Estimation of lung tumor position from multiple anatomical features on 4D-CT using multiple regression analysis.
Abstract To estimate the lung tumor position from multiple anatomical features on four-dimensional computed tomography (4D-CT) data sets using single regression analysis (SRA) and multiple regression analysis (MRA) approach and evaluate an impact of the approach on internal target volume (ITV) for stereotactic body radiotherapy (SBRT) of the lung. Eleven consecutive lung cancer patients (12 cases) underwent 4D-CT scanning. The three-dimensional (3D) lung tumor motion exceeded 5 mm. The 3D tumor position and anatomical features, including lung volume, diaphragm, abdominal wall, and chest wall positions, were measur...
Source: Journal of Applied Clinical Medical Physics - June 29, 2017 Category: Physics Authors: Ono T, Nakamura M, Hirose Y, Kitsuda K, Ono Y, Ishigaki T, Hiraoka M Tags: J Appl Clin Med Phys Source Type: research

Impacts of lung and tumor volumes on lung dosimetry for nonsmall cell lung cancer.
Abstract The purpose of this study was to determine the impacts of lung and tumor volumes on normal lung dosimetry in three-dimensional conformal radiotherapy (3DCRT), step-and-shoot intensity-modulated radiotherapy (ssIMRT), and single full-arc volumetric-modulated arc therapy (VMAT) in treatment of nonsmall cell lung cancers (NSCLC). All plans were designed to deliver a total dose of 66 Gy in 33 fractions to PTV for the 32 NSCLC patients with various total (bilateral) lung volumes, planning target volumes (PTVs), and PTV locations. The ratio of the lung volume (total lung volume excluding the PTV volume) to the ...
Source: Journal of Applied Clinical Medical Physics - June 28, 2017 Category: Physics Authors: Lei W, Jia J, Cao R, Song J, Hu L Tags: J Appl Clin Med Phys Source Type: research

Estimation of the shielding ability of a tungsten functional paper for diagnostic x-rays and gamma rays.
Abstract Tungsten functional paper (TFP) is a novel paper-based radiation-shielding material. We measured the shielding ability of TFP against x-rays and gamma rays. The TFP was supplied in 0.3-mm-thick sheets that contained 80% tungsten powder and 20% cellulose (C6 H10 O5 ) by mass. In dose measurements for x-rays (60, 80, 100, and 120 kVp), we measured doses after through 1, 2, 3, 5, 10, and 12 TFP sheets, as well as 0.3 and 0.5 mm of lead. In lead equivalence measurements, we measured doses after through 2 and 10 TFP sheets for x-rays (100 and 150 kVp), and 0, 7, 10, 20, and 30 TFP sheets for gamma rays from ce...
Source: Journal of Applied Clinical Medical Physics - June 28, 2017 Category: Physics Authors: Monzen H, Kanno I, Fujimoto T, Hiraoka M Tags: J Appl Clin Med Phys Source Type: research

Potential benefits of crawl position for prone radiation therapy in breast cancer.
CONCLUSIONS: Radiation therapy for breast and regional lymph nodes in crawl position is feasible. Good comfort and set-up precision were demonstrated. Planning results support the hypothesis that breast and regional lymph nodes can be treated in crawl position with less dose to organs at risk and equal or better dose distribution in the target volumes than in supine position. The crawl technique is a candidate methodology for further investigation for patients requiring breast and regional lymph node irradiation. PMID: 28649708 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - June 26, 2017 Category: Physics Authors: Boute B, De Neve W, Speleers B, Van Greveling A, Monten C, Van Hoof T, Van de Velde J, Paelinck L, De Gersem W, Vercauteren T, Detand J, Veldeman L Tags: J Appl Clin Med Phys Source Type: research

Comparison of DVH-based plan verification methods for VMAT: ArcCHECK-3DVH system and dynalog-based dose reconstruction.
Abstract The purpose of this study was comparing dose-volume histogram (DVH)-based plan verification methods for volumetric modulated arc therapy (VMAT) pretreatment QA. We evaluated two 3D dose reconstruction systems: ArcCHECK-3DVH system (Sun Nuclear corp.) and Varian dynalog-based dose reconstruction (DBDR) system, developed in-house. Fifteen prostate cancer patients (67.6 Gy/26 Fr), four head and neck cancer patient (66 Gy/33 Fr), and four esophagus cancer patients (60 Gy/30 Fr) treated with VMAT were studied. First, ArcCHECK measurement was performed on all plans; simultaneously, the Varian dyn...
Source: Journal of Applied Clinical Medical Physics - June 26, 2017 Category: Physics Authors: Saito M, Kadoya N, Sato K, Ito K, Dobashi S, Takeda K, Onishi H, Jingu K Tags: J Appl Clin Med Phys Source Type: research

