Dosimetry for californium-252 (252Cf) neutron-emitting brachytherapy sources and encapsulation, storage, and clinical delivery thereof

Abstract

The present invention discloses a methodology for the characterization and determination of mixed-field dosimetry for 252Cf Applicator Tube (AT)-type medical sources, utilizing ionization chambers, GM counters, and Monte Carlo methods. Unlike the previous methodologies, the present invention discloses a specification of dose to muscle, rather than dose to water, for clinical dosimetry of 252Cf medical sources. A dosimetry protocol, similar to that utilized for ICRU-45, with parameters determined specifically for 252Cf brachytherapy is disclosed. Neutron isodose distributions and data necessary for clinical implementation of 252Cf AT sources are also disclosed herein. Additionally, novel methods for the encapsulation, storage, and delivery / implantation of 252Cf radionuclide sources are disclosed.

Description

RELATED APPLICATIONS [0001] The present application claims priority to U.S. Divisional application Ser. No. 10 / 420,184, U.S. Pat. No. 7,118,524, filed Apr. 22, 2003, which claims priority to U.S. application Ser. No. 09 / 641,356, now U.S. Pat. No. 6,551,232, filed Aug. 17, 2000, which claims priority to U.S. Provisional Application Ser. No. 60 / 149,816, filed on Aug. 19, 1999, each of which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION [0002] The present invention relates to devices and methods for utilization in brachytherapy in the fields of medical physics and therapeutic radiology. More specifically, the present invention relates to brachytherapy dosimetric protocols utilizing the neutron-emitting radioisotope californium-252 (252Cf), as well as 252Cf encapsulation, storage, and remote delivery (afterloading) methodologies. BACKGROUND OF THE INVENTION I. Brachytherapy [0003] Radiation therapy refers to the treatment of diseases with ionizing radiation...

AI Technical Summary

Benefits of technology

"The present invention provides novel methodologies for use in radiation oncology, particularly in brachytherapy. The invention discusses the use of californium-252 (252Cf) as a neutron-emitting radioisotope and the importance of accurately calculating the geometry factor for extended line sources. The invention also describes a method for characterizing and determining mixed-field dosimetry for 252Cf medical sources, as well as a protocol for calculating kerma relative to muscle for different materials. The invention also discusses the use of encapsulation and containers for storing and delivering 252Cf sources, as well as a method for remote delivery of 252Cf brachytherapy sources. The invention also includes a section on radiation dosimetry, characterization of the 252Cf thermal neutron fluence field, and techniques for clinical application of neutron capture therapy (NCT) enhanced 252Cf brachytherapy using NCT agents such as 10B, 157Gd, 3He, 133Xe, or 135Xe. Overall, the invention provides valuable information and techniques for improving the accuracy and effectiveness of brachytherapy treatments using 252Cf sources."

Problems solved by technology

Accordingly, with “external beam therapy,” it generally is difficult to mitigate damage to underlying disease yet spare the normal tissues which may be included in the path of the radiation towards the target.

Although radium possesses a long half-life (i.e., approximately 1600 years), a particularly undesirable property is the requirement for careful attention to the protection of medical personnel, as well as healthy tissue of the patient.

This is due to its complex and highly penetrating gamma ray emission.

If the radiation source is not accurately positioned, there may be considerable overdosage to normal (i.e., non-tumorogenic) tissue, with serious risk of harm to the patient, or exposure of medical staff to radiation.

However, due to serious radiation safety considerations from the highly penetrating gamma-rays, this radioisotope has largely been replaced with other radionuclides.

Unfortunately, this AT-type source is rather large and cumbersome for use in restricted brachytherapy treatment geometries (e.g., the virulent brain tumor glioblastoma multiforme).

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