Application of polymer-gel dosimetry in stereotactic radiosurgery

Novotný, Josef; Spěváček, Václav; Dvořák, Pavel; Hrbáček, Jan; Tlachacova, Daniela; Schmitt, M; Vymazal, Josef; Tintěra, Jaroslav; Cechak, T.

doi:10.1088/1742-6596/3/1/049

Cited by 7 publications

(5 citation statements)

References 5 publications

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“…The large and varied body of literature pertaining to polymer gel dosimetry applications confirms the value and versatility of the technique. In addition, the recent gel dosimetry conference, DOSGEL2004, had many contributions on the applications of polymer gel dosimetry using MRI [176][177][178][179][180][181][182][183] and OCT [134,135], including one novel application to diagnostic imaging [142]. The large number of these very recent papers highlights the increasing relevance of such work.…”

Section: Gel Applicationsmentioning

confidence: 99%

Investigations in x‐ray computed tomography polyacrylamide gel dosimetry

Hilts¹

2005

Medical Physics

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Polyacrylamide gels (PAGs) are radiosensitive materials currently under development for use as three dimensional (3D) dosimeters in radiation therapy. Dose information is recorded in the gels and extracted through imaging. X-ray computed tomography (CT) has emerged as a promising gel imaging method due to a change in gel density that occurs upon irradiation. The accessibility of CT technology to cancer hospitals makes CT read-out clinically attractive, however the technique remains of limited clinical use due in part to poor dose resolution. This thesis investigates the use of CT for extracting dose information from PAG with an overall goal to improve achievable dose resolution. Thesis results are divided into three studies: a gel compositional study, a study of noise and dose resolution and a digital filtering study. The first study investigates the effects of gel composition on PAG CT dose response and the underlying density change. Systems for irradiating and imaging gels are designed and tested and dose response reproducibility is established. Results indicate dramatic variation in CT dose response sensitivity and range with gel composition. A model is developed to describe gel density change with dose, revealing two fundamental properties of the density to dose response: the density change that occurs per unit polymer yield is highest for gels with low and high concentrations of crosslinking molecule (%C) and the dose response sensitivity is linearly dependent on the total concentration of monomer in the gel. The second study investigates strategies for minimizing noise in x-ray CT polymer gel dosimetry and assesses system performance. Specifically, the effects of phantom design, scanning technique and image voxel size on image noise are investigated. This work leads to the establishment of a method of predicting image noise for any given CT imaging protocol. Image uniformity is also assessed, in the context of noise levels in gel dosimetry. The effect of scanning protocol on imaging time is established and the dose resolution achievable with an optimized system is calculated given voxel size and imaging time constraints. These results, when compared with published values for MRI and optical CT gel dosimetry indicate that CT dose resolution (e.g. 5%, 1x1x3 mm 3 voxels), is still not at the level of the best MRI or optical CT techniques, however fast imaging times makes the rapid acquisition of volumetric data most feasible with x-ray CT. The third study investigates the potential of image filtering for improved dose resolution in CT gel dosimetry. CT image noise is characterized as Gaussian distributed and independent of signal strength and niters for reducing spatially invariant noise are investigated: mean, median, midpoint, adaptive mean, alphatrimmed mean, sigma mean and a relatively new filter called SUSAN. The filters are tested on a CT image of a PAG irradiated with a clinically relevant dose distribution. Filter performance varies greatly in both achieved dose resolution and affects on the spatial di...

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Section: Gel Applicationsmentioning

confidence: 99%

Investigations in x‐ray computed tomography polyacrylamide gel dosimetry

Hilts¹

2005

Medical Physics

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“…Phantoms can easily be obtained and used as dosimeter to obtain 3-D dose distribution. Different kinds of gel dosimeters have been developed, the two main investigated groups are the aqueous gels, the Fricke gel dosimeters [4,5,6,7,8,9] and the based on radiation-induced polymerization and cross-linking of acrylic monomers, the polymer gels [3,10,11,12,13]. Imaging techniques such us spectrophotometry and MRI scanning, have been proposed [14,15,16,17].…”

