A radionuclide dosimetry toolkit based on material specific Monte Carlo dose kernels (original) (raw)
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Patient-specific dosimetry in radionuclide therapy
Radiation Protection Dosimetry, 2011
This study presents an attempt to compare individualised palliative treatment absorbed doses, by planar images data and Monte Carlo simulation, in two in vivo treatment cases, one of bone metastases and the other of liver lesions. Medical Internal Radiation Dose schema was employed to estimate the absorbed doses. Radiopharmaceutical volume distributions and absorbed doses in the lesions as well as in critical organs were also calculated by Monte Carlo simulation. Individualised planar data calculations remain the method of choice in internal dosimetry in nuclear medicine, but with the disadvantage of attenuation and scatter corrections lack and organ overlay. The overall error is about 7 % for planar data calculations compared with that using Monte Carlo simulation. Patient-specific three-dimensional dosimetric calculations using single-photon emission computed tomography with a parallel computed tomography study is proposed as an accurate internal dosimetry with the additional use of dose-volume histograms, which express dose distributions in cases with obvious inhomogeneity.
Radioprotection, 2014
For targeted radionuclide therapies, treatment planning usually consists of the administration of standard activities without accounting for the patient-specific activity distribution, pharmacokinetics and dosimetry to organs at risk. The OEDIPE software is a user-friendly interface which has an automation level suitable for performing personalized Monte Carlo 3D dosimetry for diagnostic and therapeutic radionuclide administrations. Mean absorbed doses to regions of interest (ROIs), isodose curves superimposed on a personalized anatomical model of the patient and dosevolume histograms can be extracted from the absorbed dose 3D distribution. Moreover, to account for the differences in radiosensitivity between tumoral and healthy tissues, additional functionalities have been implemented to calculate the 3D distribution of the biologically effective dose (BED), mean BEDs to ROIs, isoBED curves and BED-volume histograms along with the Equivalent Uniform Biologically Effective Dose (EUD) to ROIs. Finally, optimization tools are available for treatment planning optimization using either the absorbed dose or BED distributions. These tools enable one to calculate the maximal injectable activity which meets tolerance criteria to organs at risk for a chosen fractionation protocol. This paper describes the functionalities available in the latest version of the OEDIPE software to perform personalized Monte Carlo dosimetry and treatment planning optimization in targeted radionuclide therapies.
2007
Phantom-based and patient-specific imaging-based dosimetry methodologies have traditionally yielded mean organ absorbed doses or spatial dose distributions over tumors and normal organs. In this work, radiobiological modeling is introduced to convert the spatial distribution of absorbed dose into biologically effective dose and equivalent uniform dose parameters. The methodology is illustrated using data from a thyroid cancer patient treated with radioiodine. METHODS: Three registered SPECT/CT scans were used to generate 3-D images of radionuclide kinetics (clearance rate) and cumulated activity. The cumulated activity image and corresponding CT were provided as input into an EGSnrc-based Monte Carlo calculation; the cumulated activity image defined the distribution of decays while an attenuation image derived from CT was used to define the corresponding spatial tissue density and composition distribution. The rate images were used to convert the spatial absorbed dose distribution to a Biologically Effective Dose (BED) distribution which was then used to estimate a single Equivalent Uniform Dose (EUD) for segmented volumes of interest. EUD was also calculated from the absorbed dose distribution directly. RESULTS: Validation using simple models and also comparison of the dose-volume histogram to a previously analyzed clinical case is shown as well as the mean absorbed dose, mean biologically effective dose, and equivalent uniform dose for an illustrative clinical case of a pediatric thyroid cancer patient with diffuse lung metastases. The mean absorbed dose, mean BED and EUD for tumor was 57.7, 58.5 and 25.0 Gy, respectively. Corresponding values for normal lung tissue were 9.5, 9.8 and 8.3 Gy, respectively. CONCLUSION The analysis demonstrates the impact of radiobiological modeling on response prediction. The 57% reduction in the equivalent dose value for the tumor reflects a high level of dose non-uniformity in the tumor and a corresponding reduced likelihood of achieving a tumor response. Such analyses are expected to be useful in treatment planning for radionuclide therapy.
