinetic approach. Radiation doses to the organs were determined using computational (voxel) phantoms for the determination of the S factors. Results: The model structure consists of a central exchange compartment (blood), 2 compartments each for the liver and kidneys, 1 for spleen, 1 for urinary bladder, and 1 generic compartment accounting for the remaining material. The model can successfully describe the individual patients' data. The parameters showing the greatest interindividual variations are the blood volume (the clearance process is rapid, and early blood data are not available for several patients) and the transfer out from liver (the physical half-life of 18 F is too short to follow this long-term process with the necessary accuracy). The organs receiving the highest doses are the kidneys (reference patient, 0.079 mGy/MBq; individual values, 0.033-0.105 mGy/MBq) and the liver (reference patient, 0.062 mGy/MBq; individual values, 0.036-0.082 mGy/MBq). The dose to the urinary bladder wall of the reference patient varies between 0.017 and 0.030 mGy/MBq, depending on the assumptions on bladder voiding. Conclusion: The model gives a satisfactory description of the biodistribution of 18 F-FCH and realistic estimates of the radiation dose received by the patients.

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confidence: 99%

A Compartmental Model for Biokinetics and Dosimetry of¹⁸F-Choline in Prostate Cancer Patients

Giussani

Janzen²,

Uusijärvi-Lizana³

et al. 2012

J Nucl Med

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“…A correction for the counting efficiency at different activity levels was implemented. The distribution data of the radioactivity in the organs and tissues were used to build the compartment model of the 18 F-choline biokinetics in patients [7,9] The blood is the central exchange compartment, where the injected radiopharmaceutical is initially distributed. Compartments representing liver (divided into liver 1 and 2), kidneys (divided into kidneys through and exchange), spleen and urinary bladder were connected to the central compartment blood.…”

Section: The Compartmental Model and Parameters Of 18 F-cholinementioning

confidence: 99%

“…In the process of modeling and determination of model parameters, different software packages were used with different optimization and minimization techniques, and differential equation solvers. Additionally, the population kinetic analysis method was introduced to estimate the mean values and the standard deviations (SD) of model parameters for the participated patients [7] .…”

Section: The Compartmental Model and Parameters Of 18 F-cholinementioning

confidence: 99%

“…The sources of uncertainty of the model parameters were carefully indentified and evaluated using various software packages [7] . The model structure is one uncertainty factor; however this model uncertainty was not analyzed in the present study, because it needs further methods, e.g.…”

Section: Uncertainty Analysis Of Model Input Parametersmentioning

confidence: 99%

“…This method was applied and designed to find out the main uncertainty sources within the dose calculation procedure, so that hardware and software can be optimized to reduce the radiation doses to the patients. As an example, the developed method was applied to the new compartmental model of 18 F-choline [7] . The influence of metabolic pathways represented as model parameters on the patient organ PET images and the blood and urine sample collections was identified.…”

Section: Introductionmentioning

confidence: 99%

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Uncertainties of organ-absorbed doses to patients from¹⁸f-choline

Janzen

Zankl

et al. 2011

SPIE Proceedings

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Radiation doses of radiopharmaceuticals to patients in nuclear medicine are, as the standard method, estimated by the administered activity, medical imaging (e.g. PET imaging), compartmental modeling and Monte Carlo simulation of radiation with reference digital human phantoms. However, in each of the contributing terms, individual uncertainty due to measurement techniques, patient variability and computation methods may propagate to the uncertainties of the calculated organ doses to the individual patient. To evaluate the overall uncertainties and the quality assurance of internal absorbed doses, a method was developed within the framework of the MADEIRA Project (Minimizing Activity and Dose with Enhanced Image quality by Radiopharmaceutical Administrations) to quantitatively analyze the uncertainties in each component of the organ absorbed doses after administration of 18 F-choline to prostate cancer patients undergoing nuclear medicine diagnostics.First, on the basis of the organ PET and CT images of the patients as well as blood and urine samples, a model structure of 18 F-choline was developed and the uncertainties of the model parameters were determined. Second, the model parameter values were sampled and biokinetic modeling using these sampled parameter values were performed. Third, the uncertainties of the new specific absorbed fraction (SAF) values derived with different phantoms representing individual patients were presented. Finally, the uncertainties of absorbed doses to the patients were calculated by applying the ICRP/ICRU adult male reference computational phantom. In addition to the uncertainty analysis, the sensitivity of the model parameters on the organ PET images and absorbed doses was indicated by coupling the model input and output using regression and partial correlation analysis.The results showed that the uncertainty factors of absorbed dose to patients are in most cases less than a factor of 2 without taking into account the uncertainties caused by the variability and uncertainty of individual human phantoms. The sensitivity study showed that the metabolic transfer parameter from the blood to soft tissues has a strong influence on blood sample collection from the beginning until 500 min. post administration; the transfer pathways between blood and liver impact strongly the liver imaging during the time course. The results of this study suggest that organ image acquisition of liver and kidneys after 100 min. as well as blood and urine sample collection are necessary for the reduction of uncertainties of absorbed dose estimates to patients.

