journal
MENU ▼
Read by QxMD icon Read
search

Journal of Medical Physics

journal
https://www.readbyqxmd.com/read/29628636/bismuth-silicon-and-bismuth-polyurethane-composite-shields-for-breast-protection-in-chest-computed-tomography-examinations
#1
Parinaz Mehnati, Mehran Arash, Parisa Akhlaghi
The article aims at constructing protective composite shields for breasts in chest computed tomography and investigating the effects of applying these new bismuth composites on dose and image quality. Polyurethane and silicon with 5% of bismuth were fabricated as a protective shield. At first, their efficiency in attenuating the X-ray beam was investigated by calculating the total attenuation coefficients at diagnostic energy range. Then, a physical chest phantom was scanned without and with these shields at tube voltage of 120 kVp, and image parameters together with dose values were studied...
January 2018: Journal of Medical Physics
https://www.readbyqxmd.com/read/29628635/brachytherapy-localization-radiographs-with-conventional-diagnostic-x-ray-machine
#2
Ramamoorthy Ravichandran, Bandana Barman, Purnendu Deb Roy, Gopal Datta, Ravi Kannan
With conventional diagnostic X-ray machines with over couch X-ray tubes, it is not possible to obtain anteroposterior (AP) and lateral (Lat) radiographs without changing the posture of the patients. In an old 300 mA X-ray machine with a fluoroscopy screen (12.4 kg) (1995 model), by substituting the screen with suitable counterweight and making provision to take the hoist pillar up to the edge of the wall, we could get isocentric setup for a hospital stretcher kept near the chest stand. This setup provided acceptable AP-Lat radiographs for brachytherapy localization using "Perspex jig" (Nucletron, Netherlands) and field check radiographs in head and neck, esophagus patients for treatment planning...
January 2018: Journal of Medical Physics
https://www.readbyqxmd.com/read/29628634/dosimetric-effect-of-jaw-tracking-in-volumetric-modulated-arc-therapy
#3
Sangutid Thongsawad, Chirasak Khamfongkhruea, Chirapha Tannanonta
The aim of this study was to investigate the potential of jaw tracking with the volumetric-modulated arc therapy (VMAT) to reduce the normal tissue dose. Plans of nasopharynx, lung, and prostate cancers (10 plans for each) were used to perform VMAT with and without jaw tracking. The dose reduction was evaluated in terms of organ doses and integral doses. Organ-dose reduction with jaw tracking was statistically significant in the volume receiving a dose of 5 Gy (V5 ) of bladder, rectum, and lung, the volume receiving a dose of 10 Gy (V10 ) of bladder, rectum, and lung, and the mean dose of lung ( P < 0...
January 2018: Journal of Medical Physics
https://www.readbyqxmd.com/read/29628633/dosimetric-comparison-of-treatment-plans-using-physical-wedge-and-enhanced-dynamic-wedge-for-the-planning-of-breast-radiotherapy
#4
Zhenia Gopalakrishnan, Raghuram K Nair, P Raghukumar, B Sarin
The aim of this study is to compare the physical wedge (PW) with enhanced dynamic wedge (EDW) to determine the difference in the dose distribution affecting the treated breast and the contralateral breast, lungs, heart, esophagus, spine, and surrounding skin in the radiotherapy of breast cancer. Computed tomography (CT) data sets of 30 breast cancer patients were selected from the database for the study. The treatment plans which were executed with PW were re-planned with EDW without changing the beam parameters...
January 2018: Journal of Medical Physics
https://www.readbyqxmd.com/read/29628632/expression-of-bax-and-bcl2-genes-in-peripheral-blood-lymphocytes-of-patients-with-differentiated-thyroid-cancer
#5
Zari Hamivand, Gholamhassan Haddadi, Reza Fardid
Context: Thyroid cancer is the most common endocrine malignancy worldwide. Iodine-131 is used in the treatment of thyroid cancer with dosage of 100 mCi. In the medical applications of ionizing radiation besides the advantages such as diagnosis and treatment of diseases, the risks arising from exposure should be considered as well. Aims: The present study aimed to evaluate the changes in expression levels of apoptotic Bax and Bcl-2 and the ratio of Bax/Bcl-2, in the peripheral blood lymphocytes (PBLs) of patients with differentiated thyroid cancer (DTC)...
