# Patent

## Title
Method and system for administering radiopharmaceutical therapy (RPT)

## Abstract

A computerized system and method for determining an optimum amount of radiopharmaceutical therapy (RPT) to administer, comprising: performing processing associated with obtaining activity image information related to at least one agent for sub-units of at least one imaged organ from at least one detector; performing processing associated with running at least one calculation for the activity image information, using at least one computer application, to obtain absorbed dose rate image information; and performing processing associated with adding the absorbed dose rate image information, using, the at least one computer application, to obtain RPT total absorbed dose image information for the at least one imaged organ; wherein macroscopic distribution measurements that are related to microscopic or sub-unit distribution of the at least one agent are utilized.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application is related to U.S. patent application Ser. No. 12/687,670, filed Jan. 14, 2010; Ser. No. 12/690,471, filed Jan. 20, 2010; and Ser. No. 12/514,853, filed Sep. 15, 2009, the disclosures of which are incorporated by reference in their entireties.
BRIEF DESCRIPTION OF THE DRAWINGS
The file of this patent contains at least one drawing executed in color. Copies of this patent with color drawings will be provided by the Patent and Trademark Office upon request and payment of the necessary fee.
FIG. 1 illustrates a system 100 for administering radiopharmaceutical therapy (RPT), according to one embodiment.
FIGS. 2 and 7 illustrate a method of calculating absorbed dose from, for example, a targeted alpha-emitter, according to one embodiment.
FIG. 3A illustrates a nephron model, according to one embodiment.
FIG. 3B illustrates a model of a bone comprising a Monte Carlo simulation, according to one embodiment.
FIG. 4 illustrates a cross-section of a mouse kidney that was stained with periodic acid Schiff (PAS) stain, according to one embodiment.
FIG. 5 illustrates a composite (e.g., stitched) slide of murine kidney slice, according to one embodiment.
FIG. 6 illustrates the translation from macroscopically measured whole organ PK to microscopic sub-unit PK, according to one embodiment.
FIG. 8 illustrates an example of macro to micro calculations, according to an embodiment.
FIG. 9 illustrates a micro to macro (m2m) database scheme, according to an embodiment.


DETAILED DESCRIPTION OF EMBODIMENTS
System and Method for Administering RPT
Dosimetry can comprise the calculation of absorbed dose. Absorbed dose can be equal to energy imparted by radioactive substances divided by the mass of the target tissue and can be used to help determine the likely damage to tissue (e.g., organs, etc.). In, therapeutic nuclear medicine, in the “absorbed fraction” paradigm, the dose to a target region (e.g., an organ), used to ascertain likely toxicity to that region, may comprise dose contributions from all organs in the body which take up activity and whose emissions may deposit energy in the target organ. An equation that can describe this approach is the following:




  
    D
    t
  
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      Σ
      s
    
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              s
            
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          ·
          Δ
          ·
          
