bluuebunny/crossref_metadata_2025_split huggingface dataset:
Validation of measurement‐guided 3D VMAT dose reconstruction on a heterogeneous anthropomorphic phantom
Authors: Opp Daniel , Nelms Benjamin E. , Zhang Geoffrey , Stevens Craig , Feygelman Vladimir 
Published: February 2017

3DVH software (Sun Nuclear Corp., Melbourne, FL) is capable of generating a volumetric patient VMAT dose by applying a volumetric perturbation algorithm based on comparing measurement‐guided dose reconstruction and TPS‐calculated dose to a cylindrical phantom. The primary purpose of this paper is to validate this dose reconstruction on an anthropomorphic heterogeneous thoracic phantom by direct comparison to independent measurements. The dosimetric insert to the phantom is novel, and thus the secondary goal is to demonstrate how it can be used for the hidden target end‐to‐end testing of VMAT treatments in lung. A dosimetric insert contains a 4 cm diameter unit‐density spherical target located inside the right lung ( density). It has 26 slots arranged in two orthogonal directions, milled to hold optically stimulated luminescent dosimeters (OSLDs). Dose profiles in three cardinal orthogonal directions were obtained for five VMAT plans with varying degrees of modulation. After appropriate OSLD corrections were applied, 3DVH measurement‐guided VMAT dose reconstruction agreed 100% with the measurements in the unit density target sphere at 3%/3 mm level (composite analysis) for all profile points for the four less‐modulated VMAT plans, and for 96% of the points in the highly modulated C‐shape plan (from TG‐119). For this latter plan, while 3DVH shows acceptable agreement with independent measurements in the unit density target, in the lung disagreement with experiment is relatively high for both the TPS calculation and 3DVH reconstruction. For the four plans excluding the C‐shape, overall composite analysis passing rates for 3DVH against independent measurement ranged from 93% to 100%. The C‐shape plan was deliberately chosen as a stress test of the algorithm. The dosimetric spatial alignment hidden target test demonstrated the average distance to agreement between the measured and TPS profiles in the steep dose gradient area at the edge of the 2 cm target to be , and for the IEC X, Y, and Z directions, respectively.PACS number: 87.55Qr
Evaluation of whole‐body MR to CT deformable image registration
Authors: Akbarzadeh A. , Gutierrez D. , Baskin A. , Ay M.R. , Ahmadian A. , Alam N. Riahi , Lövblad KO , Zaidi H. 
Published: February 2017

Multimodality image registration plays a crucial role in various clinical and research applications. The aim of this study is to present an optimized MR to CT whole‐body deformable image registration algorithm and its validation using clinical studies. A 3D intermodality registration technique based on B‐spline transformation was performed using optimized parameters of the elastix package based on the Insight Toolkit (ITK) framework. Twenty‐eight (17 male and 11 female) clinical studies were used in this work. The registration was evaluated using anatomical landmarks and segmented organs. In addition to 16 anatomical landmarks, three key organs (brain, lungs, and kidneys) and the entire body volume were segmented for evaluation. Several parameters — such as the Euclidean distance between anatomical landmarks, target overlap, Dice and Jaccard coefficients, false positives and false negatives, volume similarity, distance error, and Hausdorff distance — were calculated to quantify the quality of the registration algorithm. Dice coefficients for the majority of patients () were in the 0.8–1 range for the whole body, brain, and lungs, which satisfies the criteria to achieve excellent alignment. On the other hand, for kidneys, Dice coefficients for volumes of 25% of the patients meet excellent volume agreement requirement, while the majority of patients satisfy good agreement criteria (). For all patients, the distance error was in 0–10 mm range for all segmented organs. In summary, we optimized and evaluated the accuracy of an MR to CT deformable registration algorithm. The registered images constitute a useful 3D whole‐body MR‐CT atlas suitable for the development and evaluation of novel MR‐guided attenuation correction procedures on hybrid PET‐MR systems.PACS number: 07.05.Pj
Normal variance in emphysema index measurements in 64 multidetector‐row computed tomography
Authors: Hochhegger Bruno , Irion Klaus L. , Alves Giordano R.T. , Souza Arthur S. , Holemans John , Murthy Dhivya , Marchiori Edson 
Published: February 2017

