bluuebunny/crossref_metadata_2025_split huggingface dataset:
SPARSE: Seed Point Auto‐Generation for Random Walks Segmentation Enhancement in medical inhomogeneous targets delineation of morphological MR and CT images
Authors: Chen Haibin , Zhen Xin , Gu Xuejun , Yan Hao , Cervino Laura , Xiao Yang , Zhou Linghong 
Published: February 2017

In medical image processing, robust segmentation of inhomogeneous targets is a challenging problem. Because of the complexity and diversity in medical images, the commonly used semiautomatic segmentation algorithms usually fail in the segmentation of inhomogeneous objects. In this study, we propose a novel algorithm imbedded with a seed point autogeneration for random walks segmentation enhancement, namely SPARSE, for better segmentation of inhomogeneous objects. With a few user‐labeled points, SPARSE is able to generate extended seed points by estimating the probability of each voxel with respect to the labels. The random walks algorithm is then applied upon the extended seed points to achieve improved segmentation result. SPARSE is implemented under the compute unified device architecture (CUDA) programming environment on graphic processing unit (GPU) hardware platform. Quantitative evaluations are performed using clinical homogeneous and inhomogeneous cases. It is found that the SPARSE can greatly decrease the sensitiveness to initial seed points in terms of location and quantity, as well as the freedom of selecting parameters in edge weighting function. The evaluation results of SPARSE also demonstrate substantial improvements in accuracy and robustness to inhomogeneous target segmentation over the original random walks algorithm.PACS number: 87.57.nm
Potential of 3D printing technologies for fabrication of electron bolus and proton compensators
Authors: Zou Wei , Fisher Ted , Zhang Miao , Kim Leonard , Chen Ting , Narra Venkat , Swann Beth , Singh Rachana , Siderit Richard , Yin Lingshu , Teo Boon‐keng Kevin , Mckenna Michael , McDonough James , Ning Yue J. 
Published: February 2017

In electron and proton radiotherapy, applications of patient‐specific electron bolus or proton compensators during radiation treatments are often necessary to accommodate patient body surface irregularities, tissue inhomogeneity, and variations in PTV depths to achieve desired dose distributions. Emerging 3D printing technologies provide alternative fabrication methods for these bolus and compensators. This study investigated the potential of utilizing 3D printing technologies for the fabrication of the electron bolus and proton compensators. Two printing technologies, fused deposition modeling (FDM) and selective laser sintering (SLS), and two printing materials, PLA and polyamide, were investigated. Samples were printed and characterized with CT scan and under electron and proton beams. In addition, a software package was developed to convert electron bolus and proton compensator designs to printable Standard Tessellation Language file format. A phantom scalp electron bolus was printed with FDM technology with PLA material. The HU of the printed electron bolus was . A prostate patient proton compensator was printed with SLS technology and polyamide material with HU. The profiles of the electron bolus and proton compensator were compared with the original designs. The average over all the CT slices of the largest Euclidean distance between the design and the fabricated bolus on each CT slice was found to be and for the compensator to be . It is recommended that the properties of specific 3D printed objects are understood before being applied to radiotherapy treatments.PACS number: 81.40
Use of 3D printers to create a patient‐specific 3D bolus for external beam therapy
Authors: Burleson Sarah , Baker Jamie , Hsia An Ting , Xu Zhigang 
Published: February 2017

The purpose of this paper is to demonstrate that an inexpensive 3D printer can be used to manufacture patient‐specific bolus for external beam therapy, and to show we can accurately model this printed bolus in our treatment planning system for accurate treatment delivery. Percent depth‐dose measurements and tissue maximum ratios were used to determine the characteristics of the printing materials, acrylonitrile butadiene styrene and polylactic acid, as bolus material with physical density of 1.04 and , and electron density of and , respectively. Dose plane comparisons using Gafchromic EBT2 film and the RANDO phantom were used to verify accurate treatment planning. We accurately modeled a printing material in Eclipse treatment planning system, assigning it a Hounsfield unit of 260. We were also able to verify accurate treatment planning using gamma analysis for dose plane comparisons. With gamma criteria of 5% dose difference and 2 mm DTA, we were able to have 86.5% points passing, and with gamma criteria of 5% dose difference and 3 mm DTA, we were able to have 95% points passing. We were able to create a patient‐specific bolus using an inexpensive 3D printer and model it in our treatment planning system for accurate treatment delivery.PACS numbers: 87.53.Jw, 87.53.Kn, 87.56.ng
Tangent field technique of TomoDirect improves dose distribution for whole‐breast irradiation
Authors: Hashimoto Harumitsu , Omura Motoko , Matsui Kengo , Mukai Yuki , Hongo Hideyuki , Yamakabe Wataru , Saito Kaori , Yoshida Miwa 
Published: February 2017

