bluuebunny/crossref_metadata_2025_split huggingface dataset:
Daily image‐guided localization for neuroblastoma
Authors: Beltran Chris , Panandiker Atmaram S. Pai , Krasin Matthew J. , Merchant Thomas E. 
Published: February 2017

The purpose was to quantify the setup margin for pediatric patients with neuroblastoma using cone beam CT imaging (CBCT) and ultrasound localization. Ten patients, with a median age of 4.3 years (1.8 to 7.9) underwent daily pretreatment localization CBCT and every other day post‐treatment CBCT to calculate interfractional and intrafraction movement. Localization was based on CBCT to treatment planning CT registration in the lumbar spine region. Each subject was treated in the supine position under IV general anesthesia using intensity‐modulated radiation therapy. Patients were repositioned based on the daily pretreatment CBCT. Required setup margins based on inter‐ and intrafraction positioning errors were calculated based on weekly and daily imaging scenarios. Four patients had ultrasound localization of the kidneys performed before the CBCT. Correlation between daily CBCT and ultrasound was investigated. A lateral, longitudinal and vertical setup margin of 5.4, 5.6, and 5.9 mm is required without daily CBCT. When daily CBCT was incorporated, the setup margin was reduced to 1.5, 2.1, and 1.7 mm. There was no correlation between the suggested ultrasound shifts and the shifts based on the CBCT. Daily localization based on CBCT of the lumbar spine can reduce the required setup margin for neuroblastoma patients, thereby reducing normal tissue exposure for this young patient population. The internal margin needs further investigation before PTV reduction can be made. Ultrasound localization was highly variable and not correlated to CBCT shifts.PACS number: 87.53.Jw
Correction of motion‐induced misalignment in co‐registered PET/CT and MRI (T1/T2/FLAIR) head images for stereotactic radiosurgery
Authors: Li Guang , Xie Huchen , Ning Holly , Citrin Deborah , Kaushal Aradhana , Camphausen Kevin , Miller Robert W. 
Published: February 2017

The purpose was to evaluate and correct the co‐registration of diagnostic PET/CT and MRI/MRI images for stereotactic radiosurgery (SRS) using 3D volumetric image registration (3DVIR). The 3DVIR utilizes the homogeneity of color distribution over a volumetric anatomical landmark as the registration criterion with submillimeter accuracy. Fifty‐three PET/CT and MRI (T1, T2 and FLAIR) image sets of patients with brain lesions were acquired sequentially from a hybrid PET/CT or an MRI scanner with common diagnostic head holding devices. Twenty‐five sets of head images were scanned over a 10‐minute interval and 14 whole‐body sets were scanned over a 30‐minute interval. Fourteen sets of MRI images were acquired, and each 3‐modal image set (T1, T2 and FLAIR) was scanned in sequence at time 0, and minutes. The misalignments in these “co‐registered” images were evaluated and corrected using the 3DVIR. Using the head immobilization devices commonly found in diagnostic PET/CT and MRI/MRI imaging, 80%–100% of these “co‐registered” images were identified as misaligned. For PET/CT, the magnitude of misalignment was and for 10‐minute scans, and and for 30‐minute scans. For MRI/MRI, the magnitude was and for 5‐minute scan intervals, and and for 20‐minute intervals. Small, but significant, misalignment is present in the co‐registered diagnostic PET/CT and MRI/MRI images and can be corrected in SRS treatment planning using the volumetric image registration for improved target localization within the clinical error tolerance.PACS numbers: 87.53.Ly, 87.57.nj, 87.57.uk, 87.57.Q‐, 87.61.jc, 87.19.xcConflict of Interest Statement: The authors do not have any conflict of interest on this research report.
Systematic offset of kV and MV localization systems as a function of gantry angle
Authors: Mullins John P. , Herman Michael G. 
Published: February 2017

