SU-E-T-425: Feasibility of Establishing a National Postal Dosimetry System Using EBT3 Gafchromic Film

Authors

  • Abdel-Rahman W,

    1. KING FAHAD SPECIALIST HOSPITAL, Dammam, Eastern Province
    2. King Fahd University of Petroleum & Minerals, Dhahran, Eastern Province
    3. Prince Sultan Military Medical City, Riyadh, Riyadh
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  • Mohammed I,

    1. KING FAHAD SPECIALIST HOSPITAL, Dammam, Eastern Province
    2. King Fahd University of Petroleum & Minerals, Dhahran, Eastern Province
    3. Prince Sultan Military Medical City, Riyadh, Riyadh
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  • Bamajboor S

    1. KING FAHAD SPECIALIST HOSPITAL, Dammam, Eastern Province
    2. King Fahd University of Petroleum & Minerals, Dhahran, Eastern Province
    3. Prince Sultan Military Medical City, Riyadh, Riyadh
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Abstract

Purpose:

To evaluate the performance of a postal dosimeter consisting of EBT3 films and a miniature Lucite phantom to be used for photon beams output audits for mega-voltage photon beams across the Saudi Arabia.

Methods:

Two batches of EBT3 films were calibrated in 5 mega-voltage photon beams with energies ranging between 6 MV and 18 MV in the dose range between 0 to 4 Gy. A 4×4×20 cm3 lucite phantom was constructed to be used as an irradiation phantom. The lucite irradiation phantom consists of two parts and allows for embedding a 2.5×2.0 cm2 EBT3 film at 8.9 cm depth. Factors that convert the dose measured in the lucite irradiation phantom at 8.9 cm depth to the dose at 10 cm depth in water for 10×10 cm2 field for different photon energies were calculated using the dosxyznrc/EGSnrcMP user code. The performance of the proposed postal dosimeter was tested in 17 different photon beams across 4 radiotherapy centres in Saudi Arabia. The outputs of the 17 beams are monitored by either the International Atomic Energy Agency or by the Radiological Physics Centre.

Results:

For the 17 photon beams, the average of the ratios of measured to stated outputs was 1.01 ± 0.02 and with a maximum ratio of 1.05.

Conclusion:

The results of our work indicate that the proposed postal dosimetry system can be used for national auditing of outputs for mega-voltage photon beams. The service can be offered to other national radiotherapy centres or to a be used for credentialing of centres participating in national trials.

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