Enhancement of Dose Response and Nuclear Magnetic Resonance Image of PAGAT Polymer Gel Dosimeter by Adding Silver Nanoparticles.

Rahim Sabbaghizadeh,Arman Sedghi,Roslinda Shamsudin,Najmeh Deyhimihaghighi,Yogendra Kumar Mishra

doi:10.1371/journal.pone.0168737

Rahim Sabbaghizadeh, Arman Sedghi + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0168737

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Abstract

In the present study, the normoxic polyacrylamide gelatin and tetrakis hydroxy methyl phosphoniun chloride (PAGAT) polymer gel dosimeters were synthesized with and without the presence of silver (Ag) nanoparticles. The amount of Ag nanoparticles varied from 1 to 3 ml with concentration 3.14 g/l, thus forming two types of PAGAT polymer gel dosimeters before irradiating them with 6 to 25 Gy produced by 1.25-MeV 60Co gamma rays. In this range, the predominant gamma ray interaction with matter is by Compton scattering effect, as the photoelectric absorption effect diminishes. MRI was employed when evaluating the polymerization of the dosimeters and the gray scale of the MRI film was determined via an optical densitometer. Subsequent analyses of optical densities revealed that the extent of polymerization increased with the increase in the absorbed dose, while the increase of penetration depth within the dosimeters has a reverse effect. Moreover, a significant increase in the optical density-dose response (11.82%) was noted for dosimeters containing 2 ml Ag nanoparticles.

Highlights

Radiotherapy is a form of cancer treatment using high energy x-rays or gamma rays, whereby an electron beams is delivered to stop cancer cells from growing
The significance of radiotherapy in cancer treatment and importance of MRI for diagnostics created the need for advanced dosimetric system that can quantify and verify 3D dose distribution, enhancing the dose received by cancerous tissue, while increasing the contrast in MRI for better diagnosis
The work presented here was based on impregnating Ag nanoparticles into a polymer gel as a radio-sensitizer to increase the MRI contrast, whereby the gray scale image was analyzed by optical density

Summary

Introduction

Radiotherapy is a form of cancer treatment using high energy x-rays or gamma rays, whereby an electron beams is delivered to stop cancer cells from growing. In the field of radiotherapy, metal nanoparticles are extensively studied because of their potential application in the enhancement of the received radiation dose, with the aim of improving the treatment planning stage and determining the exact dose required for destroying tumor cells. From the dosimetric point of view, the use of Au nanoparticles in radiotherapy was motivated by the fact that probability of photoelectric effect increases due to the presence of high Z (Au = 79) material inside the polymer gels, which in turn increases the absorbed dose [12]. The samples were placed inside the acrylic tank, which was filled with distilled water to create a tissue equivalent when the polymer gel was irradiated This step is required to equilibrate the secondary charge particle produced by γ-rays in the material. The gels were scanned after a minimum of 12 hours

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