J Cabahug*, S Tatu, B Lo, C Feliciano, Radiation Research Center (RRC), Philippine Nuclear Research Institute, Department of Science and Technology (DOST-PNRI), Commonwealth Avenue, Diliman, Quezon City, 1101, Philippines Health Physics Research Section, Atomic Research Division (ARD-HPRS), DOST-PNRI, Commonwealth Avenue, Diliman, Quezon City, 1101, Philippines

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  J Cabahug

PO-GePV-T-442 (Sunday, 7/10/2022)   [Eastern Time (GMT-4)]

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Purpose: The study aims to characterize the X-ray beam output generated by an X-ray irradiator (CellRad™, Precision X-ray Inc.) for use with cells using its internal plane-parallel ionization chamber and an external X-ray beam analyzer.

Methods: The internal plane-parallel ionization chamber (Varex Imaging Corporation) was used to determine X-ray dose relationships with irradiation time, tube voltage, tube current, and source-to-surface distance (SSD). A PTW Universal DIAVOLT® X-ray meter was utilized to evaluate the accuracy and repeatability of the tube voltage and exposure timer.

Results: The X-ray irradiator can generate linear doses using filtered (0.5 mm Al) and unfiltered X-ray beams with respect to time. Irradiation times lower than 20 s show high variability in dose, reaching 9% and 13% for unfiltered and filtered beams, respectively. The dose-voltage relationship follows a quadratic fit for both unfiltered and filtered beams from 40 to 130 kVp. The dose-current relationship follows a linear response for both filtered and unfiltered beams from 0.5 to 5.0 mA. Meanwhile, doses measured at different points from 13.0 cm to 52.0 cm SSD follows the inverse-square law for unfiltered beams and filtered beams. The X-ray tube voltage accuracy tests reveal that the mean kVp, max kVp, and PPV agree with the nominal values by up to ±5%. Short exposure time (5 s) differs by up to 25% with the nominal time value.

Conclusion: The CellRad™ X-ray irradiator unit of RRC, DOST-PNRI generates precise radiation doses at varied irradiation time, voltage, current and SSD settings. The input tube voltage is accurately delivered by the machine within ±5%. Irradiation time should be less than 5 s to achieve exposure timer accuracy.

Keywords

Not Applicable / None Entered.

Taxonomy

TH- Radiation Dose Measurement Devices: Instrumentation

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