Radiation Absorbed Dose

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Oliver W. Press - One of the best experts on this subject based on the ideXlab platform.

  • High-Dose 131I-Tositumomab (Anti-CD20) Radioimmunotherapy for Non-Hodgkin’s Lymphoma: Adjusting Radiation Absorbed Dose to Actual Organ Volumes
    2015
    Co-Authors: Joseph G. Rajendran, Oliver W. Press, Md Darrell, R. Fisher, Phd Ajay, K. Gopal, Md Lawrence, D. Durack, Janet F. Eary
    Abstract:

    Radioimmunotherapy (RIT) using 131I-tositumomab has been used successfully to treat relapsed or refractory B-cell non-Hodgkin’s lymphoma (NHL). Our approach to treatment plan-ning has been to determine limits on Radiation Absorbed Dose to critical nonhematopoietic organs. This study demonstrates the feasibility of using CT to adjust for actual organ volumes in calculating organ-specific Absorbed Dose estimates. Methods: Records of 84 patients who underwent biodistribution studies after a trace-labeled infusion of 131I-tositumomab for RIT (Jan-uary 1990 and April 2003) were reviewed. Serial planar -cam-era images and whole-body NaI probe counts were obtained to estimate 131I-antibody source-organ residence times as recom-mended by the MIRD Committee. The source-organ residence times for standard man or woman were adjusted by the ratio of the MIRD phantom organ mass to the CT-derived organ mass. Results: The mean Radiation Absorbed Doses (in mGy/MBq) for our data using the MIRD model were lungs 1.67; liver 1.03; kidneys 1.08; spleen 2.67; and whole body 0.3; and for CT volume-adjusted organ volumes (in mGy/MBq) were lung

  • myeloablative 131i tositumomab radioimmunotherapy in treating non hodgkin s lymphoma comparison of dosimetry based on whole body retention and Dose to critical organ receiving the highest Dose
    The Journal of Nuclear Medicine, 2008
    Co-Authors: Joseph G. Rajendran, Ajay K. Gopal, D R Fisher, Larry Durack, Ted Gooley, Oliver W. Press
    Abstract:

    Objectives: Myeloablative radioimmunotherapy (RIT) using 131I tositumomab (anti-CD 20) monoclonal antibodies is an effective new therapy for B-cell non-Hodgkins lymphoma (NHL). The goal of this work is to determine optimum methods to deliver maximal myeloablative radioactivity without exceeding the Radiation tolerance of critical normal organs such as liver and lungs, and avoiding serious toxicity. Methods: We reviewed dosimetry records for 100 consecutive patients who underwent biodistribution and dosimetry after a test infusion of 131I- tositumomab. Serial gamma camera images were used to determine organ and tissue activities over time and to calculate Radiation-Absorbed Doses. Volumes of critical normal organs were determined from CT scans to adjust the Dose estimates for the individual patient. These Dose estimates helped us determine an appropriate therapy based on projected Dose to the critical normal organ receiving a maximum tolerable Radiation Dose. We compared our method of organ-specific dosimetry for treatment planning with the standard clinical approaches using a whole-body Dose-assessment method by assessing the difference in projected amounts of Radiation-Absorbed Doses, as well as the ratios of projected amounts, that would be prescribed for therapy by each of these two strategies. Results: The mean organ Doses (mGy/MBq) estimated by both methods were (1) Wholemore » body method: liver = 0.33 and lungs = 0.33; and (2) Organ-specific method: liver 1.52 and lungs 1.72 (p = .0001). The median difference between the Radiation-Absorbed Dose estimates was 3.40 (range of 1.37 to 7.96) for the lungs, 3.05 (range of 1.04 to 6.20) for the liver, and –0.05 for whole body (range of –0.18 to 0.16). The median ratio (OS divided by WB method) of Radiation-Absorbed Dose estimates was 5.12 (range of 2.33 to 10.01) for the lungs, 4.14 (range of 2.16 to 6.67) for the liver, and 0.94 (range of 0.79 to 1.22) for whole body. There was significant difference between the Dose estimated by the two methods for liver and lungs (p = 0.0001) and a significant correlation for whole body Dose estimates by the two methods (R = 0.97) indicating confidence in the whole body Dose estimation methods. Conclusions: Dosimetry based only on whole body retention will under-estimate the organ Doses in a substantial number of patients, likely because it assumes a uniform distribution and clearance without accounting for patient-specific variations in biodistribution. Myeloablative treatment based on individual organ Radiation Absorbed Dose provides the ability to safely administer the largest possible amounts of radioactivity and deliver an optimized Radiation Dose to tumor within the tolerance of normal organs.« less