The purpose of this study was to identify the normal variance of emphysema index (EI) measured in examinations acquired with 64 multidetector‐row computed tomography (64‐MDCT). A longitudinal, noninterventional study was performed retrieving all patients in our institution who are currently registered in our lung nodule protocol. All patients with clinical, functional, or significant radiological changes were excluded. We assumed that EI should remain unchanged within a short period of time. We reviewed 475 MDCTs in order to select 50 clinically stable patients who had two sequential chest MDCTs performed within a time interval of less than three months, and who presented at least one lung free of abnormalities but emphysema. CT densitovolumetry was used to calculate EI with thresholds set at Hounsfield units (HUs) (EI‐950) and HUs (EI‐970); on both studies from each patient. We observed the variation of total lung volume (TLV), mean lung density (MDL), and EI for measurements at the baseline and at follow‐up scans. Differences observed between baseline and follow‐up measurements were: ; ; ; ; ; and ; . The correlations obtained were the following: , , . Accepting that emphysema would remain unchanged within three months on stable patients, differences of less than 0.89% for EI‐950 and of less than 0.23% for EI‐970 are within the variance of the method.PACS number: 87.50.ct
Dosimetric evaluation of four‐dimensional dose distributions of CyberKnife and volumetric‐modulated arc radiotherapy in stereotactic body lung radiotherapy
Authors: Chan Mark K.H. , Kwong Dora L.W. , Law Gilbert M.L. , Tam Eric , Tong Anthony , Lee Venus , Ng Sherry C.Y. 
Published: February 2017

Advanced image‐guided stereotatic body lung radiotherapy techniques using volumetric‐modulated arc radiotherapy (VMAT) with four‐dimensional cone‐beam computed tomography (4D CBCT) and CyberKnife with real‐time target tracking have been clinically implemented by different authors. However, dosimetric comparisons between these techniques are lacking. In this study, 4D CT scans of 14 patients were used to create VMAT and CyberKnife treatment plans using 4D dose calculations. The GTV and the organs at risk (OARs) were defined on the end‐exhale images for CyberKnife planning and were then deformed to the midventilation images (MidV) for VMAT optimization. Direct 4D Monte Carlo dose optimizations were performed for CyberKnife (). Four‐dimensional dose calculations were also applied to VMAT plans to generate the 4D dose distributions () on the exhale images for direct comparisons with the plans. and showed comparable target conformity ( vs. ). GTV mean doses were significantly higher with . Statistical differences of dose volume metrics were not observed in the majority of OARs studied, except for esophagus, with yielding marginally higher than . The normal tissue volumes receiving 80%, 50%, and 30% of the prescription dose (, and ) were higher with , whereas yielded slightly higher in posterior lesions than . VMAT resulted in much less monitor units and therefore greater delivery efficiency than CyberKnife. In general, it was possible to produce dosimetrically acceptable plans with both techniques. The selection of treatment modality should consider the dosimetric results as well as the patient's tolerance of the treatment process specific to the SBRT technique.PACS numbers: 87.53.Ly, 87.55.km
Dependence of ventilation image derived from 4D CT on deformable image registration and ventilation algorithms
Authors: Latifi Kujtim , Forster Kenneth M. , Hoffe Sarah E. , Dilling Thomas J. , van Elmpt Wouter , Dekker Andre , Zhang Geoffrey G. 
Published: February 2017

Ventilation imaging using 4D CT is a convenient and low‐cost functional imaging methodology which might be of value in radiotherapy treatment planning to spare functional lung volumes. Deformable image registration (DIR) is needed to calculate ventilation imaging from 4D CT. This study investigates the dependence of calculated ventilation on DIR methods and ventilation algorithms. DIR of the normal end expiration and normal end inspiration phases of the 4D CT images was used to correlate the voxels between the two respiratory phases. Three different DIR algorithms, optical flow (OF), diffeomorphic demons (DD), and diffeomorphic morphons (DM) were retrospectively applied to ten esophagus and ten lung cancer cases with 4D CT image sets that encompassed the entire lung volume. The three ventilation extraction methods were used based on either the Jacobian, the change in volume of the voxel, or directly calculated from Hounsfield units. The ventilation calculation algorithms used are the Jacobian, , and HU method. They were compared using the Dice similarity coefficient (DSC) index and Bland‐Altman plots. Dependence of ventilation images on the DIR was greater for the and the Jacobian methods than for the HU method. The DSC index for 20% of low‐ventilation volume for was between OF and DM, between OF and DD, and between DM and DD. The similarity comparisons for Jacobian were , and , respectively, and for HU they were , and , respectively. Dependence of extracted ventilation on the ventilation algorithm used showed good agreement between the and Jacobian methods, but differed significantly for the HU method. DSC index for using OF as DIR was between and Jacobian, between and HU, and between Jacobian and HU, respectively. When using DM or DD as DIR, similar values were obtained when comparing the different ventilation calculation methods. The similarity values for the 20% high‐ventilation volume were close to those found for the 20% low‐ventilation volume. The results obtained with DSC index were confirmed when using the Bland‐Altman plots for comparing the ventilation images. Our data suggest that ventilation calculated from 4D CT depends on the DIR algorithm employed. Similarities between and Jacobian are higher than between and HU, and Jacobian and HU.PACS number: 87.57.nj
Analysis of esophageal‐sparing treatment plans for patients with high‐grade esophagitis
Authors: Niedzielski Joshua S. , Bluett Jaques B. , Williamson Ryan T. , Liao Zhongxing , Gomez Daniel R. , Court Laurence E. 
Published: February 2017

