Photon activation therapy and brachytherapy

Laster, Brenda H.; Dixon, Dabney W.; Novick, Sara; Feldman, Jon P.; Seror, Veronique; Goldbart, Zvi I.; Kalef-Ezra, John A.

doi:10.1016/j.brachy.2008.12.008

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Volume 8, Issue 3 , Pages 324-330, July 2009

Photon activation therapy and brachytherapy

Brenda H. Laster
- Department of Nuclear Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel
- Corresponding author. Department of Nuclear Engineering, Ben Gurion University of the Negev, Beer Sheva 84105, Israel. Tel.: +972-8-646-1317; fax: +972-8-647-2955.
Dabney W. Dixon
- Department of Chemistry, Georgia State University, Atlanta, GA
Sara Novick
- Department of Nuclear Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel
Jon P. Feldman
- Department of Nuclear Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel
Veronique Seror
- Department of Nuclear Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel
Zvi I. Goldbart
- Department of Nuclear Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel
- Department of Analytical Chemistry, NRCN Negev, Beer Sheva, Israel
John A. Kalef-Ezra
- Department of Medical Physics, Medical School, University of Ioannina, Ioannina, Greece

published online 12 May 2009.

Abstract

Purpose

In photon activation therapy (PAT), energy deposition at critical sites within a tumor can be increased by complexing the DNA with higher Z atoms, and provoking the emission of Auger electrons after inducing a photoelectric effect. This in vivo study evaluates the hypothesis using X-rays from palladium-103 seeds to excite the L-edge of platinum (Pt) atoms bound to the DNA of cancerous cells.

Methods and Materials

Pt (II) tetrakis(N-methyl-4-pyridyl) porphyrin chloride was used to locate Pt atoms adjacent to the DNA of the KHJJ murine mammary carcinoma; a 2.3-mCi palladium-103 seed was implanted in the tumor.

Results

The tumor periphery received subtherapeutic doses. The rate of tumor growth in mice treated with PAT was slower than in mice treated with brachytherapy only.

Conclusions

The tumor growth delay for PAT-treated mice is attributed to Auger emission from Pt atoms that produced substantial local damage. However, other co-existing mechanisms cannot be ruled out.

Keywords: Porphyrin, Platinum, Cancer, Radiation, Auger electrons, Brachytherapy, Photoelectric absorption, L-absorption edge, Photoelectric effect, TMPyP4