            φ
            
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In the above location, D can be the absorbed dose, ÃS can be the number of disintegrations in source volume s, Δ can be the energy per decay, mt can be the mass of target region t, and φ can be the absorbed fraction of energy originating in source volume s that is absorbed in target region t.
That is, the absorbed dose in a target region (e.g., an organ) can be equal to the sum of the dose contributions from all source organs in the body. Each contribution may be equal to the time integrated activity (e.g., number of decays), Ã, in the source multiplied by the energy per decay, Δ, (isotope dependant) multiplied by the fraction of emitted energy, φ, that originates in the source organ and is deposited in the target organ.
In order to facilitate the application of this formula, a library of results may be generated which incorporates the mass, absorbed fraction and energy per decay parameters into single values (S-values). This phantom model can allow the creation of a library of data from which dosimetric calculations can be made simply by knowing the number of decays in each body organ usually estimated by imaging. A software program which exploits this library and which can be used for estimating dose may be utilized (e.g., OLINDA/EXM, which is a commercially available software package that implements a dosimetry methodology that gives the average absorbed dose over a tissue or organ; it does not account, for patient-specific anatomy or radioactivity distribution within organs; it is also unable to provide patient-specific tumor absorbed dose estimates).
In one embodiment, when absorbed dose estimates on the macroscopic or whole-organ scale fail to predict response or toxicity, it may be necessary to perform dosimetry calculations on a smaller, functional or anatomical sub-unit scale. In such cases, the information needed may be on a scale that is substantially smaller than: the resolving power of clinical imaging detectors and modalities, or the scale of human organs; or both.
For example, α-particle emitters may be utilized for cancer therapy. Alphas may be highly effective (e.g., α-particle tracks can sterilize a cell, as opposed to the thousands of tracks necessary from β-articles), may not be susceptible to chemoresistance, or may be minimally susceptible to radioresistance, or any combination thereof. Despite the shorter range of α-particle emitters (as compared to traditional β-particle emitters) the linear energy transfer (LET), or energy deposited per unit length of as can be substantially ( ̃1000×) larger than for β-particle emitters. Additionally, many potentially therapeutic α-particle emitters may decay to daughter α-particle emitters. The energy released by α-particle decay may be five to six orders of magnitude greater than the energy of the chemical bond used to attach an α-particle emitter to an antibody (e.g., via a metal chelator). Consequently daughter decay radionuclides may be released as free ions. If the decay occurs after the antibody has bound to the target cell and internalized, then the decay cascade may occur inside the target cell so that all four of the emitted alphas may bee within the target cell. If the daughters are short-lived this may make the decay highly potent and minimally susceptible to resistance mechanisms due to the combination of several emitted alphas so close to the nucleus (i.e., intracellularly) and also because of the high potency (i.e., capacity for. DNA double-strand breaks) of each α-particle emitter. The high potency may mean that an absorbed dose of 1 Gy from α-particles emitters may be three to seven times more cytotoxic (e.g., relative biological effect, or RBE) than the same absorbed dose from electrons or photons.
However, this multiplicity of α-particles can also cause additional toxicity if the daughter particles escape the cell confines and return to potential organs at risk via the blood stream before further disintegration. α-particle emitter therapy may be or become an active area of research and may become a part of the therapeutic armamentarium against cancer.
The amount of activity of a radiopharmaceutical administered to a patient for therapy may be optimized by effective dosimetry. Absorbed dose and the dose-rate-dependent radiobiological derived quantity biologic effective dose (BED) may correlate with normal organ toxicity; therefore the accurate calculation of these quantities may help provide optimal personalized therapy regimens for patients. Targeted α-emitter therapy may hold great promise as a cancer treatment but may also come with a great potential for toxicity. Understanding and correctly implementing the absorbed dose calculations to normal organs at risk may help guard from a sub-optimal implementation. Some cancer therapeutics that are effective against initial stage tumors (e.g., chemotherapy), may only be effective due to a closely monitored optimization of drug delivery. The threshold of effectiveness should be attained, while adhering to toxicity constraints. So it is with radiopharmaceutical therapy of solid and metastatic tumors. Achieving this delicate balance requires the most accurate dosimetry available.