We retrospectively generated IMRT plans for 14 NSCLC patients who had experienced grade 2 or 3 esophagitis (CTCAE version 3.0). We generated 11‐beam and reduced esophagus dose plan types to compare changes in the volume and length of esophagus receiving doses of 50, 55, 60, 65, and 70 Gy. Changes in planning target volume (PTV) dose coverage were also compared. If necessary, plans were renormalized to restore 95% PTV coverage. The critical organ doses examined were mean lung dose, mean heart dose, and volume of spinal cord receiving 50 Gy. The effect of interfractional motion was determined by applying a three‐dimensional rigid shift to the dose grid. For the esophagus plan, the mean reduction in esophagus V50, V55, V60, V65, and V70 Gy was 2.8, 4.1, 5.9, 7.3, and 9.5 cm3, respectively, compared with the clinical plan. The mean reductions in LE50, LE55, LE60, LE65, and LE70 Gy were 2.0, 3.0, 3.8, 4.0, and 4.6 cm, respectively. The mean heart and lung dose decreased 3.0 Gy and 2.4 Gy, respectively. The mean decreases in 90% and 95% PTV coverage were 1.7 Gy and 2.8 Gy, respectively. The normalized plans’ mean reduction of esophagus V50, V55, V60, V65, and V70 Gy were 1.6, 2.0, 2.9, 3.9, and 5.5 cm3, respectively, compared with the clinical plans. The normalized plans’ mean reductions in LE50, LE55, LE60, LE65, and LE70 Gy were 4.9, 5.2, 5.4, 4.9, and 4.8 cm, respectively. The mean reduction in maximum esophagus dose with simulated interfractional motion was 3.0 Gy and 1.4 Gy for the clinical plan type and the esophagus plan type, respectively. In many cases, the esophagus dose can be greatly reduced while maintaining critical structure dose constraints. PTV coverage can be restored by increasing beam output, while still obtaining a dose reduction to the esophagus and maintaining dose constraints.PACS number: 87.53 Tf
Evaluation of dose prediction error and optimization convergence error in four‐dimensional inverse planning of robotic stereotactic lung radiotherapy
Authors: Chan Mark K.H. , Kwong Dora L.W. , Tong Anthony , Tam Eric , Ng Sherry C.Y. 
Published: February 2017

Inverse optimization of robotic stereotactic lung radiotherapy is typically performed using relatively simple dose calculation algorithm on a single instance of breathing geometry. Variations of patient geometry and tissue density during respiration could reduce the dose accuracy of these 3D optimized plans. To quantify the potential benefits of direct four‐dimensional (4D) optimization in robotic lung radiosurgery, 4D optimizations using 1) ray‐tracing algorithm with equivalent path‐length heterogeneity correction (), and 2) Monte Carlo (MC) algorithm (), were performed in 25 patients. The plans were recalculated using MC algorithm () to quantify the dose prediction errors (DPEs). Optimization convergence errors (OCEs) were evaluated by comparing the and dose results. The results were analyzed by dose‐volume histogram indices for selected organs. Statistical equivalence tests were performed to determine the clinical significance of the DPEs and OCEs, compared with a 3% tolerance. Statistical equivalence tests indicated that the DPE and the OCE are significant predominately in . The DPEs in of lung, and of cord, trachea, and esophagus are within 1.2%, while the OCEs are within 10.4% in lung and within 3.5% in trachea . The marked DPE and OCE suggest that 4D MC optimization is important to improve the dosimetric accuracy in robotic‐based stereotactic body radiotherapy, despite the longer computation time.PACS numbers: 87.53.Ly, 87.55.km
Monte Carlo characterization of as a high‐dose‐rate source for brachytherapy application by FLUKA code
Authors: Anjomrouz Marzieh , Sadeghi Mahdi , Haddadi Asghar 
Published: February 2017

