A surface energy spectral study on the bone heterogeneity and beam obliquity using the flattened and unflattened photon beams

Chow, James C. L.; Owrangi, Amir

doi:10.1016/j.rpor.2015.11.001

Cited by 15 publications

(19 citation statements)

References 31 publications

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“…The Monte Carlo model was verified by comparing the Monte Carlo dosimetry with measurements using a commissioning water tank and ionization chamber. The results of verification can be found elsewhere [16,17].…”

Section: Methodsmentioning

confidence: 76%

“…Therefore, a new type of flattening-filter-free (FFF) photon beam is generated, leading to a huge increase (2 to 4-fold) of dose rate and decrease of beam-on time [15]. Although the FFF photon beam may increase the patient's skin dose due to the presence of low-energy photon [16,17], more patients can be treated within the same period of time, and some delivery uncertainties such as intrafractional organ or tumor motion can be reduced. Therefore, using a FFF photon beam would result in an increase of patient throughput and a more accurate delivery.…”

Section: Introductionmentioning

confidence: 99%

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Dose Enhancement for the Flattening-Filter-Free and Flattening-Filter Photon Beams in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Study

Martelli

Chow

2020

Nanomaterials

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Monte Carlo simulations were used to predict the dose enhancement ratio (DER) using the flattening-filter-free (FFF) and flattening-filter (FF) photon beams in prostate nanoparticle-enhanced radiotherapy, with multiple variables such as nanoparticle material, nanoparticle concentration, prostate size, pelvic size, and photon beam energy. A phantom mimicking the patient’s pelvis with various prostate and pelvic sizes was used. Macroscopic Monte Carlo simulation using the EGSnrc code was used to predict the dose at the prostate or target using the 6 MV FFF, 6 MV FF, 10 MV FFF, and 10 MV FF photon beams produced by a Varian TrueBeam linear accelerator (Varian Medical System, Palo Alto, CA, USA). Nanoparticle materials of gold, platinum, iodine, silver, and iron oxide with concentration varying in the range of 3–40 mg/ml were used in simulations. Moreover, the prostate and pelvic size were varied from 2.5 to 5.5 cm and 20 to 30 cm, respectively. The DER was defined as the ratio of the target dose with nanoparticle addition to the target dose without nanoparticle addition in the simulation. From the Monte Carlo results of DER, the best nanoparticle material with the highest DER was gold, based on all the nanoparticle concentrations and photon beams. Smaller prostate size, smaller pelvic size, and a higher nanoparticle concentration showed better DER results. When comparing energies, the 6 MV beams always had the greater enhancement ratio. In addition, the FFF photon beams always had a better DER when compared to the FF beams. It is concluded that gold nanoparticles were the most effective material in nanoparticle-enhanced radiotherapy. Moreover, lower photon beam energy (6 MV), FFF photon beam, higher nanoparticle concentration, smaller pelvic size, and smaller prostate size would all increase the DER in prostate nanoparticle-enhanced radiotherapy.

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Section: Methodsmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Dose Enhancement for the Flattening-Filter-Free and Flattening-Filter Photon Beams in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Study

Martelli

Chow

2020

Nanomaterials

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“…The Electron Gamma Shower (EGS)nrc-based code was used based on a macroscopic approach [30,31,32]. Phase-space files and photon energy spectra of the 6 and 10 MV photon beams (field size = 10 × 10 cm 2 ) with and without applying the flattening filters (i.e., 6 MV FF, 6 MV FFF, 10 MV FF and 10 MV FFF) were generated using the Geant4 and BEAMnrc Monte Carlo codes with verifications carried out and published elsewhere [27,28]. All beam models were based on the Varian TrueBeam linear accelerator (Varian Medical System, Palo Alto, CA).…”

Section: Methodsmentioning

confidence: 99%

“…With the flattening filter removed from the accelerator head, the FFF beam has more low-energy photons than the FF beam. The increase of low-energy photons in the kilovoltage range for the FFF photon beam has been studied in depth [26][27][28]. Since these low-energy photons are sensitive to the photoelectric effect affecting the contrast in portal imaging, it is worthwhile to investigate the dependency of imaging contrast enhancement on the FFF photon beams with nanoparticle addition in nanoparticle-enhanced radiotherapy.…”

Section: Introductionmentioning

confidence: 99%

Contrast Enhancement for Portal Imaging in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Evaluation Using Flattening-Filter-Free Photon Beams

Abdulle

Chow

2019

Nanomaterials

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Our team evaluated contrast enhancement for portal imaging using Monte Carlo simulation in nanoparticle-enhanced radiotherapy. Dependencies of percentage contrast enhancement on flattening-filter (FF) and flattening-filter-free (FFF) photon beams were determined by varying the nanoparticle material (gold, platinum, iodine, silver, iron oxide), nanoparticle concentration (3–40 mg/mL) and photon beam energy (6 and 10 MV). Phase-space files and energy spectra of the 6 MV FF, 6 MV FFF, 10 MV FF and 10 MV FFF photon beams were generated based on a Varian TrueBeam linear accelerator. We found that gold and platinum nanoparticles (NP) produced the highest contrast enhancement for portal imaging, compared to other NP with lower atomic numbers. The maximum percentage contrast enhancements for the gold and platinum NP were 18.9% and 18.5% with a concentration equal to 40 mg/mL. The contrast enhancement was also found to increase with the nanoparticle concentration. The maximum rate of increase of contrast enhancement for the gold NP was equal to 0.29%/mg/mL. Using the 6 MV photon beams, the maximum contrast enhancements for the gold NP were 79% (FF) and 78% (FFF) higher than those using the 10 MV beams. For the FFF beams, the maximum contrast enhancements for the gold NP were 53.6% (6 MV) and 53.8% (10 MV) higher than those using the FF beams. It is concluded that contrast enhancement for portal imaging can be increased when a higher atomic number of NP, higher nanoparticle concentration, lower photon beam energy and no flattening filter of photon beam are used in nanoparticle-enhanced radiotherapy.

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“…Both FFF beams and the VMAT technique can be accompanied by respiratory gating systems to reduce the time needed to perform the daily irradiation [32].…”

Section: Respiratory Gatingmentioning

confidence: 99%

Respiratory motion and its compensation possibilities in the modern external beam radiotherapy of lung cancer

Adamczyk¹,

Piotrowski²

2018

Nowotwory. Journal of Oncology

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The aim of this paper is to present a systematic review of the current characteristics and recent development of commercially available respiratory motion solutions and their compensation possibilities in the external beam radiotherapy treatment of lung cancer. The most commonly used X-ray and radiotherapeutic technologies are presented, as well as their division into pre-treatment methods and intra-treatment verification. The article discusses the most important technological achievements that allow radiation to be safely applied in the lung region and reports the potential advantages and limitations of each. Finally, it presents details concerning selected research trends and problems related to motion compensation. NOWOTWORY J Oncol 2017; 67, 5: 292-296

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A surface energy spectral study on the bone heterogeneity and beam obliquity using the flattened and unflattened photon beams

Abstract: Background: Surface dose enhancement is a dosimetric concern when using unflattened

Cited by 15 publications

References 31 publications

Dose Enhancement for the Flattening-Filter-Free and Flattening-Filter Photon Beams in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Study

Dose Enhancement for the Flattening-Filter-Free and Flattening-Filter Photon Beams in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Study

Contrast Enhancement for Portal Imaging in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Evaluation Using Flattening-Filter-Free Photon Beams

Respiratory motion and its compensation possibilities in the modern external beam radiotherapy of lung cancer

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