FIG. 1 illustrates a system 100 for administering radiopharmaceutical therapy (RPT), according to one embodiment. Radiopharmaceutical therapy can comprise internal radionuclide therapy (IRT). In system 100, at least one detector (e.g., camera 155) images an imaged object 160 (e.g., a person, a phantom) and uses a computer application 110 to process information from the images. A camera 155 (e.g., positron emission tomography (PET) camera, gamma camera) can be a device used to image gamma radiation emitting radioisotopes. It can be used to view and analyze images of the human body or the distribution of radionuclides emitting gamma rays (e.g., to treat cancer). The camera 155 can be connected to a computer application 150 that can control the operation of the camera and/or the acquisition and storage of acquired images. The computer application 150 can accumulate events, or counts, of gamma photons that are absorbed by the crystal in the camera.
RPT can require accurate three dimensional dose calculations to avoid toxicity and evaluate efficacy. A treatment planning methodology can be performed using a patient-specific three-dimensional radiobiologic dosimetry package (3D-RD) for RPT using computer application 150. (More information on the 3D-RD and the algorithm can be found in U.S. patent application Ser. Nos. 12/514,853, 12/687,670, and 12/690,471, which are herein incorporated by reference.) Computer application 150 and its specific implementation within 3D-RD may provide the ability to utilize, individual patient images of the radioactivity distribution with images of anatomy and density (e.g., as obtained from computed tomography (CT) imaging) to calculate the spatial distribution of absorbed dose in a particular target region. Using radiobiological modeling, the absorbed dose distribution can be related to tumor control probability or probability of normal tissue compilitions. Additionally, a parametric image of the spatial distribution of absorbed dose may be created that may adjust for differences between external radiotherapy (XRT) and radiopharmaceutical therapy (RPT) in the dose-rate at which total absorbed dose is delivered.
Computer application 150 may comprise: macro to micro module 151 and/or conversion module 152. The macro to micro modules 151 may translate macroscopically measured whole organ PK to microscopic sub-unit PK, as discussed in more detail below. The conversion module 152 may convert the animal model to the human model, as discussed in more detail below.
FIGS. 2 and 7 illustrate a method of calculating absorbed dose from, for example, a targeted alpha-emitter. In 105, geometric representations (e.g., images, models) of an organ's subunits may be developed. For example, geometric representations of marrow's and kidney's sub-units may be developed. The geometric representations may be scalable and implemented in, for example, the GEANT4 Monte Carlo code (i.e., the code needed to run MC on these structures will be generated). GEANT4 Monte. Carlo code is a generalized Monte Carlo package for simulating the passage of particles through matter. More information on GEANT4 can be found at the following web site, which is incorporated by reference: geant4.cern.ch/.
In 110, the organ's subunit's scale may be measured for in animal(s), human(s), or both. In one embodiment, the human scale may be measured in fresh cadavers to define the sub-unit anatomy for human organs as accurately as possible and provide a range of parameters. In some embodiments, time-integrated (e.g., time-independent) dose comparisons may be made. The time dependency of the dose may be incorporated by the addition of the requisite timing and compartmental modules in GEANT4.
In 115, the pharmacokinetics (PK) in whole organs and in the sub-units of the organs may be measured in animal(s), human(s), or both; mapping may be utilized to help enable a translation from macroscopically measured (imaged) whole organ PK to microscopic sub-unit PK; or the animal model may be adapted to the human model; or any combination thereof.
For example, the PK of the α-emitter labeled intact antibody and the α-emitting daughters in whole organs and in the sub-units of the organs may be measured in mice to help enable the conversion of macroscopically derived PK into microscopic kinetics applicable to the level of the sub-units. Since it may not be possible to extract tissue and perform autoradiography in humans to measure the PK at the sub-unit level, the modeled relationship between whole-organ (macro) and sub-unit (micro) PK measured in animals (e.g., mice) may be applied to humans.
As mentioned above, mapping may be utilized to help enable a translation from macroscopically measured (imaged) whole organ PK to microscopic sub-unit PK. FIG. 8 illustrates an example of macro to micro calculations. Kinetics obtained from imaging (a) may be used to obtain the area under the whole organ curve (b). This may give the total number of decays occurring in the whole organ volume. Using information from the literature (e.g., molecular imaging methods comprising immunohistochemistry florescent microscopy, magnetic resonance imaging, microCT, or audioradiography or any combination thereof to show anatomy (d) and activity localization (e)), the micro-distribution and behavior of the agent in the tissue may be projected (c, f) and used in a micro scale model to calculate AD at the micro level by MC. As can be seen from the histology and autoradiography, the uniform appearance of activity in the kidneys (a) is, in fact, very non-uniformly distributed as the micro scale. The absorbed dose to the radiosensitive cells may be, therefore, not reflected form an average AD in this tissue/radiopharmaceutical combination.
Mathematically, the translation from macroscopically measured (imaged) whole organ PK to microscopic sub-unit PK may be translated as:




