# Presentation: 373529

## THE  BASICS  OF IRRADIATION

**Dr. Harry Farrar IV**
- Chairman, ASTM Subcommittee E10.01 *Dosimetry for Radiation Processing*
**Bell Canyon, California 91307, USA**

## OVERVIEW

- ABSORBED DOSE
- RADIATION SOURCES
- DOSE DISTRIBUTION & UNIFORMITY
- EXAMPLES OF IRRADIATORS
- DOSIMETERS & DOSE MAPPING
- PERSPECTIVE & CONCLUSIONS
- TEST

## ABSORBED DOSE

**ABSORBED DOSE IS **_**THE **_**MAJOR PARAMETER**
**RADIATION DOSE IS THE AMOUNT OF ENERGY ABSORBED (4000 GY = 1 C****°)**
**DOSE CAN BE GIVEN BY: **
**    ****	****	****- GAMMA RAYS (COBALT-60 or CESIUM-137)**
**	****	****- ELECTRONS (DIRECT)  or **
**	****	****- X-RAYS (BREMSSTRAHLUNG)**
**IT MAKES**** NO**** DIFFERENCE WHICH TYPE OF SOURCE IS USED BECAUSE IT IS THE ELECTRONS THAT CREATE ALL THE EFFECTS**

## SOURCES FOR RADIATION PROCESSING

## X-RAYS ON TOTE

## Slide 8

## Slide 9

## NEED FOR ACCURATE DOSIMETRY

- EFFECTIVENESS OF THE PROCESS DEPENDS ON:
- PROPER APPLICATION OF THE DOSE
- ACCURATE MEASUREMENT OF DOSE
- ALL LOCATIONS IN THE PRODUCT MUST BE CONSIDERED
- LOWER LIMIT – MUST BE HIGH ENOUGH TO ACCOMPLISH DESIRED EFFECT
- UPPER LIMIT – NO QUALITY EFFECTS

## Slide 11

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## Slide 13

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## Hidden Slide – E-Beam Carrier

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## Hidden Slide -  Ebeam Vert

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## GRAY*STAR GENESIS

## DOSE CONSIDERATIONS

**MINIMUM DOSE**
**MUST ACCOMPLISH THE DESIRED EFFECT**
**DETERMINED BY RESEARCH**
**USUALLY DICTATED BY REGULATIONS**
**MAXIMUM DOSE**
**QUALITY EFFECTS START TO APPEAR**
**DETERMINED BY RESEARCH**
**OFTEN LIMITED BY REGULATIONS**
**GOAL**
**ALL PRODUCT GETS BETWEEN MAX & MIN DOSE**
**IDEALLY**
**ALL PRODUCT GETS SAME DOSE (MAX/MIN RATIO = 1)**

## DOSIMETER

-    A device that, when irradiated, exhibits a quantifiable change in some property of the device which can be related to absorbed dose in a given material using appropriate analytical instrumentation and techniques.

## DOSE MEASUREMENT

_**DOSIMETERS**_ MEASURE DOSE ACCURATELY
- REQUIRE INSTRUMENT TO READ
- KNOWN ENVIRONMENTAL SENSITIVITY
- CAN BE CALIBRATED ACCURATELY
- LABEL DOSIMETERS NOT YET AVAILABLE
_**RADIATION-SENSITIVE INDICATORS**_ CANNOT BE USED TO ASSURE MINIMUM DOSE
**CALLED “GO/NO GO INDICATORS”**
**INDICATE “SOME” IRRADIATION HAS OCCURRED**
**NOT CALIBRATABLE****	**
**SENSITIVE TO ENVIRONMENT**

## DOSE MAPPING

## PERSPECTIVE

- HUNDREDS OF BIG IRRADIATORS (BOTH GAMMA AND E-BEAM) ARE USED ROUTINELY FOR OTHER APPLICATIONS
- NO PUBLIC DEMONSTRATIONS OR FUSS
- 55% OF US & EUROPEAN MEDICAL DEVICES (IMPLANTS, SYRINGES, BANDAGES) STERILIZED BY RADIATION
- FDA RELIES ON DOSIMETRY FOR STERILITY ASSURANCE
- MILLIONS OF STERILE FRUIT FLIES AND OTHER INSECTS ARE ROUTINELY RELEASED IN USA
- APHIS RELIES ON DOSIMETRY FOR STERILITY ASSURANCE
- IDENTICAL PROCEDURES ARE APPLICABLE FOR QUARANTINE TREATMENT
- RELIANCE ON DOSIMETRY IS _*NOTHING NEW*_

## OVERALL EFFECTS OF RADIATION  (1)

_**DOSE**__	__(GRAYS)_	_**OBJECTIVE**_			_**EXAMPLES**_
- 0.0001		chest X-ray			humans
- 5				Lethal dose (D50)		humans
- 15-50			inactivate lymphocytes	blood
- 30-150		inhibit sprouting		potatoes
- 50-150		sterilize insects		fruit flies
- 60-500		inhibit opening		mushrooms
- 150-250		stop adult emergence	fruit flies
- 300-1000		eliminate trichinella		pork
- 250-2000		retard ripening		mango
- 500-10k		extend shelf life		fish
- 500-10k		control vibrio cholerae	frogs legs

## OVERALL EFFECTS OF RADIATION  (2)

_**DOSE**__	__(GRAYS)_		_**OBJECTIVE**_			_**EXAMPLES**_
- 1000-2200		reduce pathogens		fish products
- 1500-3000		inhibit mold			strawberries
- 1500-3000		reduce spoilage			meat
- 3000-7000		reduce salmonella		chicken
- 2000-25,000		eliminate salmonella		poultry feed
- 10,000-20,000		reduce cooking time		old beans
- 10,000-30,000		reduce pathogens		spices
- 20,000-25,000		sterilize equipment		health care
- 25,000-50,000		destroy all bacteria		shelf stable
- 50,000			oligosaccharide breakdown	beans

## CONCLUSIONS

- DOSE IS *THE* CRITICAL VARIABLE
- FACILITY TYPE IS AN ECONOMIC CONSIDERATION
- PROTOCOL SHOULD OPTIMIZE DOSE UNIFORMITY
- SELECT OPTIMUM DOSIMETRY SYSTEM
- RIGOROUSLY FOLLOW PUBLISHED STANDARDS
*THE TECHNOLOGY TO RELEASE PRODUCT ON THE BASIS OF DOSIMETRY,WHEN COMBINED WITH A PROPER QA/QC PROGRAM IS PROVEN, RELIABLE, AND ROUTINE.*

## TEST

- _QUESTION_:
*HOW MANY GRAYS OF RADIATION ARE REQUIRED TO RAISE A WATER-EQUIVALENT MATERIAL, SUCH AS AN ORANGE, BY 1 CENTIGRADE DEGREE ?*

## ANSWER

-   4000 GRAYS = 1 CENTIGRADE DEGREE