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Quantification of internal dosimetry in PET patients II: Individualized Monte Carlo‐based dosimetry for [18F]fluorocholine PET

et al. 2021

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Purpose To obtain individualized internal doses with a Monte Carlo (MC) method in patients undergoing diagnostic [18F]FCH‐PET studies and to compare such doses with the MIRD method calculations. Methods A patient cohort of 17 males were imaged after intravenous administration of a mean [18F]FCH activity of 244.3 MBq. The resulting PET/CT images were processed in order to generate individualized input source and geometry files for dose computation with the MC tool GATE. The resulting dose estimates were studied and compared to the MIRD method with two different computational phantoms. Mass correction of the S‐factors was applied when possible. Potential sources of uncertainty were closely examined: the effect of partial body images, urinary bladder emptying, and biokinetic modeling. Results Large differences in doses between our methodology and the MIRD method were found, generally in the range ±25%, and up to ±120% for some cases. The mass scaling showed improvements, especially for non‐walled and high‐uptake tissues. Simulations of the urinary bladder emptying showed negligible effects on doses to other organs, with the exception of the prostate. Dosimetry based on partial PET/CT images (excluding the legs) resulted in an overestimation of mean doses to bone, skin, and remaining tissues, and minor differences in other organs/tissues. Estimated uncertainties associated with the biokinetics of FCH introduce variations of cumulated activities in the range of ±10% in the high‐uptake organs. Conclusions The MC methodology allows for a higher degree of dosimetry individualization than the MIRD methodology, which in some cases leads to important differences in dose values. Dosimetry of FCH‐PET based on a single partial PET study seems viable due to the particular biokinetics of FCH, even though some correction factors may need to be applied to estimate mean skin/bone doses.

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Compartmental model of¹⁸F-choline

Cited by 7 publications

References 11 publications

A Compartmental Model for Biokinetics and Dosimetry of¹⁸F-Choline in Prostate Cancer Patients

A Compartmental Model for Biokinetics and Dosimetry of¹⁸F-Choline in Prostate Cancer Patients

Uncertainties of organ-absorbed doses to patients from¹⁸f-choline

Quantification of internal dosimetry in PET patients II: Individualized Monte Carlo‐based dosimetry for [18F]fluorocholine PET

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Compartmental model of18F-choline

Cited by 7 publications

References 11 publications

A Compartmental Model for Biokinetics and Dosimetry of18F-Choline in Prostate Cancer Patients

A Compartmental Model for Biokinetics and Dosimetry of18F-Choline in Prostate Cancer Patients

Uncertainties of organ-absorbed doses to patients from18f-choline

Quantification of internal dosimetry in PET patients II: Individualized Monte Carlo‐based dosimetry for [18F]fluorocholine PET

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Compartmental model of¹⁸F-choline

A Compartmental Model for Biokinetics and Dosimetry of¹⁸F-Choline in Prostate Cancer Patients

A Compartmental Model for Biokinetics and Dosimetry of¹⁸F-Choline in Prostate Cancer Patients

Uncertainties of organ-absorbed doses to patients from¹⁸f-choline