TomoDirect (TD) is an intensity‐modulated radiotherapy system that uses a fixed gantry angle instead of rotational beam delivery. Here, we investigated the effect of the multiple beam technique of TomoDirect on dose distribution compared with commonly‐used tangential beams. We included 45 consecutive patients with right breast cancer who underwent postoperative radiotherapy in our institute in the present study. Clinical target volume (CTV) was the whole right breast. The planning target volume (PTV) was created by expanding the CTV by a 0.5 cm margin. Paired TD plans were generated for each patient; a two‐beam plan using paired tangential beams and a six‐beam plan with four additional beams with modified gantry angles of from the original tangential beam set. A prescribed dose of 50 Gy was defined for 50% isodoses of the PTV. The six‐beam plan delivered significantly more homogeneous doses to the PTV than the two‐beam plan; and the mean dose to the PTV in the six‐beam plan more closely reflected the prescribed dose. and mean dose to the right lung and mean dose to the whole body were also significantly decreased in the six‐beam plan. However, duration of radiation exposure was 1 min longer in the six‐beam plan than in the two‐beam plan. The dose distribution to the target and organs at risk were improved with the six‐beam plan relative to the two‐beam plan without increasing the whole‐body radiation dose. The six‐beam plan using TD is a simple technique that can be routinely applied to whole‐breast irradiation in clinical practice.PACS number: 87.55
Evaluation of Dosimetry Check software for IMRT patient‐specific quality assurance
Authors: Narayanasamy Ganesh , Zalman Travis , Ha Chul S. , Papanikolaou Niko , Stathakis Sotirios 
Published: February 2017

The purpose of this study is to evaluate the use of the Dosimetry Check system for patient‐specific IMRT QA. Typical QA methods measure the dose in an array dosimeter surrounded by homogenous medium for which the treatment plan has been recomputed. With the Dosimetry Check system, fluence measurements acquired on a portal dosimeter is applied to the patient's CT scans. Instead of making dose comparisons in a plane, Dosimetry Check system produces isodose lines and dose‐volume histograms based on the planning CT images. By exporting the dose distribution from the treatment planning system into the Dosimetry Check system, one is able to make a direct comparison between the calculated dose and the planned dose. The versatility of the software is evaluated with respect to the two IMRT techniques — step and shoot and volumetric arc therapy. The system analyzed measurements made using EPID, PTW seven29, and IBA MatriXX, and an intercomparison study was performed. Plans from patients previously treated at our institution with treated anatomical site on brain, head & neck, liver, lung, and prostate were analyzed using Dosimetry Check system for any anatomical site dependence. We have recommendations and possible precautions that may be necessary to ensure proper QA with the Dosimetry Check system.PACS number: 87.55.Qr, 87.56.Fc
Medical Physics Practice Guideline 4.a: Development, implementation, use and maintenance of safety checklists
Authors: de los Santos E. Fong , Evans Suzanne , Ford Eric C. , Gaiser James E. , Hayden Sandra E. , Huffman Kristina E. , Johnson Jennifer L. , Mechalakos James G. , Stern Robin L. , Terezakis Stephanie , Thomadsen Bruce R. , Pronovost Peter J. , Fairobent Lynne A. 
Published: February 2017

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States.The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner.Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized.The following terms are used in the AAPM practice guidelines:

Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline.
Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances.
Implementation and evaluation of a protocol management system for automated review of CT protocols
Authors: Grimes Joshua , Leng Shuai , Zhang Yi , Vrieze Thomas , McCollough Cynthia 
Published: February 2017

Protocol review is important to decrease the risk of patient injury and increase the consistency of CT image quality. A large volume of CT protocols makes manual review labor‐intensive, error‐prone, and costly. To address these challenges, we have developed a software system for automatically managing and monitoring CT protocols on a frequent basis. This article describes our experiences in the implementation and evaluation of this protocol monitoring system. In particular, we discuss various strategies for addressing each of the steps in our protocol‐monitoring workflow, which are: maintaining an accurate set of master protocols, retrieving protocols from the scanners, comparing scanner protocols to master protocols, reviewing flagged differences between the scanner and master protocols, and updating the scanner and/or master protocols. In our initial evaluation focusing only on abdomen and pelvis protocols, we detected 309 modified protocols in a 24‐week trial period. About one‐quarter of these modified protocols were determined to contain inappropriate (i.e., erroneous) protocol parameter modifications that needed to be corrected on the scanner. The most frequently affected parameter was the series description, which was inappropriately modified 47 times. Two inappropriate modifications were made to the tube current, which is particularly important to flag as this parameter impacts both radiation dose and image quality. The CT protocol changes detected in this work provide strong motivation for the use of an automated CT protocol quality control system to ensure protocol accuracy and consistency.PACS number(s): 87.57.Q‐
Clinical implementation of the AAPM Task Group 36 recommendations on fetal dose from radiotherapy with photon beams: A head and neck irradiation case report
Authors: Prado Karl L. , Nelson Stephen J. , Nuyttens Joost J. , Williams Todd E. , Vanek Kenneth N. 
Published: February 2017

