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Author Albiol, A.; Corbi, A.; Albiol, F.
Title Automatic intensity windowing of mammographic images based on a perceptual metric Type Journal Article
Year 2017 Publication Medical Physics Abbreviated Journal Med. Phys.
Volume 44 Issue 4 Pages 1369-1378
Keywords contrast stretching; Gabor filtering; human visual system; mammogram; mutual information; window level/width
Abstract (up) Purpose: Initial auto-adjustment of the window level WL and width WW applied to mammographic images. The proposed intensity windowing (IW) method is based on the maximization of the mutual information (MI) between a perceptual decomposition of the original 12-bit sources and their screen displayed 8-bit version. Besides zoom, color inversion and panning operations, IW is the most commonly performed task in daily screening and has a direct impact on diagnosis and the time involved in the process. Methods: The authors present a human visual system and perception-based algorithm named GRAIL (Gabor-relying adjustment of image levels). GRAIL initially measures a mammogram's quality based on the MI between the original instance and its Gabor-filtered derivations. From this point on, the algorithm performs an automatic intensity windowing process that outputs the WL/WW that best displays each mammogram for screening. GRAIL starts with the default, high contrast, wide dynamic range 12-bit data, and then maximizes the graphical information presented in ordinary 8-bit displays. Tests have been carried out with several mammogram databases. They comprise correlations and an ANOVA analysis with the manual IW levels established by a group of radiologists. A complete MATLAB implementation of GRAIL is available at . Results: Auto-leveled images show superior quality both perceptually and objectively compared to their full intensity range and compared to the application of other common methods like global contrast stretching (GCS). The correlations between the human determined intensity values and the ones estimated by our method surpass that of GCS. The ANOVA analysis with the upper intensity thresholds also reveals a similar outcome. GRAIL has also proven to specially perform better with images that contain micro-calcifications and/or foreign X-ray-opaque elements and with healthy BI-RADS A-type mammograms. It can also speed up the initial screening time by a mean of 4.5 s per image. Conclusions: A novel methodology is introduced that enables a quality-driven balancing of the WL/WW of mammographic images. This correction seeks the representation that maximizes the amount of graphical information contained in each image. The presented technique can contribute to the diagnosis and the overall efficiency of the breast screening session by suggesting, at the beginning, an optimal and customized windowing setting for each mammogram.
Address [Albiol, Alberto] Univ Politecn Valencia, iTeam Res Inst, Valencia, Spain, Email: alberto.corbi@ific.uv.es
Corporate Author Thesis
Publisher Wiley Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-2405 ISBN Medium
Area Expedition Conference
Notes WOS:000400572700016 Approved no
Is ISI yes International Collaboration no
Call Number IFIC @ pastor @ Serial 3122
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Author Granero, D.; Vijande, J.; Ballester, F.; Rivard, M.J.
Title Dosimetry revisited for the HDR Ir-192 brachytherapy source model mHDR-v2 Type Journal Article
Year 2011 Publication Medical Physics Abbreviated Journal Med. Phys.
