An investigation into the effect of magnetic resonance imaging (MRI) echo time spacing and number of echoes on the sensitivity and dose resolution of PAGATUG polymer-gel dosimeter

Abtahi, Seyed Mohammad Mahdi; Khalilabadi, R. Jafari; Aftabi, Sajjad

doi:10.18869/acadpub.ijrr.15.2.185

Cited by 8 publications

(5 citation statements)

References 28 publications

(38 reference statements)

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“…Post-irradiation polymerization reactions progress up to 10 h after the irradiation [ 19 , 42 ], however, they do not fully stop due to the presence of remaining long-term radicals. In order to control the influence of the temporal dose response variations on the final result, the reading of the dosimetric information is usually recommended to be performed at least 24 h after irradiation, assuming that this time period is sufficient enough to achieve the chemical equilibrium of the system [ 7 , 12 ]. A 24 h interval between the irradiation and evaluation of the polymer gels was suggested due to the lack of detailed information regarding the time-dependent post-irradiation polymerization and gelation processes in gels, which are limited by the complexity of the required measurement methods and complicated analysis of the obtained results [ 44 ].…”

Section: Resultsmentioning

confidence: 99%

“…Radiation-sensitive polymer gels, whose response to irradiation is based on the radiation-induced polymerization of a monomer (and often co-monomer) species suspended in a gelatin matrix, have the potential to meet these limitations and can be used for the recording of dose profiles and the verification of complicated dose distributions in external beam therapy [ 6 ]. Various techniques, such as magnetic resonance imaging (MRI) [ 7 , 8 ], X-ray computed tomography (CT) [ 9 , 10 ], optical computed tomography (OCT) [ 9 , 10 , 11 , 12 , 13 ] or ultrasound [ 14 , 15 ] can be used for the evaluation of 3D dose distribution changes caused by the polymerization of irradiated polymer gels. Raman spectroscopy may also be considered as a power full tool for investigating radiation-induced changes in polymerized gel dosimeters, since the radiation-induced changes of the vibrational bands of corresponding monomers/polymers in gels correlate with the absorbed dose.…”

Section: Introductionmentioning

confidence: 99%

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The Impact of Temporal Changes in Irradiated nMAG Polymer Gels on Their Applicability in Small Field Dosimetry in Radiotherapy

Krauleidis

Adlienė

Rutkūnienė

2022

Gels

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As advanced radiotherapy techniques progress to deliver a high absorbed dose to the target volume while minimizing the dose to normal tissues using intensity-modulated beams, arcs or stereotactic radiosurgery, new challenges occur to assure that the high treatment dose is delivered homogeneously to the tumor. Small irradiation field sizes (≤1 cm2) that tightly conform to precise target regions and allow for the deliverance of doses with a high therapeutic ratio, are of particular interest. However, the small field dosimetry using conventional dosimeters is limited by the relative large size of the detector. Radiation-sensitive polymer gels have the potential to meet this dosimetry challenge due to their almost unlimited ability in resolving three-dimensional dose distributions of any shape and makes them unique and suitable for the evaluation of dose profiles and the verification of complex doses. In this work, dose distributions in nMAG gels that have been irradiated to different doses by applying a 6 MV FFF photon beam collimated to 1 cm2, were analyzed and the dose profiles were evaluated by applying a gamma passing rate criteria of 3%/3 mm and considering different post-irradiation time intervals between the irradiation and the gels read out process. X-ray CT and NMR imaging procedures were used for the dose evaluation. It was found that the shape and uniformity of the dose profiles were changing due to post-irradiation polymerization and gelation processes, indicating time dependent growing uniformity which was better expressed for the higher delivered doses. It was estimated that in order to obtain acceptably symmetric small field dose profiles, a longer post-irradiation time is needed for getting the full scope of the polymerization as compared with the recently recommended 24 h period between irradiation and the read out processes of the dose gels. An estimated overall uncertainty (double standard deviation, 95% confidence level) of 3.66% was achieved by applying R2 measurements (NMR read out), and a 3.81–applying X-ray CT read out for 12 Gy irradiated gels 56 h post-irradiation. An increasing tendency for the uncertainty was observed with a decreasing post-irradiation time. A gamma passing rate of 90.3% was estimated for the 12 Gy irradiated gels and, 56 h post-irradiation, the X-ray CT evaluated gels as well as a gamma passing rate of 92.7% was obtained for the NMR evaluated gels applying a 3%/3mm passing criteria.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Impact of Temporal Changes in Irradiated nMAG Polymer Gels on Their Applicability in Small Field Dosimetry in Radiotherapy