Section: Introductionmentioning

confidence: 99%

“…Applied in radiation therapy, the main advantages of MRI are the high spatial resolution and the direct acquisition of multiplanar and 3-D imaging data. The Fricke gel dosimeter has been studied for determine both dose and dose distribution with accuracy and precision [12,13] ) occurs when the dosimeter is exposed the ionizing radiation [14] with the oxidation yield proportional to the absorbed dose and the absorbed dose distributions can be imaged by MRI. The studied Fricke gel solutions have been prepared using 300 Bloom gelatin [8,14,19,20] that is imported and very expensive in Brazil.…”

Section: Introductionmentioning

confidence: 99%

A dosimetric evaluation of tissue equivalent phantom prepared using 270 Bloom gelatin for absorbed dose imaging in Gamma knife radiosurgery

Cavinato

Rodrigues

Cervantes

et al. 2009

J. Phys.: Conf. Ser.

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Abstract. Tissue equivalent gel phantoms have been widely studied in radiation therapy for both relative and reference dosimetry. A Fricke xylenol gel (FXG) spherical phantom was evaluated by means of magnetic resonance image method (MRI) to measure absorbed dose distribution resulted from gamma knife irradiation. The FXG phantom was prepared using 270 Bloom gelatin. The gelatin is a tissue equivalent material, of easy preparation, can be used to mold phantoms into different shapes and volumes, is commercially available and inexpensive. The results show that the Fricke gel phantom prepared with 270 Bloom gelatin satisfy the requirements to be used for the quality control in stereotactic radiosurgery using Gamma Knife technique and may constitute one more option of dosimeter in radiation therapy applications.

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“…De Deene et al (2002), Salomons et al (2002), , , Lepage et al (2001aLepage et al ( , 2001b), investigating different imaging modalities for the extraction of dose information (e.g. Mather and Baldock (2003), Oldham et al (2001), Hilts et al (2000)) and applications of polymer gel dosimetry to the verification of complex dose distributions (Novotny et al 2004, Gustavsson et al 2003, De Deene 2002. X-ray computed tomography (CT) imaging has been shown to be a promising imaging modality for dose information extraction (Hilts et al 2000, 2005, Trapp et al 2001 due to its ease of operation, robustness and availability in the radiation clinic.…”

Section: Introductionmentioning

confidence: 99%

Investigation of a 2D two-point maximum entropy regularization method for signal-to-noise ratio enhancement: application to CT polymer gel dosimetry

et al. 2006

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This study presents a new method of image signal-to-noise ratio (SNR) enhancement by utilizing a newly developed 2D two-point maximum entropy regularization method (TPMEM). When utilized as an image filter, it is shown that 2D TPMEM offers unsurpassed flexibility in its ability to balance the complementary requirements of image smoothness and fidelity. The technique is evaluated for use in the enhancement of x-ray computed tomography (CT) images of irradiated polymer gels used in radiation dosimetry. We utilize a range of statistical parameters (e.g. root-mean square error, correlation coefficient, error histograms, Fourier data) to characterize the performance of TPMEM applied to a series of synthetic images of varying initial SNR. These images are designed to mimic a range of dose intensity patterns that would occur in x-ray CT polymer gel radiation dosimetry. Analysis is extended to a CT image of a polymer gel dosimeter irradiated with a stereotactic radiation therapy dose distribution. Results indicate that TPMEM performs strikingly well on radiation dosimetry data, significantly enhancing the SNR of noise-corrupted images (SNR enhancement factors >15 are possible) while minimally distorting the original image detail (as shown by the error histograms and Fourier data). It is also noted that application of this new TPMEM filter is not restricted exclusively to x-ray CT polymer gel dosimetry image data but can in future be extended to a wide range of radiation dosimetry data.

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Application of polymer-gel dosimetry in stereotactic radiosurgery

Cited by 7 publications

References 5 publications

Investigations in x‐ray computed tomography polyacrylamide gel dosimetry

Investigations in x‐ray computed tomography polyacrylamide gel dosimetry

A dosimetric evaluation of tissue equivalent phantom prepared using 270 Bloom gelatin for absorbed dose imaging in Gamma knife radiosurgery

Investigation of a 2D two-point maximum entropy regularization method for signal-to-noise ratio enhancement: application to CT polymer gel dosimetry

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