The more IGRT systems, the merrier?
PMID: 28649749 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - June 26, 2017 Category: Physics Authors: Sun B, Chang J, Rong Y Tags: J Appl Clin Med Phys Source Type: research

Development of the breast immobilization system in prone setup: The effect of bra in prone position to improve the breast setup error.
CONCLUSION: The use of an immobilizing bra reduced the setup margin for prone position fixation of breast tumors. PMID: 28594079 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - June 8, 2017 Category: Physics Authors: Kawamura M, Maeda Y, Yamamoto K, Takamatsu S, Sato Y, Minami H, Saga Y, Kume K, Tameshige Y, Sasaki M, Tamamura H, Ohta K, Itoh Y, Naganawa S Tags: J Appl Clin Med Phys Source Type: research

Preliminary study of clinical application on IMRT three-dimensional dose verification-based EPID system.
Abstract The three-dimensional dose (3D) distribution of intensity-modulated radiation therapy (IMRT) was verified based on electronic portal imaging devices (EPIDs), and the results were analyzed. Thirty IMRT plans of different lesions were selected for 3D EPID-based dose verification. The gamma passing rates of the 3D dose verification-based EPID system (Edose, Version 3.01, Raydose, Guangdong, China) and Delta4 measurements were then compared with treatment planning system (TPS) calculations using global gamma criteria of 5%/3 mm, 3%/3 mm, and 2%/2 mm. Furthermore, the dose-volume histograms (DVHs) for planning...
Source: Journal of Applied Clinical Medical Physics - June 8, 2017 Category: Physics Authors: Huang M, Huang D, Zhang J, Chen Y, Xu B, Chen L Tags: J Appl Clin Med Phys Source Type: research

Technical Note: Monte Carlo calculations of the AAPM TG-43 brachytherapy dosimetry parameters for a new titanium-encapsulated Yb-169 source.
In this study, the original MC source model was modified to accurately match the specifications of the manufactured Yb-169 source. The modified MC model was then used to obtain a complete set of the AAPM TG-43 parameters for the new titanium-encapsulated Yb-169 source. The MC-calculated dose rate constant for this titanium-encapsulated Yb-169 source was 1.19 ± 0.03 cGy·h-1·U-1, indicating no significant change from the values reported for stainless steel-encapsulated Yb-169 sources. The source anisotropy and radial dose function for the new source were also found similar to those reported for the stain...
Source: Journal of Applied Clinical Medical Physics - June 6, 2017 Category: Physics Authors: Reynoso FJ, Munro Iii JJ, Cho SH Tags: J Appl Clin Med Phys Source Type: research

Effect of VERO pan-tilt motion on the dose distribution.
Abstract Tumor tracking is an option for intra-fractional motion management in radiotherapy. The VERO gimbal tracking system creates a unique beam geometry and understanding the effect of the gimbal motion in terms of dose distribution is important to assess the dose deviation from the reference conditions. Beam profiles, output factors (OF) and percentage depth doses (PDD) were measured and evaluated to investigate this effect. In order to find regions affected by the pan-tilt motion, synthesized 2D dose distributions were generated. An evaluation of the 2D dose distribution with the reference position was done u...
Source: Journal of Applied Clinical Medical Physics - June 6, 2017 Category: Physics Authors: Prasetio H, Yohannes I, Bert C Tags: J Appl Clin Med Phys Source Type: research

Investigation of error detection capabilities of phantom, EPID and MLC log file based IMRT QA methods.
In this study, we will compare the ability of three QA methods (Delta(4) ®, MU-EPID, Dynalog QA) to detect specific errors. Multileaf collimator (MLC) errors, gantry angle, and dose errors were introduced into five volumetric modulated arc therapy (VMAT) plans for a total of 30 plans containing errors. The original plans (without errors) were measured five times with each method to set a threshold for detectability using two standard deviations from the mean and receiver operating characteristic (ROC) derived limits. Gamma passing percentages as well as percentage error of planning target volume (PTV) were used for pas...
Source: Journal of Applied Clinical Medical Physics - June 6, 2017 Category: Physics Authors: Defoor DL, Stathakis S, Roring JE, Kirby NA, Mavroidis P, Obeidat M, Papanikolaou N Tags: J Appl Clin Med Phys Source Type: research