Volume 38 Issue 1 Pages 487-494
Keywords Ir-192; brachytherapy; dosimetry; TG-43; PSS model; MCNP5; PENELOPE2008; GEANT4
Abstract (up) Purpose: Recently, the manufacturer of the HDR Ir-192 mHDR-v2 brachytherapy source reported small design changes (referred to herein as mHDR-v2r) that are within the manufacturing tolerances but may alter the existing dosimetric data for this source. This study aimed to (1) check whether these changes affect the existing dosimetric data published for this source; (2) obtain new dosimetric data in close proximity to the source, including the contributions from 192Ir electrons and considering the absence of electronic equilibrium; and (3) obtain scatter dose components for collapsed cone treatment planning system implementation. Methods: Three different Monte Carlo (MC) radiation transport codes were used: MCNP5, PENELOPE2008, and GEANT4. The source was centrally positioned in a 40 cm radius water phantom. Absorbed dose and collision kerma were obtained using 0.1 mm (0.5 mm) thick voxels to provide high-resolution dosimetry near (far from) the source. Dose-rate distributions obtained with the three MC codes were compared. Results: Simulations of mHDR-v2 and mHDR-v2r designs performed with three radiation transport codes showed agreement typically within 0.2% for r >= 0.25 cm. Dosimetric contributions from source electrons were significant for r<0.25 cm. The dose-rate constant and radial dose function were similar to those from previous MC studies of the mHDR-v2 design. The 2D anisotropy function also coincided with that of the mHDR-v2 design for r >= 0.25 cm. Detailed results of dose distributions and scatter components are presented for the modified source design. Conclusions: Comparison of these results to prior MC studies showed agreement typically within 0.5% for r >= 0.25 cm. If dosimetric data for r<0.25 cm are not needed, dosimetric results from the prior MC studies will be adequate. c 2011 American Association of Physicists in Medicine.
Address [Granero, Domingo] Hosp Gen Univ, Dept Radiat Phys, ERESA, E-46014 Valencia, Spain, Email: dgranero@eresa.com
Corporate Author Thesis
Publisher Amer Assoc Physicists Medicine Amer Inst Physics Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-2405 ISBN Medium
Area Expedition Conference
Notes ISI:000285769800050 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 557
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Author Candela-Juan, C.; Niatsetski, Y.; van der Laarse, R.; Granero, D.; Ballester, F.; Perez-Calatayud, J.; Vijande, J.
Title Design and characterization of a new high-dose-rate brachytherapy Valencia applicator for larger skin lesions Type Journal Article
Year 2016 Publication Medical Physics Abbreviated Journal Med. Phys.
Volume 43 Issue 4 Pages 1639-1648
Keywords skin applicator; Valencia applicator; HDR brachytherapy; dosimetry; Monte Carlo
Abstract (up) Purpose: The aims of this study were (i) to design a new high-dose-rate (HDR) brachytherapy applicator for treating surface lesions with planning target volumes larger than 3 cm in diameter and up to 5 cm in size, using the microSelectron-HDR or Flexitron afterloader (Elekta Brachytherapy) with a Ir-192 source; (ii) to calculate by means of the Monte Carlo (MC) method the dose distribution for the new applicator when it is placed against a water phantom; and (iii) to validate experimentally the dose distributions in water. Methods: The PENELOPE2008 MC code was used to optimize dwell positions and dwell times. Next, the dose distribution in a water phantom and the leakage dose distribution around the applicator were calculated. Finally, MC data were validated experimentally for a 192Ir mHDR-v2 source by measuring (i) dose distributions with radiochromic EBT3 films (ISP); (ii) percentage depth-dose (PDD) curve with the parallel-plate ionization chamber Advanced Markus (PTW); and (iii) absolute dose rate with EBT3 films and the PinPoint T31016 (PTW) ionization chamber. Results: The new applicator is made of tungsten alloy (Densimet) and consists of a set of interchangeable collimators. Three catheters are used to allocate the source at prefixed dwell positions with preset weights to produce a homogenous dose distribution at the typical prescription depth of 3 mm in water. The same plan is used for all available collimators. PDD, absolute dose rate per unit of air kerma strength, and off-axis profiles in a cylindrical water phantom are reported. These data can be used for treatment planning. Leakage around the applicator was also scored. The dose distributions, PDD, and absolute dose rate calculated agree within experimental uncertainties with the doses measured: differences of MC data with chamber measurements are up to 0.8% and with radiochromic films are up to 3.5%. Conclusions: The new applicator and the dosimetric data provided here will be a valuable tool in clinical practice, making treatment of large skin lesions simpler, faster, and safer. Also the dose to surrounding healthy tissues is minimal.