  • high Dose 131i tositumomab anti cd20 radioimmunotherapy for non hodgkin s lymphoma adjusting Radiation Absorbed Dose to actual organ volumes
    The Journal of Nuclear Medicine, 2004
    Co-Authors: Joseph G. Rajendran, Lawrence D. Durack, Darrell R. Fisher, Oliver W. Press, Ajay K. Gopal, Janet F. Eary
    Abstract:

    Radioimmunotherapy (RIT) using 1 3 1 I-tositumomab has been used successfully to treat relapsed or refractory B-cell non-Hodgkin's lymphoma (NHL). Our approach to treatment planning has been to determine limits on Radiation Absorbed Dose to critical nonhematopoietic organs. This study demonstrates the feasibility of using CT to adjust for actual organ volumes in calculating organ-specific Absorbed Dose estimates. Methods: Records of 84 patients who underwent biodistribution studies after a trace-labeled infusion of 1 3 1 I-tositumomab for RIT (January 1990 and April 2003) were reviewed. Serial planar γ-camera images and whole-body Nal probe counts were obtained to estimate 1 3 1 I-antibody source-organ residence times as recommended by the MIRD Committee. The source-organ residence times for standard man or woman were adjusted by the ratio of the MIRD phantom organ mass to the CT-derived organ mass. Results: The mean Radiation Absorbed Doses (in mGy/MBq) for our data using the MIRD model were lungs = 1.67; liver = 1.03; kidneys = 1.08; spleen = 2.67; and whole body = 0.3; and for CT volume-adjusted organ volumes (in mGy/MBq) were lungs = 1.30; liver = 0.92; kidneys = 0.76; spleen = 1.40; and whole body = 0.22. We determined the following correlation coefficients between the 2 methods for the various organs: lungs, 0.49 (P = 0.0001); liver, 0.64 (P = 0.004); kidneys, 0.45 (P = 0.0004); spleen, 0.22 (P = 0.0001); and whole body, 0.78 (P = 0.0001), for the residence times. For therapy, patients received mean 1 3 1 I administered activities of 19.2 GBq (520 mCi) after adjustment for CT-derived organ mass compared with 16.0 GBq (433 mCi) that would otherwise have been given had therapy been based only using standard MIRD organ volumes-a statistically significant difference (P = 0.0001). Conclusion: We observed large variations in organ masses among our patients. Our treatments were planned to deliver the maximally tolerated Radiation Dose to the Dose-limiting normal organ. This work provides a simplified method for calculating patient-specific Radiation Doses by adjusting for the actual organ mass and shows the value of this approach in treatment planning for RIT.

  • High-Dose 131I-Tositumomab (Anti-CD20) Radioimmunotherapy for Non-Hodgkin’s Lymphoma: Adjusting Radiation Absorbed Dose to Actual Organ Volumes
    Journal of nuclear medicine : official publication Society of Nuclear Medicine, 2004
    Co-Authors: Joseph G. Rajendran, Lawrence D. Durack, Darrell R. Fisher, Oliver W. Press, Ajay K. Gopal, Janet F. Eary
    Abstract:

