journal
MENU ▼
Read by QxMD icon Read
search

Physica Medica: PM

journal
https://www.readbyqxmd.com/read/28412136/dose-painting-by-means-of-monte-carlo-treatment-planning-at-the-voxel-level
#1
E Jiménez-Ortega, A Ureba, A Vargas, J A Baeza, A Wals-Zurita, F J García-Gómez, A R Barbeiro, A Leal
PURPOSE: To develop a new optimization algorithm to carry out true dose painting by numbers (DPBN) planning based on full Monte Carlo (MC) calculation. METHODS: Four configurations with different clustering of the voxel values from PET data were proposed. An optimization method at the voxel level under Lineal Programming (LP) formulation was used for an inverse planning and implemented in CARMEN, an in-house Monte Carlo treatment planning system. RESULTS: Beamlet solutions fulfilled the objectives and did not show significant differences between the different configurations...
April 12, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28412135/moving-beyond-quality-control-in-diagnostic-radiology-and-the-role-of-the-clinically-qualified-medical-physicist
#2
REVIEW
H Delis, K Christaki, B Healy, G Loreti, G L Poli, P Toroi, A Meghzifene
Quality control (QC), according to ISO definitions, represents the most basic level of quality. It is considered to be the snapshot of the performance or the characteristics of a product or service, in order to verify that it complies with the requirements. Although it is usually believed that "the role of medical physicists in Diagnostic Radiology is QC", this, not only limits the contribution of medical physicists, but is also no longer adequate to meet the needs of Diagnostic Radiology in terms of Quality...
April 12, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28395963/dosimetric-impact-assessment-using-a-general-algorithm-in-geant4-simulations-for-a-complex-shaped-multileaf-collimator
#3
Á Perales, M A Cortés-Giraldo, H Miras, R Arráns, M I Gallardo
PURPOSE: We have developed an inhouse algorithm for the multileaf collimator (MLC) geometry model construction with an appropriate accuracy for dosimetric tests. Our purpose is to build a complex type of MLC and analyze the influence of the modeling parameters on the dose calculation. METHODS: Using radiochromic films as detector the following tests were done: (I) Density test field: to compare measured and calculated dose distributions in order to determine the tungsten alloy physical density value...
April 7, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28392313/uncomplicated-and-cancer-free-control-probability-ucfcp-a-new-integral-approach-to-treatment-plan-optimization-in-photon-radiation-therapy
#4
Beatriz Sánchez-Nieto, Maite Romero-Expósito, José A Terrón, Francisco Sánchez-Doblado
PURPOSE: Biological treatment plan evaluation does not currently consider second cancer induction from peripheral doses associated to photon radiotherapy. The aim is to propose a methodology to characterize the therapeutic window by means of an integral radiobiological approach, which considers not only Tumour Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) but also Secondary Cancer Probability (SCP). METHODS: Uncomplicated and Cancer-Free Control Probability (UCFCP) function has been proposed assuming a statistically uncorrelated response for tumour and normal tissues...
April 6, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28392312/out-of-field-doses-in-radiotherapy-input-to-epidemiological-studies-and-dose-risk-models
#5
Roger Harrison
Out-of-field doses in radiotherapy have been increasingly studied in recent years because of the generally improved survival of patients who have received radiotherapy as part of their treatment for cancer and their subsequent risk of a second malignancy. This short article attempts to identify some current problems, challenges and opportunities for dosimetry developments in this field. Out-of-field doses and derived risk estimates contribute to general knowledge about radiation effects on humans as well as contributing to risk-benefit considerations for the individual patient...
April 6, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28392311/two-examples-of-indication-specific-radiation-dose-calculations-in-dental-cbct-and-multidetector-ct-scanners
#6
Andreas Stratis, Guozhi Zhang, Xochitl Lopez-Rendon, Constantinus Politis, Robert Hermans, Reinhilde Jacobs, Ria Bogaerts, Eman Shaheen, Hilde Bosmans
PURPOSE: To calculate organ doses and estimate the effective dose for justification purposes in patients undergoing orthognathic treatment planning purposes and temporal bone imaging in dental cone beam CT (CBCT) and Multidetector CT (MDCT) scanners. METHODS: The radiation dose to the ICRP reference male voxel phantom was calculated for dedicated orthognathic treatment planning acquisitions via Monte Carlo simulations in two dental CBCT scanners, Promax 3D Max (Planmeca, FI) and NewTom VGi evo (QR s...
April 6, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28391959/does-clinical-indication-play-a-role-in-ct-radiation-dose-in-pediatric-patients
#7
Sotiria Triantopoulou, Virginia Tsapaki
PURPOSE: The purpose of this study was to identify the main pathologies for which CT is applied on pediatric patients and the related radiation doses as reported in the literature in order to facilitate justification and CT optimization. METHODS: A critical analysis of a literature review was performed. Different search engines were used such as PubMed, Google Scholar and Science Direct. Various terms and keywords were used to locate pertinent articles such as Pediatric, Computed tomography, Radiation Dose, Organ dose, Effective dose...