January 2018: Journal of Medical Physics
https://www.readbyqxmd.com/read/29628631/dosimetric-and-radiobiological-evaluation-of-patient-setup-accuracy-in-head-and-neck-radiotherapy-using-daily-computed-tomography-on-rails-based-corrections
#6
Ines-Ana Jurkovic, Esengul Kocak-Uzel, Abdallah Sherif Radwan Mohamed, Eleftherios Lavdas, Sotirios Stathakis, Nikos Papanikolaou, David C Fuller, Panayiotis Mavroidis
Introduction: This study evaluates treatment plans aiming at determining the expected impact of daily patient setup corrections on the delivered dose distribution and plan parameters in head-and-neck radiotherapy. Materials and Methods: In this study, 10 head-and-neck cancer patients are evaluated. For the evaluation of daily changes of the patient internal anatomy, image-guided radiation therapy based on computed tomography (CT)-on-rails was used. The daily-acquired CT-on-rails images were deformedly registered to the CT scan that was used during treatment planning...
January 2018: Journal of Medical Physics
https://www.readbyqxmd.com/read/29628630/interfraction-variations-in-organ-filling-and-their-impact-on-dosimetry-in-ct-image-based-hdr-intracavitary-brachytherapy
#7
Ramya Rangarajan
Aim: Since anatomical and geometric variations occur with every fraction, planning, and dose optimization is necessary for every fraction of high-dose rate intracavitary brachytherapy of carcinoma cervix. In this study, we have tried to quantify the differences in doses to organs at risk (OAR) for each fraction of brachytherapy. Methods and Materials: One hundred and seventy computed tomography datasets of cervical cancer patients receiving intracavitary brachytherapy at our institution between January and April 2015 were analyzed...
January 2018: Journal of Medical Physics
https://www.readbyqxmd.com/read/29628629/comparison-of-volumetric-modulated-arc-therapy-and-intensity-modulated-radiation-therapy-for-whole-brain-hippocampal-sparing-treatment-plans-based-on-radiobiological-modeling
#8
Ethan Kendall, Ozer Algan, Salahuddin Ahmad
Introduction: In this article, we report the results of our investigation on comparison of radiobiological aspects of treatment plans with linear accelerator-based intensity-modulated radiation therapy and volumetric-modulated arc therapy for patients having hippocampal avoidance whole-brain radiation therapy. Materials and Methods: In this retrospective study using the dose-volume histogram, we calculated and compared biophysical indices of equivalent uniform dose, tumor control probability, and normal tissue complication probability (NTCP) for 15 whole-brain radiotherapy patients...
January 2018: Journal of Medical Physics
https://www.readbyqxmd.com/read/29628628/a-treatment-planning-method-for-better-management-of-radiation-induced-oral-mucositis-in-locally-advanced-head-and-neck-cancer
#9
Hao Howard Zhang, Warren D D'Souza
Purpose/Aim: To describe a two-phase intensity-modulated radiation therapy (IMRT) treatment planning approach, that is, promising for reduction of oral mucositis risk in locally advanced head-and-neck cancer. Materials and Methods: Ten locally advanced head-and-neck cancer patients who underwent RT were retrospectively collected. Conventional IMRT and volumetric-modulated arc therapy (VMAT) plans were generated for these patients following clinical protocol. Following the first phase of generating conventional IMRT plans, our approach utilized data from Monte Carlo-based kernel superposition dose calculations corresponding to beam apertures (generated from the conventional IMRT plans) and used an exact mathematical programming-based optimization approach applying linear programming (LP) to dose optimization in the second phase...
