Evaluation of blood irradiation indicators for dose verification and FDA recommendation compliance

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.

Justin Czerniawski PhD, Vice President – R&D and Peter Daniel

Blood irradiation protects patients from transfusion-associated graft-versus-host disease (TA-GVHD), a rare but serious condition where donor immune cells attack the recipient’s body. Irradiation indicators are the small labels placed on blood products to show that irradiation happened. We wanted to know how well today’s indicators show the dose a product actually received, so we put three of them to the test.

Background and Objective

Irradiation of cellular blood components is performed to prevent transfusion-associated graft-versus-host disease (TA-GVHD). FDA recommendations specify a minimum dose of 15 Gy and target dose of 25 Gy for all irradiated blood products intended for transfusion.^1,2 Gy (gray) is the unit used to measure absorbed radiation dose. While irradiation indicators are routinely used as part of quality assurance programs, many are designed only to indicate exposure and not to verify a specific delivered dose.^3,4 The objective of this study was to compare the response of three commercially available blood irradiation indicators across clinically relevant dose levels and assess their ability to visually differentiate delivered dose.

Materials and Methods

AccuTag^TM (15 Gy), Rad-Sure^TM (15 Gy), and RAD-CONTROL (15 Gy) blood irradiation indicators were irradiated using a calibrated RS^® 3400 X-ray blood irradiator at doses of 10, 15, 25, 50, and 75 Gy and unirradiated control (0 Gy). For each dose level, a single unirradiated indicator of each type was placed at evenly spaced locations within the central region of a blood phantom (a stand-in that mimics a blood product). Immediately following irradiation, indicators were visually evaluated by primary researchers under fluorescent light for dose-dependent visual response and their ability to differentiate between irradiation dose levels.

Results

AccuTag exhibited a progressive dose-dependent visual response across the evaluated dose range. Color changes were distinguishable between under-irradiation (10 Gy), FDA-recommended dose range (15 Gy minimum and 25 Gy target), and higher-dose conditions (50-75 Gy). Response enabled visual identification of the FDA-recommended dose under the conditions tested.^1,2,5 In contrast, Rad-Sure and RAD-CONTROL confirmed irradiation exposure but did not provide distinguishable dose-level verification.

Visual Comparison of Indicator Response Across Clinically Relevant Irradiation Doses

AccuTag

Center dot compared with the reference ring = dose level.

0 Gy: Not irradiated
10 Gy: Center lighter than ring. Under-irradiated
15 Gy: Center matches ring. 15-25 Gy minimum / target met
25 Gy: Center matches ring. 15-25 Gy minimum / target met
50 Gy: Center darker than ring. Over-irradiated
75 Gy: Center darker than ring. Over-irradiated

Rad-Sure

“Not” blacked out = irradiated.

0 Gy: Not irradiated
10, 15, 25, 50 and 75 Gy: Irradiated

RAD-CONTROL

Red window turns black = irradiated.

0 Gy: Not irradiated
10, 15, 25, 50 and 75 Gy: Irradiated

See all three indicators side by side at every dose in the full research poster. Click to view the full PDF here.

Conclusions

Under the conditions tested, AccuTag exhibited a dose-dependent visual response across the evaluated dose range.⁵ Rad-Sure and RAD-CONTROL confirmed irradiation exposure but did not provide distinguishable dose-level verification, consistent with their intended design and labeling.^3,4

Dose-responsive indicators such as AccuTag may provide additional quality assurance information beyond confirmation of irradiation exposure and support verification of target dose delivery during blood irradiation in accordance with FDA recommendations for blood products intended for transfusion.^1,2,5

Clinical Relevance

Effective prevention of TA-GVHD depends on delivery of the intended irradiation dose. Dose-responsive indicators may provide additional quality assurance information by helping verify that irradiation targets have been achieved and may support compliance with FDA blood irradiation recommendations.^1,2

Have questions about the study or about dose verification in your lab? Reach out to our team. We’re always happy to talk.
Submit an inquiry here.

Authors are employees of Rad Source Technologies, manufacturer of the RS 3400 and AccuTag

References

FDA. Medical Devices; Radiology Devices; Classification of Blood Irradiators. A Proposed Rule by the Food and Drug Administration on 03/18/2026
AABB. Standards for Blood Banks and Transfusion Services. 35th ed.; 2026
Directions for Use RAD-CONTROL LBL-00563.8
Use Instructions Rad-Sure rev. 0 January 2023
AccuTag Validation Guide (v1.01 updated 01 Oct 2025)

Product Literature & Links

RS 3400 Product Brochure (Model 2019)

Please click link below to view brochure.

RS 3400 Product Brochure (Model 2021)

Please click link below to view brochure.

RS 3400 Accessories Brochures

Please click link below to view brochure.

Useful Industry Links

Preventing a Dirty Bomb: Case Studies and Lessons Learned

CFR - Code of Federal Regulations Title 21

Literature & References

A Sample of Rad Source Customers

General Questions

What is Ionizing Radiation?

How is Ionizing Radiation Generated?

What is Ionizing Radiation Used for?

Why use x-ray versus gamma produced Ionizing radiation?

Does the RS 3400 require external cooling?

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

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

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

Evaluation of blood irradiation indicators for dose verification and FDA recommendation compliance

Background and Objective

Materials and Methods

Results

Visual Comparison of Indicator Response Across Clinically Relevant Irradiation Doses

AccuTag

Rad-Sure

RAD-CONTROL

Conclusions

Clinical Relevance

References

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