We present the results of our efforts in estimating and diminishing the fetal dose expected when a 29‐year‐old patient, 22 weeks pregnant, received external beam radiation therapy for a squamous cell carcinoma of the tongue. We explain our use of the information contained, and recommendations made, in the Report of the American Association of Physicists in Medicine Radiation Therapy Committee Task Group 36 [Med. Phys. 22, 63–82 (1995)]. We also explain our dose estimation, describe our validation measurements, and demonstrate the effectiveness of supplemental shielding. Consequently, this case report will serve as a guide to radiation oncologists and medical physicists who may encounter similar cases.PACS number(s): 87.53.–j, 87.52.–g
Beam‐commissioning methodology for a three‐dimensional convolution/superposition photon dose algorithm
Authors: Starkschall George , Steadham Roy E. , Popple Richard A. , Ahmad Salahuddin , Rosen Isaac I. 
Published: February 2017

Commissioning beam data for the convolution/superposition dose‐calculation algorithm used in a commercial three‐dimensional radiation treatment planning (3D RTP) system (, ADAC Laboratories, Milpitas, CA) can be difficult and time consuming. Sixteen adjustable parameters, as well as spectral weights representing a discrete energy spectrum, must be fit to sets of central‐axis depth doses and off‐axis profiles for a large number of field sizes. This paper presents the beam‐commissioning methodology that we used to generate accurate beam models. The methodology is relatively rapid and provides physically reasonable values for beam parameters. The methodology was initiated by using vendor‐provided automodeling software to generate a single set of beam parameters that gives an approximate fit to relative dose distributions for all beams, open and wedged, in a data set. A limited number of beam parameters were adjusted by small amounts to give accurate beam models for four open‐beam field sizes and three wedged‐beam field sizes. Beam parameters for other field sizes were interpolated and validated against measured beam data. Using this methodology, a complete set of beam parameters for a single energy can be generated and validated in approximately 40 h. The resulting parameter values yielded calculated relative doses that matched measured relative doses in a water phantom to within 0.5–1.0% along the central axis and 2% along off‐axis beam profiles for field sizes from to the largest field size available. While the methodology presented is specific to the ADAC treatment planning system, the approach should apply to other implementations of the dose model in other treatment planning system.PACS number(s): 87.53.–j, 87.66.–a
Quality Assurance of Beam Accuracy for Leksell Gamma Unit
Authors: Yu Cheng , Petrovich Zbigniew , Luxton Gary 
Published: February 2017

For the acceptance test and annual quality assurance of the Leksell Gamma Unit, measurement of the beam accuracy, defined as a distance between mechanical and radiological isocenters, poses a challenge to medical physicists. The specification for the beam accuracy is within 0.5 mm for the 4‐mm collimator helmet. In this report, we introduce a simple technique to analyze the beam accuracy by using a conventional film densitometer plus mathematical modeling. A small piece of film was placed inside the film cassette containing a sharp needle. The needle is located such that its tip is exactly positioned at the mechanical isocenter. Before exposure, the film was pierced by the needle. Density profile was measured by using a densitometer with a spatial resolution of 0.8 mm. The profile was then fitted to a model of the two Gaussian functions. One is for the radiation field profile, the other for a dip caused by the narrow hole. The difference between the centers of the two Gaussian functions defines the deviation of the beam accuracy from the mechanical center of the unit. The deviations for x, y, and z directions from one of our annual measurements are 0.032, 0.054, and 0.195 mm, respectively. The combined deviation is 0.20 mm, which is well within the specification and in excellent agreement with the results from the manufacture's laser measurement. This technique provides a simple, accurate and practical tool for measurement of the beam accuracy in the acceptance test and annual quality assurance of the Leksell Gamma Unit.PACS number(s): 87.66.–a, 87.53.–j
Protecting patients by training physicians in fluoroscopic radiation management
Authors: Archer Benjamin R. , Wagner Louis K. 
Published: February 2017

During the past 15 years, developments in x‐ray technologies have substantially enhanced the ability of practitioners to treat patients using fluoroscopically guided interventional techniques. However, many of these procedures require a greater use of fluoroscopy and serial imaging (cine). This has increased the potential for radiation‐induced dermatitis, epilation, and severe radiation‐induced burns to patients. It has also increased the potential for radiation injury and radiation‐induced cancer in personnel. This work will describe a number of the cases that have appeared in the literature and current recommendations and credentialing requirements of various organizations whose members use fluoroscopy. Finally, a program for implementing training of physicians in radiation management as a means of reducing the risk of injury to patients and personnel is recommended.PACS number(s): 87.52.–g, 87.90.+y
Measurement of the interplay effect in lung IMRT treatment using EDR2 films
Authors: Berbeco Ross I. , Pope Cynthia J. , Jiang Steve B. 
Published: February 2017

