Sensitivity enhancement of methacrylic acid gel dosimeters by incorporating iodine for computed tomography scans

Shih, Tian Yu; Hsieh, Bor‐Tsung; Yen, Tsung Hsien; Lin, Fang Yi; Wu, Jen-Ming

doi:10.1016/j.ejmp.2019.05.014

Cited by 5 publications

(3 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recently, addition of high atomic elements (such as bismuth, gadolinium, silver or gold nanoparticles, etc.) has been investigated for increasing photon sensitivity [80][81][82][83][84][85][86][87][88][89][90][91][92].…”

Section: Characterization and Performancementioning

confidence: 99%

Hydrogels for Three-Dimensional Ionizing-Radiation Dosimetry

Marrale

D’Errico

2021

Gels

View full text Add to dashboard Cite

Radiation-sensitive gels are among the most recent and promising developments for radiation therapy (RT) dosimetry. RT dosimetry has the twofold goal of ensuring the quality of the treatment and the radiation protection of the patient. Benchmark dosimetry for acceptance testing and commissioning of RT systems is still based on ionization chambers. However, even the smallest chambers cannot resolve the steep dose gradients of up to 30–50% per mm generated with the most advanced techniques. While a multitude of systems based, e.g., on luminescence, silicon diodes and radiochromic materials have been developed, they do not allow the truly continuous 3D dose measurements offered by radiation-sensitive gels. The gels are tissue equivalent, so they also serve as phantoms, and their response is largely independent of radiation quality and dose rate. Some of them are infused with ferrous sulfate and rely on the radiation-induced oxidation of ferrous ions to ferric ions (Fricke-gels). Other formulations consist of monomers dispersed in a gelatinous medium (Polyacrylamide gels) and rely on radiation-induced polymerization, which creates a stable polymer structure. In both gel types, irradiation causes changes in proton relaxation rates that are proportional to locally absorbed dose and can be imaged using magnetic resonance imaging (MRI). Changes in color and/or opacification of the gels also occur upon irradiation, allowing the use of optical tomography techniques. In this work, we review both Fricke and polyacrylamide gels with emphasis on their chemical and physical properties and on their applications for radiation dosimetry.

show abstract

Section: Characterization and Performancementioning

confidence: 99%

Hydrogels for Three-Dimensional Ionizing-Radiation Dosimetry

Marrale

D’Errico

2021

Gels

View full text Add to dashboard Cite

show abstract

“…Recently, it has been reported that three‐dimensional (3D) dosimetry using a polymer gel dosimeter is an effective method for directly measuring the dose distribution 21,22 . This method is used as a quality assurance tool in radiation therapy, 23 and to measure slice thickness and CT dose index (CTDI) in CT scans 24–26 . However, since polymer gel dosimeters require MRI for reading, magnetic field inhomogeneities and temperature rise due to radiofrequency pulses may lead to uncertainty 27,28 .…”

Section: Introductionmentioning

confidence: 99%

“…21,22 This method is used as a quality assurance tool in radiation therapy, 23 and to measure slice thickness and CT dose index (CTDI) in CT scans. [24][25][26] However, since polymer gel dosimeters require MRI for reading, magnetic field inhomogeneities and temperature rise due to radiofrequency pulses may lead to uncertainty. 27,28 In recent years, a leuco crystal violet (LCV) dosimeter with low uncertainty has attracted attention 29,30 (Figure 2a).…”

mentioning

confidence: 99%

Head CT dose reduction with organ‐based tube current modulation

et al. 2022

View full text Add to dashboard Cite

Background A helical head CT examination uses a pitch factor (PF) of <1.0, resulting in a part of the slice being directly irradiated twice. This raises the possibility of double irradiation, which may increase the amount of radiation to the lens. Organ‐based tube current modulation (OBTCM) is an effective method for reducing lens exposure because it reduces the dose to the anterior aspect of the patient. However, it is challenging to visualize the complex dose distribution when factoring in double irradiation. Purpose To visualize twice‐irradiated areas in helical head CT in three dimensions and to clarify the exposure reduction effect of OBTCM. Material and methods A leuco crystal violet (LCV) dosimeter was placed into an empty polyethylene terephthalate bottle 16.5 cm in diameter. Helical scans were performed without and with OBTCM using the following parameters: tube voltage 120 kV, tube current 600 mA, pitch factor 0.637, rotation time 0.5 s, 80 (detector rows) × 0.5 mm (detector collimation), and ten scans. Exposed areas were visualized using an optical computed tomography (OCT) system designed by our group. The dose reduction rate of OBTCM was defined as the ratio of the average values of the histogram with the dose value on the x‐axis and the frequency on the y‐axis without and with OBTCM at 90° to the anterior midline. Results The LCV dosimeter visualized the spiral‐shaped twice‐irradiated areas. Double irradiation resulted in a dose of 2.19/1.90 and 1.38/1.19 Gy (15.0% and 15.9% increase) without and with OBTCM, respectively. The dose reduction using OBTCM was 29.6% at 90° anterolateral. Conclusion The LCV dosimeter visualized the complex three‐dimensional irradiated areas and enabled dose measurement in twice‐irradiated areas. Increased exposure from double irradiation was attenuated by OBTCM.

show abstract