April 5, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28391958/the-role-of-dosimetry-audit-in-lung-sbrt-multi-centre-clinical-trials
#8
Catharine H Clark, Coen W Hurkmans, Stephen F Kry
Stereotactic Body Radiotherapy (SBRT) in the lung is a challenging technique which requires high quality clinical trials to answer the un-resolved clinical questions. Quality assurance of these clinical trials not only ensures the safety of the treatment of the participating patients but also minimises the variation in treatment, thus allowing the lowest number of patient treatments to answer the trial question. This review addresses the role of dosimetry audits in the quality assurance process and considers what can be done to ensure the highest accuracy of dose calculation and delivery and it's assessment in multi-centre trials...
April 5, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28385495/dosimetric-characterization-of-small-fields-using-a-plastic-scintillator-detector-a-large-multicenter-study
#9
Pietro Mancosu, Massimo Pasquino, Giacomo Reggiori, Laura Masi, Serenella Russo, Michele Stasi
PURPOSE: In modern radiation therapy accurate small fields dosimetry is a challenge and its standardization is fundamental to harmonize delivered dose in different institutions. This study presents a multicenter characterization of MLC-defined small field for Elekta and Varian linear accelerators. Measurements were performed using the Exradin W1 plastic scintillator detector. MATERIALS AND METHODS: The project enrolled 24 Italian centers. Each center performed Tissue Phantom Ratio (TPR), in-plane and cross-plane dose profiles of 0...
April 3, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28372877/peripheral-equivalent-neutron-dose-model-implementation-for-radiotherapy-patients
#10
L Irazola, J A Terrón, B Sánchez-Nieto, B Roberto, F Sánchez-Doblado
PURPOSE: Neutron peripheral contamination in high-energy radiotherapy implies an increase of secondary radiation-induced cancer risk. Although peripheral neutron dose (PND) has been evaluated in organs, few studies have been performed regarding patient size. This work aims to improve an existing methodology for adult patient PND estimations to generalize it to young and children, for its implementation in treatment planning systems (TPS). METHODS: As a first step, we aimed to generalize the previous model to be usable with any thermal neutron detector...
March 31, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28366555/about-the-non-consistency-of-ptv-based-prescription-in-lung
#11
S Lebredonchel, T Lacornerie, E Rault, A Wagner, N Reynaert, F Crop
PURPOSE: The goal of this study is to show that the PTV concept is inconsistent for prescribing lung treatments when using type B algorithms, which take into account lateral electron transport. It is well known that type A dose calculation algorithms are not capable of calculating dose in lung correctly. Dose calculations should be based on type B algorithms. However, the combination of a type B algorithm with the PTV concept leads to prescription inconsistencies. METHODS: A spherical isocentric setup has been simulated, using multiple realistic values for lung density, tumor density and collimator size...
March 30, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28366554/comparative-study-of-the-calculated-risk-of-radiation-induced-cancer-after-photon-and-proton-beam-based-radiosurgery-of-liver-metastases
#12
Gracinda Mondlane, Michael Gubanski, Pehr A Lind, Ana Ureba, Albert Siegbahn
INTRODUCTION: The potential of proton therapy to improve the sparing of the healthy tissue has been demonstrated in several studies. However, even small doses delivered to the organs at risk (OAR) may induce long-term detriments after radiotherapy. In this study, we investigated the possibility to reduce the risk of radiation-induced secondary cancers with intensity modulated proton therapy (IMPT), when used for radiosurgery of liver metastases. MATERIAL AND METHODS: Ten patients, previously treated for liver metastases with photon-beam based stereotactic body radiation therapy (SBRT) were retrospectively planned for radiosurgery with IMPT...
March 30, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28363341/risk-of-secondary-cancers-bridging-epidemiology-and-modeling
#13
Uwe Schneider, Linda Walsh
Epidemiological studies of long term radiotherapy survivors provide useful insights into dose-response relationships for secondary cancer induction risk at high doses. There are uncertainties involved in estimating the dose to the location of the second malignancy, because the dose distributions in radiotherapy patients can be spatially highly heterogeneous and the size of the diagnosed tumor is on the order of a few cm. Therefor it is nearly impossible to obtain the exact dose corresponding to the exact tumor induction location and so organ specific dose-response relationships have large errors not only in the reported risk, but also in the estimated dose...