Intrafraction organ motion during the dynamic delivery of intensity‐modulated radiation therapy (IMRT) treatment of lung tumors may cause unexpected hot/cold spots within the target volume, due to the interplay effect between tumor motion and multileaf collimator (MLC) leaf motion. In the past, this has been investigated through theoretical analysis, computer simulation, and experimental measurement using an ionization chamber dosimeter. In the work presented here, the interplay effect was studied experimentally in 2D, using Kodak EDR2 films. A five‐field lung IMRT plan was delivered to a solid water phantom with embedded film. The phantom was placed on a motor‐driven platform with a sinusoidal motion to simulate the respiration‐induced tumor motion. The delivery of each field began at one of eight equally spaced initial breathing phases. The dose distribution for each treatment fraction was estimated by combining the dose distributions for all fields with randomly sampled initial breathing phases. The dose variation caused by the interplay effect was estimated by looking at the dose values from 1000 trials of 30 fractions. It was found that, on a day‐to‐day basis, the standard deviation of the dose to a given pixel in the high‐dose region could be as high as 2% to 4% due to the motion interplay effect. After 30 fractions, the standard deviation in the dose to each pixel is reduced to 0.4% to 0.7%. However, compared to the static delivery, the dose distribution from a 30‐fraction case in the presence of motion shows some underdosing in the region of interest. We found that the maximum dose in the target remains within 1% of the maximum dose in the static case, but the minimum dose in the target is most likely to be about 6% lower than the static case. Our results indicate that there can be some underdosing of the tumor due to the interplay effect in lung IMRT delivery over the entire course of a 30‐fraction treatment.PACS number: 87.53.Mr
Treatment of exceptionally large prostate cancer patients with low‐energy intensity‐modulated photons
Authors: Sun Mei , Ma Lijun 
Published: February 2017

An inverse planning technique using 6‐MV intensity‐modulated photon beams was developed for treating large‐size patients with prostate cancer. Comparisons of treatment plans using 6‐MV and 18‐MV intensity‐modulated beams were carried out for a cohort of 10 patient cases. For these cases, we analyzed the dependence of plan quality on the beam energies. We found that 6‐MV beams resulted in plans equivalent to those for 18‐MV beams both for targets and for critical structures such as the rectum and bladder. The differences between the plans in the integral dose and the mean dose to the normal tissue surrounding the target were found to be small, in contrast to those for 3D conformal plans. Our findings showed that the low entrance dose of the high‐energy photon beams is mostly compensated by the high exit dose for even exceptionally large patients. In conclusion, 6‐MV intensity‐modulated beams are a feasible choice for treating large‐size patients with prostate cancer, provided that proper inverse planning techniques are adopted.PACS number: 87.50.Gi, 87.53.Tf
Observed intercamera variability in clinically relevant performance characteristics for Siemens Symbia gamma cameras
Authors: Kappadath S. Cheenu , Erwin William D. , Wendt Richard E. 
Published: February 2017

We conducted an evaluation of the intercamera (i.e., between cameras) variability in clinically relevant performance characteristics for Symbia gamma cameras (Siemens Medical Solutions, Malvern, PA) based on measurements made using nine separate systems. The significance of the observed intercamera variability was determined by comparing it to the intracamera (i.e., within a single camera) variability. Measurements of performance characteristics were based on the standards of the National Electrical Manufacturers Association and reports 6, 9, 22, and 52 from the American Association of Physicists in Medicine. All measurements were performed using (except used for extrinsic resolution) and low‐energy, high‐resolution collimation. Of the nine cameras, four have crystals 3/8 in. thick and five have crystals 5/8 in. thick. We evaluated intrinsic energy resolution, intrinsic and extrinsic spatial resolution, intrinsic integral and differential flood uniformity over the useful field‐of‐view, count rate at 20% count loss, planar sensitivity, single‐photon emission computed tomography (SPECT) resolution, and SPECT integral uniformity. The intracamera variability was estimated by repeated measurements of the performance characteristics on a single system. The significance of the observed intercamera variability was evaluated using the two‐tailed F distribution. The planar sensitivity of the gamma cameras tested was found be variable at the 99.8% confidence level for both the 3/8‐in. and 5/8‐in. crystal systems. The integral uniformity and energy resolution were found to be variable only for the 5/8‐in. crystal systems at the 98% and 90% confidence level, respectively. All other performance characteristics tested exhibited no significant variability between camera systems. The measured variability reported here could perhaps be used to define nominal performance values of Symbia gamma cameras for planar and SPECT imaging.PACS numbers: 87.62.+n, 87.58.Pm, 87.58.Ce