January 2018: Journal of Medical Physics
https://www.readbyqxmd.com/read/29628627/monte-carlo-investigation-of-photon-beam-characteristics-and-its-variation-with-incident-electron-beam-parameters-for-indigenous-medical-linear-accelerator
#10
Subhalaxmi Mishra, P K Dixit, T Palani Selvam, Sanket S Yavalkar, D D Deshpande
Purpose: A Monte Carlo model of a 6 MV medical linear accelerator (linac) unit built indigenously was developed using the BEAMnrc user code of the EGSnrc code system. The model was benchmarked against the measurements. Monte Carlo simulations were carried out for different incident electron beam parameters in the study. Materials and Methods: Simulation of indigenously developed linac unit has been carried out using the Monte Carlo based BEAMnrc user-code of the EGSnrc code system...
January 2018: Journal of Medical Physics
https://www.readbyqxmd.com/read/29296044/comments-on-radiological-risk-assessment-of-cosmic-radiation-at-aviation-altitudes-a-trip-from-houston-intercontinental-airport-to-lagos-international-airport
#11
Munish Kumar, D Datta
No abstract text is available yet for this article.
October 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/29296043/evaluation-of-radiation-shielding-properties-of-the-polyvinyl-alcohol-iron-oxide-polymer-composite
#12
K Srinivasan, E James Jabaseelan Samuel
Context: Lead is the conventional shielding material against gamma/X-rays. It has some limitations such as toxic, high density, nonflexibility, and also bremsstrahlung production during electron interaction. It may affect the accuracy of radiotherapy outcome. Aims: To theoretically analyze the radiation shielding properties of flexible polyvinyl alcohol/iron oxide polymer composite with five different concentrations of magnetite over the energy range of 15 KeV-20 MeV...
October 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/29296042/a-study-to-determine-whether-the-volume-weighted-computed-tomography-dose-index-gives-reasonable-estimates-of-organ-doses-for-thai-patients-undergoing-abdomen-and-pelvis-computed-tomography-examinations
#13
Supawitoo Sookpeng, Colin J Martin, Chitsanupong Butdee
Introduction: Values for the CTDIvol , which is displayed on scanner consoles, give doses relative to a phantom much larger than most Thai patients, and the CTDIvol does not take account of differences in patient size, which affect organ doses. Objective: The purpose of this study was to evaluate relationships for size specific dose estimate (SSDE) and volume weighted computed tomography (CT) dose index (CTDIvol ) with patient size for CT scanners operating under automatic tube current modulation (ATCM)...
October 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/29296041/verification-of-dosimetric-commissioning-accuracy-of-intensity-modulated-radiation-therapy-and-volumetric-modulated-arc-therapy-delivery-using-task-group-119-guidelines
#14
Karunakaran Kaviarasu, N Arunai Nambi Raj, Misba Hamid, A Ananda Giri Babu, Lingampally Sreenivas, Kammari Krishna Murthy
Aim: The purpose of this study is to verify the accuracy of the commissioning of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) based on the recommendation of the American Association of Physicists in Medicine Task Group 119 (TG-119). Materials and Methods: TG-119 proposes a set of clinical test cases to verify the accuracy of IMRT planning and delivery system. For these test cases, we generated two sets of treatment plans, the first plan using 7-9 IMRT fields and a second plan utilizing two-arc VMAT technique for both 6 MV and 15 MV photon beams...
October 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/29296040/evaluation-and-performance-of-arccheck-and-film-using-gamma-criteria-in-pre-treatment-quality-assurance-of-stereotactic-ablative-radiotherapy
#15
Prabhakar Ramachandran, Abdulrahman Tajaldeen, David Taylor, Derrick Wanigaratne, Karl Roozen, Moshi Geso
Aim: The aim of this study is to assess the use of ArcCHECK (AC) as an alternative method to replace film dosimetry for pre-treatment quality assurance (QA) of three-dimensional conformal radiation therapy, intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT) stereotactic ablative radiotherapy (SABR) treatment plans. Materials and Methods: Twenty-five patients with a varied diagnosis of lung, spine, sacrum, sternum, ribs, scapula, and femur undergoing SABR were selected for this study...
