bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface imaging, laser positioning or volumetric imaging for breast cancer with nodal involvement treated by helical TomoTherapy
Authors: Crop Frederik , Pasquier David , Baczkiewic Amandine , Doré Julie , Bequet Lena , Steux Emeline , Gadroy Anne , Bouillon Jacqueline , Florence Clement , Muszynski Laurence , Lacour Mathilde , Lartigau Eric 
Published: February 2017

A surface imaging system, Catalyst (C‐Rad), was compared with laser‐based positioning and daily mega voltage computed tomography (MVCT) setup for breast patients with nodal involvement treated by helical TomoTherapy. Catalyst‐based positioning performed better than laser‐based positioning. The respective modalities resulted in a standard deviation (SD), 68% confidence interval (CI) of positioning of left–right, craniocaudal, anterior–posterior, roll: 2.4 mm, 2.7 mm, 2.4 mm, 0.9° for Catalyst positioning, and 6.1 mm, 3.8 mm, 4.9 mm, 1.1° for laser‐based positioning, respectively. MVCT‐based precision is a combination of the interoperator variability for MVCT fusion and the patient movement during the time it takes for MVCT and fusion. The MVCT fusion interoperator variability for breast patients was evaluated at one SD left–right, craniocaudal, ant–post, roll as: 1.4 mm, 1.8 mm, 1.3 mm, 1.0°.There was no statistically significant difference between the automatic MVCT registration result and the manual adjustment; the automatic fusion results were within the 95% CI of the mean result of 10 users, except for one specific case where the patient was positioned with large yaw. We found that users add variability to the roll correction as the automatic registration was more consistent.The patient position uncertainty confidence interval was evaluated as 1.9 mm, 2.2 mm, 1.6 mm, 0.9° after 4 min, and 2.3 mm, 2.8 mm, 2.2 mm, 1° after 10 min. The combination of this patient movement with MVCT fusion interoperator variability results in total standard deviations of patient position when treatment starts 4 or 10 min after initial positioning of, respectively: 2.3 mm, 2.8 mm, 2.0 mm, 1.3° and 2.7 mm, 3.3 mm, 2.6 mm, 1.4°.Surface based positioning arrives at the same precision when taking into account the time required for MVCT imaging and fusion. These results can be used on a patient‐per‐patient basis to decide which positioning system performs the best after the first 5 fractions and when daily MVCT can be omitted. Ideally, real‐time monitoring is required to reduce important intrafraction movement.PACS number(s): 87.53.Jw, 87.53.Kn, 87.56.Da, 87.63.L‐, 81.70.Tx
Secondary cancer‐incidence risk estimates for external radiotherapy and high‐dose‐rate brachytherapy in cervical cancer: phantom study
Authors: Lee Boram , Ahn Sung Hwan , Kim Hyeyoung , Son Jaeman , Sung Jiwon , Han Youngyih , Huh Seung Jae , Kim Jin Sung , Kim Dong Wook , Yoon Myonggeun 
Published: February 2017

This study was designed to estimate radiation‐induced secondary cancer risks from high‐dose‐rate (HDR) brachytherapy and external radiotherapy for patients with cervical cancer based on measurements of doses absorbed by various organs. Organ doses from HDR brachytherapy and external radiotherapy were measured using glass rod dosimeters. Doses to out‐of‐field organs were measured at various locations inside an anthropomorphic phantom. Brachytherapy‐associated organ doses were measured using a specialized phantom that enabled applicator insertion, with the pelvis portion of the existing anthropomorphic phantom replaced by this new phantom. Measured organ doses were used to calculate secondary cancer risk based on Biological Effects of Ionizing Radiation (BEIR) VII models. In both treatment modalities, organ doses per prescribed dose (PD) mostly depended on the distance between organs. The locations showing the highest and lowest doses were the right kidney (external radiotherapy: 215.2 mGy; brachytherapy: 655.17 mGy) and the brain (external radiotherapy: 15.82 mGy; brachytherapy: 2.49 mGy), respectively. Organ doses to nearby regions were higher for brachytherapy than for external beam therapy, whereas organ doses to distant regions were higher for external beam therapy. Organ doses to distant treatment regions in external radiotherapy were due primarily to out‐of‐field radiation resulting from scattering and leakage in the gantry head. For brachytherapy, the highest estimated lifetime attributable risk per 100,000 population was to the stomach (88.6), whereas the lowest risks were to the brain (0.4) and eye (0.4); for external radiotherapy, the highest and lowest risks were to the thyroid (305.1) and brain (2.4). These results may help provide a database on the impact of radiotherapy‐induced secondary cancer incidence during cervical cancer treatment, as well as suggest further research on strategies to counteract the risks of radiotherapy‐associated secondary malignancies.PACS number(s): 87.52.‐g, 87.52.Px, 87.53.Dq, 87.53.Jw
Diode‐based transmission detector for IMRT delivery monitoring: a validation study
Authors: Li Taoran , Wu Q. Jackie , Matzen Thomas , Yin Fang‐Fang , O'Daniel Jennifer C. 
Published: February 2017

