Dosimetric verification of lung phantom calculated by collapsed cone convolution: A Monte Carlo and experimental evaluation

Najafzadeh, Milad; Nickfarjam, Abolfazl; Jabbari, Keyvan; Markel, Daniel; Chow, J; Takabi, Fatemeh Shirani

doi:10.3233/xst-180425

Cited by 9 publications

(7 citation statements)

References 38 publications

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“…CCC algorithm had a very large difference in the buildup region which is due to the fact that this algorithm does not model the buildup region when entering from a low density to a high-density region. 42 All evaluated algorithms had better results in bigger fields and with a decrease of field size, deviations with MC simulation increased, as reported in previous studies. 6,40,42 The source of these differences in small fields is reported to be the loss of lateral charged particle equilibrium.…”

Section: Discussionsupporting

confidence: 84%

“…42 All evaluated algorithms had better results in bigger fields and with a decrease of field size, deviations with MC simulation increased, as reported in previous studies. 6,40,42 The source of these differences in small fields is reported to be the loss of lateral charged particle equilibrium. 42,43 As reported by different authors most deviations appear in fields smaller than 1×1 cm 2 .…”

Section: Discussionsupporting

confidence: 84%

“…This algorithm accurately models primary photons from source and also scattered photon and electron fluence, for this job it solves the linear Boltzmann transform equation. 42 All model-based algorithms that investigated had an agreement with MC simulation in small photon fields in a homogenous media concerning this that CCC algorithm from Monaco TPS had a superior accuracy toward the others. Clarkson algorithm as we discussed as a correction based algorithm had good accuracy in larger fields and homogenous media, but with decrease of field size and appearing of loss of charged particle equilibrium its accuracy drops dramatically.…”

Section: Discussionmentioning

confidence: 86%

“…6,40,42 The source of these differences in small fields is reported to be the loss of lateral charged particle equilibrium. 42,43 As reported by different authors most deviations appear in fields smaller than 1×1 cm 2 . Palmans et al have stated that partial occlusion of primary photons from source happens when the field size is comparable with focal spot size, also they mentioned that in medical accelerators focal spot size is about 0.5 cm.…”

Section: Discussionmentioning

confidence: 99%

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Dose calculation accuracy for photon small fields in treatment planning systems with comparison by Monte Carlo simulations

Abazarfard

Azadeh

Mostaar

2021

Polish Journal of Medical Physics and Engineering

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Purpose: Advanced radiation therapy techniques use small fields in treatment planning and delivery. Small fields have the advantage of more accurate dose delivery, but with the cost of some complications in dosimetry. Different dose calculation algorithms imported in various treatment planning systems (TPSs) which each of them has different accuracy. Monte Carlo (MC) simulation has been reported as one of the accurate methods for calculating dose distribution in radiation therapy. The aim of this study was the evaluation of TPS dose calculation algorithms in small fields against 2 MC codes. Methods: A linac head was simulated in 2 MC codes, MCNPX, and GATE. Then three small fields (0.5×0.5, 1×1 and 1.5×1.5 cm2) were simulated with 2 MC codes, and also these fields were planned with different dose calculation algorithms in Isogray and Monaco TPS. PDDs and lateral dose profiles were extracted and compared between MC simulations and dose calculation algorithms. Results: For 0.5×0.5 cm2 field mean differences in PDDs with MCNPX were 2.28, 4.6, 5.3, and 7.4% and with GATE were -0.29, 2.3, 3 and 5% for CCC, superposition, FFT and Clarkson algorithms respectively. For 1×1 cm2 field mean differences in PDDs with MCNPX were 1.58, 0.6, 1.1 and 1.4% and with GATE were 0.77, 0.1, 0.6 and 0.9% for CCC, superposition, FFT and Clarkson algorithms respectively. For 1.5×1.5 cm2 field mean differences in PDDs with MCNPX were 0.82, 0.4, 0.6 and -0.4% and with GATE were 2.38, 2.5, 2.7 and 1.7% for CCC, superposition, FFT and Clarkson algorithms respectively. Conclusions: Different dose calculation algorithms were evaluated and compared with MC simulation in small fields. Mean differences with MC simulation decreased with the increase of field sizes for all algorithms.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Dose calculation accuracy for photon small fields in treatment planning systems with comparison by Monte Carlo simulations

Abazarfard

Azadeh

Mostaar

2021

Polish Journal of Medical Physics and Engineering

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“…An understanding of the dose distribution for different phantom sizes may be useful for calculating the dose to an organ at a specific position within a patient of a certain size [24]. Organ dose estimation has indeed been proposed using the SSDE concept [25], but it generally obtained using Monte Carlo simulations on various phantom models [26][27][28] or using anthropomorphic phantoms [29]. Direct organ dose calculation using the patient image is undergoing development and faces many challenges that need to be addressed [30].…”

Section: Introductionmentioning

confidence: 99%

Comparison of central, peripheral, and weighted size-specific dose in CT

Anam

Adhianto

Sutanto

et al. 2020

XST

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The objective of this study is to determine X-ray dose distribution and the correlation between central, peripheral and weighted-centre peripheral doses for various phantom sizes and tube voltages in computed tomography (CT). We used phantoms developed in-house, with various water-equivalent diameters (Dw) from 8.5 up to 42.1 cm. The phantoms have one hole in the centre and four holes at the periphery. By using these five holes, it is possible to measure the size-specific central dose (Ds,c), peripheral dose (Ds,p), and weighted dose (Ds,w).The phantoms are scanned using a CT scanner (Siemens Somatom Definition AS), with the tube voltage varied from 80 up to 140 kVps. The doses are measured using a pencil ionization chamber (Ray safe X2 CT Sensor) in every hole for all phantoms. The relationships between Ds,c, Ds,p, and Ds,w, and the water-equivalent diameter are established. The size-conversion factors are calculated. Comparisons between Ds,c, Ds,p, and Ds,ware also established. We observe that the dose is relatively homogeneous over the phantom for water-equivalent diameters of 12-14 cm. For water-equivalent diameters less than 12 cm, the dose in the centre is higher than at the periphery, whereas for water-equivalent diameters greater than 14 cm, the dose at the centre is lower than that at the periphery. We also find that the distribution of the doses is influenced by the tube voltage. These dose distributions may be useful for calculating organ doses for specific patients using their CT images in future clinical practice.

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Quantified difference of the collapsed cone convolution (CCC) and Monte Carlo (MC) algorithms based on DVH and gamma analysis for cervical cancer radiation therapy

Zhang,

Bai,

Wang

et al. 2024

Applied Radiation and Isotopes

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Dosimetric verification of lung phantom calculated by collapsed cone convolution: A Monte Carlo and experimental evaluation

Cited by 9 publications

References 38 publications

Dose calculation accuracy for photon small fields in treatment planning systems with comparison by Monte Carlo simulations

Dose calculation accuracy for photon small fields in treatment planning systems with comparison by Monte Carlo simulations

Comparison of central, peripheral, and weighted size-specific dose in CT

Quantified difference of the collapsed cone convolution (CCC) and Monte Carlo (MC) algorithms based on DVH and gamma analysis for cervical cancer radiation therapy

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