Krauleidis

Adlienė

Rutkūnienė

2022

Gels

View full text Add to dashboard Cite

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“…It can be seen that hemoglobin can measure various indexes of athletes' physical function and play an important role in athletes' physical function (20,21). In addition to the subject matter, imaging have been widely used in many other subjects (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40).…”

Section: Discussionmentioning

confidence: 99%

Atomic force microscope observation of athletes' hemoglobin imaging

Zhang

Luo

Hajee

et al. 2020

Cell Mol Biol (Noisy-le-grand)

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Hemoglobin (Hb) is a protein and its functional form has a tetrameric structure. This structure is the result of a combination of four sub-units called globin and indicates the dynamic interaction between them. Each subunit has a ring-shaped organic molecule called a heme that contains an iron atom; Heme is a group that mediates the reversible binding of oxygen by hemoglobin. This research was performed to observe the image of Hb by an atomic force microscope (AFM) and measure the physical function of athletes. For this purpose, based on the principle of AFM imaging, the hemoglobin crosslinking method was used to measure the morphology and size of cross-linked Hb, glutaraldehyde and Hb diameter were detected to prepare cross-linked Hb samples with different molar ratio, the activity of peroxidase was detected by Trinder reaction. The AFM was used to detect the influence of physiological environment changes such as pH, temperature, oxygen partial pressure and osmotic pressure on the absorption spectrum of Hb imaging. Results showed that the size of the uncrosslinked Hb was 6.64 nm. With the increase of the molar ratio of glutaraldehyde to Hb, the number of Hb molecules involved in the crosslinking increased, and the molecular size increased. During the crosslinking process, the aggregation of the cross-linked molecules would make the particle size of some Hb molecules reach 80-100 nm. The peak height, peak position and peak shape of the characteristic absorption peaks of pH to hemoglobin at 550 and 589 nm occurred. When the temperature changes continuously in the range of 30-55â„ƒ, the peak height of Hb absorption spectrum of normal red blood cells at 550 nm and 589 nm decreases gradually with the increase of temperature, and the peak shape at 610 nm changes obviously at 42â„ƒ, which indicates that the molecular structure of Hb changes; the absorption spectrum curve of deoxygenation disappears at 500 nm, the oxygen-binding capacity of Hb is very low, and the oxygen affinity and oxygenated hemoglobin are low (The concentration of HbO2) decreased, the osmotic pressure increased, the RBC dehydrated, the volume decreased, and the concentration of Hb increased. Conclusion: It is more accurate and comprehensive to use AFM to observe athletes' hemoglobin.

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“…Imaging has many applications in biological research (24)(25)(26)(27)(28)(29)(30)(31)(32)(33). Imaging is used in angiogenesis of ovarian tumors (34), breast cancer (35), nasopharyngeal carcinoma (36), prostate cancer (37,38), dosimetry purpose (39,40) and tumor research (41).…”

Section: Discussionmentioning

confidence: 99%

Application of intravoxel incoherent motion imaging in the study of migration and movement of cancer cells

Wang

Ahmed

2020

Cell Mol Biol (Noisy-le-grand)

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IVIM imaging technology can obtain physiological information of tissue cells and blood perfusion at the same time in one imaging process. Taking female patients in Shenzhen Maternal and Child Health Hospital affiliated to Southern Medical University as an example, the migration and movement of breast cancer cells and hepatocellular carcinoma cells are studied by intravoxel incoherent motion imaging. Apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo-diffusion coefficient (D*) and perfusion fraction (f) are measured by the IVIM bi-index model, and statistical analysis is made. The results show that the IVIM bi-index model can truly reflect the diffusion of water molecules in breast mass-like lesions, and reflect the migration and movement of breast cancer cells. Especially D value has important reference significance for the research and diagnosis of breast cancer cells. IVIM bi-index model has limited diagnostic value for the migration and movement of common hepatocellular carcinoma cells, and ADC value may have higher diagnostic efficiency.

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An investigation into the effect of magnetic resonance imaging (MRI) echo time spacing and number of echoes on the sensitivity and dose resolution of PAGATUG polymer-gel dosimeter

Abstract: An investigation into the effect of magnetic resonance imaging (MRI) echo time spacing and number of echoes on the sensitivity and dose resolution of PAGATUG polymer-gel dosimeter

Cited by 8 publications

References 28 publications

The Impact of Temporal Changes in Irradiated nMAG Polymer Gels on Their Applicability in Small Field Dosimetry in Radiotherapy

The Impact of Temporal Changes in Irradiated nMAG Polymer Gels on Their Applicability in Small Field Dosimetry in Radiotherapy

Atomic force microscope observation of athletes' hemoglobin imaging

Application of intravoxel incoherent motion imaging in the study of migration and movement of cancer cells

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