Address [Candela-Juan, C.; Perez-Calatayud, J.] La Fe Univ & Polytech Hosp, Dept Radiat Oncol, Valencia 46026, Spain, Email: ccanjuan@gmail.com
Corporate Author Thesis
Publisher Amer Assoc Physicists Medicine Amer Inst Physics Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-2405 ISBN Medium
Area Expedition Conference
Notes WOS:000373711000007 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2620
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Author Oliver, S.; Gimenez-Alventosa, V.; Berumen, F.; Gimenez, V.; Beaulieu, L.; Ballester, F.; Vijande, J.
Title Benchmark of the PenRed Monte Carlo framework for HDR brachytherapy Type Journal Article
Year 2023 Publication Zeitschrift für Medizinische Physik Abbreviated Journal Z. Med. Phys.
Volume 33 Issue 4 Pages 511-528
Keywords Monte Carlo; PenRed; Brachytherapy; DICOM; Medical physics
Abstract (up) Purpose: The purpose of this study is to validate the PenRed Monte Carlo framework for clinical applications in brachytherapy. PenRed is a C++ version of Penelope Monte Carlo code with additional tallies and utilities. Methods and materials: Six benchmarking scenarios are explored to validate the use of PenRed and its improved bachytherapy-oriented capabilities for HDR brachytherapy. A new tally allowing the evaluation of collisional kerma for any material using the track length kerma estimator and the possibility to obtain the seed positions, weights and directions processing directly the DICOM file are now implemented in the PenRed distribution. The four non-clinical test cases developed by the Joint AAPM-ESTRO-ABG-ABS WG-DCAB were evaluated by comparing local and global absorbed dose differences with respect to established reference datasets. A prostate and a palliative lung cases, were also studied. For them, absorbed dose ratios, global absorbed dose differences, and cumulative dose-volume histograms were obtained and discussed. Results: The air-kerma strength and the dose rate constant corresponding to the two sources agree with the reference datatests within 0.3% (Sk) and 0.1% (K). With respect to the first three WG-DCAB test cases, more than 99.8% of the voxels present local (global) differences within +/- 1%(+/- 0.1%) of the reference datasets. For test Case 4 reference dataset, more than 94.9%(97.5%) of voxels show an agreement within +/- 1%(+/- 0.1%), better than similar benchmarking calculations in the literature. The track length kerma estimator scorer implemented increases the numerical efficiency of brachytherapy calculations two orders of magnitude, while the specific brachytherapy source allows the user to avoid the use of error-prone intermediate steps to translate the DICOM information into the simulation. In both clinical cases, only minor absorbed dose differences arise in the low-dose isodoses. 99.8% and 100% of the voxels have a global absorbed dose difference ratio within +/- 0.2%for the prostate and lung cases, respectively. The role played by the different segmentation and composition material in the bone structures was discussed, obtaining negligible absorbed dose differ-ences. Dose-volume histograms were in agreement with the reference data.Conclusions: PenRed incorporates new tallies and utilities and has been validated for its use for detailed and precise high-dose-rate brachytherapy simulations.
Address [Oliver, S.] Univ Politecn Valencia, Inst Segur Ind, Radiofis & Medioambiental ISIRYM, Camide Vera s n, Valencia 46022, Spain, Email: sanolgi@upvnet.upv.es
Corporate Author Thesis
Publisher Elsevier Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0939-3889 ISBN Medium
Area Expedition Conference
Notes WOS:001137118400001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5885
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Author Fletcher, E.M.; Ballester, F.; Beaulieu, L.; Morrison, H.; Poher, A.; Rivard, M.J.; Sloboda, R.S.; Vijande, J.; Thomson, R.M.
Title Generation and comparison of 3D dosimetric reference datasets for COMS eye plaque brachytherapy using model-based dose calculations Type Journal Article
Year 2024 Publication Medical Physics Abbreviated Journal Med. Phys.