The purpose of this work was to evaluate the potential of a new transmission detector for real‐time quality assurance of dynamic‐MLC‐based radiotherapy. The accuracy of detecting dose variation and static/dynamic MLC position deviations was measured, as well as the impact of the device on the radiation field (surface dose, transmission). Measured dose variations agreed with the known variations within 0.3%. The measurement of static and dynamic MLC position deviations matched the known deviations with high accuracy (0.7–1.2 mm). The absorption of the device was minimal (). The increased surface dose was small (1%–9%) but, when added to existing collimator scatter effects could become significant at large field sizes (). Overall the accuracy and speed of the device show good potential for real‐time quality assurance.PACS number(s): 87.55.Qr
A noise power spectrum study of a new model‐based iterative reconstruction system: Veo 3.0
Authors: Li Guang , Liu Xinming , Dodge Cristina T. , Jensen Corey T. , Rong X. John 
Published: February 2017

The purpose of this study was to evaluate performance of the third generation of model‐based iterative reconstruction (MBIR) system, Veo 3.0, based on noise power spectrum (NPS) analysis with various clinical presets over a wide range of clinically applicable dose levels. A CatPhan 600 surrounded by an oval, fat‐equivalent ring to mimic patient size/shape was scanned 10 times at each of six dose levels on a GE HD 750 scanner. NPS analysis was performed on images reconstructed with various Veo 3.0 preset combinations for comparisons of those images reconstructed using Veo 2.0, filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASiR). The new Target Thickness setting resulted in higher noise in thicker axial images. The new Texture Enhancement function achieved a more isotropic noise behavior with less image artifacts. Veo 3.0 provides additional reconstruction options designed to allow the user choice of balance between spatial resolution and image noise, relative to Veo 2.0. Veo 3.0 provides more user selectable options and in general improved isotropic noise behavior in comparison to Veo 2.0. The overall noise reduction performance of both versions of MBIR was improved in comparison to FBP and ASiR, especially at low‐dose levels.PACS number(s): 87.57.‐s, 87.57.Q‐, 87.57.C‐, 87.57.nf, 87.57.C‐, 87.57.cm
Patient‐specific 17‐segment myocardial modeling on a bull's‐eye map
Authors: Jung Joonho , Kim Young‐Hak , Kim Namkug , Yang Dong Hyun 
Published: February 2017

The purpose of this study was to develop and validate cardiac computed tomography (CT) quantitative analysis software with a patient‐specific, 17‐segment myocardial model that uses electrocardiogram (ECG)‐gated cardiac CT images to differentiate between normal controls and severe aortic stenosis (AS) patients. ECG‐gated cardiac CT images from 35 normal controls and 144 AS patients were semiautomatically segmented to create a patient‐specific, 17‐segment myocardial model. Two experts then manually determined the anterior and posterior interventricular grooves to be boundaries between the 1st and 2nd segments and between the 3rd and 4th segments, respectively, to correct the model. Each segment was automatically identified as follows. The outer angle of two boundaries was divided to differentiate the 1st, 4th, 5th, and 6th segments in the basal plane, whereas the inner angle divided the 2nd and 3rd segments. The segments of the midplane were similarly divided. Segmental area distributions were quantitatively evaluated on the bull's‐eye map on the basis of the morphological boundaries by measuring the area of each segment. Segmental areas of severe AS patients and normal controls were significantly different (t‐test, ) in the proposed model because the septal regions of the severe AS patients were smaller than those of normal controls and the difference was enough to divide the two groups. The capabilities of the 2D segmental areas () may be equivalent to those of 3D segmental analysis () for differentiating the two groups (t‐test, ). The proposed method is superior to the conventional 17‐segment in relation to reflection of patient‐specific morphological variation and allows to obtain a more precise mapping between segments and the AHA recommended nomenclature. It can be used to differentiate severer AS patients and normal controls and also helps to understand the left ventricular morphology at a glance.PACS number(s): 87.57.N‐, 87.57.R‐, 87.57.qp
Difference in dose‐volumetric data between the analytical anisotropic algorithm, the dose‐to‐medium, and the dose‐to‐water reporting modes of the Acuros XB for lung stereotactic body radiation therapy
Authors: Mampuya Wambaka A. , Nakamura Mitsuhiro , Hirose Yoshinori , Kitsuda Kenji , Ishigaki Takashi , Mizowaki Takashi , Hiraoka Masahiro 
Published: February 2017

