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Physica Medica: PM

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https://www.readbyqxmd.com/read/29129741/risk-of-second-cancer-following-radiotherapy
#1
EDITORIAL
Iuliana Toma-Dasu, Andrzej Wojcik, Emely Kjellsson Lindblom
No abstract text is available yet for this article.
November 9, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29113724/imaging-with-ultra-small-angle-x-ray-scattering-using-a-laue-case-analyzer-and-its-application-to-human-breast-tumors
#2
Daisuke Shimao, Naoki Sunaguchi, Tenta Sasaya, Tetsuya Yuasa, Shu Ichihara, Tomonori Kawasaki, Masami Ando
PURPOSE: In this study, we demonstrate a novel imaging technique, based on ultra-small-angle X-ray scattering (USAXS) that uses a Laue-case Si wafer as the angle analyzer. METHODS: We utilized the (1 1 1) diffraction plane of a 356 μm thick, symmetrically cut Si wafer as the angle analyzer, denoted by A[L]. With this device, we performed USAXS imaging experiments using 19.8 keV synchrotron X-rays. The objects we imaged were formalin-fixed, paraffin-embedded breast tumors (an invasive carcinoma and an intraductal papilloma)...
November 4, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29103987/special-radiobiological-features-of-second-cancer-risk-after-particle-radiotherapy
#3
Klaus-Rüdiger Trott
In absolute terms: second cancer risks from radiotherapy of first cancers in adults are small compared to the benefits from radiotherapy but this is not so for radiotherapy of childhood cancers. Moreover, the radiation dose dependence of cancer induction differs between organs and tissues. The organ-specific dose dependence of second cancer risks may indicate the existence of different radiobiological mechanisms. As an inevitable consequence of the age dependence of organ sensitivity to second cancer induction, the organ/tissue weighting factors which have been proposed by ICRP for calculating effective dose (the dose unit Sv) and for risk estimation in the general population should not be used in medical radiation exposures...
November 2, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29111386/method-for-determining-the-half-value-layer-in-computed-tomography-scans-using-a-real-time-dosimeter-application-to-dual-source-dual-energy-acquisition
#4
Kosuke Matsubara, Hiroji Nagata, Rena Okubo, Tadanori Takata, Masanao Kobayashi
PURPOSE: We have proposed a method for determining the half-value layers (HVL) in dual-source dual-energy computed tomography (DS-DECT) scans without the need for the X-ray tubes to be fixed. METHODS: A custom-made lead-covered case and an ionizing chamber connected with a multi-function digitizer module (a real-time dosimeter) were used. The chamber was placed in the center of the case, and aluminum or copper filters were placed in front of the aperture. The HVL was measured using aperture widths of 1...
October 27, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29102154/three-dimensional-printer-generated-patient-specific-phantom-for-artificial-in-vivo-dosimetry-in-radiotherapy-quality-assurance
#5
Takeshi Kamomae, Hidetoshi Shimizu, Takayoshi Nakaya, Kuniyasu Okudaira, Takahiro Aoyama, Hiroshi Oguchi, Masataka Komori, Mariko Kawamura, Kazuhiro Ohtakara, Hajime Monzen, Yoshiyuki Itoh, Shinji Naganawa
Pretreatment intensity-modulated radiotherapy quality assurance is performed using simple rectangular or cylindrical phantoms; thus, the dosimetric errors caused by complex patient-specific anatomy are absent in the evaluation objects. In this study, we construct a system for generating patient-specific three-dimensional (3D)-printed phantoms for radiotherapy dosimetry. An anthropomorphic head phantom containing the bone and hollow of the paranasal sinus is scanned by computed tomography (CT). Based on surface rendering data, a patient-specific phantom is formed using a fused-deposition-modeling-based 3D printer, with a polylactic acid filament as the printing material...
October 25, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29054516/eye-lens-dosimetry-and-the-study-on-radiation-cataract-in-interventional-cardiologists
#6
Kosuke Matsubara, Vorarit Lertsuwunseri, Suphot Srimahachota, Anchali Krisanachinda, Wasee Tulvatana, Bharkbhum Khambhiphant, Waraporn Sudchai, Madan Rehani
PURPOSE: To determine the eye lens dose of the Interventional Cardiology (IC) personnel using optically stimulated luminescent dosimeter (OSLD) and the prevalence and risk of radiation - associated lens opacities in Thailand. METHODS AND RESULTS: 48 IC staff, with age- and sex- matches 37 unexposed controls obtained eye examines. Posterior lens change was graded using a modified Merriam-Focht technique by two independent ophthalmologists. Occupational exposure (mSv) was measured in 42 IC staff, using 2 OSLD badges place at inside lead apron and at collar...
October 17, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29032028/comments-on-radiological-protection-for-pregnant-women-at-a-large-academic-medical-cancer-center
#7
LETTER
S M J Mortazavi
No abstract text is available yet for this article.