    Radioimmunotherapy (RIT) using 1 3 1 I-tositumomab has been used successfully to treat relapsed or refractory B-cell non-Hodgkin's lymphoma (NHL). Our approach to treatment planning has been to determine limits on Radiation Absorbed Dose to critical nonhematopoietic organs. This study demonstrates the feasibility of using CT to adjust for actual organ volumes in calculating organ-specific Absorbed Dose estimates. Methods: Records of 84 patients who underwent biodistribution studies after a trace-labeled infusion of 1 3 1 I-tositumomab for RIT (January 1990 and April 2003) were reviewed. Serial planar γ-camera images and whole-body Nal probe counts were obtained to estimate 1 3 1 I-antibody source-organ residence times as recommended by the MIRD Committee. The source-organ residence times for standard man or woman were adjusted by the ratio of the MIRD phantom organ mass to the CT-derived organ mass. Results: The mean Radiation Absorbed Doses (in mGy/MBq) for our data using the MIRD model were lungs = 1.67; liver = 1.03; kidneys = 1.08; spleen = 2.67; and whole body = 0.3; and for CT volume-adjusted organ volumes (in mGy/MBq) were lungs = 1.30; liver = 0.92; kidneys = 0.76; spleen = 1.40; and whole body = 0.22. We determined the following correlation coefficients between the 2 methods for the various organs: lungs, 0.49 (P = 0.0001); liver, 0.64 (P = 0.004); kidneys, 0.45 (P = 0.0004); spleen, 0.22 (P = 0.0001); and whole body, 0.78 (P = 0.0001), for the residence times. For therapy, patients received mean 1 3 1 I administered activities of 19.2 GBq (520 mCi) after adjustment for CT-derived organ mass compared with 16.0 GBq (433 mCi) that would otherwise have been given had therapy been based only using standard MIRD organ volumes-a statistically significant difference (P = 0.0001). Conclusion: We observed large variations in organ masses among our patients. Our treatments were planned to deliver the maximally tolerated Radiation Dose to the Dose-limiting normal organ. This work provides a simplified method for calculating patient-specific Radiation Doses by adjusting for the actual organ mass and shows the value of this approach in treatment planning for RIT.

  • Importance of pre-treatment Radiation Absorbed Dose estimation for radioimmunotherapy of non-Hodgkin's lymphoma
    Nuclear medicine and biology, 1997
    Co-Authors: Janet F. Eary, Lawrence D. Durack, Kenneth A. Krohn, Oliver W. Press, Irwin D. Bernstein
    Abstract:

    Non-Hodgkin's lymphoma I-131 radioimmunotherapy data were analyzed to determine whether a predictive relationship exists between Radiation Absorbed Doses calculated from biodistribution studies and Doses derived from patient size. Radioactivity treatment administrations scaled to patient size (MBq/kg or MBq/m2) or fixed MBq Doses do not produce consistent Radiation Absorbed Dose to critical organs. Treatment trials that do not provide Dose estimates for critical normal organs are less likely to succeed in identifying a clinical role for radioimmunotherapy.

Janet F. Eary - One of the best experts on this subject based on the ideXlab platform.

  • High-Dose 131I-Tositumomab (Anti-CD20) Radioimmunotherapy for Non-Hodgkin’s Lymphoma: Adjusting Radiation Absorbed Dose to Actual Organ Volumes
    2015
    Co-Authors: Joseph G. Rajendran, Oliver W. Press, Md Darrell, R. Fisher, Phd Ajay, K. Gopal, Md Lawrence, D. Durack, Janet F. Eary
    Abstract:

    Radioimmunotherapy (RIT) using 131I-tositumomab has been used successfully to treat relapsed or refractory B-cell non-Hodgkin’s lymphoma (NHL). Our approach to treatment plan-ning has been to determine limits on Radiation Absorbed Dose to critical nonhematopoietic organs. This study demonstrates the feasibility of using CT to adjust for actual organ volumes in calculating organ-specific Absorbed Dose estimates. Methods: Records of 84 patients who underwent biodistribution studies after a trace-labeled infusion of 131I-tositumomab for RIT (Jan-uary 1990 and April 2003) were reviewed. Serial planar -cam-era images and whole-body NaI probe counts were obtained to estimate 131I-antibody source-organ residence times as recom-mended by the MIRD Committee. The source-organ residence times for standard man or woman were adjusted by the ratio of the MIRD phantom organ mass to the CT-derived organ mass. Results: The mean Radiation Absorbed Doses (in mGy/MBq) for our data using the MIRD model were lungs 1.67; liver 1.03; kidneys 1.08; spleen 2.67; and whole body 0.3; and for CT volume-adjusted organ volumes (in mGy/MBq) were lung