The purpose of this study was to evaluate the difference in dose‐volumetric data between the analytical anisotropic algorithms (AAA) and the two dose reporting modes of the Acuros XB, namely, the dose to water () and dose to medium () in lung stereotactic body radiotherapy (SBRT). Thirty‐eight plans were generated using the in Eclipse Treatment Planning System (TPS) and then recalculated with the and AAA, using identical beam setup. A dose of 50 Gy in 4 fractions was prescribed to the isocenter and the planning target volume (PTV) D95%. The isocenter was always inside the PTV. The following dose‐volumetric parameters were evaluated; D2%, D50%, D95%, and D98% for the internal target volume (ITV) and the PTV. Two‐tailed paired Student's t‐tests determined the statistical significance. Although for most of the parameters evaluated, the mean differences observed between the AAA, and were statistically significant (), absolute differences were rather small, in general less than 5% points. The maximum mean difference was observed in the ITV D50% between the and the AAA and was 1.7% points under the isocenter prescription and 3.3% points under the D95 prescription. produced higher values than with differences ranging from 0.4 to 1.1% points under isocenter prescription and 0.0 to 0.7% points under the PTV D95% prescription. The differences observed under the PTV D95% prescription were larger compared to those observed for the isocenter prescription between and AAA, and , and and AAA. Although statistically significant, the mean differences between the three algorithms are within 3.3% points.PACS number(s): 87.55.x, 87.55.D‐, 87.55.dk
Thin‐film CdTe detector for microdosimetric study of radiation dose enhancement at gold‐tissue interface
Authors: Paudel Nava Raj , Shvydka Diana , Parsai E. Ishmael 
Published: February 2017

Presence of interfaces between high and low atomic number (Z) materials, often encountered in diagnostic imaging and radiation therapy, leads to radiation dose perturbation. It is characterized by a very narrow region of sharp dose enhancement at the interface. A rapid falloff of dose enhancement over a very short distance from the interface makes the experimental dosimetry nontrivial. We use an in‐house‐built inexpensive thin‐film Cadmium Telluride (CdTe) photodetector to study this effect at the gold‐tissue interface and verify our experimental results with Monte Carlo (MC) modeling. Three‐micron thick thin‐film CdTe photodetectors were fabricated in our lab. One‐, ten‐ or one hundred‐micron thick gold foils placed in a tissue‐equivalent‐phantom were irradiated with a clinical Ir‐192 high‐dose‐rate (HDR) source and current measured with a CdTe detector in each case was compared with the current measured for all uniform tissue‐equivalent phantom. Percentage signal enhancement (PSE) due to each gold foil was then compared against MC modeled percentage dose enhancement (PDE), obtained from the geometry mimicking the experimental setup. The experimental PSEs due to 1, 10, and thick gold foils at the closest measured distance of from the interface were , , and , respectively. The corresponding MC modeled PDEs were , , and , respectively. The experimental and MC modeled values showed a closer agreement at the larger distances from the interface. The dose enhancement in the vicinity of gold‐tissue interface was successfully measured using an in‐house‐built, high‐resolution CdTe‐based photodetector and validated with MC simulations. A close agreement between experimental and the MC modeled results shows that CdTe detector can be utilized for mapping interface dose distribution encountered in the application of ionizing radiation.PACS number(s): 29.40.Wk, 73.50.Pz, 87.53.Jw, 87.55.K‐
Simple quality assurance method of dynamic tumor tracking with the gimbaled linac system using a light field
Authors: Miura Hideharu , Ozawa Shuichi , Hayata Masahiro , Tsuda Shintaro , Yamada Kiyoshi , Nagata Yasushi 
Published: February 2017