MR-safe personal radiation dosimeters.
Abstract Magnetic resonance imaging (MRI) is being rapidly integrated for cancer treatments-such systems are referred to as MRI-guided radiation therapy (MRIgRT). As the magnet of an MRI scanner is always on, the presence of a strong static magnetic field from the MRI scanner during radiotherapy delivery presents new challenges. One of the challenges is that a personal radiation dosimeter used to estimate the radiation dose deposited in an individual wearing the device must be MR-safe. No such devices, however, are currently available. In this work we first modified an existing personal dosimeter (by removing a me...
Source: Journal of Applied Clinical Medical Physics - June 6, 2017 Category: Physics Authors: Tchistiakova E, Kim A, Song WY, Pang G Tags: J Appl Clin Med Phys Source Type: research

Does liver resection/transplantation affect respiratory induced liver motion in patients with hepatocellular carcinoma?
Abstract The purpose of this study was to evaluate the changes in magnitude of three-dimensional (3D) liver motion after liver resection/transplantation in patients with hepatocellular carcinoma (HCC) using four-dimensional (4D)-computed tomography (CT) images. From January 2012 to April 2016, 74 HCC patients underwent 4D-CT scans under a free-breathing state to assess respiratory liver motion. Of the 74 patients, 40 did not have a liver resection/transplantation (Group A), 34 with liver resection/transplantation. 15 underwent major or minor resection in the right liver lobe (Group B), 14 underwent major or minor ...
Source: Journal of Applied Clinical Medical Physics - June 6, 2017 Category: Physics Authors: Hu Y, Zhou YK, Chen YX, Ye LX, Zeng ZC Tags: J Appl Clin Med Phys Source Type: research

Assessment of volumetric absorbed dose for mobile fluoroscopic 3D image acquisition.
Abstract Mobile fluoroscopy (c-arm) units offering 3D image reconstruction are becoming more common in surgical settings. Although these images are "CT-like" and sometimes replace the postoperative CT, the acquisition is technically very different from a traditional CT acquisition. Dose assessment is complicated by a large beam width, automatic exposure rate control, and a rotation of less than 360°. The purpose of this work was to explore the impact of these factors on the volumetric dose calculation and to provide practical recommendations for clinical physicists assessing dose from these units usi...
Source: Journal of Applied Clinical Medical Physics - June 6, 2017 Category: Physics Authors: Leon S Tags: J Appl Clin Med Phys Source Type: research

Cost-effective immobilization for whole brain radiation therapy.
Abstract To investigate the inter- and intra-fraction motion associated with the use of a low-cost tape immobilization technique as an alternative to thermoplastic immobilization masks for whole-brain treatments. The results of this study may be of interest to clinical staff with severely limited resources (e.g., in low-income countries) and also when treating patients who cannot tolerate standard immobilization masks. Setup reproducibility of eight healthy volunteers was assessed for two different immobilization techniques. (a) One strip of tape was placed across the volunteer's forehead and attached to the sides...
Source: Journal of Applied Clinical Medical Physics - June 6, 2017 Category: Physics Authors: Rubinstein AE, Ingram WS, Anderson BM, Gay SS, Fave XJ, Ger RB, McCarroll RE, Owens CA, Netherton TJ, Kisling KD, Court LE, Yang J, Li Y, Lee J, Mackin DS, Cardenas CE Tags: J Appl Clin Med Phys Source Type: research

Feasibility study of ultrasound imaging for stereotactic body radiation therapy with active breathing coordinator in pancreatic cancer.
CONCLUSIONS: Our ultrasound system can be potentially used for real-time monitoring during pancreas SBRT without compromising planning quality. The phantom study showed high monitoring accuracy of the system, and the volunteer study showed feasibility of the clinical workflow. PMID: 28574192 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - June 2, 2017 Category: Physics Authors: Su L, Iordachita I, Zhang Y, Lee J, Ng SK, Jackson J, Hooker T, Wong J, Herman JM, Sen HT, Kazanzides P, Lediju Bell MA, Yang C, Ding K Tags: J Appl Clin Med Phys Source Type: research

Comparison of the recommendations of the AAPM TG-51 and TG-51 addendum reference dosimetry protocols.
Abstract This work quantified differences between recommendations of the TG-51 and TG-51 addendum reference dosimetry protocols. Reference dosimetry was performed for flattened photon beams with nominal energies of 6, 10, 15, and 23 MV, as well as flattening-filter free (FFF) beam energies of 6 and 10 MV, following the recommendations of both the TG-51 and TG-51 addendum protocols using both a Farmer(®) ionization chamber and a scanning ionization chamber with calibration coefficients traceable to absorbed dose-to-water (Dw ) standards. Differences in Dw determined by the two protocols were 0.1%-0.3%...
Source: Journal of Applied Clinical Medical Physics - June 2, 2017 Category: Physics Authors: McCaw TJ, Hwang MS, Jang SY, Huq MS Tags: J Appl Clin Med Phys Source Type: research