  • 166Ho-DOTMP Radiation-Absorbed Dose Estimation for Skeletal Targeted Radiotherapy
    Journal of nuclear medicine : official publication Society of Nuclear Medicine, 2006
    Co-Authors: Hazel B. Breitz, Richard E. Wendt, Michael S. Stabin, Sui Shen, William D. Erwin, Joseph G. Rajendran, Janet F. Eary, Lawrence D. Durack, Ebrahim Delpassand, William H. Martin
    Abstract:

    UNLABELLED 166Ho-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene-phosphonate (DOTMP) is a tetraphosphonate molecule radiolabeled with 166Ho that localizes to bone surfaces. This study evaluated pharmacokinetics and Radiation-Absorbed Dose to all organs from this beta-emitting radiopharmaceutical. METHODS After two 1.1-GBq administrations of 166Ho-DOTMP, data from whole-body counting using a gamma-camera or uptake probe were assessed for reproducibility of whole-body retention in 12 patients with multiple myeloma. The Radiation-Absorbed Dose to normal organs was estimated using MIRD methodology, applying residence times and S values for 166Ho. Marrow Dose was estimated from measured activity retained after 18 h. The activity to deliver a therapeutic Dose of 25 Gy to the marrow was determined. Methods based on region-of-interest (ROI) and whole-body clearance were evaluated to estimate kidney activity, because the radiotracer is rapidly excreted in the urine. The Dose to the surface of the bladder wall was estimated using a dynamic bladder model. RESULTS In clinical practice, gamma-camera methods were more reliable than uptake probe-based methods for whole-body counting. The intrapatient variability of Dose calculations was less than 10% between the 2 tracer studies. Skeletal uptake of 166Ho-DOTMP varied from 19% to 39% (mean, 28%). The activity of 166Ho prescribed for therapy ranged from 38 to 67 GBq (1,030-1,810 mCi). After high-Dose therapy, the estimates of Absorbed Dose to the kidney varied from 1.6 to 4 Gy using the whole-body clearance-based method and from 8.3 to 17.3 Gy using the ROI-based method. Bladder Dose ranged from 10 to 20 Gy, bone surface Dose ranged from 39 to 57 Gy, and Doses to other organs were less than 2 Gy for all patients. Repetitive administration had no impact on tracer biodistribution, pharmacokinetics, or organ Dose. CONCLUSION Pharmacokinetics analysis validated gamma-camera whole-body counting of 166Ho as an appropriate approach to assess clearance and to estimate Radiation-Absorbed Dose to normal organs except the kidneys. Quantitative gamma-camera imaging is difficult and requires scatter subtraction because of the multiple energy emissions of 166Ho. Kidney Dose estimates were approximately 5-fold higher when the ROI-based method was used rather than the clearance-based model, and neither appeared reliable. In future clinical trials with 166Ho-DOTMP, we recommend that Dose estimation based on the methods described here be used for all organs except the kidneys. Assumptions for the kidney Dose require further evaluation.

  • high Dose 131i tositumomab anti cd20 radioimmunotherapy for non hodgkin s lymphoma adjusting Radiation Absorbed Dose to actual organ volumes
    The Journal of Nuclear Medicine, 2004
    Co-Authors: Joseph G. Rajendran, Lawrence D. Durack, Darrell R. Fisher, Oliver W. Press, Ajay K. Gopal, Janet F. Eary
    Abstract:

    Radioimmunotherapy (RIT) using 1 3 1 I-tositumomab has been used successfully to treat relapsed or refractory B-cell non-Hodgkin's lymphoma (NHL). Our approach to treatment planning has been to determine limits on Radiation Absorbed Dose to critical nonhematopoietic organs. This study demonstrates the feasibility of using CT to adjust for actual organ volumes in calculating organ-specific Absorbed Dose estimates. Methods: Records of 84 patients who underwent biodistribution studies after a trace-labeled infusion of 1 3 1 I-tositumomab for RIT (January 1990 and April 2003) were reviewed. Serial planar γ-camera images and whole-body Nal probe counts were obtained to estimate 1 3 1 I-antibody source-organ residence times as recommended by the MIRD Committee. The source-organ residence times for standard man or woman were adjusted by the ratio of the MIRD phantom organ mass to the CT-derived organ mass. Results: The mean Radiation Absorbed Doses (in mGy/MBq) for our data using the MIRD model were lungs = 1.67; liver = 1.03; kidneys = 1.08; spleen = 2.67; and whole body = 0.3; and for CT volume-adjusted organ volumes (in mGy/MBq) were lungs = 1.30; liver = 0.92; kidneys = 0.76; spleen = 1.40; and whole body = 0.22. We determined the following correlation coefficients between the 2 methods for the various organs: lungs, 0.49 (P = 0.0001); liver, 0.64 (P = 0.004); kidneys, 0.45 (P = 0.0004); spleen, 0.22 (P = 0.0001); and whole body, 0.78 (P = 0.0001), for the residence times. For therapy, patients received mean 1 3 1 I administered activities of 19.2 GBq (520 mCi) after adjustment for CT-derived organ mass compared with 16.0 GBq (433 mCi) that would otherwise have been given had therapy been based only using standard MIRD organ volumes-a statistically significant difference (P = 0.0001). Conclusion: We observed large variations in organ masses among our patients. Our treatments were planned to deliver the maximally tolerated Radiation Dose to the Dose-limiting normal organ. This work provides a simplified method for calculating patient-specific Radiation Doses by adjusting for the actual organ mass and shows the value of this approach in treatment planning for RIT.

  • High-Dose 131I-Tositumomab (Anti-CD20) Radioimmunotherapy for Non-Hodgkin’s Lymphoma: Adjusting Radiation Absorbed Dose to Actual Organ Volumes
    Journal of nuclear medicine : official publication Society of Nuclear Medicine, 2004
    Co-Authors: Joseph G. Rajendran, Lawrence D. Durack, Darrell R. Fisher, Oliver W. Press, Ajay K. Gopal, Janet F. Eary
    Abstract:

    Radioimmunotherapy (RIT) using 1 3 1 I-tositumomab has been used successfully to treat relapsed or refractory B-cell non-Hodgkin's lymphoma (NHL). Our approach to treatment planning has been to determine limits on Radiation Absorbed Dose to critical nonhematopoietic organs. This study demonstrates the feasibility of using CT to adjust for actual organ volumes in calculating organ-specific Absorbed Dose estimates. Methods: Records of 84 patients who underwent biodistribution studies after a trace-labeled infusion of 1 3 1 I-tositumomab for RIT (January 1990 and April 2003) were reviewed. Serial planar γ-camera images and whole-body Nal probe counts were obtained to estimate 1 3 1 I-antibody source-organ residence times as recommended by the MIRD Committee. The source-organ residence times for standard man or woman were adjusted by the ratio of the MIRD phantom organ mass to the CT-derived organ mass. Results: The mean Radiation Absorbed Doses (in mGy/MBq) for our data using the MIRD model were lungs = 1.67; liver = 1.03; kidneys = 1.08; spleen = 2.67; and whole body = 0.3; and for CT volume-adjusted organ volumes (in mGy/MBq) were lungs = 1.30; liver = 0.92; kidneys = 0.76; spleen = 1.40; and whole body = 0.22. We determined the following correlation coefficients between the 2 methods for the various organs: lungs, 0.49 (P = 0.0001); liver, 0.64 (P = 0.004); kidneys, 0.45 (P = 0.0004); spleen, 0.22 (P = 0.0001); and whole body, 0.78 (P = 0.0001), for the residence times. For therapy, patients received mean 1 3 1 I administered activities of 19.2 GBq (520 mCi) after adjustment for CT-derived organ mass compared with 16.0 GBq (433 mCi) that would otherwise have been given had therapy been based only using standard MIRD organ volumes-a statistically significant difference (P = 0.0001). Conclusion: We observed large variations in organ masses among our patients. Our treatments were planned to deliver the maximally tolerated Radiation Dose to the Dose-limiting normal organ. This work provides a simplified method for calculating patient-specific Radiation Doses by adjusting for the actual organ mass and shows the value of this approach in treatment planning for RIT.