October 12, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28951047/hippocampal-dose-during-linac-based-stereotactic-radiotherapy-for-brain-metastases-an-observational-study
#8
Alba Fiorentino, Umberto Tebano, Gianluisa Sicignano, Francesco Ricchetti, Gioacchino Di Paola, Dario Aiello, Niccolò Giaj-Levra, Rosario Mazzola, Sergio Fersino, Ruggero Ruggieri, Filippo Alongi
INTRODUCTION: Aim of the present study is to evaluate homolateral and contralateral hippocampus (H-H, C-H, respectively) dose during Fractionated Stereotactic Radiotherapy (FSRT) or Radiosurgery (SRS) for brain metastases (BM). MATERIALS & METHODS: Patients with BM<5, size≤30mm, KPS≥80 and a life expectancy>3months, were considered for SRS/FSRT (total dose 15-30Gy, 1-5 fractions). For each BM, a Flattening Filter Free (FFF) Volumetric Modulated Arc Therapy (VMAT) plan was generated with one or two arcs...
September 23, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28947188/deformable-image-registration-applied-to-lung-sbrt-usefulness-and-limitations
#9
REVIEW
David Sarrut, Thomas Baudier, Myriam Ayadi, Ronan Tanguy, Simon Rit
Radiation therapy (RT) of the lung requires deformation analysis. Deformable image registration (DIR) is the fundamental method to quantify deformations for various applications: motion compensation, contour propagation, dose accumulation, etc. DIR is therefore unavoidable in lung RT. DIR algorithms have been studied for decades and are now available both within commercial and academic packages. However, they are complex and have limitations that every user must be aware of before clinical implementation. In this paper, the main applications of DIR for lung RT with their associated uncertainties and their limitations are reviewed...
September 22, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28947187/monte-carlo-study-of-the-influence-of-energy-spectra-mesh-size-high-z-element-on-dose-and-pvdr-based-on-1-d-and-3-d-heterogeneous-mouse-head-phantom-for-microbeam-radiation-therapy
#10
Hui Lin, Jia Jing, Liangfeng Xu, Xiaoli Mao
PURPOSE: To evaluate the influence of energy spectra, mesh sizes, high Z element on dose and PVDR in Microbeam Radiation Therapy (MRT) based on 1-D analogy-mouse-head-model (1-D MHM) and 3-D voxel-mouse-head-phantom (3-D VMHP) by Monte Carlo simulation. METHODS: A Microbeam-Array-Source-Model was implemented into EGSnrc/DOSXYZnrc. The microbeam size is assumed to be 25μm, 50μm or 75μm in thickness and fixed 1mm in height with 200μmc-t-c. The influence of the energy spectra of ID17@ESRF and BMIT@CLS were investigated...
September 22, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28943130/estimation-and-reduction-of-the-radiation-dose-to-the-fetus-from-external-beam-radiotherapy
#11
REVIEW
Michalis Mazonakis, John Damilakis
The appearance of a malignant disease during pregnancy is relatively rare. The use of external-beam radiation therapy is limited to non-pelvic tumors which are usually located above the diaphragm. However, supradiaphragmatic radiotherapy unavoidably exposes the fetus to secondary radiation due to head leakage, scatter from the machine and scatter produced inside the patient. This fetal exposure may be associated with an elevated risk for the development of deterministic harmful effects and/or carcinogenesis...
September 21, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28941740/fetal-radiation-dose-in-three-common-ct-examinations-during-pregnancy-monte-carlo-study
#12
A Kelaranta, T Mäkelä, T Kaasalainen, M Kortesniemi
PURPOSE: To determine fetal doses in different stages of pregnancy in three common computed tomography (CT) examinations: pulmonary CT angiography, abdomino-pelvic and trauma scan with Monte Carlo (MC) simulations. METHODS: An adult female anthropomorphic phantom was scanned with a 64-slice CT using pulmonary angiography, abdomino-pelvic and trauma CT scan protocols. Three different sized gelatin boluses placed on the phantom's abdomen simulated different stages of pregnancy...
September 20, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28941739/the-influence-of-inter-fractional-anatomy-variation-on-secondary-cancer-risk-estimates-following-radiotherapy
#13
Camilla Hanquist Stokkevåg, Grete May Engeseth, Liv Bolstad Hysing, Kristian Smeland Ytre-Hauge, Ludvig Paul Muren
PURPOSE: In silico studies comparing estimated risks of radiation-induced secondary cancer (SC) are frequently performed in assessment of radiotherapy techniques. Since inter-patient anatomy variations can result in considerable differences in estimated risk we aimed to explore the influence of inter-fractional organ motion patterns on SC risk. METHODS: Volumetric modulated arc therapy (VMAT) and intensity-modulated proton therapy (IMPT) plans were generated on the planning CT (pCT) scans of eight prostate cancer patients...
