Dosimetric evaluation of two treatment planning systems for high dose rate brachytherapy applications

Shwetha, B; Ravikumar, M; Supe, Sanjay S.; Sathiyan, S; Lokesh, V.; Keshava, S L

doi:10.1016/j.meddos.2010.12.015

Cited by 4 publications

(3 citation statements)

References 10 publications

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“…Stereoelectroencephalography (SEEG) uses multiple depth electrodes implanted in the brain to identify seizure zones, with robotic and computer assisted trajectory planning gaining interest. [36][37][38] Treatment planning systems play a large role in radiotherapy, including brachytherapy, [39][40][41][42][43][44][45][46] where the radiation dose to patient-specific targets and organs at risk (OAR) are analyzed and treatments are planned accordingly. IMT differs from external electric fields devices in that electrodes are implanted directly in or adjacent tumor volumes, requiring trajectory planning of multiple electrodes.…”

Section: Introductionmentioning

confidence: 99%

Planning system for the optimization of electric field delivery using implanted electrodes for brain tumor control

et al. 2022

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Background: The use of non-ionizing electric fields from low-intensity voltage sources (< 10 V) to control malignant tumor growth is showing increasing potential as a cancer treatment modality. A method of applying these low-intensity electric fields using multiple implanted electrodes within or adjacent to tumor volumes has been termed as intratumoral modulation therapy (IMT). Purpose: This study explores advancements in the previously established IMT optimization algorithm, and the development of a custom treatment planning system for patient-specific IMT.The practicality of the treatment planning system is demonstrated by implementing the full optimization pipeline on a brain phantom with robotic electrode implantation, postoperative imaging, and treatment stimulation. Methods: The integrated planning pipeline in 3D Slicer begins with importing and segmenting patient magnetic resonance images (MRI) or computed tomography (CT) images. The segmentation process is manual, followed by a semi-automatic smoothing step that allows the segmented brain and tumor mesh volumes to be smoothed and simplified by applying selected filters. Electrode trajectories are planned manually on the patient MRI or CT by selecting insertion and tip coordinates for a chosen number of electrodes. The electrode tip positions and stimulation parameters (phase shift and voltage) can then be optimized with the custom semi-automatic IMT optimization algorithm where users can select the prescription electric field, voltage amplitude limit, tissue electrical properties, nearby organs at risk, optimization parameters (electrode tip location, individual contact phase shift and voltage), desired field coverage percent, and field conformity optimization. Tables of optimization results are displayed, and the resulting electric field is visualized as a field-map superimposed on the MR or CT image, with 3D renderings of the brain, tumor, and electrodes. Optimized electrode coordinates are transferred to robotic electrode implantation software to enable planning and subsequent implantation of the electrodes at the desired trajectories. Results: An IMT treatment planning system was developed that incorporates patient-specific MRI or CT, segmentation, volume smoothing, electrode trajectory planning, electrode tip location and stimulation parameter optimization, and results visualization. All previous manual pipeline steps operating on diverse software platforms were coalesced into a single semi-automated 3D Slicerbased user interface.Brain phantom validation of the full system implementation was successful in preoperative planning, robotic electrode implantation, and postoperative treatment planning to adjust stimulation parameters based on

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Section: Introductionmentioning

confidence: 99%

Planning system for the optimization of electric field delivery using implanted electrodes for brain tumor control

et al. 2022

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“…The percentage deviations of the dose calibration between Abacus TPS and TG-43U1 formalism at P (8cm, 90°) were −2.30%, 1.76%, and 2.10% with the distances (between the dwell positions) of 0cm, 0.5cm, and 1cm, respectively. Shwetha et al 14 calculated similar dose differences, up to 1.88%, along the perpendicular axis of the source. They observed that the absorbed dose D ( r, θ ) strongly depends on the radial distance r and the angle between the source center and the point of interest.…”

Section: Discussionmentioning

confidence: 79%

<p>The Measurement of the Air-Kerma Rate in Air and a Solid Phantom with Ionization Chambers for a <sup>192</sup>Ir HDR Brachytherapy Source</p>

Zeng¹,

Qu²,

Pang³

et al. 2020

CMAR

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Introduction This study aims to measure the air-kerma rate of 192-Ir-HDR-afterloading source with an ionization chamber in air and a solid cylindrical phantom separately and to compare the dose calibration by the American Association of Physicists in Medicine (AAPM) Task Group TG-43U1 formalism with the Abacus treatment planning system (TPS). Materials and Methods The air-kerma rate of 192 Ir source was measured by an ionization chamber in air and a solid cylindrical phantom separately. For the interesting point position P (8cm, 90°), the values of the dose were calculated with the TG-43U1 formula and compared with data from the Abacus TPS with single and multiple dwell positions, respectively. Results The air-kerma rate percentage deviations between the detector measurements in air and the source certificate were −1.28%, −0.91%, −0.71%, and 0.33% at the distances of 25cm, 50cm, 75cm, and 100cm, respectively. For the measurement in solid cylindrical phantom, the percent deviation from the air-kerma rate certificate was 1.85%. The percentage deviations of the dose calibration between Abacus TPS and TG-43U1 formalism at P (8cm, 90°) were −2.30%, 1.76%, and 2.10% with different distances (between the dwell positions) of 0cm, 0.5cm, and 1cm, respectively. Conclusion The in-air technique was a new attempt for clinic routine measurement. Further studies are still necessary. As a treatment planning system, the Abacus TPS should apply the AAPM TG-43U1 formulism for the development required in the future.