Mechanical flex of the gantry and mounted imaging panels leads to systematic offsets in localization image isocenter as a function of gantry angle for linear accelerator‐mounted image guidance systems. Subsequently, object positions obtained from localization radiographs may be offset, resulting in greater target positioning uncertainty. While current QA procedures measure kV/MV image agreement, these measurements do not provide insight to apparent isocenter position for either single imaging system as a function of gantry rotation. This study measures offset as a function of gantry angle in kV and MV imaging systems on four treatment machines to investigate the magnitude of systematic offsets and their reproducibility between systems and machines, as well as over time. It is shown that each machine and energy has a reproducible pattern of offset as a function of gantry angle that is independent of kV/MV agreement, and it varies by machine. kV and MV offset ranges are on the order of 1.5 mm in the R/L and A/P directions, and 0.5 mm in the S/I direction. Variability of kV‐MV agreement is on the order of 0.7 mm. At certain angles, combinations of localization images could show a compounded offset of over 2 mm, exceeding the desired certainty threshold. Since these trends are persistent over time for each machine, online correction for image offsets as a function of gantry angle could improve the margin of positioning uncertainty.PACS number: 87.55.Qr
A planning study for palliative spine treatment using StatRT and megavoltage CT simulation
Authors: Rong Yi , Yadav Poonam , Paliwal Bhudatt , Shang Lu , Welsh James S. 
Published: February 2017

Megavoltage CT (MVCT) simulation on the TomoTherapy Hi·Art system is an alternative to conventional CT for treatment planning in the presence of severe metal artifact. StatRT is a new feature that was implemented on the TomoTherapy operator station for performing online MVCT scanning, treatment planning and treatment delivery in one session. The clinical feasibility of using the StatRT technique and MVCT simulation to palliative treatment for a patient with substantial spinal metallic hardware is described. A patient with metastatic non‐small‐cell lung cancer involving the thoracic spine underwent conventional kilovoltage CT simulation. The metal artifact due to stainless steel spine‐stabilizing rods was too severe for treatment planning, despite attempts to correct using density override. The patient was then re‐scanned using MVCT on a tomotherapy unit. Plans were generated using both StatRT and conventional tomotherapy planning (Tomo plan) with different settings for comparison. StatRT planning ran a total of five iterations in a short planning window (10–15 min). Two Tomo plans were generated using: (1) five iterations in the “full scatter” mode, and (2) 300 iterations in the “beamlet” mode. It was noted that the DVH of the StatRT plan was almost identical to the Tomo plan optimized by the “full scatter” mode and the same number of iterations. Dose distribution analysis reveals that these three planning methods yielded comparable doses to heart, lungs and targets. This work also demonstrated that undermodulation can result in a high degree of thread effects. The overall time for the treatment process (including 7 minutes for simulation, 15 minutes for contouring, 10 minutes for planning and 5 minutes for delivery) decreases from hours to around 40 minutes using the StatRT procedure. StatRT is a feasible treatment‐planning tool for physicians to scan, contour and treat patients within one hour. This can be particularly beneficial in urgent palliative treatments.Conflict of Interest Statement: James S. Welsh has received honoraria for speaking for TomoTherapy, Inc.; Yi Rong has received travel sponsorship for TomoTherapy, Inc.PACS numbers: 87.55.D‐, 87.57.C‐
Dosimetric evaluation of a novel high dose rate (HDR) intraluminal / interstitial brachytherapy applicator for gastrointestinal and bladder cancers
Authors: Tabrizi Sanaz Hariri , Aghamiri Seyyed Mahmoud Reza , Najarian Siamak , Jaberi Ramin 
Published: February 2017

High dose rate (HDR) brachytherapy is one of the accepted treatment modalities in gastro‐intestinal tract and bladder carcinomas. Considering the shortcoming of contact brachytherapy routinely used in gastrointestinal tract in treatment of big tumors or invasive method of bladder treatment, an intraluminal applicator with the capability of insertion into the tumor depth seems to be useful. This study presents some dosimetric evaluations to introduce this applicator to the clinical use. The radiation attenuation characteristics of the applicator were evaluated by means of two dosimetric methods including well‐type chamber and radiochromic film. The proposed 110 cm long applicator has a flexible structure made of stainless steel for easy passage through lumens and a needle tip to drill into big tumors. The 2 mm diameter of the applicator is thick enough for source transition, while easy passage through any narrow lumen such as endoscope or cystoscope working channel is ensured. Well‐chamber results showed an acceptably low attenuation of this steel springy applicator. Performing absolute dosimetry resulted in a correlation coefficient of between standard interstitial applicator and the one proposed in this article. This study not only introduces a novel applicator with acceptable attenuation but also proves the response independency of the GAFCHROMIC EBT films to energy. By applying the dose response of the applicator in the treatment planning software, it can be used as a new intraluminal / interstitial applicator.PACS number: 87.53.Bn, 87.53.Jw, 29.40.Cs
A quality assurance method with submillimeter accuracy for stereotactic linear accelerators
Authors: Grimm Jimm , Grimm Shu‐Ya Lisa , Das Indra J. , Zhu Yunping , Yeo Inhwan , Xue Jinyu , Simpson Larry , Jacob Dayee , Sarkar Abhirup 
Published: February 2017