September 20, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28927752/the-iaea-radiotracer-biodistribution-template-a-community-resource-for-supporting-the-standardization-and-reporting-of-radionuclide-pre-dosimetry-data
#14
Adam Leon Kesner, Gian Luca Poli, Seval Beykan, Michael Lassmann
Radionuclide absorbed-dose dosimetry is an active area of development and has the potential to positively impact molecular radiotherapies. At present, many of the operations required to perform dosimetry calculations are unstandardized and unestablished. While the current methodology allows reasonable dosimetry estimates to be derived and published, it can be difficult to understand, and reproduce, each others' work. To help alleviate this we have identified the collection of biodistribution information as a key step in all internal dosimetry calculations, and present a template that can be used to standardize its documentation and reporting...
September 15, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28899649/small-field-characterization-of-a-nanochamber-prototype-under-flattening-filter-free-photon-beams
#15
G Reggiori, A Stravato, P Mancosu, F Lobefalo, L Paganini, F Zucconi, V Palumbo, A Gaudino, M Scorsetti, S Tomatis
INTRODUCTION: Nanochambers present some advantages in terms of energy independence and absolute dose measurement for small field dosimetry in the SBRT scenario. Characterization of a micro-chamber prototype was carried out both under flattened and flattening-filter-free (FFF) beams with particular focus on stem effect. METHODS: The study included characterization of leakage and stem effects, dose rate and dose per pulse dependence, measurement of profiles, and percentage depth doses (PDDs)...
September 9, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28882410/radiological-protection-of-foetuses-and-breast-fed-children-of-occupationally-exposed-women-in-nuclear-medicine-challenges-for-hospitals
#16
A Almén, S Mattsson
This paper describes issues of concern for protecting foetuses and breast-fed children of occupationally exposed women in nuclear medicine from unnecessary exposure of ionising radiation. The protection principle is to ensure the same level of protection for the foetus and child as for the general public. Therefore international radiation protection standards recommend a dose constraint of 1mSv to a foetus during the remaining time of pregnancy after it is known/declared and a yearly dose constraint of 1mSv to a breast-fed child...
September 4, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28869137/the-optimal-balance-between-quality-and-efficiency-in-proton-radiography-imaging-technique-at-various-proton-beam-energies-a-monte-carlo-study
#17
A K Biegun, M-J van Goethem, E R van der Graaf, M van Beuzekom, E N Koffeman, T Nakaji, J Takatsu, J Visser, S Brandenburg
Proton radiography is a novel imaging modality that allows direct measurement of the proton energy loss in various tissues. Currently, due to the conversion of so-called Hounsfield units from X-ray Computed Tomography (CT) into relative proton stopping powers (RPSP), the uncertainties of RPSP are 3-5% or higher, which need to be minimized down to 1% to make the proton treatment plans more accurate. In this work, we simulated a proton radiography system, with position-sensitive detectors (PSDs) and a residual energy detector (RED)...
August 28, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28188080/the-effect-of-18f-fdg-pet-image-reconstruction-algorithms-on-the-expression-of-characteristic-metabolic-brain-network-in-parkinson-s-disease
#18
Petra Tomše, Luka Jensterle, Sebastijan Rep, Marko Grmek, Katja Zaletel, David Eidelberg, Vijay Dhawan, Yilong Ma, Maja Trošt
PURPOSE: To evaluate the reproducibility of the expression of Parkinson's Disease Related Pattern (PDRP) across multiple sets of 18F-FDG-PET brain images reconstructed with different reconstruction algorithms. METHODS: 18F-FDG-PET brain imaging was performed in two independent cohorts of Parkinson's disease (PD) patients and normal controls (NC). Slovenian cohort (20 PD patients, 20 NC) was scanned with Siemens Biograph mCT camera and reconstructed using FBP, FBP+TOF, OSEM, OSEM+TOF, OSEM+PSF and OSEM+PSF+TOF...
September 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28826776/risk-of-low-dose-radiation-and-the-beir-vii-report-a-critical-review-of-what-it-does-and-doesn-t-say
#19
REVIEW
Michael K O'Connor
This article briefly reviews the history behind the BEIR VII report and the use of the linear no-threshold hypothesis. The BEIR VII committee considered four primary sources of data on the stochastic effects of ionizing radiation. These were environmental studies, occupational studies, medical studies and studies on the atomic bomb survivors. These sources are briefly reviewed along with key studies that run counter to the LNT hypothesis. We review many of the assumptions, hypotheses and subjective decisions used to generate risk estimates in the BEIR VII report...
August 18, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28789933/radiation-protection-in-dental-radiology-recent-advances-and-future-directions
#20
V Tsapaki
Dental radiology uses X-ray technology to diagnose and design treatment of various clinical problems related to the oral cavity and surrounding tissues. As technology quickly evolves, there are numerous X-ray modalities using different tools in the attempt to best image and treat efficiently these diseases, disorders or other related clinical conditions. The reported numbers of dental X-rays, the fact that these may be under-reported in many countries and because dental X-rays are performed more on younger individuals, whose teeth and dentition are still developing, calls for increased need on radiation protection...
August 5, 2017: Physica Medica: PM
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