Volume 51 Issue Pages 694-706
Keywords Monte Carlo; ocular brachytherapy; treatment planning
Abstract (up) PurposeA joint Working Group of the American Association of Physicists in Medicine (AAPM), the European Society for Radiotherapy and Oncology (ESTRO), and the Australasian Brachytherapy Group (ABG) was created to aid in the transition from the AAPM TG-43 dose calculation formalism, the current standard, to model-based dose calculations. This work establishes the first test cases for low-energy photon-emitting brachytherapy using model-based dose calculation algorithms (MBDCAs).Acquisition and Validation MethodsFive test cases are developed: (1) a single model 6711 125I brachytherapy seed in water, 13 seeds (2) individually and (3) in combination in water, (4) the full Collaborative Ocular Melanoma Study (COMS) 16-mm eye plaque in water, and (5) the full plaque in a realistic eye phantom. Calculations are done with four Monte Carlo (MC) codes and a research version of a commercial treatment planning system (TPS). For all test cases, local agreement of MC codes was within & SIM;2.5% and global agreement was & SIM;2% (4% for test case 5). MC agreement was within expected uncertainties. Local agreement of TPS with MC was within 5% for test case 1 and & SIM;20% for test cases 4 and 5, and global agreement was within 0.4% for test case 1 and 10% for test cases 4 and 5.Data Format and Usage NotesDose distributions for each set of MC and TPS calculations are available online () along with input files and all other information necessary to repeat the calculations.Potential ApplicationsThese data can be used to support commissioning of MBDCAs for low-energy brachytherapy as recommended by TGs 186 and 221 and AAPM Report 372. This work additionally lays out a sample framework for the development of test cases that can be extended to other applications beyond eye plaque brachytherapy.
Address [Fletcher, Elizabeth M.; Thomson, Rowan M.] Carleton Univ, Phys Dept, Carleton Lab Radiotherapy Phys, Ottawa, ON, Canada, Email: rthomson@physics.carleton.ca
Corporate Author Thesis
Publisher Wiley Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-2405 ISBN Medium
Area Expedition Conference
Notes WOS:001058112300001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5632
Permanent link to this record
 

 
Author Ma, Y.Z.; Vijande, J.; Ballester, F.; Tedgren, A.C.; Granero, D.; Haworth, A.; Mourtada, F.; Fonseca, G.P.; Zourari, K.; Papagiannis, P.; Rivard, M.J.; Siebert, F.A.; Sloboda, R.S.; Smith, R.; Chamberland, M.J.P.; Thomson, R.M.; Verhaegen, F.; Beaulieu, L.
Title A generic TG-186 shielded applicator for commissioning model-based dose calculation algorithms for high-dose-rate Ir-192 brachytherapy Type Journal Article
Year 2017 Publication Medical Physics Abbreviated Journal Med. Phys.
Volume 44 Issue 11 Pages 5961-5976
Keywords Ir-192; HDR brachytherapy; model based dose calculation; Monte Carlo methods; shielded applicator; TG-186
Abstract (up) PurposeA joint working group was created by the American Association of Physicists in Medicine (AAPM), the European Society for Radiotherapy and Oncology (ESTRO), and the Australasian Brachytherapy Group (ABG) with the charge, among others, to develop a set of well-defined test case plans and perform calculations and comparisons with model-based dose calculation algorithms (MBDCAs). Its main goal is to facilitate a smooth transition from the AAPM Task Group No. 43 (TG-43) dose calculation formalism, widely being used in clinical practice for brachytherapy, to the one proposed by Task Group No. 186 (TG-186) for MBDCAs. To do so, in this work a hypothetical, generic high-dose rate (HDR) Ir-192 shielded applicator has been designed and benchmarked. MethodsA generic HDR Ir-192 shielded applicator was designed based on three commercially available gynecological applicators as well as a virtual cubic water phantom that can be imported into any DICOM-RT compatible treatment planning system (TPS). The absorbed dose distribution around the applicator with the TG-186 Ir-192 source located at one dwell position at its center was computed using two commercial TPSs incorporating MBDCAs (Oncentra((R)) Brachy with Advanced Collapsed-cone Engine, ACE, and BrachyVision ACUROS) and state-of-the-art Monte Carlo (MC) codes, including ALGEBRA, BrachyDose, egs_brachy, Geant4, MCNP6, and Penelope2008. TPS-based volumetric dose distributions for the previously reported source centered in water and source