The Stereotactic Alignment for Linear Accelerator (S. A. Linac) system is developed to conveniently improve the alignment accuracy of a conventional linac equipped with stereotactic cones. From the Winston‐Lutz test, the SAlinac system performs three‐dimensional (3D) reconstruction of the quality assurance (QA) ball coordinates with respect to the radiation isocenter, and combines this information with digital images of the laser target to determine the absolute position of the room lasers. A handheld device provides near‐real‐time repositioning advice to enable the user to align the QA ball and room lasers to within 0.25 mm of the centroid of the radiation isocenter. The results of 37 Winston‐Lutz tests over 68 days showed that the median 3D QA ball alignment error was 0.09 mm, and 97% of the time the 3D error was . All 3D isocentric errors in the study were 0.3 mm or less. The median x and y laser alignment coordinate error was 0.09 mm, and 94% of the time the x and y laser error was . A phantom test showed that the system can make submillimeter end‐to‐end accuracy achievable, making a conventional linac a “Submillimeter Knife”.PACS numbers: 87.53.Ly, 87.55.Qr
Consistency and reproducibility of the VMAT plan delivery using three independent validation methods
Authors: Chandraraj Varatharaj , Stathakis Sotirios , Manickam Ravikumar , Esquivel Carlos , Supe Sanjay S , Papanikolaou Nikos 
Published: February 2017

The complexity of VMAT delivery requires new methods and potentially new tools for the commissioning of these systems. It appears that great consideration is needed for quality assurance (QA) of these treatments since there are limited devices that are dedicated to the QA of rotational delivery. In this present study, we have evaluated the consistency and reproducibility of one prostate and one lung VMAT plans for 31 consecutive days using three different approaches: 1) MLC DynaLog files, 2) in vivo measurements using the multiwire ionization chamber DAVID, and 3) using PTWseven29 2D ARRAY with the OCTAVIUS phantom at our Varian Clinac linear accelerator. Overall, the three methods of testing the reproducibility and consistency of the VMAT delivery were in agreement with each other. All methods showed minimal daily deviations that contributed to clinically insignificant dose variations from day to day. Based on our results, we conclude that the VMAT delivery using a Varian 2100CD linear accelerator equipped with 120 MLC is highly reproducible.PACS numbers: 87.55.Qr and 87.56.Fc
A rapid communication from the AAPM Task Group 201: Recommendations for the QA of external beam radiotherapy data transfer. AAPM TG 201: Quality assurance of external beam radiotherapy data transfer
Authors: Siochi R. Alfredo , Balter Peter , Bloch Charles D. , Santanam Lakshmi , Blodgett Kurt , Curran Bruce H. , Engelsman Martijn , Feng Wenzheng , Mechalakos Jim , Pavord Dan , Simon Tom , Sutlief Steven , Zhu X. Ronald 
Published: February 2017

The transfer of radiation therapy data among the various subsystems required for external beam treatments is subject to error. Hence, the establishment and management of a data transfer quality assurance program is strongly recommended. It should cover the QA of data transfers of patient specific treatments, imaging data, manually handled data and historical treatment records. QA of the database state (logical consistency and information integrity) is also addressed to ensure that accurate data are transferred.PACS numbers: 87.56.bd, 87.55.D, 87.55.Gh, 87.55.km, 87.55.Qr, 87.55.T
Evaluation of the dynamic conformal arc therapy in comparison to intensity‐modulated radiation therapy in prostate, brain, head‐and‐neck and spine tumors
Authors: Morales‐Paliza Manuel A. , Coffey Charles W. , Ding George X. 
Published: February 2017