Optimization of the dosimetric leaf gap for use in planning VMAT treatments of spine SABR cases.
This study therefore investigated the use of radiochromic film measurements to optimize the DLG specifically for the purpose of producing accurate VMAT plans using a flattening-filter-free (FFF) beam, for use in treating vertebral targets using a stereotactic (SABR, also known as SBRT) fractionation schedule. Four test treatments were planned using a VMAT technique, to deliver a prescription of 24 Gy in 3 fractions to four different spine SABR treatment sites. Measurements of the doses delivered by these treatments were acquired using an ionization chamber and radiographic film. These measurements were compared with t...
Source: Journal of Applied Clinical Medical Physics - June 2, 2017 Category: Physics Authors: Middlebrook ND, Sutherland B, Kairn T Tags: J Appl Clin Med Phys Source Type: research

Validation of a method for in  vivo 3D dose reconstruction in SBRT using a new transmission detector.
In this study, we evaluated the method for in vivo 3D dose reconstruction for SBRT using this new transmission detector. We confirmed the accuracy of COMPASS with Dolphin for SBRT using multi leaf collimator (MLC) test patterns and clinical SBRT cases. We compared the results between the COMPASS, the treatment planning system, the Kodak EDR2 film, and the Monte Carlo (MC) calculations. MLC test patterns were set up to investigate various aspects of dose reconstruction for SBRT: (a) simple open fields (2 × 2-10 × 10 cm(2) ), (b) a square wave chart pattern, and (c) the MLC position ...
Source: Journal of Applied Clinical Medical Physics - June 2, 2017 Category: Physics Authors: Nakaguchi Y, Ono T, Maruyama M, Shimohigashi Y, Kai Y Tags: J Appl Clin Med Phys Source Type: research

AAPM Medical Physics Practice Guideline 8.a.: Linear accelerator performance tests.
CONCLUSION: This guideline will assist the QMP in developing a comprehensive QA program for linacs in the external beam radiation therapy setting. The committee sought to prioritize tests by their implication on quality and patient safety. The QMP is ultimately responsible for implementing appropriate tests. In the spirit of the report from American Association of Physicists in Medicine Task Group 100, individual institutions are encouraged to analyze the risks involved in their own clinical practice and determine which performance tests are relevant in their own radiotherapy clinics. PMID: 28548315 [PubMed - as suppl...
Source: Journal of Applied Clinical Medical Physics - May 26, 2017 Category: Physics Authors: Smith K, Balter P, Duhon J, White GA, Vassy DL, Miller RA, Serago CF, Fairobent LA Tags: J Appl Clin Med Phys Source Type: research

Practical considerations of linear accelerator-based frameless extracranial radiosurgery for treatment of occipital neuralgia for nonsurgical candidates.
Abstract Occipital neuralgia generally responds to medical or invasive procedures. Repeated invasive procedures generate increasing complications and are often contraindicated. Stereotactic radiosurgery (SRS) has not been reported as a treatment option largely due to the extracranial nature of the target as opposed to the similar, more established trigeminal neuralgia. A dedicated phantom study was conducted to determine the optimum imaging studies, fusion matrices, and treatment planning parameters to target the C2 dorsal root ganglion which forms the occipital nerve. The conditions created from the phantom were ...
Source: Journal of Applied Clinical Medical Physics - May 18, 2017 Category: Physics Authors: Denton TR, Shields LBE, Howe JN, Shanks TS, Spalding AC Tags: J Appl Clin Med Phys Source Type: research

A quantitative method to the analysis of MLC leaf position and speed based on EPID and EBT3 film for dynamic IMRT treatment with different types of MLC.
Abstract A quantitative method based on the electronic portal imaging system (EPID) and film was developed for MLC position and speed testing; this method was used for three MLC types (Millennium, MLCi, and Agility MLC). To determine the leaf position, a picket fence designed by the dynamic (DMLC) model was used. The full-width half-maximum (FWHM) values of each gap measured by EPID and EBT3 were converted to the gap width using the FWHM versus nominal gap width relationship. The algorithm developed for the picket fence analysis was able to quantify the gap width, the distance between gaps, and each individual lea...
Source: Journal of Applied Clinical Medical Physics - May 18, 2017 Category: Physics Authors: Li Y, Chen L, Zhu J, Wang B, Liu X Tags: J Appl Clin Med Phys Source Type: research