displaced test cases, and the new source centered in applicator test case, were analyzed here using the MCNP6 dose distribution as a reference. Volumetric dose comparisons of TPS results against results for the other MC codes were also performed. Distributions of local and global dose difference ratios are reported. ResultsThe local dose differences among MC codes are comparable to the statistical uncertainties of the reference datasets for the source centered in water and source displaced test cases and for the clinically relevant part of the unshielded volume in the source centered in applicator case. Larger local differences appear in the shielded volume or at large distances. Considering clinically relevant regions, global dose differences are smaller than the local ones. The most disadvantageous case for the MBDCAs is the one including the shielded applicator. In this case, ACUROS agrees with MC within [-4.2%, +4.2%] for the majority of voxels (95%) while presenting dose differences within [-0.12%, +0.12%] of the dose at a clinically relevant reference point. For ACE, 95% of the total volume presents differences with respect to MC in the range [-1.7%, +0.4%] of the dose at the reference point. ConclusionsThe combination of the generic source and generic shielded applicator, together with the previously developed test cases and reference datasets (available in the Brachytherapy Source Registry), lay a solid foundation in supporting uniform commissioning procedures and direct comparisons among treatment planning systems for HDR Ir-192 brachytherapy.
Address [Ma, Yunzhi; Beaulieu, Luc] CHU Quebec, Dept Radio Oncol & Axe Oncol, Ctr Rech, Quebec City, PQ G1R 2J6, Canada, Email: yunzhi.Ma@crchuq.ulaval.ca
Corporate Author Thesis
Publisher Wiley Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-2405 ISBN Medium
Area Expedition Conference
Notes WOS:000414970800039 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3370
Permanent link to this record
 

 
Author Peppa, V.; Thomson, R.M.; Enger, S.A.; Fonseca, G.P.; Lee, C.N.; Lucero, J.N.E.; Mourtada, F.; Siebert, F.A.; Vijande, J.; Papagiannis, P.
Title A MC-based anthropomorphic test case for commissioning model-based dose calculation in interstitial breast 192-Ir HDR brachytherapy Type Journal Article
Year 2023 Publication Medical Physics Abbreviated Journal Med. Phys.
Volume 50 Issue 7 Pages 4675-4687
Keywords anthropomorphic phantom; commissioning; HDR brachytherapy; model based dose calculation algorithms; Monte Carlo
Abstract (up) PurposeTo provide the first clinical test case for commissioning of Ir-192 brachytherapy model-based dose calculation algorithms (MBDCAs) according to the AAPM TG-186 report workflow. Acquisition and Validation MethodsA computational patient phantom model was generated from a clinical multi-catheter Ir-192 HDR breast brachytherapy case. Regions of interest (ROIs) were contoured and digitized on the patient CT images and the model was written to a series of DICOM CT images using MATLAB. The model was imported into two commercial treatment planning systems (TPSs) currently incorporating an MBDCA. Identical treatment plans were prepared using a generic Ir-192 HDR source and the TG-43-based algorithm of each TPS. This was followed by dose to medium in medium calculations using the MBDCA option of each TPS. Monte Carlo (MC) simulation was performed in the model using three different codes and information parsed from the treatment plan exported in DICOM radiation therapy (RT) format. Results were found to agree within statistical uncertainty and the dataset with the lowest uncertainty was assigned as the reference MC dose distribution. Data Format and Usage NotesThe dataset is available online at ,. Files include the treatment plan for each TPS in DICOM RT format, reference MC dose data in RT Dose format, as well as a guide for database users and all files necessary to repeat the MC simulations. Potential ApplicationsThe dataset facilitates the commissioning of brachytherapy MBDCAs using TPS embedded tools and establishes a methodology for the development of future clinical test cases. It is also useful to non-MBDCA adopters for intercomparing MBDCAs and exploring their benefits and limitations, as well as to brachytherapy researchers in need of a dosimetric and/or a DICOM RT information parsing benchmark. Limitations include specificity in terms of radionuclide, source model, clinical scenario, and MBDCA version used for its preparation.