To evaluate dynamic conformal arc therapy (DAT) dose distribution and clinical applicability in comparison to intensity‐modulated radiotherapy (IMRT) in different types of tumors and locations, twelve patients with prostate cancer with no node involvement and three patients with single tumors in the pituitary, in the neck and in the thoracic spinal region treated with IMRT, were retrospectively planned with DAT using Eclipse (V8.1). The prostate cases were also planned with three‐dimensional conformal radiation therapy (3DCRT). Dose distributions were evaluated through comparisons of dose‐volumetric histograms and in‐house IMRT protocol constraints, as well as validated via ion chamber array measurements. DAT plans for prostate showed a statistically comparable achievement of tumor conformity and dose sparing for bladder and rectum when compared to IMRT. Dose on femoral heads were similar to those achieved using 3DCRT. DAT could be planned with similar results to those obtained in IMRT for the dose constraints of the defined structures by using a 360° arc for the brain lesion and several arcs including noncoplanar ones for the head‐and‐neck and spinal tumors. Experimental validation of the calculated dose distributions via gamma analysis of composite distributions for DAT provided that more than 95% of the pixels satisfy the criteria 3 mm–3%, which was similar to that of IMRT. The average number of monitor units was approximately five times lower than IMRT. In conclusion, DAT is capable of providing conformal dose distributions to the targets accomplishing many of the IMRT dose constraints simultaneously. Experimental dose‐validation accuracy, ease of planning and reduced treatment times make DAT both acceptable and attractive for clinical use.PACS numbers: 87.55.D‐, 87.55.dk, 87.55.Qr, 87.56.bd, 87.56.Fc, 87.53.Kn, 87.55. de, 87.55.kd
Accuracy of relocation, evaluation of geometric uncertainties and clinical target volume (CTV) to planning target volume (PTV) margin in fractionated stereotactic radiotherapy for intracranial tumors using relocatable Gill‐Thomas‐Cosman (GTC) frame
Authors: Das Saikat , Isiah Rajesh , Rajesh B. , Ravindran B. Paul , Singh Rabi Raja , Backianathan Selvamani , Subhashini J. 
Published: February 2017

The present study is aimed at determination of accuracy of relocation of Gill‐Thomas‐Cosman frame during fractionated stereotactic radiotherapy. The study aims to quantitatively determine the magnitudes of error in anteroposterior, mediolateral and craniocaudal directions, and determine the margin between clinical target volume to planning target volume based on systematic and random errors. Daily relocation error was measured using depth helmet and measuring probe. Based on the measurements, translational displacements in anteroposterior (z), mediolateral (x), and craniocaudal (y) directions were calculated. Based on the displacements in x, y and z directions, systematic and random error were calculated and three‐dimensional radial displacement vector was determined. Systematic and random errors were used to derive CTV to PTV margin. The errors were within in 99.2% cases in anteroposterior direction (AP), in 99.6% cases in mediolateral direction (ML), and in 97.6% cases in craniocaudal direction (CC). In AP, ML and CC directions, systematic errors were 0.56, 0.38, 0.42 mm and random errors were 1.86, 1.36 and 0.73 mm, respectively. Mean radial displacement was 1.03 mm . CTV to PTV margins calculated by ICRU formula were 1.86, 1.45 and 0.93 mm; by Stroom's formula they were 2.42, 1.74 and 1.35 mm; by van Herk's formula they were 2.7, 1.93 and 1.56 mm (AP, ML and CC directions). Depth helmet with measuring probe provides a clinically viable way for assessing the relocation accuracy of GTC frame. The errors were within in all directions. Systematic and random errors were more along the anteroposterior axes. According to the ICRU formula, a margin of 2 mm around the tumor seems to be adequate.PACS number: 87.55.‐x
Dosimetric characterization of whole brain radiotherapy of pediatric patients using modulated proton beams
Authors: Jin Hosang , Hsi Wen , Yeung Daniel , Li Zuofeng , Mendenhall Nancy P. , Marcus Robert B. 
Published: February 2017