  
    
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In the above formula, Ãorgan can be the number of disintegrations in an organ, Aorgan can be the disintegration rate at a particular point in time t. The index i can iterate over the compartments making up the organ and the index j over the isotopes. By plotting the Aorgan and Aij values measured at different time points t, a graphical map such as the one shown in FIG. 6 may be established. This may help enabling a time-ordered PK conversion of macroscopically measured activity at multiple time points to the corresponding activity values at multiple time points in sub-compartments of the organ. In FIG. 7, a dual-compartment single isotope scenario is illustrated with functional fitting. The conversion shown by the arrows may also be at multiple time points and does not have to correspond to the time points used to create the conversion map. The individual Aij(t) values may then be allocated to the sub-unit models based upon the ratio of individual sub-unit volume to volume of occupancy within the whole organ.
FIG. 8 illustrates a micro to macro (m2n) database scheme, according to an embodiment. A dosimetry software package such as 3D-RD may query a web-accessible database that is keyed according to tissue and radiopharmaceutical (or radiopharmaceutical class). If a match is found, the database may identify the appropriate module for performing the micro-scale or cell-scale calculation. In this way, patient-specific macrocopic measurements may be used to perform micro-scale dosimetry calcuations. These m2m modules may be developed using information obtained from studies that describe the micro-level distribution of different normal organ/therapeutic radiopharmaceutical combination and also from a general understanding of the properties of different classes of radiopharmaceuticals.
FIG. 9 illustrates a flow chart for the process of performing micro scale calculations for the example of a Na131I salivary gland. A match in ROI and RPT entries with one of the module libraries (NAI, peptide, 153Sm and antibody (ab) arc shown as examples) may bring up the proposed micro-level calculation described in the salivary gland (SG) model table. A fraction of the decays obtained from the ROI may be assigned to SG duct lumen and the dose to the SG duct wall may be calculated. Reference geometrical models of the relevant anatomy, corresponding volumes, and apportionment factors, f, may be developed and used in a Monte Carlo or point-kernel calculation within 3D-RD.
As also mentioned above, the animal model may be adapted to the human model. For example, the mouse model may be extrapolated to a human models. For a representative sample size of time points (e.g., 2x-3x more than used to create the conversion map), the equation below may be used to convert mouse model derived organ and sub-compartment PK to corresponding human organ sub-compartment PK:




  
    