Implementation of absolute quantification in small-animal SPECT imaging: Phantom and animal studies.
CONCLUSION: The results indicate that the proposed attenuation correction algorithm based on the first-order Chang's method, as implemented in our dedicated small-animal SPECT system, significantly improves accuracy of the quantitative analysis as well as the absolute quantification. PMID: 28508491 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - May 16, 2017 Category: Physics Authors: Gerdekoohi SK, Vosoughi N, Tanha K, Assadi M, Ghafarian P, Rahmim A, Ay MR Tags: J Appl Clin Med Phys Source Type: research

Evaluation of initial setup errors of two immobilization devices for lung stereotactic body radiation therapy (SBRT).
as IJ Abstract The aim of this study was to investigate the accuracy and efficacy of two commonly used commercial immobilization systems for stereotactic body radiation therapy (SBRT) in lung cancer. This retrospective study assessed the efficacy and setup accuracy of two immobilization systems: the Elekta Body Frame (EBF) and the Civco Body Pro-Lok (CBP) in 80 patients evenly divided for each system. A cone beam CT (CBCT) was used before each treatment fraction for setup correction in both devices. Analyzed shifts were applied for setup correction and CBCT was repeated. If a large shift (>5 mm) occurred in any...
Source: Journal of Applied Clinical Medical Physics - May 14, 2017 Category: Physics Authors: Ueda Y, Teshima T, Cárdenes H, Das IJ Tags: J Appl Clin Med Phys Source Type: research

Exploratory study of the association of volumetric modulated arc therapy (VMAT) plan robustness with local failure in head and neck cancer.
Abstract This work is to show which is more relevant to cause local failures (LFs) due to patient setup uncertainty between the planning target volume (PTV) underdosage and the potential target underdosage subject to patient setup uncertainties in head and neck (H&N) cancer treated with volumetric-modulated arc therapy (VMAT). Thirteen LFs in 10 H&N patients treated by VMAT were analyzed. Measures have been taken to minimize the chances of insufficient target delineation for these patients and the patients were clinically determined to have LF based on the PET/CT scan results by an experienced radiologist ...
Source: Journal of Applied Clinical Medical Physics - May 14, 2017 Category: Physics Authors: Liu W, Patel SH, Harrington DP, Hu Y, Ding X, Shen J, Halyard MY, Schild SE, Wong WW, Ezzell GE, Bues M Tags: J Appl Clin Med Phys Source Type: research

Optimization of a novel large field of view distortion phantom for MR-only treatment planning.
CONCLUSION: The design and implementation of a modular, extendable distortion phantom was optimized for several bore configurations. The phantom and analysis software will be available for multi-institutional collaborations and cross-validation trials to support MR-only planning. PMID: 28497476 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - May 12, 2017 Category: Physics Authors: Price RG, Knight RA, Hwang KP, Bayram E, Nejad-Davarani SP, Glide-Hurst CK Tags: J Appl Clin Med Phys Source Type: research

AAPM medical physics practice guideline 6.a.: Performance characteristics of radiation dose index monitoring systems.
Abstract 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 r...
Source: Journal of Applied Clinical Medical Physics - May 12, 2017 Category: Physics Authors: Gress DA, Dickinson RL, Erwin WD, Jordan DW, Kobistek RJ, Stevens DM, Supanich MP, Wang J, Fairobent LA Tags: J Appl Clin Med Phys Source Type: research

Patient specific methods for room-mounted x-ray imagers for monoscopic/stereoscopic prostate motion monitoring.
CONCLUSIONS: This is the first demonstration of toggled monoscopic/stereoscopic localization using room-mounted dual x-ray imagers, enabling continuous intrafraction motion monitoring for these systems. We showed that both pretreatment individualization and intrafraction updating should be used to provide the most accurate motion monitoring. PMID: 28470816 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - May 4, 2017 Category: Physics Authors: Stevens MTR, Parsons DD, Robar JL Tags: J Appl Clin Med Phys Source Type: research

