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Journal of Applied Clinical Medical Physics

Nadya Shusharina, Barbara Fullerton, Judy A Adams, Gregory C Sharp, Annie W Chan
This study determines the impact of change in aeration in sinonasal cavities on the robustness of passive-scattering proton therapy plans in patients with sinonasal and nasopharyngeal malignancies. Fourteen patients, each with one planning CT and one CT acquired during radiotherapy were studied. Repeat and planning CTs were rigidly aligned and contours were transferred using deformable registration. The amount of air, tumor, and fluid within the cavity containing the tumor were measured on both CTs. The original plans were recalculated on the repeat CT...
February 12, 2019: Journal of Applied Clinical Medical Physics
Angela U Pathmanathan, Maria A Schmidt, Douglas H Brand, Evanthia Kousi, Nicholas J van As, Alison C Tree
BACKGROUND AND PURPOSE: Intraprostatic fiducial markers (FM) improve the accuracy of radiotherapy (RT) delivery. Here we assess geometric integrity and contouring consistency using a T2*-weighted (T2*W) sequence alone, which allows visualization of the FM. MATERIAL AND METHODS: Ten patients scanned within the Prostate Advances in Comparative Evidence (PACE) trial (NCT01584258) had prostate images acquired with computed tomography (CT) and Magnetic Resonance (MR) Imaging: T2-weighted (T2W) and T2*W sequences...
February 12, 2019: Journal of Applied Clinical Medical Physics
Steve Braunstein, Li Wang, Wayne Newhauser, Todd Tenenholz, Yi Rong, Albert van der Kogel, Michael Dominello, Michael C Joiner, Jay Burmeister
No abstract text is available yet for this article.
February 8, 2019: Journal of Applied Clinical Medical Physics
Andrew L Fielding, Jessica Benitez Mendieta, Sarah Maxwell, Catherine Jones
There is an increasing need to develop methods for in vivo verification of the delivery of radiotherapy treatments. Electronic portal imaging devices (EPID's) have been demonstrated to be of use for this application. The basic principle is relatively straightforward, the EPID is used to measure a two-dimensional (2D) planar exit or portal dose map behind the patient during the treatment delivery that can provide information on any errors in linear accelerator output or changes in the patient anatomy. In this paper we focused on the effect of intra-fraction motion, particularly respiratory motion, on the measured 2D EPID dose-response...
February 5, 2019: Journal of Applied Clinical Medical Physics
Yuki Kasai, Yukihide Fukuyama, Hiromi Terashima, Katsumasa Nakamura, Tomonari Sasaki
TomoDirect has been reported to have some advantages over TomoHelical in delivering total body irradiation (TBI). This study aimed to investigate the relationships between the number of ports and the dose evaluation indices in low-dose TBI in TomoDirect mode using 2-12 ports and to compare these data with those for the TomoHelical mode in a simulation study. Thirteen patients underwent low-dose TBI in TomoHelical mode from June 2015 to June 2016. We used the same computed tomography data sets for these patients to create new treatment plans for upper-body parts using TomoDirect mode with 2-12 beam angles as well as TomoHelical mode...
February 5, 2019: Journal of Applied Clinical Medical Physics
Carina Jensen, Jesper Carl, Lars Boesen, Niels Christian Langkilde, Lasse Riis Østergaard
PURPOSE: To automatically assess the aggressiveness of prostate cancer (PCa) lesions using zonal-specific image features extracted from diffusion weighted imaging (DWI) and T2W MRI. METHODS: Region of interest was extracted from DWI (peripheral zone) and T2W MRI (transitional zone and anterior fibromuscular stroma) around the center of 112 PCa lesions from 99 patients. Image histogram and texture features, 38 in total, were used together with a k-nearest neighbor classifier to classify lesions into their respective prognostic Grade Group (GG) (proposed by the International Society of Urological Pathology 2014 consensus conference)...
February 3, 2019: Journal of Applied Clinical Medical Physics
Silu Han, Fang-Fang Yin, Jing Cai
PURPOSE: MRI-based treatment planning is a promising technique for liver stereotactic-body radiation therapy (SBRT) treatment planning to improve target volume delineation and reduce radiation dose to normal tissues. MR geometric distortion, however, is a source of potential error in MRI-based treatment planning. The aim of this study is to investigate dosimetric uncertainties caused by MRI geometric distortion in MRI-based treatment planning for liver SBRT. MATERIALS AND METHODS: The study was conducted using computer simulations...