This study was designed to investigate dosimetric variations between proton plans with (PPW) and without (PPWO), a compensator for whole brain radiotherapy (WBRT). The retrospective study on PPW and PPWO in Eclipse and XiO systems and photon plans (XP) using controlled segments in Pinnacle system was performed on nine pediatric patients for craniospinal irradiations. DVHs and derived metrics, such as the homogeneity index (HI), the doses to and volumes, and mean dose of the whole brain (i.e., PTV), and the organs at risk (OARs) such as lens and skull, were obtained. The PPW plans from both Eclipse and XiO systems uncovered the following advantages: (1) encompassing a cribriform plate area with the 100% isodose line was better than either PPWO or XP, according to calculated two‐dimensional distributions of one patient; (2) the mean value of for lens was reduced to 23.6% of from 54.1% for PPWO or 41.6% for XP; and (3) the mean value of for skull was reduced to 94.8% of from either 98.4% for PPWO or 98.3% for XP. However, the PPW plans also exposed several disadvantages including: (1) the HI of PTV increased to 7.7 from 4.7 for PPWO or 3.7 for XP; (2) to PTV increased to 108.8% of from 104.8% for PPWO or 105.1% for XP; and (3) to the skull increased to 104.9% of from 101.6% for PPWO or 103.4% of for XP. One‐half of the observed variations were caused by different penumbra on lateral profiles and distal fall‐off depth doses of protons in Eclipse and XiO. Because the utilization on the sharp proton distal fall‐off was limited for WBRT, the difference between PPW and PPWO or XP indicated no distinguishable improvement by using a compensator in proton plans.PACS number: 87.55.‐x
MRI‐based polymer gel dosimetry for validating plans with multiple matrices in Gamma Knife stereotactic radiosurgery
Authors: Gopishankar N. , Watanabe Yoichi , Subbiah Vivekanandhan 
Published: February 2017

One of treatment planning techniques with Leksell GammaPlan (LGP) for Gamma Knife stereotactic radiosurgery (GKSRS) uses multiple matrices with multiple dose prescriptions. Computational complexity increases when shots are placed in multiple matrices with different grid sizes. Hence, the experimental validation of LGP calculated dose distributions is needed for those cases. For the current study, we used BANG3 polymer gel contained in a head‐sized glass bottle to simulate the entire treatment process of GKSRS. A treatment plan with three 18 mm shots and one 8 mm shot in separate matrices was created with LGP. The prescribed maximum dose was 8 Gy to three shots and 16 Gy to one of the 18 mm shots. The 3D dose distribution recorded in the gel dosimeter was read using a Siemens 3T MRI scanner. The scanning parameters of a CPMG pulse sequence with 32 equidistant echoes were as follows: s, , and . Interleaved acquisition mode was used to obtain 15 to 45 2‐mm‐thick slices. Using a calibration relationship between absorbed dose and the spin‐spin relaxation rate (R2), we converted R2 images to dose images. MATLAB‐based in‐house programs were used for R2 estimation and dose comparison. Gamma‐index analysis for the 3D data showed gamma values less than unity for 86% of the voxels. Through this study we accomplished the first application of polymer gel dosimetry for a true comparison between measured 3D dose distributions and LGP calculations for plans using multiple matrices for multiple targets.PACS number: 87.53.Ly, 87.55‐x, 87.56 ‐g
Quality assurance of electron and photon beam energy using the BQ‐Check phantom
Authors: Speight Richard J. , Esmail Ashraf , Weston Steve J. 
Published: February 2017

The BQ‐CHECK phantom (PTW Freiburg, Germany) has been designed to be used with a 2D ion chamber array to facilitate the quality assurance (QA) of electron and photon beam qualities (BQ). The BQ‐CHECK phantom has three wedges covering the diagonal axes of the beam: two opposed aluminum wedges used to measure electron energy and a single copper wedge used to measure photon energy. The purpose of this work was to assess the suitability of the BQ‐CHECK phantom for use in a routine QA program.A range of percentage depth dose (PDD) curves for two photon beams and four electron beams were measured using a MP3 plotting tank (PTW Freiburg). These beams were used to irradiate a STARCHECK array (PTW Freiburg) with and without the BQ‐CHECK phantom on top of the array. For photons, the ratio of the signals from two chambers underneath the copper wedge was used as an effective TPR measurement and, for electrons, the full width at half maximum of the profile underneath the aluminum wedges was used as an electron energy constancy measurement. PDD measurements were compared with and to assess the sensitivity of the BQ‐CHECK phantom.The clinical tolerances of were determined for 6 MV (0.634–0.649), and 10MV (0.683–0.692). For electrons, the clinical tolerances of were determined for 6 MeV (94.8–103.4 mm), 8 MeV (105.5–114.0 mm), 10 MeV (125.4–133.9 mm) and 12 MeV (138.8–147.3 mm).Electron and photon energy metrics are presented which demonstrate that the BQ‐CHECK phantom could be used to form part of an efficient routine monthly QA program. Acceptable beam quality limits for various nominal beam energies were established and at these limits, modified profiles were acquired using the STARCHECK array. From the modified profiles, and were determined for the electron and photon beams, respectively. It was demonstrated that both and the have a linear relationship with conventional beam quality metrics.PACS numbers: 87.56.bd, 87.56.‐v