We proposed a simple visual method for evaluating the dynamic tumor tracking (DTT) accuracy of a gimbal mechanism using a light field. A single photon beam was set with a field size of at a gantry angle of 90°. The center of a cube phantom was set up at the isocenter of a motion table, and 4D modeling was performed based on the tumor and infrared (IR) marker motion. After 4D modeling, the cube phantom was replaced with a sheet of paper, which was placed perpendicularly, and a light field was projected on the sheet of paper. The light field was recorded using a web camera in a treatment room that was as dark as possible. Calculated images from each image obtained using the camera were summed to compose a total summation image. Sinusoidal motion sequences were produced by moving the phantom with a fixed amplitude of 20 mm and different breathing periods of 2, 4, 6, and 8 s. The light field was projected on the sheet of paper under three conditions: with the moving phantom and DTT based on the motion of the phantom, with the moving phantom and non‐DTT, and with a stationary phantom for comparison. The values of tracking errors using the light field were , , , and for breathing periods of 2, 4, 6, and 8 s, respectively. The tracking accuracy showed dependence on the breathing period. We proposed a simple quality assurance (QA) process for the tracking accuracy of a gimbal mechanism system using a light field and web camera. Our method can assess the tracking accuracy using a light field without irradiation and clearly visualize distributions like film dosimetry.PACS number(s): 87.56 Fc, 87.55.Qr
Dose reduction in CT urography and vasculature phantom studies using model‐based iterative reconstruction
Authors: Page Leland , Wei Wei , Kundra Vikas , Rong X. John 
Published: February 2017

To evaluate the feasibility of radiation dose reduction using model‐based iterative reconstruction (MBIR) for evaluating the ureters and vasculature in a phantom, a tissue‐equivalent CT dose phantom was scanned using a 64‐channel CT scanner. Tubes of varying diameters filled with different dilutions of a contrast agent, simulating ureters or vessels, were inserted into the center of the phantom. Each combination was scanned using an existing renal protocol at 140 kVp or 120 kVp, yielding a display volumetric CT dose index () of 24 mGy. The scans were repeated using reduced scan techniques to achieve lower radiation doses down to 0.8 mGy. The images were reconstructed using filtered back‐projection (FBP) and model‐based iterative reconstruction (MBIR). The noise and contrast‐to‐noise ratio (CNR) was measured for each contrast object. Comparisons between the two reconstruction methods at different dose levels were evaluated using a factorial design. At each the measured image noise was lower using MBIR compared to FBP (). At low doses, the percent change in measured image noise between FBP and MBIR was larger. For the 12 mm object simulating a ureter or large vessel with an HU of 600, the measured CNR using MBIR at a of 1.7 mGy was greater than the CNR of FBP at a of 24 mGy (). For the 5 mm object simulating a medium‐sized vessel with a HU of 250, the measured CNR using MBIR at a of 1.7 mGy was equivalent to that of FBP at a of 24 mGy. For the 2 mm, 100 HU object simulating a small vessel, the measured CNR using MBIR at a of 1.7 mGy was equivalent to that of FBP at a of 24 mGy. Low‐dose (3.6 mGy) CT imaging of vasculature and ureter phantoms using MBIR results in similar noise and CNR compared to FBP at approximately one‐sixth the dose. This suggests that, using MBIR, a one milliSievert exam of the ureters and vasculature may be clinically possible whilst still maintaining adequate image qualityPACS number(s): 87.57.‐s, 87.57.Q‐, 87.57.C‐, 87.57.nf, 87.57.cj, 87.57.cm
Investigation of the optimum location of external markers for patient setup accuracy enhancement at external beam radiotherapy
Authors: Miandoab Payam Samadi , Torshabi Ahmad Esmaili , Nankali Saber 
Published: February 2017

In external beam radiotherapy, one of the most common and reliable methods for patient geometrical setup and/or predicting the tumor location is use of external markers. In this study, the main challenging issue is increasing the accuracy of patient setup by investigating external markers location. Since the location of each external marker may yield different patient setup accuracy, it is important to assess different locations of external markers using appropriate selective algorithms. To do this, two commercially available algorithms entitled a) canonical correlation analysis (CCA) and b) principal component analysis (PCA) were proposed as input selection algorithms. They work on the basis of maximum correlation coefficient and minimum variance between given datasets. The proposed input selection algorithms work in combination with an adaptive neuro‐fuzzy inference system (ANFIS) as a correlation model to give patient positioning information as output. Our proposed algorithms provide input file of ANFIS correlation model accurately. The required dataset for this study was prepared by means of a NURBS‐based 4D XCAT anthropomorphic phantom that can model the shape and structure of complex organs in human body along with motion information of dynamic organs. Moreover, a database of four real patients undergoing radiation therapy for lung cancers was utilized in this study for validation of proposed strategy. Final analyzed results demonstrate that input selection algorithms can reasonably select specific external markers from those areas of the thorax region where root mean square error (RMSE) of ANFIS model has minimum values at that given area. It is also found that the selected marker locations lie closely in those areas where surface point motion has a large amplitude and a high correlation.PACS number(s): 87.55.km, 87.55.N
Gafchromic EBT‐XD film: Dosimetry characterization in high‐dose, volumetric‐modulated arc therapy
Authors: Miura Hideharu , Ozawa Shuichi , Hosono Fumika , Sumida Naoki , Okazue Toshiya , Yamada Kiyoshi , Nagata Yasushi 
Published: February 2017