      
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where the ratio on the left side of the equation may represent the ratio of compartmental activities (Aij) to the measured activity (Aorgan) at time t in the human (M). Note that p may represent other parameters not explicitly shown in the equation (e.g., parameters that may be needed to account for differences in nephron occupancy factor in different patients, depending upon the patient's age, the patient's sex, the patient's prior treatment history, or any combination thereof). This may be equal to the same ratios in the mouse (m) adjusted for measured fraction of occupancies in the two species. This does not necessarily imply an identical functional form of the total measured activity in the human versus the mouse.
FIGS. 2 and 7 thus illustrates a methodology that integrates sub-organ modeling, according to an embodiment of the invention. This methodology may be suited for α-particle therapy in some embodiments. The absorbed fraction paradigm may give average dose to an organ, may not account for local deposition of dose, and may be insensitive to the temporal aspects of pharmacokinetics and cell mobility. This absorbed fraction paradigm may rely on the relatively long-ranged energy deposition typical of β- and γ-particle emitters. However, the range of α-particles may be only a few cell diameters long. Local uptake of activity driven by biological imperatives that exist at the functional sub-unit level may be taken into account for effective and safe α-particle emitter therapy.
This dosimetry methodology 200 of FIG. 2 may be utilized with α-particles. In some embodiments, this dosimetry methodology 200 may be founded on Monte Carlo modeling within the GEANT4 framework, accurate 3-dimensional anatomical data from human cadavers, or pharmacokinetics established in animal models (e.g., mouse models), or any combination thereof. In addition, in normal organs, the spatiotemporal distribution needed to utilize absorbed fractions defined at the microscopic level may be obtained from macroscopic measurements by apportioning the macroscopic distribution to different microscopic compartments for a given radiopharmaceutical agent. In addition, the link between macroscopic and microscopic spatiotemporal relationship for a given agent measured in a pre-clinical model may be applied to a human because the distribution of the agent to the different microscopic compartments should remain the same. Specific adjustments for scale and known pharmacological/physiological differences may improve the translation to the human.
The dosimetry methodology 200 may provide specific models for organs most at risk of toxicity in the existing pre-clinical and clinical α-particles experiments. In the examples set forth below (e.g., marrow, kidney) dose distribution may be determined in the functional and anatomical sub-units, but results may be provided at the cellular level within each sub-organ compartment.
EXAMPLES
Marrow Example. Bone marrow may be the dose-limiting organ in radioimmunotherapy. Accurate dosimetry of bone marrow may be difficult because of its complex geometry and the presence of tissue inhomogeneities. For example, bone marrow may be modeled, and the model may comprise a Monte Carlo simulation of an α-particle emitter decay in an idealized marrow cavity unit (a simple sphere) of, for example, radius 250-500 μm, with an endosteal layer 10 μm thick. (See, e.g., FIG. 3B). This model may be of particular relevance for 223Ra, which may localize to the endosteal layer. The energy from the simulation may be collected and the dose to each bone marrow cell may be calculated.
Chord length distributions from human cadavers may be used to generate realistic geometries. The human anatomical information may be gathered from cadavers for anatomical accuracy and may be used to provide an array of parameters that reflect human diversity. For example, a comprehensive library of microCT images of trabecular spongiosa for internal dosimetry calculations may be used, comprising libraries for: an 18-year male, 40-year male, 45-year female, 64-year male, and 66-year female. Modeled regions may include the bone trabeculae, the 10-μm layer of endosteum, and 50-μm layer of shallow marrow, a remaining layer of deep marrow. Labeled cellular voxelized units may include the marrow adipocytes, osteoblasts, osteoclasts, osteoprogenitor cells, hematopoietic stem and progenitor cells, supporting marrow structures, and blood sinuses and vessels. The spatial distribution of HSPC may be based upon CD34+ histology studies (e.g., by Bourke et al. (50)). Confirmatory MCNPX simulations of alpha-particle transport for comparison to the GEANT4 results may also be utilized.
Kidney Example. Renal toxicity may be a concern for toxicity for low molecular weight constructs, such as those used in radiopeptide therapy of neuroendocrine tumors. Since peptides, other low molecular weight antibody constructs, and heavy metalloid atoms (α-emitters) may be mainly deposited in the renal cortex, which is associated with a greater radiobiological sensitivity, the localization of the absorbed dose may increase the risk of renal toxicity. However, the range of α-particle emissions means that even the delineation between renal cortex, medulla, and pelvis is insufficient to explain the elevated levels of renal toxicity observed in experimental murine studies. Indeed, considering that the functional sub-unit of the kidney is the nephron, an entity whose dimensions are comparable to those of the range of emitted α-particles, a model of toxicity based on the nephron, including uptake at the cellular level, rather than the whole kidney, may be useful.
A simple idealized nephron model may use simple geometrical shapes (cylinders, spheres and toroids) and may be initially based on parameters taken from medical textbooks. FIG. 3A illustrates a nephron model. The proximal tubule may be the region where the free metalloids are most likely to be absorbed; and together with the glomerulus, they may be the regions which exhibit toxicity in murine studies of renal toxicity due to 225Ac therapy. The glomerulus may be modeled as a simple sphere, the proximal tubule as hollow cylinders and toroids through which the fluid to be filtered is passed. Proximal tubules may be typically convoluted as they first leave the glomerulus before the tubule descends as the descending loop of Henle. The tubule (and glomerulus) in FIG. 3A has also been subdivided into individual cells. For the tubule, these comprise simple cuboidal epithelial cells. Because the range of the α-particles is slightly larger than the tubule radius, nearest neighbor tubules may also be taken into account in the dosimetry. Some tubules will be distal may be modeled containing no activity.