Higher initial dose rate and simplifying HDR room treatment of element among other brachytherapy sources has led to investigating its feasibility as high‐dose‐rate seed. In this work, Monte Carlo calculation was performed to obtain dosimetric parameters of , Model M42 source at different radial distances according to AAPM TG‐43U1 and HEBD Report about HDR sources in both air vacuum and spherical homogeneous water phantom. The deposited energy resulted by FLUKA as Monte Carlo code using binning estimators around source was converted into radial dose rate distribution in polar coordinates surrounding the brachytherapy source. The results indicate a dose rate constant of with approximate uncertainty of 0.04%, air kerma strength, and anisotropy function ranging from 0.386 to 1.00 for radial distances of 0.5–10 cm and polar angles of 0°–180°. Overall, FLUKA dosimetric outputs were benchmarked with those published by Cazeca et al. via MCNP5 as one of validate dosimetry datasets related to HDR source. As a result, it seems that FLUKA code can be applicable as a valuable tool to Monte Carlo evaluation of novel HDR brachytherapy sources.PACS number: 87.15.ak
Evaluation of the sensitivity of two 3D diode array dosimetry systems to setup error for quality assurance (QA) of volumetric‐modulated arc therapy (VMAT)
Authors: Li Guangjun , Bai Sen , Chen Nianyong , Henderson Lansdale , Wu Kui , Xiao Jianghong , Zhang Yingjie , Jiang Qingfeng , Jiang Xiaoqin 
Published: February 2017

The purpose of this study is to evaluate the sensitivities of 3D diode arrays to setup error for patient‐specific quality assurance (QA) of volumetric‐modulated arc therapy (VMAT). Translational setup errors of , and mm in the RL, SI, and AP directions and rotational setup errors of and in the pitch, roll, and yaw directions were set up in two phantom systems, ArcCHECK and , with VMAT plans for 11 patients. Cone‐beam computed tomography (CBCT) followed by automatic correction using a HexaPOD 6D treatment couch ensured the position accuracy. Dose distributions of the two phantoms were compared in order to evaluate the agreement between calculated and measured values by using γ analysis with 3%/3 mm, 3%/2 mm, and 2%/2 mm criteria. To determine the impact on setup error for VMAT QA, we evaluated the sensitivity of results acquired by both 3D diode array systems to setup errors in translation and rotation. For the VMAT QA of all patients, the pass rate with the 3%/3 mm criteria exceeded 95% using either phantom. For setup errors of 3 mm and 2°, respectively, the pass rates with the 3%/3 mm criteria decreased by a maximum of 14.0% and 23.5% using ArcCHECK, and 14.4% and 5.0% using . Both systems are sensitive to setup error, and do not have mechanisms to account for setup errors in the software. The sensitivity of both VMAT QA systems was strongly dependent on the patient‐specific plan. The sensitivity of ArcCHECK to the rotational error was higher than that of . In order to achieve less than 3% mean pass rate reduction of VMAT plan QA with the 3%/3 mm criteria, a setup accuracy of 2 mm/1° and 2 mm/2° is required for ArcCheck and devices, respectively. The cumulative effect of the combined 2 mm translational and 1° rotational errors caused 3.8% and 2.4% mean pass rates reduction with 3%/3 mm criteria, respectively, for ArcCHECK and systems. For QA of VMAT plans for nasopharyngeal cancer (NPC) using the ArcCHECK system, the setup should be more accurate.PACS numbers: 87.55.ne, 87.55.Qr, 87.55.km
Effects of interportal error on dose distribution in patients undergoing breath‐holding intensity‐modulated radiotherapy for pancreatic cancer: evaluation of a new treatment planning method
Authors: Takakura Toru , Nakamura Mitsuhiro , Shibuya Keiko , Nakata Manabu , Nakamura Akira , Yukinori Matsuo , Shiinoki Takeshi , Higashimura Kyoji , Teshima Teruki , Hiraoka Masahiro 
Published: February 2017