Radiochromic films are important tools for assessing complex dose distributions. Gafchromic EBT‐XD films have been designed for optimal performance in the 40–4,000 cGy dose range. We investigated the dosimetric characteristics of these films, including their dose‐response, postexposure density growth, and dependence on scanner orientation, beam energy, and dose rate with applications to high‐dose volumetric‐modulated arc therapy (VMAT) verification. A 10 MV beam from a TrueBeam STx linear accelerator was used to irradiate the films with doses in the 0–4,000 cGy range. Postexposure coloration was analyzed at postirradiation times ranging from several minutes to 48 h. The films were also irradiated with 6 MV (dose rate (DR): 600 MU/min), 6 MV flattening filter‐free (FFF) (DR: 1,400 MU/ min), and 10 MV FFF (DR: 2,400 MU/min) beams to determine the energy and dose‐rate dependence. For clinical examinations, we compared the dose distribution measured with EBT‐XD films and calculated by the planning system for four VMAT cases. The red channel of the EBT‐XD film exhibited a wider dynamic range than the green and blue channels. Scanner orientation yielded a variation of in the net optical density (OD). The difference between the film front and back scan orientations was negligible, with variation of in the net OD. The net OD increased sharply within the first 6 hrs after irradiation and gradually afterwards. No significant difference was observed for the beam energy and dose rate, with a variation of in the net OD. The gamma passing rates (at 3%, 3 mm) between the film‐ measured and treatment planning system (TPS)‐calculated dose distributions under a high dose VMAT plan in the absolute dose mode were more than 98.9%.PACS number(s): 87.56 Fc
EPID‐based dosimetry to verify IMRT planar dose distribution for the aS1200 EPID and FFF beams
Authors: Miri Narges , Keller Peter , Zwan Benjamin J. , Greer Peter 
Published: February 2017

We proposed to perform a basic dosimetry commissioning on a new imager system, the Varian aS1200 electronic portal imaging device (EPID) and TrueBeam 2.0 linear accelerator for flattened (FF) and flattening filter‐free (FFF) beams, then to develop an image‐based quality assurance (QA) model for verification of the system delivery accuracy for intensity‐modulated radiation therapy (IMRT) treatments. For dosimetry testing, linearity of dose response with MU, imager lag, and effectiveness of backscatter shielding were investigated. Then, an image‐based model was developed to convert images to planar dose onto a virtual water phantom. The model parameters were identified using energy fluence of the Acuros treatment planning system (TPS) and, reference dose profiles and output factors measured at depths of 5, 10, 15, and 20 cm in water phantom for square fields. To validate the model, its calculated dose was compared to measured dose from MapCHECK 2 diode arrays for 36 IMRT fields at 10 cm depth delivered with 6X, 6XFFF, 10X, and 10XFFF energies. An in‐house gamma function was used to compare planar doses pixel‐by‐pixel. Finally, the method was applied to the same IMRT fields to verify their pretreatment delivery dose compared with Eclipse TPS dose. For the EPID commissioning, dose linearity was within 0.4% above 5 MU and above 2 MU, measured lag was smaller than the previous EPIDs, and profile symmetry was improved. The model was validated with mean gamma pass rates (standard deviation) of 99.0% (0.4%), 99.5% (0.6%), 99.3% (0.4%), and 98.0% (0.8%) at 3%/3 mm for respectively 6X, 6XFFF, 10X, and 10XFFF beams. Using the same comparison criteria, the beam deliveries were verified with mean pass rates of 100% (0.0%), 99.6% (0.3%), 99.9% (0.1%), and 98.7% (1.4%). Improvements were observed in dosimetric response of the aS1200 imager compared to previous EPID models, and the model was successfully developed for the new system and delivery energies of 6 and 10 MV, FF, and FFF modes.PACS number(s): 87.53.Oq, 87.53.Xd