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Physica Medica: PM

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https://www.readbyqxmd.com/read/28943130/estimation-and-reduction-of-the-radiation-dose-to-the-fetus-from-external-beam-radiotherapy
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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/28826776/risk-of-low-dose-radiation-and-the-beir-vii-report-a-critical-review-of-what-it-does-and-doesn-t-say
#8
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
#9
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
https://www.readbyqxmd.com/read/28784573/on-site-audits-to-investigate-the-quality-of-radiation-physics-of-radiation-therapy-institutions-in-the-republic-of-korea
#10
Jong Min Park, So-Yeon Park, Minsoo Chun, Sang-Tae Kim
PURPOSE: To investigate and improve the domestic standard of radiation therapy in the Republic of Korea. METHODS: On-site audits were performed for 13 institutions in the Republic of Korea. Six items were investigated by on-site visits of each radiation therapy institution, including collimator, gantry, and couch rotation isocenter check; coincidence between light and radiation fields; photon beam flatness and symmetry; electron beam flatness and symmetry; physical wedge transmission factors; and photon beam and electron beam outputs...
August 4, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28784572/the-influence-of-plan-modulation-on-the-interplay-effect-in-vmat-liver-sbrt-treatments
#11
Emily Hubley, Greg Pierce
Volumetric modulated arc therapy (VMAT) uses multileaf collimator (MLC) leaves, gantry speed, and dose rate to modulate beam fluence, producing the highly conformal doses required for liver radiotherapy. When targets that move with respiration are treated with a dynamic fluence, there exists the possibility for interplay between the target and leaf motions. This study employs a novel motion simulation technique to determine if VMAT liver SBRT plans with an increase in MLC leaf modulation are more susceptible to dosimetric differences in the GTV due to interplay effects...
August 4, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28760508/effects-of-gamma-low-dose-irradiation-on-skin-flap-survival-in-rats
#12
Mojtaba Karimipour, Vahid Amanzade, Nasrollah Jabbari, Gholam Hossein Farjah
PURPOSE: Skin flap necrosis due to inadequate blood supply has remained a common postoperative problem in constructive surgery. As low-dose irradiation (LDI) has been shown to promote the wound-healing process, this study aims to investigate whether LDI could increase neovascularization and skin flap survival in rats. METHODS: McFarlane flaps were created in 21 male rats, which were divided into one control and two treatment groups (Ta and Tb). The treatment groups received a whole body single dose of 100cGy gamma ray irradiation before (Tb) and after (Ta) flap surgery...
July 28, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28760507/use-of-a-second-dose-calculation-algorithm-to-check-dosimetric-parameters-for-the-dose-distribution-of-a-first-dose-calculation-algorithm-for-lung-sbrt-plans
#13
Yusuke Tsuruta, Mitsuhiro Nakamura, Yuki Miyabe, Manabu Nakata, Yoshitomo Ishihara, Nobutaka Mukumoto, Mami Akimoto, Tomohiro Ono, Shinsuke Yano, Kyoji Higashimura, Yukinori Matsuo, Takashi Mizowaki, Masahiro Hiraoka
PURPOSE: To verify lung stereotactic body radiotherapy (SBRT) plans using a secondary treatment planning system (TPS) as an independent method of verification and to define tolerance levels (TLs) in lung SBRT between the primary and secondary TPSs. METHODS: A total of 147 lung SBRT plans calculated using X-ray voxel Monte Carlo (XVMC) were exported from iPlan to Eclipse in DICOM format. Dose distributions were recalculated using the Acuros XB (AXB) and the anisotropic analytical algorithm (AAA), while maintaining monitor units (MUs) and the beam arrangement...
July 28, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28760506/a-comparison-of-treatment-plan-quality-between-tri-co-60-intensity-modulated-radiation-therapy-and-volumetric-modulated-arc-therapy-for-cervical-cancer
#14
Jong Min Park, So-Yeon Park, Jung-In Kim, Hyun-Cheol Kang, Chang Heon Choi
PURPOSE: To investigate the plan quality of tri-Co-60 intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) for cervical cancer. METHODS: A total of 20 patients who received postoperative radiotherapy for cervical cancer were selected. For each patient, a tri-Co-60 IMRT plan for which the target volume was the planning target volume (PTV) generated by adding 1mm isotropic margins from the clinical target volume (CTV) and a VMAT plan for which the target volume was the PTV generated by adding 7mm and 10mm margins from the CTV were generated...
