Output calculation of electron therapy at extended SSD using an improved LBR method

Alkhatib, H; Gebreamlak, W; Tedeschi, David; Mihailidis, Dimitris; Wright, Ben W.; Neglia, William J.; Sobash, Philip T.; Fontenot, Jonas D.

doi:10.1118/1.4905375

Cited by 2 publications

(5 citation statements)

References 16 publications

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“…In our previous publications [12,13], we demonstrated that σ R (z) is dependent on the size of the cutout. By considering this size dependence of σ R (z), we illustrated a significant improvement in the accuracy of PDD and output factor calculations.…”

Section: Introductionmentioning

confidence: 67%

“…In our previous publications [12,13] we calculated the percentage depth dose curves and output factors of irregular cutouts. In this article, we extended our work to calculate the relative dose distribution of irregular cutouts at d max .…”

Section: Resultsmentioning

confidence: 99%

“…Depth dose curves were acquired at standard SSD using an IBA blue-phantom 2 [14] water tank and PTW Dosimetry Diode E detectors. The experimental setup for depth dose measurements has been previously detailed in our publications [12,13]. The depth of the maximum dose (d max ) for each cutout and electron beam energy was determined from the measured depth dose curves.…”

Section: Methodsmentioning

confidence: 99%

“…In our prior publication [13], we have shown that output factor and PDD of an irregular cutout at standard SSD and depth z can be determined using the equation is the gap factor of a circular cutout with radius R i,c at distance g 0 ; LBR 0 (R i,c , z) is the lateral build-up ratio of the circular cutout of radius R i,c at depth z. becomes equal to one. The value of g 0 was determined using both film and diodes with good agreement between the two methods.…”

mentioning

confidence: 99%

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Planar dose calculation of electron therapy

Gebreamlak,

Alkhatib

2024

Biomed. Phys. Eng. Express

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Purpose:The purpose of this study is to compute the planar dose distribution of irregularly shaped electron beams at their maximum dose depth (zmax) using the modiﬁed lateral build-up-ratio (LBR) and curve-fitting methods.Methods:Circular and irregular cutouts were created using Cerrobend alloy for a 14×14 cm2 applicator. Percentage depth dose (PDD) at the standard source-surface-distance (SSD = 100 cm) and point dose at diﬀerent SSD were measured for each cutout. Orthogonal proﬁles of the cutouts were measured at zmax. The data were collected for 6, 9, 12, and 15 MeV electron beam energies on a VERSA HDTM LINAC using the iba Blue Phantom2 3D water phantom system. The planar dose distributions of the cutouts were also measured at zmax in solid water using EDR2 ﬁlms.Results:The measured PDD curves were normalized to a normalization depth (d0) of 1 mm. Each cutout's lateral-buildup-ratio (LBR), lateral spread parameter (σR(z)), and eﬀective SSD (SSDeff) were calculated using the PDD of the open applicator as the reference ﬁeld. The modified LBR method was then used to calculate the planar dose distribution of the irregular cutouts inside the field at least 5 mm from the edge. A simple curve-fitting model was developed based on the profile shapes of the circular cutouts around the field edge. This model was used to calculate the planar dose distribution of irregular cutouts in the region from 3 mm outside to 5 mm inside the field edge. Finally, the calculated dose distribution was compared with the film measurement. Conclusions:The planar dose distribution of electron therapy for irregular cutouts at zmax was calculated using the improved LBR method and a simple curve-fitting model. The calculated profiles were within 3% of the measured. The gamma passing rate with 3%/3mm was more than 96%.

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Section: Introductionmentioning

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Planar dose calculation of electron therapy

Gebreamlak,

Alkhatib

2024

Biomed. Phys. Eng. Express

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“…The off-axis of this method could be developed for higher accuracy. In addition, several studies found that MCI is less accurate than Monte Carlo simulation for complex dose distributions and is recommended for one point secondary dose check or simple geometry dose verification [23,24].…”

Section: Resultsmentioning

confidence: 99%

The Comparison of 2d Dose Patient-Specific Quality Assurance Between Monte Carlo-Convolution and Modified Clarkson Integration Algorithm

Azzi,

Pawiro,

Mart

2023

SPEKTRA

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A sophisticated machine of radiotherapy treatment process follows the complexity of the quality assurance (QA) measurement. Non-measurement QA becomes one of the solutions to reduce the medical physicists’ workload. However, this method has not been clinically established. This study compared two non-measurement methods of patient-specific quality assurance (PSQA) to find the feasible algorithm for the adaptive radiotherapy process. Monte Carlo-based (MC) PSQA used a phase space file of the medical linear accelerator (Linac) to obtain the photon energy fluence and forward projected to the isoplane. In contrast, Modified Clarkson Integration-based (MCI) used a non-uniform fluence map in the isoplane. For the modulated intensity, we used a pair of the dynamic log files of the multileaf-collimator (MLC) and then employed them in the algorithms. The dose distributions of MC and MCI methods were compared to the treatment planning system (TPS) using gamma index analysis. We found that the gamma pass rates (GPR) for MC-TPS and MCI-TPS were 99.54% and 99.57%, respectively. Further, the dose distribution in the off-axis region for the MCI method showed lesser accuracy due to the higher secondary dose contribution. The linac log file information can be used and calculated into a 2D dose distribution using both MC and MCI methods, providing high-accuracy results.

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Output calculation of electron therapy at extended SSD using an improved LBR method

Cited by 2 publications

References 16 publications

Planar dose calculation of electron therapy

Planar dose calculation of electron therapy

The Comparison of 2d Dose Patient-Specific Quality Assurance Between Monte Carlo-Convolution and Modified Clarkson Integration Algorithm

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