Tuning of AcurosXB source size setting for small intracranial targets.
This study details a method to evaluate the source size selection for small field intracranial stereotactic radiosurgery (SRS) deliveries in Eclipse treatment planning system (TPS) for AcurosXB dose calculation algorithm. Our method uses end-to-end dosimetric data to evaluate a total of five source size selections (0.50 mm, 0.75 mm, 1.00 mm, 1.25 mm, and 1.50 mm). The dosimetric leaf gap (DLG) was varied in this analysis (three DLG values were tested for each scenario). We also tested two MLC leaf designs (standard and high-definition MLC) and two delivery types for intracranial SRS (volumetric modulated arc therapy [VMAT]...
Source: Journal of Applied Clinical Medical Physics - May 4, 2017 Category: Physics Authors: Gardner SJ, Lu S, Liu C, Wen N, Chetty IJ Tags: J Appl Clin Med Phys Source Type: research

MRI scanner-independent specific absorption rate measurements using diffusion coefficients.
CONCLUSION: The scanner-independent SAR measurements using diffusion coefficients described in this study can play a significant role in estimating accurate SAR values as a standardized method. PMID: 28470956 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - May 4, 2017 Category: Physics Authors: Seo Y, Wang ZJ Tags: J Appl Clin Med Phys Source Type: research

The geographic penetration of the JACMP and the benefits of AAPM membership for clinical medical physicists worldwide.
PMID: 28464490 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - May 2, 2017 Category: Physics Authors: Mills MD Tags: J Appl Clin Med Phys Source Type: research

Long-term dosimetric stability of multiple TomoTherapy delivery systems.
Abstract The dosimetric stability of six TomoTherapy units was analyzed to investigate changes in performance over time and with system upgrades. Energy and output were tracked using monitor chamber signal, onboard megavoltage computed tomography (MVCT) detector profile, and external ion chamber measurements. The systems (and monitoring periods) include three Hi-Art (67, 61, and 65 mos.), two TomoHDA (31 and 26 mos.), and one Radixact unit (11 mos.), representing approximately 10 years of clinical use. The four newest systems use the Dose Control Stability (DCS) system and Fixed Target Linear Accelerator (linac) (...
Source: Journal of Applied Clinical Medical Physics - May 2, 2017 Category: Physics Authors: Smilowitz JB, Dunkerley D, Hill PM, Yadav P, Geurts MW Tags: J Appl Clin Med Phys Source Type: research

Analysis of modulation factor to shorten the delivery time in helical tomotherapy.
Abstract A low modulation factor (MF) maintaining a good dose distribution contributes to the shortening of the delivery time and efficiency of the treatment plan in helical tomotherapy. The purpose of this study was to reduce the delivery time using initial values and the upper limit values of MF. First, patients with head and neck cancer (293 cases) or prostate cancer (181 cases) treated between June 2011 and July 2015 were included in the analysis of MF values. The initial MF value (MFinitial ) was defined as the average MFactual value, and the upper limit of the MF value (MFUL ) was defined according the follo...
Source: Journal of Applied Clinical Medical Physics - April 26, 2017 Category: Physics Authors: Shimizu H, Sasaki K, Tachibana H, Tomita N, Makita C, Nakashima K, Yokoi K, Kubota T, Yoshimoto M, Iwata T, Kodaira T Tags: J Appl Clin Med Phys Source Type: research

TOPAS Simulation of the Mevion S250 compact proton therapy unit.
This study shows that Monte Carlo simulation studies involving the Mevion S250 proton therapy unit can be a viable tool in commissioning and verification of the proton treatment planning system. PMID: 28444840 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 26, 2017 Category: Physics Authors: Prusator M, Ahmad S, Chen Y Tags: J Appl Clin Med Phys Source Type: research

Dosimetric validation of a magnetic resonance image gated radiotherapy system using a motion phantom and radiochromic film.
CONCLUSIONS: Our results suggest that the device can be used to compensate respiratory motion using a 3 mm gating margin and 10% allowed excursion results in conjunction with repeated breath holds. Full clinical validation requires a comprehensive evaluation of tracking performance in actual patient images, outside the scope of this study. PMID: 28436094 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 24, 2017 Category: Physics Authors: Lamb JM, Ginn JS, O'Connell DP, Agazaryan N, Cao M, Thomas DH, Yang Y, Lazea M, Lee P, Low DA Tags: J Appl Clin Med Phys Source Type: research

A complete 4DCT-ventilation functional avoidance virtual trial: Developing strategies for prospective clinical trials.
CONCLUSIONS: Our work demonstrated that 60-70% of stage III patients would be eligible for functional planning and that a typical functional lung mean dose reduction of 2.8 Gy can be expected relative to standard clinical plans. These findings provide salient data for the development of functional clinical trials. PMID: 28436107 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 24, 2017 Category: Physics Authors: Waxweiler T, Schubert L, Diot Q, Faught A, Stuhr K, Castillo R, Castillo E, Guerrero T, Rusthoven C, Gaspar L, Kavanagh B, Miften M, Vinogradskiy Y Tags: J Appl Clin Med Phys Source Type: research

