Validation of a dose-point kernel convolution technique for internal dosimetry

Giap, Huan; Macey, Daniel J.; Bayouth, John E.; Boyer, Arthur L.

doi:10.1088/0031-9155/40/3/003

Cited by 63 publications

(54 citation statements)

References 15 publications

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“…The DPK convolution technique, which is based on convolving a radionuclide DPK with a cumulative activity distribution, was used to calculate intratumoral dose distributions. 4,22,23 The EGSnrc Monte Carlo simulation user code EDKnrc was used to generate DPKs, which include both beta and photon emissions of 186 Re and…”

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confidence: 99%

Direct intratumoral infusion of liposome encapsulated rhenium radionuclides for cancer therapy: Effects of nonuniform intratumoral dose distribution

Hrycushko

Goins

et al. 2011

Medical Physics

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Purpose: Focused radiation therapy by direct intratumoral infusion of lipid nanoparticle ͑liposome͒-carried beta-emitting radionuclides has shown promising results in animal model studies; however, little is known about the impact the intratumoral liposomal radionuclide distribution may have on tumor control. The primary objective of this work was to investigate the effects the intratumoral absorbed dose distributions from this cancer therapy modality have on tumor control and treatment planning by combining dosimetric and radiobiological modeling with in vivo imaging data. Methods:99m Tc-encapsulated liposomes were intratumorally infused with a single injection location to human head and neck squamous cell carcinoma xenografts in nude rats. High resolution in vivo planar imaging was performed at various time points for quantifying intratumoral retention following infusion. The intratumoral liposomal radioactivity distribution was obtained from 1 mm resolution pinhole collimator SPECT imaging coregistered with CT imaging of excised tumors at 20 h postinfusion. Coregistered images were used for intratumoral dosimetric and radiobiological modeling at a voxel level following extrapolation to the therapeutic analogs, 186Re / 188Re liposomes. Effective uniform dose ͑EUD͒ and tumor control probability ͑TCP͒ were used to assess therapy effectiveness and possible methods of improving upon tumor control with this radiation therapy modality. Results: Dosimetric analysis showed that average tumor absorbed doses of 8.6 Gy/MBq ͑318.2 Gy/mCi͒ and 5.7 Gy/MBq ͑209.1 Gy/mCi͒ could be delivered with this protocol of radiation delivery for 186 Re / 188Re liposomes, respectively, and 37-92 MBq ͑1-2.5 mCi͒/g tumor administered activity; however, large intratumoral absorbed dose heterogeneity, as seen in dose-volume histograms, resulted in insignificant values of EUD and TCP for achieving tumor control. It is indicated that the use of liposomes encapsulating radionuclides with higher energy beta emissions, dose escalation through increased specific activity, and increasing the number of direct tumor infusion sites improve tumor control. For larger tumors, the use of multiple infusion locations was modeled to be much more efficient, in terms of activity usage, at improving EUD and TCP to achieve a tumoricidal effect. Conclusions: Direct intratumoral infusion of beta-emitting radionuclide encapsulated liposomes shows promise for cancer therapy by achieving large focally delivered tumor doses. However, the results of this work also indicate that average tumor dose may underestimate tumoricidal effect due to substantial heterogeneity in intratumoral liposomal radionuclide distributions. The resulting intratumoral distribution of liposomes following infusion should be taken into account in treatment planning and evaluation in a clinical setting for an optimal cancer therapy.

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confidence: 99%

Direct intratumoral infusion of liposome encapsulated rhenium radionuclides for cancer therapy: Effects of nonuniform intratumoral dose distribution

Hrycushko

Goins

et al. 2011

Medical Physics

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“…DPKs correspond to the energy deposited at a distance from a point source in spheric shells (9) and can be calculated analytically or more often using Monte Carlo methods (10). The convolution approach is fast and takes into account the geometry of a given patient (11)(12)(13). However, this approach is prone to errors if applied to varying tissue densities, as DPKs are calculated for particles propagating in uniform medium, usually assumed to be water or soft tissue.…”

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Effect of Patient Morphology on Dosimetric Calculations for Internal Irradiation as Assessed by Comparisons of Monte Carlo Versus Conventional Methodologies