Journal of Nuclear Medicine, 2007
Phantom-based and patient-specific imaging-based dosimetry methodologies have traditionally yielded mean organ-absorbed doses or spatial dose distributions over tumors and normal organs. In this work, radiobiologic modeling is introduced to convert the spatial distribution of absorbed dose into biologically effective dose and equivalent uniform dose parameters. The methodology is illustrated using data from a thyroid cancer patient treated with radioiodine. Methods: Three registered SPECT/CT scans were used to generate 3-dimensional images of radionuclide kinetics (clearance rate) and cumulated activity. The cumulated activity image and corresponding CT scan were provided as input into an EGSnrc-based Monte Carlo calculation: The cumulated activity image was used to define the distribution of decays, and an attenuation image derived from CT was used to define the corresponding spatial tissue density and composition distribution. The rate images were used to convert the spatial absorbed dose distribution to a biologically effective dose distribution, which was then used to estimate a single equivalent uniform dose for segmented volumes of interest. Equivalent uniform dose was also calculated from the absorbed dose distribution directly. Results: We validate the method using simple models; compare the dose-volume histogram with a previously analyzed clinical case; and give the mean absorbed dose, mean biologically effective dose, and equivalent uniform dose for an illustrative case of a pediatric thyroid cancer patient with diffuse lung metastases. The mean absorbed dose, mean biologically effective dose, and equivalent uniform dose for the tumor were 57.7, 58.5, and 25.0 Gy, respectively. Corresponding values for normal lung tissue were 9.5, 9.8, and 8.3 Gy, respectively. Conclusion: The analysis demonstrates the impact of radiobiologic modeling on response prediction. The 57% reduction in the equivalent dose value for the tumor reflects a high level of dose nonuniformity in the tumor and a corresponding reduced likelihood of achieving a tumor response. Such analyses are expected to be useful in treatment planning for radionuclide therapy.
Journal of Nuclear …, 1997
three-dimensional distribution of dose was significantly nonuniform. Conclusion: Initialresults suggest that this method offers a means of determining the absorbed dose distribution within a tumor result ing from intralesional infusion. This method extends the Medical Internal Radiation Dose computation, which, in these circum stances, would make erroneous assumptions. Furthermore, it will enable individual patient treatment planning and optimization of the parameters that are within the clinician's control.
Journal of Nuclear Medicine, 2012
In internal radionuclide therapy, a growing interest in voxel-level estimates of tissue-absorbed dose has been driven by the desire to report radiobiologic quantities that account for the biologic consequences of both spatial and temporal nonuniformities in these dose estimates. This report presents an overview of 3-dimensional SPECT methods and requirements for internal dosimetry at both regional and voxel levels. Combined SPECT/CT image-based methods are emphasized, because the CT-derived anatomic information allows one to address multiple technical factors that affect SPECT quantification while facilitating the patient-specific voxel-level dosimetry calculation itself. SPECT imaging and reconstruction techniques for quantification in radionuclide therapy are not necessarily the same as those designed to optimize diagnostic imaging quality. The current overview is intended as an introduction to an upcoming series of MIRD pamphlets with detailed radionuclide-specific recommendations intended to provide best-practice SPECT quantification-based guidance for radionuclide dosimetry.
Cancer biotherapy & radiopharmaceuticals, 2016
The aim of this work is to evaluate the application of tissue-specific dose kernels instead of water dose kernels to improve the accuracy of patient-specific dosimetry by taking tissue heterogeneities into consideration. Tissue-specific dose point kernels (DPKs) and dose voxel kernels (DVKs) for yttrium-90 ((90)Y), lutetium-177 ((177)Lu), and phosphorus-32 ((32)P) are calculated using the Monte Carlo (MC) simulation code GATE (version 7). The calculated DPKs for bone, lung, adipose, breast, heart, intestine, kidney, liver, and spleen are compared with those of water. The dose distribution in normal and tumorous tissues in lung, liver, and bone of a Zubal phantom is calculated using tissue-specific DVKs instead of those of water in conventional methods. For a tumor defined in a heterogeneous region in the Zubal phantom, the absorbed dose is calculated using a proposed algorithm, taking tissue heterogeneity into account. The algorithm is validated against full MC simulations. The simu...
Voxeldose: A Computer Program for 3-D Dose Calculation in Therapeutic Nuclear Medicine
Cancer Biotherapy and Radiopharmaceuticals, 2003
A computer program, VoxelDose, was developed to calculate patient specific 3-D-dose maps at the voxel level. The 3-D dose map is derived in three steps: i) The SPECT acquisitions are reconstructed using a filtered back projection method, with correction for attenuation and scatter; ii) the 3-D cumulated activity map is generated by integrating the SPECT data; and iii) a 3-D dose map is computed by convolution (using the Fourier Transform) of the cumulated activity map and corresponding MIRD voxel S values. To validate the VoxelDose software, a Liqui-Phil™ abdominal phantom with four simulated organ inserts and one spherical tumor (radius 4.2 cm) was filled with known activity concentrations of 111 In. Four cylindrical calibration tubes (from 3.7 to 102 kBq/mL) were placed on the phantom. Thermoluminescent mini-dosimeters (mini-TLDs) were positioned on the surface of the organ inserts. Percent differences between the known and measured activity concentrations were determined to be 12.1 (tumor), 1.8 (spleen), 1.4, 8.1 (right and left kidneys), and 38.2% (liver), leading to percent differences between the calculated and TLD measured doses of 41, 16, 3, 5, and 62%. Large differences between the measured and calculated dose in the tumor and the liver may be attributed to several reasons, such as the difficulty in precisely associating the position of the TLD to a voxel and limits of the quantification method (mainly the scatter correction and partial volume effect). Further investigations should be performed to better understand the impact of each effect on the results and to improve absolute quantification. For all other organs, activity concentration measurements and dose calculations agree well with the known activity concentrations.