Measurement of skin surface dose distributions in radiation therapy using poly(vinyl alcohol) cryogel dosimeters.
This study demonstrates the suitability of radiochromic cryogels for superficial dose measurements in megavoltage photon beams. PMID: 28436134 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 24, 2017 Category: Physics Authors: Eyadeh MM, Wierzbicki M, Diamond KR Tags: J Appl Clin Med Phys Source Type: research

The Mobius AIRO mobile CT for image-guided proton therapy: Characterization & commissioning.
CONCLUSIONS: The localization accuracy of AIRO was determined to be within 0.6° and 0.5 mm despite its slightly lower image quality overall compared to other CT imaging systems at our institution. Based on our study, the Mobile AIRO CT system can be utilized accurately and reliably for image-guided proton therapy. PMID: 28436155 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 24, 2017 Category: Physics Authors: Oliver JA, Zeidan OA, Meeks SL, Shah AP, Pukala J, Kelly P, Ramakrishna NR, Willoughby TR Tags: J Appl Clin Med Phys Source Type: research

Comparison of multi-institutional Varian ProBeam pencil beam scanning proton beam commissioning data.
CONCLUSION: Beam data for the two sites and between different gantry rooms were well matched. PMID: 28422381 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Authors: Langner UW, Eley JG, Dong L, Langen K Tags: J Appl Clin Med Phys Source Type: research

A novel radiation protection device based on tungsten functional paper for application in interventional radiology.
Abstract Tungsten functional paper (TFP), which contains 80% tungsten by weight, has radiation-shielding properties. We investigated the use of TFP for the protection of operators during interventional or therapeutic angiography. The air kerma rate of scattered radiation from a simulated patient was measured, with and without TFP, using a water-equivalent phantom and fixed C-arm fluoroscopy. Measurements were taken at the level of the operator's eye, chest, waist, and knee, with a variable number of TFP sheets used for shielding. A Monte Carlo simulation was also utilized to analyze the dose rate delivered with an...
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Authors: Monzen H, Tamura M, Shimomura K, Onishi Y, Nakayama S, Fujimoto T, Matsumoto K, Hanaoka K, Kamomae T Tags: J Appl Clin Med Phys Source Type: research

MLC-based penumbra softener of EDW borders to reduce junction inhomogeneities.
Abstract Junctions of fields are known to be susceptible to developing cold or hot spots in the presence of even small geometrical misalignments. Reduction of these dose inhomogeneities can be accomplished through decreasing the dose gradients in the penumbra, but currently it cannot be done for enhanced dynamic wedges (EDW). An MLC-based penumbra softener was developed in the developer mode of TrueBeam linacs to reduce dose gradients across the side border of EDWs. The movement of each leaf was individually synchronized with the movement of the dynamic Y jaw to soften the penumbra in the same manner along the ent...
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Authors: Szpala S, Kohli K Tags: J Appl Clin Med Phys Source Type: research

Comparability of three output prediction models for a compact passively double-scattered proton therapy system.
Abstract The purpose of this study was to investigate comparability of three output prediction models for a compact double-scattered proton therapy system. Two published output prediction models are commissioned for our Mevion S250 proton therapy system. Model A is a correction-based model (Sahoo et al., Med Phys, 2008;35(11):5088-5097) and model B is an analytical model which employs a function of r = (R'-M')/M' (Kooy et al., Phys Med Biol, 2005;50:5487-5456) where R' is defined as depth of distal 100% dose with straggling and M' is the width between distal 100% dose and proximal 100% dose wit...
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Authors: Ferguson S, Chen Y, Ferreira C, Islam M, Keeling VP, Lau A, Ahmad S, Jin H Tags: J Appl Clin Med Phys Source Type: research

AAPM Spring Clinical Meeting - Program 2017 AAPM Spring Clinical Meeting March 18 - 21, 2017 New Orleans, LA.
Authors: PMID: 28422414 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Tags: J Appl Clin Med Phys Source Type: research

