Murali Nair, Presenter: Nothing to Disclose

Rufus Mark, Abstract Co-Author: Nothing to Disclose

Paul J. Anderson MD, Abstract Co-Author: Nothing to Disclose

Thomas Neumann MD, Abstract Co-Author: Nothing to Disclose

To present the results of the quality assurance, dosimetric and radiation safety parameters observed from our experience of treating 37 patients of non-Hodgkin’s Lymphoma with RIT.

Radioactive I-131 labeled monoclonal antibody called tositumomab ( Glaxo Smith Kline ) was used for treatment of non-Hodgkin’s lymphoma at our center. The mouse antibody interacts with CD 20 expressing tumors and serves as the carrier for transport of radioactive material, I-131 to the cancer cells, leading to cell death. Starting from 2001 to April 10, 2007, we have treated 37 patients ( 19 Female and 18 Male ) with RIT as outpatient. The age group of patients treated were from 45 to 80 years at a median age of 70 years. Initial dosimetric study was performed on each patient administered with 5mCi of the same antibody, in order to calculate the total body residence time (TBRT). The whole body dose used for treatment was 65 cGy and 75 cGy based on platelet counts. The therapeutic dose was calculated using the patient’s residence time. The radiation safety precautions used consisted of using an L-shield which had attenuation effect of 1/20th of the exposure.

The measured residence time (TBRT) is plotted as a function of the mCi/Kgm injected to the patient, and is used for calculating the required activity by knowing the residence time and the weight of the patient. Also the distribution, of the exposure rate measured at one meter from the patient, the calculated life time exposure to the public and the residence time is shown in Fig 1 . The uptake of the I-131 activity inside the lymph nodes during tracer study is shown in the whole body scan (Fig 2.)

We have evaluated the dosimetry and radiation safety parameters associated with the RIT on 37 patients and the results of this evaluation are reported. The calculated public exposure dose for all the patients treated in this study was less than 500 mrem for total decay .

Nair, M, Mark, R, Anderson, P, Neumann, T, Radiation Safety and Dosimetric Data Obtained from 37 Patients Treated with Radio-immunotherapy (RIT) for Non- Hodgkin's Lymphoma.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/6001130.html