  • Importance of pre-treatment Radiation Absorbed Dose estimation for radioimmunotherapy of non-Hodgkin's lymphoma
    Nuclear medicine and biology, 1997
    Co-Authors: Janet F. Eary, Lawrence D. Durack, Kenneth A. Krohn, Oliver W. Press, Irwin D. Bernstein
    Abstract:

    Non-Hodgkin's lymphoma I-131 radioimmunotherapy data were analyzed to determine whether a predictive relationship exists between Radiation Absorbed Doses calculated from biodistribution studies and Doses derived from patient size. Radioactivity treatment administrations scaled to patient size (MBq/kg or MBq/m2) or fixed MBq Doses do not produce consistent Radiation Absorbed Dose to critical organs. Treatment trials that do not provide Dose estimates for critical normal organs are less likely to succeed in identifying a clinical role for radioimmunotherapy.

Martin A. Lodge - One of the best experts on this subject based on the ideXlab platform.

  • Radiation Absorbed Dose distribution in a patient treated with yttrium-90 microspheres for hepatocellular carcinoma.
    Medical physics, 2004
    Co-Authors: Mehrdad Sarfaraz, Andrew S. Kennedy, Martin A. Lodge
    Abstract:

    We have implemented a three-dimensional Dose calculation technique accounting for Dose inhomogeneity within the liver and tumor of a patient treated with 90 Y microspheres. Single-photon emission computed tomography(SPECT)images were used to derive the activity distribution within liver. A Monte Carlo calculation was performed to create a voxel Dose kernel for the 90 Y source. The activity distribution was convolved with the voxel Dose kernel to obtain the three-dimensional (3D) Radiation Absorbed Dose distribution. An automated technique was developed to accurately register the computed tomography(CT) and SPECT scans in order to display the 3D Dose distribution on the CT scans. In addition, Dose-volume histograms were generated to fully analyze the tumor and liver Doses. The calculated Dose-volume histogram indicated that although the patient was treated to the nominal whole liver Dose of 110 Gy, only 16% of the liver and 83% of the tumor received a Dose higher than 110 Gy. The mean tumor and liver Doses were 163 and 58 Gy, respectively.

  • Physical aspects of yttrium-90 microsphere therapy for nonresectable hepatic tumors
    Medical physics, 2003
    Co-Authors: Mehrdad Sarfaraz, Andrew S. Kennedy, Martin A. Lodge, Zong J. Cao, Gregory D. Sackett, Ravi Murthy, Bruce R. Line, David A. Van Echo
    Abstract:

    Administration of yttrium-90 microspheres via the hepatic artery is an attractive approach to selectively delivertherapeuticDoses of Radiation to livermalignancies. This procedure allows deliveringRadiation Absorbed Doses in excess of 100 Gy to the tumors without significant liver toxicity. The microsphere therapy involves different specialties including medicaloncology,Radiationoncology, nuclear medicine, interventional radiology, medical physics, and Radiation safety. We have treated 80 patients with nonresectable hepatic tumors with yttrium-90 microspheres during the past two years on an institutional study protocol. The nominal Radiation Absorbed Dose to the tumor in this study was 150 Gy. Required activity was calculated based on the nominal Radiation Absorbed Dose and patient’s liver volume obtained from the CT scan, assuming a uniform distribution of the microspheres within the liver. Microspheres were administered via a catheter placed into the hepatic artery. The actual Radiation Absorbed Doses to tumors and normal liver tissue were calculated retrospectively based on the patient’s 99 m Tc-MAA study and CT scans. As expected, the activity uptake within the liver was found to be highly nonuniform and multifold tumor to nontumor uptake was observed. A partition model was used to calculate the Radiation Absorbed Dose within each region. For a typical patient the calculated Radiation Absorbed Doses to the tumor and liver were 402 and 118 Gy, respectively. The Radiation safety procedure involves confinement of the source and proper disposal of the contaminated materials. The average exposure rates at 1 m from the patients and on contact just anterior to the liver were 6 and 135 uSv/h, respectively. The special physics and dosimetry protocol developed for this procedure is presented.