FIG. 4 illustrates a cross-section of a mouse kidney that was stained with periodic acid Schiff (PAS) stain. PAS positive material shows up along the brush border (lumen surface) of the proximal tubules (see examples of 415). Note that basement membrane material outside the tubular epithelium is also PAS positive, but not specific for proximal tubules (see examples of 405). Also note the glomeruli are distinguishable (see example of 410).
The ratio of dose from the nephron model to dose from the kidney model depends in a critical way upon the percentage of volume, or fraction of occupancy (focc) allocated in the kidney to the sub-units (e.g., proximal tubules and glomeruli). For example, from contours drawn on five different images from five kidney cross-section slides each (25 total), preliminary foccs for the proximal tubule, distal tubules (both with (81%) and without (66%) lumen space) and glomeruli (2.3%) within the whole kidney and cortex may be established, and may contribute to a greater accuracy as well as providing theoretical constraints for quality control. These values will be improved upon with a more representative selection of slices ( ̃50 per kidney). For example, the use of a microscope (e.g., Nikon 600 HL microscope) and software (e.g., NIS-Elements BR software, which is a commercially available software package for image analysis; more information may be found at the following web site, which is herein incorporated by reference: http://www.nis-elements.com/) may help stitch together magnified images into a single slice image. For example, FIG. 5 illustrates a composite (e.g., stitched) slide of murine kidney slice from 20 separate images.
The establishment of the full human kidney model may involve using human cadaver data to establish full 3-dimensional anatomically accurate and diverse (e.g., for different kidneys sizes) models for comparison with the idealized geometrical models. Here too, given that kidney mass has been shown to be a vital factor in establishing dose-response (e.g., BED-toxicity response) for kidneys in radio peptide planned therapy of neuroendocrine tumors, a kidney mass depended array of geometric models may be used whose results may be interpolated either functionally or with linear segments for a dosimetric model whose inputs may be kidney mass as well as whole organ pharmacokinetics from several time point imaging.
To obtain high-resolution images of the human kidney for α-particle transport modeling, in one embodiment, human kidneys may be acquired and imaged at high resolution under nuclear magentic resonance (NMR) microscopy. For example, imaging studies may be conducted at the wide-bore. 17.6 T (750 MHz) NMR spectrometer within the Advanced Magnetic Resonance Imaging and Spectrometry (AMRIS) facility in. the University of Florida's McKnight Brain Institute. A voxel image resolution of between 10 to 50 μm may be targeted for model construction. Multiple human kidney samples may be sought. Kidneys sought for imaging may include kidneys where one can study more macroscopic variations in kidney structure such as the overall and relative sizes of the cortex/medullary and number of medullary pyramids. These images may be compared to in-vivo MR images of the kidneys of the Visible Human Project (http://en.wikipedia.org/wikiNisible_Human_Project) to confirm no gross anatomical changes following tissue embalming. A supplemental set of cross-sectional histology images may be prepared following MR microscopy.
Images for which normal anatomy is captured may be segmented in a voxelized format for GEANT4 simulations. Two versions of the model may be implemented. One model may comprise the entire organ showing regions of the renal cortex, each individual medullary pyramid, and the renal pelvis. A higher-resolution regional kidney model may also be constructed from a Volume of Interest (VOI) of perhaps several localized medullary pyramids and surrounding renal cortex in which individual nephrons and collecting ducts may be segmented. As needed, supplemental NURBS (non-uniform rational B-spline) surface models of the glomerular capsule and proximal/distal renal tubules may be created, based upon the imaged anatomy, and then inserted within the final voxelized kidney model. Final model format, spatial extent, and functional unit definition may also be devised.
CONCLUSION
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail can be made therein without departing from the spirit and scope of the present invention. Thus, the present invention should not be limited by any of the above-described exemplary embodiments.
In addition, it should be understood that the figures described above, which highlight the functionality and advantages of the present invention, are presented for example purposes only. The architecture of the present invention is sufficiently flexible and configurable, such that it may be utilized in ways other than that shown in the figures.
For consistency reasons, used the phrase “comprising” throughout the claims instead of “including, but not limited to”. However, it should be noted that “comprising” should be interpreted as meaning “including, but not limited to”.
In addition, it should be noted that, if not already set forth explicitly in the claims, the term “a” should be interpreted as “at least one” and “the”, “said”, etc. should be interpreted as “the at least one”, “said at least one”, etc.
Further, the purpose of the Abstract of the Disclosure is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The Abstract of the Disclosure is not intended to be limiting as to the scope of the present invention in any way.
Finally, it is the applicant's intent that only claims that include the express language “means for” or “step for” be interpreted under 35 U.S.C. 112, paragraph 6. Claims that do not expressly include the phrase “means for” or “step for” are not to be interpreted under 35 U.S.C. 112, paragraph 6.

