Evaluation of dose rate and photon energy dependence of gafchromic EBT3 film irradiating with 6 MV and Co-60 photon beams

Ataei, Gholamreza; Rezaei, Maral; Gorji, Kourosh Ebrahimnejad; Banaei, Amin; Goushbolagh, Nouraddin Abdi; Farhood, Bagher; Bagheri, Mohsen; Firouzjah, Razzagh Abedi

doi:10.4103/jmss.jmss_45_18

Cited by 6 publications

(1 citation statement)

References 23 publications

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“…It is crucial to avoid exposing them to temperatures above 50 degrees Celsius to ensure their quality and longevity [17,18]. Several studies have been conducted on Gafchromic film characteristics, demonstrating they are energy-and dose-rate independent [19][20][21][22]. In particular, Sipilä et al [21] measured the response of EBT3 films to photon (6 MV) and electron beams (6 to 16 MeV) and showed the energy dependence of EBT3 film is uniform within 0.5% across all electron beams.…”

Section: Gafchromic Filmsmentioning

confidence: 99%

Advances in Radiotherapy Dosimetry Techniques and Pre-Treatment Verification

Salari,

Ishmael Parsai

2023

Advances in Dosimetry and New Trends in Radiopharmaceuticals

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In the fight against cancer, radiation therapy plays a vital role, with its two essential approaches: internal, involving the insertion or implantation of radioactive material into the patient’s body, or uptake of radiopharmaceutical, and external. Precise delivery of the appropriate radiation dosage to the tumor is critical for achieving favorable outcomes. This is where dosimetry becomes crucial—a scientific discipline that involves measuring, calculating, and evaluating radiation doses. Medical physicists utilize dosimetry to ensure the accuracy and proper calibration of machines that administer ionizing radiation, ensuring safety. This chapter provides a brief overview of advanced techniques and equipment used in dosimetry, with a primary focus on photon and electron dosimetry, the most widely employed forms of radiation for radiotherapy worldwide.

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Section: Gafchromic Filmsmentioning

confidence: 99%

Advances in Radiotherapy Dosimetry Techniques and Pre-Treatment Verification

Salari,

Ishmael Parsai

2023

Advances in Dosimetry and New Trends in Radiopharmaceuticals

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Dose‐rate dependence and IMRT QA suitability of EBT3 radiochromic films for pulse reduced dose‐rate radiotherapy (PRDR) dosimetry

Khan,

Radtke,

Hammer

et al. 2023

J Applied Clin Med Phys

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BackgroundPulsed reduced dose rate (PRDR) is an emerging radiotherapy technique for recurrent diseases. It is pertinent that the linac beam characteristics are evaluated for PRDR dose rates and a suitable dosimeter is employed for IMRT QA.PurposeThis study sought to investigate the pulse characteristics of a 6 MV photon beam during PRDR irradiations on a commercial linac. The feasibility of using EBT3 radiochromic film for use in IMRT QA was also investigated by comparing its response to a commercial diode array phantom.MethodsA plastic scintillator detector was employed to measure the photon pulse characteristics across nominal repetition rates (NRRs) in the 5–600 MU/min range. Film was irradiated with dose rates in the 0.033–4 Gy/min range to study the dose rate dependence. Five clinical PRDR treatment plans were selected for IMRT QA with the Delta4 phantom and EBT3 film sheets. The planned and measured dose were compared using gamma analysis with a criterion of 3%/3 mm. EBT3 film QA was performed using a cumulative technique and a weighting factor technique.ResultsNegligible differences were observed in the pulse width and height data between the investigated NRRs. The pulse width was measured to be 3.15 ± 0.01 and the PRF was calculated to be 3–357 Hz for the 5–600 MU/min NRRs. The EBT3 film was found to be dose rate independent within 3%. The gamma pass rates (GPRs) were above 99% and 90% for the Delta4 phantom and the EBT3 film using the cumulative QA method, respectively. GPRs as low as 80% were noted for the weighting factor EBT3 QA method.ConclusionsAltering the NRRs changes the mean dose rate while the instantaneous dose rate remains constant. The EBT3 film was found to be suitable for PRDR dosimetry and IMRT QA with minimal dose rate dependence.

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A two‐layer cylinder phantom developed for film‐based isocenter verification of radiotherapy machine

Song

Yan

et al. 2021

Medical Physics

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Purpose A two‐layer cylinder (TLC) phantom was developed for simplifying film‐based isocenter verification of linear accelerators in radiotherapy. Methods and materials The phantom mainly consists of two parts: (1) two nested solid cylinders between which a radiochromic film can be inserted and irradiated; (2) a tungsten ball supported by a thin rod and located at the phantom center for alignment with the mechanical isocenter. In practice, the phantom was first positioned by the room laser to align the tungsten ball to the mechanical isocenter of the linear accelerator. Then, a radiochromic film was precisely inserted into the gap between the two cylinders of the phantom and irradiated by beams with preset gantry and couch angles. Later the irradiated film was scanned and processed by an in‐house developed analysis software. Finally, the offset of the radiation isocenter from the mechanical isocenter was determined by the built‐in three‐dimensional (3D) reconstruction algorithms. The accuracy of this method was evaluated by positioning the phantom with a known couch shift, then checking the residual error after couch shift correction. The reliability of this method was evaluated by comparing the calculated offset with the corresponding result determined by the traditional star‐shot method. Results For the accuracy test, the residual errors were −0.14 ± 0.03 mm, 0.05 ± 0.06 mm, and 0.05 ± 0.06 mm in the lateral, longitudinal, and vertical axes, respectively. For the reliability test, the differences between the calculated offset and the result determined by the star‐shot method were −0.10 mm, 0.12 mm, and 0.12 mm in the lateral, longitudinal, and vertical axes, respectively. Conclusion The proposed method is able to reconstruct beams in 3D with one film, which is more time‐saving and accurate. Additionally, with this design, the phantom positioning, film loading, beam delivery, and data analyzing are simpler. This phantom and analysis software provides an efficient and effective way to perform film‐based isocenter verification of linear accelerators in radiotherapy.

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Evaluation of dose rate and photon energy dependence of gafchromic EBT3 film irradiating with 6 MV and Co-60 photon beams

Cited by 6 publications

References 23 publications

Advances in Radiotherapy Dosimetry Techniques and Pre-Treatment Verification

Advances in Radiotherapy Dosimetry Techniques and Pre-Treatment Verification

Dose‐rate dependence and IMRT QA suitability of EBT3 radiochromic films for pulse reduced dose‐rate radiotherapy (PRDR) dosimetry

A two‐layer cylinder phantom developed for film‐based isocenter verification of radiotherapy machine

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