Bulletin of the American Physical Society
APS April Meeting 2014
Volume 59, Number 5
Saturday–Tuesday, April 5–8, 2014; Savannah, Georgia
Session H3: Invited Session: Frontiers of the Interface Between Physics and Medicine |
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Sponsoring Units: DNP DPB Chair: Jerry Nolen, Argonne National Laboratories Room: Chatham Ballroom B |
Sunday, April 6, 2014 8:30AM - 9:06AM |
H3.00001: New Methods for Targeted Alpha Radiotherapy Invited Speaker: J. David Robertson Targeted radiotherapies based on alpha emitters are a promising alternative to beta emitting radionuclides. Because of their much shorter range, targeted $\alpha $-radiotherapy (TAT) agents have great potential for application to small, disseminated tumors and micro metastases and treatment of hematological malignancies consisting of individual, circulating neoplastic cells. A promising approach to TAT is the use of the \textit{in vivo} $\alpha $-generator radionuclides $^{\mathrm{223}}$Ra (t$_{\mathrm{1/2}} \quad =$ 11.4 d) and $^{\mathrm{225}}$Ac (t$_{\mathrm{1/2}} \quad =$ 10.0 d). In addition to their longer half-lives, these two isotopes have the potential of dramatically increasing the therapeutic efficacy of TAT as they each emit four $\alpha $ particles in their decay chain. This principle has recently been exploited in the development of Xofigo$^{\mathrm{\mbox{\textregistered }}}$, the first TAT agent approved for clinical use by the U.S. FDA. Xofigo, formulated as $^{\mathrm{223}}$RaCl$_{\mathrm{2}}$, is used for treatment of metastatic bone cancer in men with castration-resistant prostate cancer. TAT with $^{\mathrm{223}}$Ra works, however, only in the case of bone cancer because radium, as a chemical analogue of calcium, efficiently targets bone. In order to bring the benefits of TAT with $^{\mathrm{223}}$Ra or $^{\mathrm{225}}$Ac to other tumor types, a new delivery method must be devised. Retaining the \textit{in vivo} $\alpha $ generator radionuclides at the target site through the decay process is one of the major challenges associated with the development of TAT. Because the recoil energy of the daughter radionuclides from the $\alpha $-emission is $\sim$ 100 keV -- a value which is four orders of magnitude greater than the energy of a covalent bond - the daughters will not remain bound to the bioconjugate at the targeting site. Various approaches have been attempted to achieve retention of the $\alpha $-generator daughter radionuclides at the target site, including incorporation of the \textit{in vivo} generator into liposomes and fullerenes. Unfortunately, to date single wall liposomes and fullerenes are able to retain less than 10{\%} of the daughter radionuclides. We have recently demonstrated that a multilayered nanoparticle-antibody conjugate can deliver multiple $\alpha $ radiations from the \textit{in vivo }$\alpha $-generator $^{\mathrm{225}}$Ac at biologically relevant receptor sites. The nanoparticles retained over 90{\%} of the $^{\mathrm{221}}$Fr daughter over the course of three weeks in \textit{in vitro} experiments. In \textit{in vivo} experiments, approximately 90{\%} of the $^{\mathrm{213}}$Bi was retained in the target tissue 24 hours after injection of the antibody labeled nanoparticle. An overview of the development and application of this promising, new approach to targeted alpha therapy will be presented. [Preview Abstract] |
Sunday, April 6, 2014 9:06AM - 9:42AM |
H3.00002: Accelerator Production of Isotopes for Medical Use Invited Speaker: Suzanne Lapi The increase in use of radioisotopes for medical imaging and therapy has led to the development of novel routes of isotope production. For example, the production and purification of longer-lived position emitting radiometals has been explored to allow for nuclear imaging agents based on peptides, antibodies and nanoparticles. These isotopes ($^{\mathrm{64}}$Cu, $^{\mathrm{89}}$Zr, $^{\mathrm{86}}$Y) are typically produced via irradiation of solid targets on smaller medical cyclotrons at dedicated facilities. Recently, isotope harvesting from heavy ion accelerator facilities has also been suggested. The Facility for Rare Isotope Beams (FRIB) will be a new national user facility for nuclear science to be completed in 2020. Radioisotopes could be produced by dedicated runs by primary users or may be collected synergistically from the water in cooling-loops for the primary beam dump that cycle the water at flow rates in excess of hundreds of gallons per minute. A liquid water target system for harvesting radioisotopes at the National Superconducting Cyclotron Laboratory (NSCL) was designed and constructed as the initial step in proof-of-principle experiments to harvest useful radioisotopes in this manner. This talk will provide an overview of isotope production using both dedicated machines and harvesting from larger accelerators typically used for nuclear physics. [Preview Abstract] |
Sunday, April 6, 2014 9:42AM - 10:18AM |
H3.00003: Hadron Cancer Therapy - relative merits of X-ray, proton and carbon beams Invited Speaker: Oliver Jakel Heidelberg University has a long experience in radiotherapy with carbon ions, starting with a pilot project at GSI in 1997. This project was jointly run by the Dep. for Radiation Oncology of Heidelberg University, GSI and the German Cancer Research Center (DKFZ). A hospital based heavy ion center at Heidelberg University, the Heidelberg Ion Beam Therapy Center (HIT) was proposed by the same group in 1998 and started clinical operation in late 2009. Since then nearly 2000 patients were treated with beams of carbon ions and protons. Just recently the operation of the world's first and only gantry for heavy ions also started at HIT. Patient treatments are performed in three rooms. Besides that, a lot of research projects are run in the field of Medical Physics and Radiobiology using a dedicated experimental area and the possibility to use beams of protons, carbon, helium and oxygen ions being delivered with the raster scanning technique. [Preview Abstract] |
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