Divoli

Chiavassa²,

Ferrer³

et al. 2009

J Nucl Med

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Dosimetric calculations are performed with an increasing frequency before or after treatment in targeted radionuclide therapy, as well as for radiation protection purposes in diagnostic nuclear medicine. According to the MIRD committee formalism, the mean absorbed dose to a target is given by the product of the cumulated activity and a dose-conversion factor, known as the S factor. Standard S factors have been published for mathematic phantoms and for unit-density spheres. The accuracy of the results from the use of these S factors is questionable, because patient morphology can vary significantly. The aim of this work was to investigate differences between patient-specific dosimetric results obtained using Monte Carlo methodology and results obtained using S factors calculated on standard models. Methods: The CT images of 9 patients, who ranged in size, were used. Patient-specific S factors for 131 I were calculated with the MCNPX2.5.0 Monte Carlo code using a tool for personalized internal dose assessment, OEDIPE; standard S factors from OLINDA/EXM were compared against the patient-specific S factors. Furthermore, realistic biodistributions and cumulated activities for normal organs and tumors were used, and mean organ-and tumor-absorbed doses calculated with OEDIPE and OLINDA/EXM were compared. Results: The ratio of the standard and the patient-specific S factors were between 0.49 and 1.84 for a target distant from the source for 4 organs and 2 tumors studied as source and targets. For the case of self-irradiation, the equivalent ratio ranged between 0.45 and 2.47 and between 1.00 and 1.06 when mass correction was applied. Differences in mean absorbed doses were as high as 140% when realistic cumulated activity values were used. These values decreased to less than 26% in all cases studied when mass correction was applied to the self-irradiation given by OLINDA/EXM. Conclusion: Standard S factors can yield mean absorbed doses for normal organs or tumors with a reasonable accuracy (26% for the cases studied) as compared with absorbed doses calculated with Monte Carlo, provided that they have been corrected for mass.

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“…The imaging device was a double-head Picker Prism 2000 gamma camera lated using a point source dose kernel approach that has been studied previously by Sgouros et al, 4,5 Giap connected to an Odyssey VP computer (Picker International Inc., Highland Heights, OH). The SPECT acquisiet al, 6,7 and Erdi et al 8 The point kernel approach has been shown to provide three dimensional (3D) tion was performed by collecting 30 second frames within 3Њ angles using a medium energy all purpose absorbed dose distributions from an activity distribution of iodine-131 ( 131 I). 7 parallel hole collimator optimal up to 300 kiloelectron volt (keV) g-rays.…”

Section: Methodsmentioning

confidence: 99%

“…The SPECT acquisiet al, 6,7 and Erdi et al 8 The point kernel approach has been shown to provide three dimensional (3D) tion was performed by collecting 30 second frames within 3Њ angles using a medium energy all purpose absorbed dose distributions from an activity distribution of iodine-131 ( 131 I). 7 parallel hole collimator optimal up to 300 kiloelectron volt (keV) g-rays. SPECT images were reconstructed Pseudomyxoma peritonei (PP) is a rare clinical diagnosis of massive abdominal swelling by a gelatinous using filtered back-projection.…”

Section: Methodsmentioning

confidence: 99%

The effect of three dimensional activity distribution on the dose planning of radioimmunotherapy for patients with advanced intraperitoneal pseudomyxoma

Laitinen¹,

Kairemo

Jekunen

et al. 1997

Cancer

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pseudomyxomas were treated with radioimmunotherapy. with single photon emission computed tomography (SPECT) at 3, 10, and 24 days after the therapeutic infusion. Treatment-planning software has been developed 2 Laboratory of Biomedical Engineering, Helin which functional information obtained from SPECT is integrated with anatomic sinki University of Technology, Espoo, Finland. METHODS.information obtained from computed tomography (CT). The activity distribution 3 Department of Oncology, Helsinki University from SPECT images is converted to absorbed dose distributions using a point Central Hospital, Helsinki, Finland.source kernel convolution dose calculation. The absorbed dose calculation requires 4 Department of Radiology, Helsinki University a radionuclide specific dose kernel. The activity map is divided into equally sized Central Hospital, Helsinki, Finland.source voxels from which the distribution is calculated for the target voxels that cover the patient volume. The resulting three dimensional (3D) absorbed dose distribution is viewed as isodose contours superimposed on the CT images or as 3D isodose surfaces. RESULTS.The measured activity distribution shows that the cumulated activity and biologic half-life vary in the patient's body. The developed planning system provides a method for calculating patient specific absorbed dose distributions. CONCLUSIONS. The variation of biologic clearance indicates that a 3D dose calcula-Presented at the Sixth Conference on Radioimtion method incorporating measured activity distributions is needed to quantify munodetection and Radioimmunotherapy of absorbed dose distribution. of management for cancer. 1There is a lack of accurate dosimetry in clinical RIT.

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Validation of a dose-point kernel convolution technique for internal dosimetry

Cited by 63 publications

References 15 publications

Direct intratumoral infusion of liposome encapsulated rhenium radionuclides for cancer therapy: Effects of nonuniform intratumoral dose distribution

Direct intratumoral infusion of liposome encapsulated rhenium radionuclides for cancer therapy: Effects of nonuniform intratumoral dose distribution

Effect of Patient Morphology on Dosimetric Calculations for Internal Irradiation as Assessed by Comparisons of Monte Carlo Versus Conventional Methodologies

The effect of three dimensional activity distribution on the dose planning of radioimmunotherapy for patients with advanced intraperitoneal pseudomyxoma

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