Mehrdad Sarfaraz - One of the best experts on this subject based on the ideXlab platform.

  • Radiation Absorbed Dose distribution in a patient treated with yttrium-90 microspheres for hepatocellular carcinoma.
    Medical physics, 2004
    Co-Authors: Mehrdad Sarfaraz, Andrew S. Kennedy, Martin A. Lodge
    Abstract:

    We have implemented a three-dimensional Dose calculation technique accounting for Dose inhomogeneity within the liver and tumor of a patient treated with 90 Y microspheres. Single-photon emission computed tomography(SPECT)images were used to derive the activity distribution within liver. A Monte Carlo calculation was performed to create a voxel Dose kernel for the 90 Y source. The activity distribution was convolved with the voxel Dose kernel to obtain the three-dimensional (3D) Radiation Absorbed Dose distribution. An automated technique was developed to accurately register the computed tomography(CT) and SPECT scans in order to display the 3D Dose distribution on the CT scans. In addition, Dose-volume histograms were generated to fully analyze the tumor and liver Doses. The calculated Dose-volume histogram indicated that although the patient was treated to the nominal whole liver Dose of 110 Gy, only 16% of the liver and 83% of the tumor received a Dose higher than 110 Gy. The mean tumor and liver Doses were 163 and 58 Gy, respectively.

  • Physical aspects of yttrium-90 microsphere therapy for nonresectable hepatic tumors
    Medical physics, 2003
    Co-Authors: Mehrdad Sarfaraz, Andrew S. Kennedy, Martin A. Lodge, Zong J. Cao, Gregory D. Sackett, Ravi Murthy, Bruce R. Line, David A. Van Echo
    Abstract:

    Administration of yttrium-90 microspheres via the hepatic artery is an attractive approach to selectively delivertherapeuticDoses of Radiation to livermalignancies. This procedure allows deliveringRadiation Absorbed Doses in excess of 100 Gy to the tumors without significant liver toxicity. The microsphere therapy involves different specialties including medicaloncology,Radiationoncology, nuclear medicine, interventional radiology, medical physics, and Radiation safety. We have treated 80 patients with nonresectable hepatic tumors with yttrium-90 microspheres during the past two years on an institutional study protocol. The nominal Radiation Absorbed Dose to the tumor in this study was 150 Gy. Required activity was calculated based on the nominal Radiation Absorbed Dose and patient’s liver volume obtained from the CT scan, assuming a uniform distribution of the microspheres within the liver. Microspheres were administered via a catheter placed into the hepatic artery. The actual Radiation Absorbed Doses to tumors and normal liver tissue were calculated retrospectively based on the patient’s 99 m Tc-MAA study and CT scans. As expected, the activity uptake within the liver was found to be highly nonuniform and multifold tumor to nontumor uptake was observed. A partition model was used to calculate the Radiation Absorbed Dose within each region. For a typical patient the calculated Radiation Absorbed Doses to the tumor and liver were 402 and 118 Gy, respectively. The Radiation safety procedure involves confinement of the source and proper disposal of the contaminated materials. The average exposure rates at 1 m from the patients and on contact just anterior to the liver were 6 and 135 uSv/h, respectively. The special physics and dosimetry protocol developed for this procedure is presented.

Joseph J. Sanger - One of the best experts on this subject based on the ideXlab platform.

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