Article: article from journal or magazin.
A treatment planning method for sequentially combining radiopharmaceutical therapy and external radiation therapy.
International Journal of Radiation Oncology, Biology, Physics
Publication types: Case Reports ; Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't Publication Status: ppublish
PURPOSE: Effective cancer treatment generally requires combination therapy. The combination of external beam therapy (XRT) with radiopharmaceutical therapy (RPT) requires accurate three-dimensional dose calculations to avoid toxicity and evaluate efficacy. We have developed and tested a treatment planning method, using the patient-specific three-dimensional dosimetry package 3D-RD, for sequentially combined RPT/XRT therapy designed to limit toxicity to organs at risk. METHODS AND MATERIALS: The biologic effective dose (BED) was used to translate voxelized RPT absorbed dose (D(RPT)) values into a normalized total dose (or equivalent 2-Gy-fraction XRT absorbed dose), NTD(RPT) map. The BED was calculated numerically using an algorithmic approach, which enabled a more accurate calculation of BED and NTD(RPT). A treatment plan from the combined Samarium-153 and external beam was designed that would deliver a tumoricidal dose while delivering no more than 50 Gy of NTD(sum) to the spinal cord of a patient with a paraspinal tumor. RESULTS: The average voxel NTD(RPT) to tumor from RPT was 22.6 Gy (range, 1-85 Gy); the maximum spinal cord voxel NTD(RPT) from RPT was 6.8 Gy. The combined therapy NTD(sum) to tumor was 71.5 Gy (range, 40-135 Gy) for a maximum voxel spinal cord NTD(sum) equal to the maximum tolerated dose of 50 Gy. CONCLUSIONS: A method that enables real-time treatment planning of combined RPT-XRT has been developed. By implementing a more generalized conversion between the dose values from the two modalities and an activity-based treatment of partial volume effects, the reliability of combination therapy treatment planning has been expanded.
Adult, Algorithms, Combined Modality Therapy/methods, Humans, Male, Organometallic Compounds/therapeutic use, Organophosphorus Compounds/therapeutic use, Organs at Risk/radiation effects, Osteosarcoma/radiotherapy, Radiation Injuries/prevention & control, Radioisotopes/therapeutic use, Radiotherapy Dosage, Radiotherapy Planning, Computer-Assisted/methods, Relative Biological Effectiveness, Samarium/therapeutic use, Spinal Cord/radiation effects, Spinal Neoplasms/radiotherapy, Tomography, Emission-Computed, Single-Photon/methods, Tomography, X-Ray Computed/methods
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