In patients with pancreatic cancer, intensity‐modulated radiotherapy (IMRT) under breath holding facilitates concentration of the radiation dose in the tumor, while sparing the neighboring organs at risk and minimizing interplay effects between movement of the multileaf collimator and motion of the internal structures. Although the breath‐holding technique provides high interportal reproducibility of target position, dosimetric errors caused by interportal breath‐holding positional error have not been reported. Here, we investigated the effects of interportal breath‐holding positional errors on IMRT dose distribution by incorporating interportal positional error into the original treatment plan, using random numbers in ten patients treated for pancreatic cancer. We also developed a treatment planning technique that shortens breath‐holding time without increasing dosimetric quality assurance workload. The key feature of our proposed method is performance of dose calculation using the same optimized fluence map as the original plan, after dose per fraction in the original plan was cut in half and the number of fractions was doubled. Results confirmed that interportal error had a negligible effect on dose distribution over multiple fractions. Variations in the homogeneity index and the dose delivered to 98%, 2%, and 50% of the volume for the planning target volume, and the dose delivered to 1 cc of the volume for the duodenum and stomach were , on average, in comparison with the original plan. The new treatment planning method decreased breath‐holding time by 33%, and differences in dose‐volume metrics between the original and the new treatment plans were within . An additional advantage of our proposed method is that interportal errors can be better averaged out; thus, dose distribution in the proposed method may be closer to the planned dose distribution than with the original plans.PACS number: 87.53.Bn, 87.55.D‐, 87.55.‐x
Monte Carlo characterization of biocompatible beta‐emitting glass seed incorporated with the radionuclide as a SPECT marker for brachytherapy applications
Authors: Hadadi Asghar , Sadeghi Mahdi , Sardari Dariush , Khanchi Alireza , Shirazi Alireza 
Published: February 2017

A glass seed consisting of the ‐emitting radionuclide incorporated with radionuclide as SPECT marker is proposed for potential application in brachytherapy in order to reduce the undesirable dose to healthy adjacent organs. The aim of this work is to determine the dosimetric characteristics, as suggested in the AAPM TG‐60/TG‐149 reports, for this seed using Monte Carlo simulation. Monte Carlo codes MCNP5, EGSnrc, and FLUKA were used to calculate the absorbed dose distribution around the seed. Dosimetric parameters, such as reference absorbed dose rate, radial dose function, and one‐dimensional (1D) and two‐dimensional (2D) anisotropy functions, were obtained. The computational results from these three codes are in agreement within 5.4% difference on average. The absorbed dose rate at the reference point was estimated to be 5.01 cGy and self absorption of YAS glass seed amounted to 30.51%. The results showed that, with thermal neutron bombardment of 5 hours in a typical flux, sufficient activity for applications in brachytherapy may be achieved. With a 5 mCi initial activity, the total dose of a YAS glass seed was estimated to be 1.38 Gy at 1.0 cm from the seed center. Comparing with gamma emitting seeds, the seed could reduce undesirable doses to adjacent organs, because of the rapid dose falloff of beta ray. Because of the high value of 5.5 mm, fewer number of seeds will be required for an interstitial brachytherapy treatment using permanent implant, in comparison with other beta‐emitting seeds. The results would be helpful in the development of the radioactive implants using glass seeds for the brachytherapy treatment.PACS numbers: 87.53.Jw, 87.56.bg
A feasibility study using TomoDirect for craniospinal irradiation
Authors: Langner Ulrich W. , Molloy Janelle A. , Gleason John F. , Feddock Jonathan M. 
Published: February 2017

The feasibility of delivering craniospinal irradiation (CSI) with TomoDirect is investigated. A method is proposed to generate TomoDirect plans using standard three‐dimensional (3D) beam arrangements on Tomotherapy with junctioning of these fields to minimize hot or cold spots at the cranial/spinal junction. These plans are evaluated and compared to a helical Tomotherapy and a three‐dimensional conformal therapy (3D CRT) plan delivered on a conventional linear accelerator (linac) for CSI. The comparison shows that a TomoDirect plan with an overlap between the cranial and spinal fields might be preferable over Tomotherapy plans because of decreased low dose to large volumes of normal tissues outside of the planning target volume (PTV). Although the TomoDirect plans were not dosimetrically superior to a 3D CRT linac plan, the patient can be easily treated in the supine position, which is often more comfortable and efficient from an anesthesia standpoint. TomoDirect plans also have only one setup position which obviates the need for matching of fields and feathering of junctions, two issues encountered with conventional 3D CRT plans. TomoDirect plans can be delivered with comparable treatment times to conventional 3D plans and in shorter times than a Tomotherapy plan. In this paper, a method is proposed for creating TomoDirect craniospinal plans, and the dosimetric consequences for choosing different planning parameters are discussed.PACS number: 87.55.D‐