March 28, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28351527/imaging-practices-and-radiation-doses-from-imaging-in-radiotherapy
#14
Teemu Siiskonen, Sampsa Kaijaluoto, Tudor Florea
Modern radiotherapy treatments require frequent imaging for accurate patient positioning relative to the therapeutic radiation beam. Imaging practices in five Finnish radiotherapy clinics were assessed and discussed from the patient dose optimization point of view. The results show that imaging strategies are not jointly established and variations exist. The organ absorbed doses depend on imaging technique and imaging frequency. In particular, organ doses from the cone beam computed tomography can have very large variations (a factor of 10-50 in breast imaging and factor of 5 in prostate imaging)...
March 25, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28343906/comparative-analysis-of-iterative-reconstruction-algorithms-with-resolution-recovery-and-new-solid-state-cameras-dedicated-to-myocardial-perfusion-imaging
#15
Marco Brambilla, Michela Lecchi, Roberta Matheoud, Lucia Leva, Giovanni Lucignani, Claudio Marcassa, Orazio Zoccarato
New technologies are available in myocardial perfusion imaging. They include new software that recovers image resolution and limits image noise, multifocal collimators and dedicated cardiac cameras in which solid-state detectors are used and all available detectors are constrained to imaging just the cardiac field of view. These innovations resulted in shortened study times or reduced administered activity to patients, while preserving image quality. Many single center and some multicenter studies have been published during the introduction of these innovations in the clinical practice...
March 23, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28302493/the-risk-of-second-primary-cancers-due-to-peripheral-photon-and-neutron-doses-received-during-prostate-cancer-external-beam-radiation-therapy
#16
Eva Bezak, Rundgham Takam, Eric Yeoh, Loredana G Marcu
BACKGROUND: Out-of-field organs can be affected by secondary radiations originating from high energy linear accelerators, leading to an increased risk of carcinogenesis. The aim of this work was to determine the risk of second primary cancers (SPC) in the organs distal to the prostate during 3D conformal radiotherapy. MATERIALS AND METHODS: Based on previously measured peripheral photon and neutron doses in a Rando phantom using an 18MV photon beam, SPC risks in the out-of-field organs were estimated using the linear-no-threshold and the competitive risk models...
March 13, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28242140/mri-guided-lung-sbrt-present-and-future-developments
#17
REVIEW
Martin J Menten, Andreas Wetscherek, Martin F Fast
Stereotactic body radiotherapy (SBRT) is rapidly becoming an alternative to surgery for the treatment of early-stage non-small cell lung cancer patients. Lung SBRT is administered in a hypo-fractionated, conformal manner, delivering high doses to the target. To avoid normal-tissue toxicity, it is crucial to limit the exposure of nearby healthy organs-at-risk (OAR). Current image-guided radiotherapy strategies for lung SBRT are mostly based on X-ray imaging modalities. Although still in its infancy, magnetic resonance imaging (MRI) guidance for lung SBRT is not exposure-limited and MRI promises to improve crucial soft-tissue contrast...
February 24, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28242139/models-for-the-risk-of-secondary-cancers-from-radiation-therapy
#18
Alexandru Dasu, Iuliana Toma-Dasu
The interest in the induction of secondary tumours following radiotherapy has greatly increased as developments in detecting and treating the primary tumours have improved the life expectancy of cancer patients. However, most of the knowledge on the current levels of risk comes from patients treated many decades ago. As developments of irradiation techniques take place at a much faster pace than the progression of the carcinogenesis process, the earlier results could not be easily extrapolated to modern treatments...
February 24, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28238577/geometrical-and-dosimetrical-uncertainties-in-hypofractionated-radiotherapy-of-the-lung-a-review
#19
REVIEW
Marco Schwarz, Giovanni Mauro Cattaneo, Livia Marrazzo
The application of high precision hypofractionated regimes (a.k.a. stereotactic body radiotherapy (SBRT)) to the treatment of lung cancer is a 'success story' of radiotherapy. From the technical perspective, lung SBRT is a challenging technique as all aspects of the treatment workflow, from imaging to dose calculation to treatment delivery, should be carefully handled in order to ensure consistency between planned and delivered dose. In this review such technical aspects are presented and discussed, looking at what has been developed over the years...
February 23, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28236558/dosimetry-applications-in-gate-monte-carlo-toolkit
#20
Panagiotis Papadimitroulas
PURPOSE: Monte Carlo (MC) simulations are a well-established method for studying physical processes in medical physics. The purpose of this review is to present GATE dosimetry applications on diagnostic and therapeutic simulated protocols. There is a significant need for accurate quantification of the absorbed dose in several specific applications such as preclinical and pediatric studies. METHODS: GATE is an open-source MC toolkit for simulating imaging, radiotherapy (RT) and dosimetry applications in a user-friendly environment, which is well validated and widely accepted by the scientific community...
February 21, 2017: Physica Medica: PM
journal
journal
31255
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"