October 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/29296039/modulation-of-radiation-induced-base-excision-repair-pathway-gene-expression-by-melatonin
#16
Saeed Rezapoor, Alireza Shirazi, Sakineh Abbasi, Javad Tavakkoly Bazzaz, Pantea Izadi, Hamed Rezaeejam, Majid Valizadeh, Farid Soleimani-Mohammadi, Masoud Najafi
Objective: Approximately 70% of all cancer patients receive radiotherapy. Although radiotherapy is effective in killing cancer cells, it has adverse effects on normal cells as well. Melatonin (MLT) as a potent antioxidant and anti-inflammatory agent has been proposed to stimulate DNA repair capacity. We investigated the capability of MLT in the modification of radiation-induced DNA damage in rat peripheral blood cells. Materials and Methods: In this experimental study, male rats ( n = 162) were divided into 27 groups (n = 6 in each group) including: irradiation only, vehicle only, vehicle with irradiation, 100 mg/kg MLT alone, 100 mg/kg MLT plus irradiation in 3 different time points, and control...
October 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/29296038/melatonin-ameliorates-radiation-induced-oxidative-stress-at-targeted-and-nontargeted-lung-tissue
#17
Alireza Ghobadi, Alireza Shirazi, Masoud Najafi, Masoud Heidari Kahkesh, Saeed Rezapoor
Purpose: Radiation causes damage to irradiated tissues and also tissues that do not receive direct irradiation through a phenomenon called out-of-field effects. This damage through signals such as inflammatory responses can be transmitted to unirradiated cells/tissues and causes many effects such as oxidative damage. The radioprotective and anti-inflammatory effects of melatonin have been demonstrated in various studies. The aim of this study was to evaluate the effect of pretreatment with melatonin on oxidative damage caused by direct irradiation and out-of-field effects on the lung tissue after pelvic irradiation in rats...
October 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/29296037/estimating-second-malignancy-risk-in-intensity-modulated-radiotherapy-and-volumetric-modulated-arc-therapy-using-a-mechanistic-radiobiological-model-in-radiotherapy-for-carcinoma-of-left-breast
#18
Vasanthan Sakthivel, Ganesh Kadirampatti Mani, Sunil Mani, Raghavendiran Boopathy, Jothybasu Selvaraj
Objectives: The aim of this study is to estimate second cancer risk (SCR) in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) using a mechanistic radiobiological model. The model also takes into account patient age at exposure and the gender-specific correction factors of SCR. Materials and Methods: Fifty IMRT and VMAT plans were selected for the study. Monte Carlo-based dose calculation engine was used for dose calculation. Appropriate model parameters were taken from the literature for the mechanistic model to calculate excess absolute risk (EAR), lifetime attributable risk, integral dose and relative risk (RR) for lungs, contralateral breast, heart, and spinal cord...
October 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/29296036/a-unified-dose-response-relationship-to-predict-high-dose-fractionation-response-in-the-lung-cancer-stereotactic-body-radiation-therapy
#19
Than S Kehwar, Kashmiri L Chopra, Durg V Rai
Aim: This study is designed to investigate the superiority and applicability of the model among the linear-quadratic (LQ), linear-quadratic-linear (LQ-L) and universal-survival-curve (USC) models by fitting published radiation cell survival data of lung cancer cell lines. Materials and Method: The radiation cell survival data for small cell (SC) and non-small cell (NSC) lung cancer cell lines were obtained from published reports, and were used to determine the LQ and cell survival curve parameters, which ultimately were used in the curve fitting of the LQ, LQ-L and USC models...
October 2017: Journal of Medical Physics
https://www.readbyqxmd.com/read/29296035/grid-block-design-based-on-monte-carlo-simulated-dosimetry-the-linear-quadratic-and-hug-kellerer-radiobiological-models
#20
Somayeh Gholami, Hassan Ali Nedaie, Francesco Longo, Mohammad Reza Ay, Sharifeh A Dini, Ali S Meigooni
Purpose: The clinical efficacy of Grid therapy has been examined by several investigators. In this project, the hole diameter and hole spacing in Grid blocks were examined to determine the optimum parameters that give a therapeutic advantage. Methods: The evaluations were performed using Monte Carlo (MC) simulation and commonly used radiobiological models. The Geant4 MC code was used to simulate the dose distributions for 25 different Grid blocks with different hole diameters and center-to-center spacing...
October 2017: Journal of Medical Physics
journal
journal
32112
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"