January 29, 2019: Journal of Applied Clinical Medical Physics
Tonghe Wang, Beth Bradshaw Ghavidel, Jonathan J Beitler, Xiangyang Tang, Yang Lei, Walter J Curran, Tian Liu, Xiaofeng Yang
PURPOSE: Dual-energy computed tomography (DECT) using TwinBeam CT (TBCT) is a new option for radiation oncology simulators. TBCT scanning provides virtual monoenergetic images which are attractive in treatment planning since lower energies offer better contrast for soft tissues, and higher energies reduce noise. A protocol is needed to achieve optimal performance of this feature. In this study, we investigated the TBCT scan schema with the head-and-neck radiotherapy workflow at our clinic and selected the optimal energy with best contrast-noise-ratio (CNR) in organs-at-risks (OARs) delineation for head-and-neck treatment planning...
January 28, 2019: Journal of Applied Clinical Medical Physics
Todd Pawlicki, Arno J Mundt
No abstract text is available yet for this article.
January 24, 2019: Journal of Applied Clinical Medical Physics
Noor Mail, Suliman M Al-Ghamdi, Carelse Chantel, Farid Sedhu, Atique Rana, Abdelhamid Saoudi
Malignancies with a superficial involvement of the scalp/skull present technical challenges for radiation-treatment-planning, such as achieving skin coverage with the prescribed dose and with the desirable conformity, homogeneity, and lower brain dose. We report a radiotherapy treatment technique for a patient diagnosed with diffuse basosquamous cell carcinoma of the scalp and adjacent skull-bone. This study presents the plan's quality parameters, patient's dosimetry, and patient's outcome. The patient was treated using volume-modulated-arc therapy (VMAT) and a double-shell-bolus full-head device (DSBFD) designed for patient immobilization and better skin coverage...
January 24, 2019: Journal of Applied Clinical Medical Physics
Rami Nachabe, Keith Strauss, Beth Schueler, Mohamad Bydon
Careful protocol selection is required during intraoperative three-dimensional (3D) imaging for spine surgery to manage patient radiation dose and achieve clinical image quality. Radiation dose and image quality of a Medtronic O-arm commonly used during spine surgery, and a Philips hybrid operating room equipped with XperCT C-arm 3D cone-beam CT (hCBCT) are compared. The mobile O-arm (mCBCT) offers three different radiation dose settings (low, standard, and high), for four different patient sizes (small, medium, large, and extra large)...
January 24, 2019: Journal of Applied Clinical Medical Physics
Keisuke Yasui, Toshiyuki Toshito, Chihiro Omachi, Kensuke Hayashi, Hideto Kinou, Masaki Katsurada, Naoki Hayashi, Hiroyuki Ogino
The purpose of this study was to propose a verification method and results of intensity-modulated proton therapy (IMPT), using a commercially available heterogeneous phantom. We used a simple simulated head and neck and prostate phantom. An ionization chamber and radiochromic film were used for measurements of absolute dose and relative dose distribution. The measured doses were compared with calculated doses using a treatment planning system. We defined the uncertainty of the measurement point of the ionization chamber due to the effective point of the chamber and mechanical setup error as 2 mm and estimated the dose variation base on a 2 mm error...
January 23, 2019: Journal of Applied Clinical Medical Physics
Hyun Joon Choi, Hyojun Park, Wook-Geun Shin, Jung-In Kim, Chul Hee Min
Despite the improvements in the dose calculation models of the commercial treatment planning systems (TPS), their ability to accurately predict patient dose is still limited. One of the limitations is caused by the simplified model of the multileaf collimator (MLC). The aim of this study was to develop a Monte Carlo (MC) method-based independent patient dose validation system with an elaborate MLC model for more accurate dose evaluation. Varian Clinac 2300 IX was simulated using Geant4 toolkits, after which MC commissioning with measurements was performed to validate the simulation model...
January 23, 2019: Journal of Applied Clinical Medical Physics
Minsik Lee, KyoungJun Yoon, Byungchul Cho, Su Ssan Kim, Si Yeol Song, Eun Kyung Choi, SeungDo Ahn, Sang-Wook Lee, JungWon Kwak
PURPOSE: To compare the dosimetric impact and treatment delivery efficacy of phase-gated volumetric modulated arc therapy (VMAT) vs amplitude-gated VMAT for stereotactic body radiation therapy (SBRT) for lung cancer by using realistic three-dimensional-printed phantoms. METHODS: Four patient-specific moving lung phantoms that closely simulate the heterogeneity of lung tissue and breathing patterns were fabricated with four planning computed tomography (CT) images for lung SBRT cases...