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“…These tallies were then normalized to the tally at 1 cm at an angle, θ 0 , of 90 degrees ( π 2 radians) and multiplied by the appropriate ratio of the geometry function, calculated at the reference point and divided by the geometry function at the specified r and π 2 radians, as in equation (3). Radial dose function values computed using MCNP6.2 were compared against those used in the Oncentra treatment planning system (TPS) (Shwetha et al 2012, Singh et al 2012, Ferre et al 2013 at the University of Texas Heath San Antonio Mays Cancer Center. The radial dose was calculated using a line source approximation and the ratio of each dose rate was multiplied by the appropriate ratio of the geometry function at specified distances to obtain g L (r,θ) at each distance.…”

Section: Tg-43 Ir-192 Source Verificationmentioning

confidence: 99%

A detailed Monte Carlo evaluation of ¹⁹²Ir dose enhancement for gold nanoparticles and comparison with experimentally measured dose enhancements

et al. 2020

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Gold nanoparticles (GNPs) have been studied extensively as promising radiation dose enhancing agents. In the current study, the dose enhancement effect of GNPs for Ir-192 HDR brachytherapy is studied using Monte Carlo N-Particle code, version 6.2 (MCNP6.2) and compared with experimental results obtained using Burlin cavity theory formalism. The Ir-192 source is verified using TG-43 parameters and dose enhancement factors (DEFs) from GNPs are simulated for three different mass percentages of gold in the GNP solution. These results are compared to DEFs previously reported experimentally by our group (Bassiri et al Med. Phys.) for a GNP-containing volume in an apparatus designed in-house to measure dose enhancement with GNPs for high dose rate (HDR) Ir-192 brachytherapy. An HDR Ir-192 Microselectron v2 r HDR brachytherapy source was modeled using MCNP6.2 using the TG-43 formalism in water. Anisotropy and radial dose function were verified against known values. An apparatus designed to measure dose enhancement to a 0.75 cm3 volume of GNPs from an Ir-192 brachytherapy seed with average energy of 0.38 MeV was built in-house and modeled using MCNP6.2. Burlin cavity correction factors were applied to experimental measurements. The macroscopic DEF was calculated for GNPs of size 30 nm at mass percentages of gold of 0.28%, 0.56% and 0.77%, using the repeating structures capability of MCNP6.2. DEF was calculated by dividing dose to the GNP solution by dose to water in the same volume. The radial dose function and anisotropy factor values at varying angles and distances were accurate when compared against known values. DEFs of 1.018 ± 0.003, 1.031 ± 0.003, and 1.041 ± 0.003 for GNP solutions containing mass percent of gold of 0.28%, 0.56% and 0.77%, respectively, were computed. These DEFs were within 2% of experimental values with Burlin cavity correction factors applied for all three mass percentages of gold.

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Dosimetric evaluation of two treatment planning systems for high dose rate brachytherapy applications

Cited by 4 publications

References 10 publications

Planning system for the optimization of electric field delivery using implanted electrodes for brain tumor control

Planning system for the optimization of electric field delivery using implanted electrodes for brain tumor control

<p>The Measurement of the Air-Kerma Rate in Air and a Solid Phantom with Ionization Chambers for a <sup>192</sup>Ir HDR Brachytherapy Source</p>

A detailed Monte Carlo evaluation of ¹⁹²Ir dose enhancement for gold nanoparticles and comparison with experimentally measured dose enhancements

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Dosimetric evaluation of two treatment planning systems for high dose rate brachytherapy applications

Cited by 4 publications

References 10 publications

Planning system for the optimization of electric field delivery using implanted electrodes for brain tumor control

Planning system for the optimization of electric field delivery using implanted electrodes for brain tumor control

<p>The Measurement of the Air-Kerma Rate in Air and a Solid Phantom with Ionization Chambers for a <sup>192</sup>Ir HDR Brachytherapy Source</p>

A detailed Monte Carlo evaluation of 192Ir dose enhancement for gold nanoparticles and comparison with experimentally measured dose enhancements

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A detailed Monte Carlo evaluation of ¹⁹²Ir dose enhancement for gold nanoparticles and comparison with experimentally measured dose enhancements