Short Communication: Nanoparticle Thermotherapy and External Beam Radiation Therapy for Human Prostate Cancer Cells

General Questions

What is Ionizing Radiation?

Ionizing radiation consists of subatomic particles or electromagnetic waves that are energetic enough to detach electrons from atoms or molecules, ionizing them.

Two of the most common forms of ionizing radiation are gamma rays and x-rays. Both forms of ionizing radiation are almost identical with exception to their source of origination.

How is Ionizing Radiation Generated?

Ionizing radiation comes from radioactive sources such as cobalt 60 and cesium 137 and non-radioactive sources such as x-ray tubes. Radioactive sources are unstable materials where gamma rays originate from the nucleus. x-rays originate in the electron fields surrounding the nucleus or are machine-produced.

What is Ionizing Radiation Used for?

Because of the penetrating properties of ionizing radiation and their ability to kill microorganisms, ionizing radiation is used to sterilize or reduce the microbial load of many different types of products such as medical devices, packaging, cosmetics, foods, and agricultural products. It is also used to alter the properties of many different polymers through recombination, cross-linkage, and cross scission.

Why use x-ray versus gamma produced Ionizing radiation?

Gamma ionizing radiation is produced by radioactive sources such as cobalt 60 or cesium 137 and is dangerous requiring heavy shielding and high levels of security to protect. The unstable material is constantly decaying and cannot be turned off. x-ray ionizing radiation is produced by a x-ray tube therefore it can be turned off when it is not being used and it requires much less shielding. At the end the of unit’s lifecycle, the unit does not have any radioactive source and therefore does not require the expensive disposal costs associated with radioactive sources that continue to degrade over hundreds of years.

Does the RS 3400 require external cooling?

No, the RS 3400 uses a self-contained water to air exchange system.

Is the RS 3400 Blood Irradiator cleared by the FDA for GVHD?

Yes, the RS 3400 was cleared by the USFDA for marketing for the irradiation of blood for the prevention of graft verses host disease (GVHD).

How does the RS 3400 differ from other x-ray irradiators?

The RS 3400 is designed to have the blood bags rotate around the Quastar™ x-ray emitter using our patented carousel and therefore delivers superior uniformity.
Unlike other x-ray blood irradiators, the RS 3400 is completely self-contained and requires no external water supply for tube cooling.
The RS 3400 is engineered for extreme reliability as it uses the proven Quastar™ x-ray emitter.
The RS 3400 has only ONE x-ray tube and ONE power supply.

How does the RS 3400 differ from a Cs-137 gamma irradiator??

The RS 3400 uses a Rad Source patented Quastar™ x-ray emitter and therefore contains NO radioactive isotopes. It can be turned on and off, similar to a light bulb. As a result, there is no Nuclear Site License, Homeland Security issues, or room shielding requirements.

Abstract: Nanoparticle thermotherapy (NPTT) uses monoclonal antibody-linked iron oxide magnetic nanoparticles (bioprobes) for the tumor-specific thermotherapy of cancer by hysteretic heating of the magnetic component of the probes through an externally applied alternating magnetic field (AMF). The present study investigated the effect of NPTT on a human prostate cancer cell line, DU145. The concept of total heat dose (THD) as a measure for NPTT was validated on a cellular level and THD was correlated to cell death in vitro. The study, furthermore, explored the potential enhancement of the NPTT effect through added external beam radiation therapy (EBRT), because both forms of treatment have a different, and potentially complementary, mechanism of causing cell death. METHODS: Using carbodiimide, (111)In-DOTA-ChL6 was conjugated to dextran iron oxide 20-nm particles with polyethylene glycol COOH groups on the surface and purified as (111)In-bioprobes. NPTT and EBRT were applied alone and combined to cells labeled with the bioprobes. Cell response was monitored by measuring lactate dehydrogenase (LDH), a product of cytolysis, in the medium. This distinct focus on the response to NPTT was possible, since we found in previous studies that the LDH assay was relatively insensitive to the response of cells (without bioprobes) to EBRT in the dose levels given here. RESULTS: NPTT showed a significantly increased cell death at a total calculated heat dose of 14.51 and 29.02 J/g cells (50% and 100% AMF duty, 350 Oe, 136 kHz, 12 cycles, 20 minutes total), compared with AMF exposure in the absence of bioprobes. Adding EBRT to NPTT did not increase cell death, as measured by LDH. However, EBRT given to cells labeled with bioprobes caused significant cell death at radiation doses of 10 Gy and higher. CONCLUSIONS: In human prostate cancer cell cultures, NPTT applied as a single modality caused cell death that correlated with THD estimation; complete cell death occurred at 14.51 J/g cells. Consequently, enhancement of the NPTT effect through the addition of EBRT could not be addressed. Interestingly, EBRT induced cell death on bioprobe-labeled cells at EBRT levels that did not show cell death in the absence of bioprobes; this phenomenon is worth investigating further. Citation: Cancer Biother Radiopharm. 2008 Apr;23(2):265-71. Website: https://www.liebertonline.com/doi/abs/10.1089/cbr.2007.0411