## Claims

1. A computerized method for determining an optimum amount of radiopharmaceutical therapy (RPT) to administer, comprising:
performing processing associated with obtaining, with a detector, macroscopic activity image information related to an agent for an imaged organ for a first species and a second species;
performing processing associated with obtaining, with the detector, microscopic activity image information related to the agent for the imaged organ for the second species;
performing processing associated with running calculations, using a computer application, using the macroscopic activity image information for the second species and the microscopic activity image information for the second species to derive microscopic activity image information for the first species;
performing processing related to running calculations, using the computer application, using the microscopic activity image information for the first species to derive microscopic absorbed dose rate image information for the first species, wherein a uniform distribution at a microscopic level of the agent is not assumed in the first species;
performing processing associated with running calculations, using the computer application, using the microscopic absorbed dose rate information for the second species to derive RPT macroscopic absorbed dose image information and microscopic absorbed dose image information for the imaged organ in the first species;
performing processing associated with running calculations, using the at least one computer application, using the RPT macroscopic absorbed dose rate information and the microscopic absorbed dose image information to derive the optimum amount of RPT to administer to the first species; and
performing processing associated with outputting, using the at least one computer application, the optimum amount of RPT to administer to the first species.

2. The method of claim 1, wherein:
molecular imaging methods are utilized to provide distribution of a therapeutic agent;
the RPT comprises internal radionuclide therapy (IRT);
uncertainty evaluation is performed;
the one detector is at least one camera; or
the calculations comprise a Monte Carlo simulation; a point kernel convolution; or both; or
any combination thereof.

3. The method of claim 2, wherein the molecular imaging methods comprising immunohistochemistry, florescent microscopy, magnetic resonance imaging, microCT, or audioradiography, or any combination thereof.

4. The method of claim 1, wherein the imaged organ for the second species is from an animal and/or the animal is a mouse.

5. The method of claim 4, wherein the first species is human, and/or wherein the RPT total absorbed dose image information for the imaged organ of the at least one animal is used to determine RPT total absorbed dose image information for an organ for a human organ.

6. The method of claim 4, wherein microscopic absorbed dose rate information for multiple times is obtained and utilized.

7. The method of claim 1, wherein obtaining the macroscopic activity image information and/or the microscopic activity image information further comprises:
performing processing associated with obtaining at least two anatomy images relating to anatomy of an imaged object;
performing processing associated with obtaining multiple images regarding radioactivity distribution over time; and
performing processing associated with combining each radioactivity image with each anatomy image to create activity image information.

8. The method of claim 7, further comprising: performing processing associated with registering the anatomy images related to the radioactivity distribution over time.

9. The method of claim 1, further comprising: performing processing associated with adjusting, using the at least one computer application, the optimum amount of RPT to administer.

10. The method of claim 9, wherein the performing processing associated with adjusting accounts for any already delivered doses.