Radiochromic film calibration for the RQT9 quality beam

Costa, Kamila; Gomez, Alvaro Mauricio Ladino; Alonso, Thêssa Cristina; Mourão, Arnaldo Prata

doi:10.1016/j.radphyschem.2017.02.032

Cited by 11 publications

(6 citation statements)

References 2 publications

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“…The absorbed dose values are obtained from the pixel intensity values using calibration curves for each voltage value to get air kerma values [10]. The conversion factors used to determine the dose profile for each protocol in the anthropomorphic phantoms.…”

Section: Methodsmentioning

confidence: 99%

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Dosimetry Study in Head and Neck of Anthropomorphic Phantoms in Computed Tomography Scans

2020

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Objectives: To determine the CT absorbed dose profiles for routine adult scan parameters in adults, using male and female anthropomorphic phantoms. Compare the levels of absorbed dose of the phantoms and perform image quality analysis by making noise percentage measurements on the CT images obtained. Methods: Radiochromic film strips were introduced in the central region of the phantoms for to record the dose profile in head and neck in order to determine the amount of the dose deposited along the central axis of the phantoms. The scans were performedon a 64 - channel CT scanner (General Electric), programmed in helical scaning mode. In addition to the routine acquisition protocol with fixed current value, it was performed other three scans with the voltage of 80, 100 and 120 kV, using automatic exposure control. Results: Absorbed dose values were found between 15.54 to 24.38 mGy on average for anthropomorphic male phantom and values of 13.13 to 21.49 mGy for anthropomorphic female phantom. Noise analysis was performed, finding that all are acceptable diagnostic parameters according to ministerial order 453/98 of the Brazilian Ministry of Health. The acquisition parameters of CT images were found that deposited on average less doses in the head and neck for both phantoms, maintaining the image quality for diagnosis.

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Section: Methodsmentioning

confidence: 99%

“…The radiochromic films are calibrated for different energy intensities separately, due to their energy dependence. Studies carries out with PMMA cylindrical head phantom and ionization chambers determined the calibration curves for radiochromic films GAFCHROMIC XR-AQ2 for different voltages of CT X-ray tube [10,11].…”

Section: Introductionmentioning

confidence: 99%

Dosimetry Study in Head and Neck of Anthropomorphic Phantoms in Computed Tomography Scans

2020

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“…for each voltage level, and corrected by the width of the X-ray beam, were calculated values of absorbed dose deposited in each of the strips [11,12].…”

Section: Gafchromic Xr-qa2 Filmmentioning

confidence: 99%

Dose Profile Study in Head CT Scans Using a Male Anthropomorphic Phantom

Ladino¹,

Carmo²,

Prata³

2020

Int J Radiol Imaging Technol

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Computed Tomography (CT) is an efficient and non-invasive method to obtain data about internal structures of the human body. CT scans contribute with the highest absorbed doses in population due X-ray beam attenuation and it has raised concern in radiosensitive tissues. Techniques for the optimization of CT scanning protocols in diagnostic services have been developing with the objective of decreasing the absorbed dose in patient, aiming image quality within acceptable parameters for diagnosis by noise control. Routine head scans were performed using GE CT scan of 64 channels programmed with automatic exposure control and voltages of 80, 100 and 120 kV attaching the noise index in approximately 0.5%, using the tool of smart mA. Radiochromic film strips were placed into an anthropomorphic adult male phantom to measure the absorbed dose deposited in areas such as lens, thyroid and pituitary gland for study of dose deposited in these important areas containing radiosensitive tissues. Different head scans were performed using optimized values of mA.s for the different voltages. The absorbed dose measured by the film strips were in the range of the 0.58 and 44.36 mGy. The analysis of noise in the images is within the acceptable levels for diagnosis, and the optimized protocol happens with the voltage of 100 kV. The use of other voltage values can allow obtain better protocols for head scans.

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“…Among the methods used for dose measurement in clinical practice, radiochromic films are commonly used in radiation therapy for dosimetric verification of treatment plans, [5][6][7]8 whereas in interventional radiology, they are used to assess the surface dose on the patient's skin(peak skin dose). 3,9 This kind of film is also used for instance to improve CT acquisition image processes 10 and to check the distributions of the laser-accelerated proton beams. 11 Since this dosimetric method is a relative one, the proper calibration curve needs to be determined prior to its use for dose assessment.…”

Section: Introductionmentioning

confidence: 99%

“…11 Since this dosimetric method is a relative one, the proper calibration curve needs to be determined prior to its use for dose assessment. 2,3,4,[10][11][12][13][14] In the literature there is still an insufficient number of detailed descriptions of the calibration curve fitting analysis for XR-RV3 films. Due to the relatively low dose rate of ionizing radiation of X-ray units used in interventional radiology compared to radiotherapeutic units, this process performed in clinical conditions is somewhat time-consuming.…”

Section: Introductionmentioning

confidence: 99%

Calibration of Gafchromic XR-RV3 film under interventional radiology conditions

Kidoń

Polaczek-Grelik

Gołba

et al. 2021

Polish Journal of Medical Physics and Engineering

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Introduction: The purpose of the study was the calibration of Gafchromic films in clinical interventional radiology conditions and the assessment of the influence of dose range, the shape of the fitting curve, and its practical application. The aim of the work was to show how practically perform calibration in a wide range of doses. Material and methods: Gafchromic XR–RV3 films were included in the study. The calibration was performed for A and B film series separately. Doses from the range of 0 – 8 Gy were used. Film dosimeters were read out in reflective mode with a commercial flatbed scanner. Results: Among various degrees of a polynomial function, the best fit, which fulfilled the chosen criterion of 95% agreement between measured and reconstructed doses and simple equation criterion, was observed for third-degree polynomial. The fitting curve where the dose is the function of optical density (logMPV) was demonstrated to be more precise than the fitting curve based on MPV only. To minimize the difference between dose absorbed by the film and dose reconstructed from the fitting curve below 5% it is necessary to divide the calibration range of 0 – 8 Gy into two subranges for use in interventional radiology. This difference was set at a maximum level of 3.8% and 1.9% for the lowand high-dose range, respectively. Each series of films may have a slightly different calibration curve, especially for the low dose range. A deviation of up to 36% between two batches of Gafchromic film was observed. Conclusions: For the third-degree polynomial fitting function (one of the recommended in the literature) calibration should be done into low and high dose ranges and for each batch separately. A systematic error higher than 20% could be introduced when the fitting curve from one film batch is applied to the other film batch.

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Radiochromic film calibration for the RQT9 quality beam

Cited by 11 publications

References 2 publications

Dosimetry Study in Head and Neck of Anthropomorphic Phantoms in Computed Tomography Scans

Dosimetry Study in Head and Neck of Anthropomorphic Phantoms in Computed Tomography Scans

Dose Profile Study in Head CT Scans Using a Male Anthropomorphic Phantom

Calibration of Gafchromic XR-RV3 film under interventional radiology conditions

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