July 28, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28760505/-pulmonary-embolism-diagnostics-of-pregnant-patients-what-is-the-recommended-clinical-pathway-considering-the-clinical-value-and-associated-radiation-risks-of-available-imaging-tests
#15
Georgios Z Papadakis, Apostolos H Karantanas, Kostas Perisinakis
Pulmonary embolism (PE) during pregnancy remains the leading preventable cause of maternal morbidity and mortality in the developed countries. Diagnosis of PE in pregnant patients is a challenging clinical problem, since pregnancy-related physiologic changes can mimic signs and symptoms of PE. Patient mismanagement may result into unjustified anticoagulant treatment or unnecessary imaging tests involving contrast-related or/and radiation-related risks for both the expectant mother and embryo/fetus. On the other hand, missing or delaying diagnosis of PE could lead to life-threatening conditions for both the mother and the embryo/fetus...
July 28, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28743619/organ-and-effective-doses-from-paediatric-interventional-cardiology-procedures-in-chile
#16
Carlos Ubeda, Patricia Miranda, Eliseo Vano, Diego Nocetti, Carlos Manterola
The aim of this study was to present the results of organ and effective doses for paediatric patients for different types of interventional cardiology procedures for age and weight groups, derived from a patient dosimetry pilot programme carried out in Chile, under the auspices of the International Atomic Energy Agency. Over seven years, a retrospective collection of demographic and patient dose data was obtained: age, gender, weight, height, number of cine series, total number of cine frames, fluoroscopy time, dose-area product (DAP) and cumulative dose at patient entrance reference point...
July 22, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28743618/deep-architecture-neural-network-based-real-time-image-processing-for-image-guided-radiotherapy
#17
Shinichiro Mori
INTRODUCTION: To develop real-time image processing for image-guided radiotherapy, we evaluated several neural network models for use with different imaging modalities, including X-ray fluoroscopic image denoising. METHODS & MATERIALS: Setup images of prostate cancer patients were acquired with two oblique X-ray fluoroscopic units. Two types of residual network were designed: a convolutional autoencoder (rCAE) and a convolutional neural network (rCNN). We changed the convolutional kernel size and number of convolutional layers for both networks, and the number of pooling and upsampling layers for rCAE...
July 22, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28743617/can-the-day-0-ct-scan-predict-the-post-implant-scanning-results-from-136-prostate-cancer-patients
#18
Federica Cattani, Andrea Vavassori, Stefania Comi, Federica Gherardi, Stefania Russo, Roberto Orecchia, Barbara A Jereczek-Fossa
PURPOSE: Post-implant CT-scanning is an essential part of permanent prostate brachytherapy. However, the evaluation of post-implant CT dosimetry is not straightforward due to the edema that can modify the dose to the prostate and to the organs at risk. The aim of this study is to evaluate the impact of the timing of the post-implant CT-scan on the dosimetric results and to verify if the Day 0 scan findings can predict Day 50 scanning. METHODS: 136 consecutive patients who received monotherapy with I-125 implants were selected for this study...
July 22, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28743616/heart-position-variability-during-voluntary-moderate-deep-inspiration-breath-hold-radiotherapy-for-breast-cancer-determined-by-repeat-cbct-scans
#19
Paul van Haaren, Fiere Claassen-Janssen, Ingrid van de Sande, Liesbeth Boersma, Maurice van der Sangen, Coen Hurkmans
Voluntary moderate deep inspiration breath hold (vmDIBH) in left-sided breast cancer radiotherapy reduces cardiac dose. The aim of this study was to investigate heart position variability in vmDIBH using CBCT and to compare this variability with differences in heart position between vmDIBH and free breathing (FB). For 50 patients initial heart position with respect to the field edge (HP-FE) was measured on a vmDIBH planning CT scan. Breath-hold was monitored using an in-house developed vertical plastic stick...
July 22, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28739143/prediction-of-time-integrated-activity-coefficients-in-prrt-using-simulated-dynamic-pet-and-a-pharmacokinetic-model
#20
Deni Hardiansyah, Ali Asgar Attarwala, Peter Kletting, Felix M Mottaghy, Gerhard Glatting
PURPOSE: To investigate the accuracy of predicted time-integrated activity coefficients (TIACs) in peptide-receptor radionuclide therapy (PRRT) using simulated dynamic PET data and a physiologically based pharmacokinetic (PBPK) model. METHODS: PBPK parameters were estimated using biokinetic data of 15 patients after injection of (152±15)MBq of (111)In-DTPAOC (total peptide amount (5.78±0.25)nmol). True mathematical phantoms of patients (MPPs) were the PBPK model with the estimated parameters...
July 21, 2017: Physica Medica: PM
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