January 22, 2019: Journal of Applied Clinical Medical Physics
Jonathan Bogue, Jui Wan, Robert S Lavey, E Ishmael Parsai
Volumetric modulated arc therapy (VMAT) has been implemented for left breast irradiation to reduce prescription dose to the heart and improve dose homogeneity across the targeted breast. Our in-house method requires application of a bolus during the optimization process with a target outside of the body, then removing the bolus during the final calculation in order to incorporate skin flash in VMAT plans. To quantify the dosimetric trade-offs between traditional 3D field-in-field tangents and VMAT with integrated skin flash for these patients, we compared nine consecutive patients who recently received radiation to their entire left breast but not their regional lymphatics...
January 17, 2019: Journal of Applied Clinical Medical Physics
Bradley J Beattie
OBJECTIVES: The phantom filling procedures currently specified by the American College of Radiology (ACR) for its PET accreditation program unnecessarily limit how tight the tolerances can be made on the accuracy requirements for the concentrations measured in the resultant images. METHODS: New procedures are proposed to improve the accuracy and consistency of the concentrations within the phantom at the time of imaging. These improvements are gained by exchanging the difficult process of accurately measuring a dose with the more easily achieved accurate measurements of time and liquid volume to control final radioactivity concentrations...
January 16, 2019: Journal of Applied Clinical Medical Physics
Akira Nakamura, Hugh A Prichard, Jennifer Y Wo, John A Wolfgang, Theodore S Hong
PURPOSE: We evaluate the feasibility of the elective nodal irradiation strategy in stereotactic body radiotherapy (SBRT) for pancreatic cancer. METHODS: Three simultaneous integrated boost (SIB)-SBRT plans (Boost1, Boost2, and Boost3) were retrospectively generated for each of 20 different patients. Boost1 delivered 33 and 25 Gy to PTV1 and PTV2, respectively. Boost2 delivered 40, 33, and 25 Gy to boostCTV, PTV1, and PTV2, respectively. Boost3 delivered 33 and 25 Gy to PTV1 and PTV3, respectively...
January 13, 2019: Journal of Applied Clinical Medical Physics
Yoshihiro Tanaka, Hirokazu Mizuno, Yuichi Akino, Masaru Isono, Norimasa Masai, Toshijiro Yamamoto
If the vendor's representative beam data (RBD) for TrueBeam linear accelerators are to be valid for use in clinical practice, the variations in the beam data used for beam modeling must be small. Although a few studies have reported the variation of the beam data of the TrueBeam machines, the numbers of machines analyzed in those studies were small. In this study, we investigated the variation in the beam data for 21 TrueBeam machines collected from 17 institutions with their agreement. In the exponential regions, the percent depth dose (PDD) values showed very small variation, <1% for all the photon energies analyzed...
January 13, 2019: Journal of Applied Clinical Medical Physics
Görkem Güngör, Gökhan Aydın, Teuta Zoto Mustafayev, Enis Özyar
PURPOSE: The electron energy characteristics of mobile intraoperative radiotherapy (IORT) accelerator LIAC® differ from commonly used linear accelerators, thus some of the frequently used detectors can give less accurate results. The aim of this study is to evaluate the output factors (OFs) of several ionization chambers (IC) and solid state detectors (SS) for electron beam energies generated by LIAC® and compare with the output factor of Monte Carlo model (MC) in order to determine the adequate detectors for LIAC® ...
January 10, 2019: Journal of Applied Clinical Medical Physics
Senait Aknaw Debebe, Malek Adjouadi, Seza A Gulec, Juan Franquiz, Anthony J McGoron
INTRODUCTION: Yttrium-90 (90 Y) microsphere post-treatment imaging reflects the true distribution characteristics of microspheres in the tumor and liver compartments. However, due to its decay spectra profile lacking a pronounced photopeak, the bremsstrahlung imaging for 90 Y has inherent limitations. The absorbed dose calculations for 90 Y microspheres radiomicrosphere therapy (RMT) sustain a limitation due to the poor quality of 90 Y imaging. The aim of this study was to develop quantitative methods to improve the post-treatment 90 Y bremsstrahlung single photon emission tomography (SPECT)/computed tomography (CT) image analysis for dosimetric purposes and to perform a quantitative comparison with the 99m Tc-MAA SPECT/CT images, which is used for theranostics purposes for liver and tumor dosimetry...
January 9, 2019: Journal of Applied Clinical Medical Physics
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