Address [Peppa, Vasiliki; Papagiannis, Panagiotis] Natl & Kapodistrian Univ Athens, Med Sch, Med Phys Lab, Athens, Greece, Email: ppapagi@med.uoa.gr
Corporate Author Thesis
Publisher Wiley Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-2405 ISBN Medium
Area Expedition Conference
Notes WOS:000989616100001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5529
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Author Beaulieu, L.; Ballester, F.; Granero, D.; Tedgren, A.C.; Haworth, A.; Lowenstein, J.R.; Ma, Y.Z.; Mourtada, F.; Papagiannis, P.; Rivard, M.J.; Siebert, F.A.; Sloboda, R.S.; Smith, R.L.; Thomson, R.M.; Verhaegen, F.; Fonseca, G.; Vijande, J.
Title AAPM WGDCAB Report 372: A joint AAPM, ESTRO, ABG, and ABS report on commissioning of model-based dose calculation algorithms in brachytherapy Type Journal Article
Year 2023 Publication Medical Physics Abbreviated Journal Med. Phys.
Volume 50 Issue 8 Pages e946–e960
Keywords brachytherapy; commissioning; dose calculation; model-based dose calculation; Monte Carlo; TG-186
Abstract (up) The introduction of model-based dose calculation algorithms (MBDCAs) in brachytherapy provides an opportunity for a more accurate dose calculation and opens the possibility for novel, innovative treatment modalities. The joint AAPM, ESTRO, and ABG Task Group 186 (TG-186) report provided guidance to early adopters. However, the commissioning aspect of these algorithms was described only in general terms with no quantitative goals. This report, from the Working Group on Model-Based Dose Calculation Algorithms in Brachytherapy, introduced a field-tested approach to MBDCA commissioning. It is based on a set of well-characterized test cases for which reference Monte Carlo (MC) and vendor-specific MBDCA dose distributions are available in a Digital Imaging and Communications in Medicine-Radiotherapy (DICOM-RT) format to the clinical users. The key elements of the TG-186 commissioning workflow are now described in detail, and quantitative goals are provided. This approach leverages the well-known Brachytherapy Source Registry jointly managed by the AAPM and the Imaging and Radiation Oncology Core (IROC) Houston Quality Assurance Center (with associated links at ESTRO) to provide open access to test cases as well as step-by-step user guides. While the current report is limited to the two most widely commercially available MBDCAs and only for Ir-192-based afterloading brachytherapy at this time, this report establishes a general framework that can easily be extended to other brachytherapy MBDCAs and brachytherapy sources. The AAPM, ESTRO, ABG, and ABS recommend that clinical medical physicists implement the workflow presented in this report to validate both the basic and the advanced dose calculation features of their commercial MBDCAs. Recommendations are also given to vendors to integrate advanced analysis tools into their brachytherapy treatment planning system to facilitate extensive dose comparisons. The use of the test cases for research and educational purposes is further encouraged.
Address [Beaulieu, Luc; Ma, Yunzhi] CHU Quebec Univ Laval, Serv Phys Med & Radioprotect, Quebec City, PQ, Canada, Email: beaulieu@phy.ulaval.ca
Corporate Author Thesis
Publisher Wiley Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-2405 ISBN Medium
Area Expedition Conference
Notes WOS:001026540300001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 5579
Permanent link to this record