Results of a 10-year survey of workload for 10 treatment vaults at a high-throughput comprehensive cancer center.
In this study, we report on the workload for 10 treatment vaults in terms of dose to isocenter (cGy), monitor units delivered (MUs), number of treatment sessions (Txs), as well as, use factors (U) and modulation factors (CI) for different treatment techniques. The survey was performed for the years between 2006 and 2015 and included 16 treatment machines which represent different generations of Varian linear accelerators (6EX, 600C, 2100C, 2100EX, and TrueBeam) operating at different electron and x-ray energies (6, 9, 12, 16 and 20 MeV electrons and, 6 and 15 MV x-rays). An institutional review board (IRB) approval was acq...
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Authors: Saleh ZH, Jeong J, Quinn B, Mechalakos J, St Germain J, Dauer LT Tags: J Appl Clin Med Phys Source Type: research

AAPM Spring Clinical Meeting - Abstract SATURDAY, MARCH 18.
Authors: PMID: 28422430 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 19, 2017 Category: Physics Tags: J Appl Clin Med Phys Source Type: research

Evaluation of the truebeam machine performance check (MPC): mechanical and collimation checks.
Abstract Machine performance check (MPC) is an automated and integrated image-based tool for verification of beam and geometric performance of the TrueBeam linac. The aims of the study were to evaluate the performance of the MPC geometric tests relevant to beam collimation (MLC and jaws) and mechanical systems (gantry and collimator). Evaluation was performed by comparing MPC to QA tests performed routinely in the department over a 4-month period. The MPC MLC tests were compared to an in-house analysis of the Picket Fence test. The jaw positions were compared against an in-house EPID-based method, against the trad...
Source: Journal of Applied Clinical Medical Physics - April 17, 2017 Category: Physics Authors: Barnes MP, Greer PB Tags: J Appl Clin Med Phys Source Type: research

Evaluation of stability of stereotactic space defined by cone-beam CT for the Leksell Gamma Knife Icon.
In this study, we used an in-house built marker tool to evaluate the stability of the CBCT-based stereotactic space and its agreement with the standard frame-based stereotactic space. We imaged the tool with a CT indicator box using our CT-simulator at the beginning, middle, and end of the study period (6 weeks) for determining the frame-based stereotactic space. The tool was also scanned with the Icon's CBCT on a daily basis throughout the study period, and the CBCT images were used for determining the CBCT-based stereotactic space. The coordinates of each marker were determined in each CT and CBCT scan using the Leksell ...
Source: Journal of Applied Clinical Medical Physics - April 17, 2017 Category: Physics Authors: AlDahlawi I, Prasad D, Podgorsak MB Tags: J Appl Clin Med Phys Source Type: research

Dosimetric impacts of endorectal balloon in CyberKnife stereotactic body radiation therapy (SBRT) for early-stage prostate cancer.
CONCLUSIONS: Significant reductions of dose to the rectum using ERB were observed. This may lead to improvement of the rectal toxicity profiles in prostate SBRT. PMID: 28407345 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 13, 2017 Category: Physics Authors: Xiang HF, Lu HM, Efstathiou JA, Zietman AL, Armas R, Harris K, Bloch BN, Qureshi MM, Keohan S, Hirsch AE Tags: J Appl Clin Med Phys Source Type: research

Insight gained from responses to surveys on reference dosimetry practices.
CONCLUSIONS: The results of these surveys offer insight on clinical reference dosimetry practices and will be useful in identifying current and future needs for reference dosimetry. PMID: 28397396 [PubMed - as supplied by publisher] (Source: Journal of Applied Clinical Medical Physics)
Source: Journal of Applied Clinical Medical Physics - April 11, 2017 Category: Physics Authors: Muir B, Culberson W, Davis S, Kim GY, Huang Y, Lee SW, Lowenstein J, Sarfehnia A, Siebers J, Tolani N Tags: J Appl Clin Med Phys Source Type: research

Development of a novel low-radiation-absorbent lok-bar to reduce X-ray scattering and absorption in RapidArc( ®) treatment planning and dose delivery.
Development of a novel low-radiation-absorbent lok-bar to reduce X-ray scattering and absorption in RapidArc(®) treatment planning and dose delivery. J Appl Clin Med Phys. 2017 Apr 06;: Authors: Monzen H, Kubo K, Tamura M, Hayakawa M, Nishimura Y Abstract We developed a novel low-radiation-absorbent lok-bar (HM-bar) that is used to secure the immobilizers to the couch. The aim of this study was to investigate the X-ray scattering and absorption properties of the HM-bar in computed tomography (CT) simulation and radiotherapy dose delivery using the Varian Exact™ lok-bar (VL-bar) as a benchmar...
Source: Journal of Applied Clinical Medical Physics - April 6, 2017 Category: Physics Authors: Monzen H, Kubo K, Tamura M, Hayakawa M, Nishimura Y Tags: J Appl Clin Med Phys Source Type: research