scholarly journals Evaluation of VMAT Planning Strategies for Prostate Patients with Bilateral Hip Prosthesis

2021 ◽  
Vol 20 ◽  
pp. 153303382110384
Author(s):  
David To ◽  
Ilma Xhaferllari ◽  
Manju Liu ◽  
Jian Liang ◽  
Cory Knill ◽  
...  
Keyword(s):  
Hip Prosthesis ◽  
Volumetric Modulated Arc Therapy ◽  
Field Analysis ◽  
Pass Rates ◽  
Hip Prostheses ◽  
Entrance Dose ◽  
Dose Volume ◽  
Significant Difference ◽  
Prescription Dose ◽  
Planning Strategies

Purpose: In this study, we investigate linac volumetric-modulated arc therapy (VMAT) planning strategies for bilateral hip prostheses prostate patients with respect to plan quality and deliverability, while limiting entrance dose to the prostheses. Methods: Three VMAT plans were retrospectively created for 20 patients: (1) partial arcs (PA), (2) 2 full arcs optimized with 500 cGy max prostheses dose (MD), and (3) 2 full arcs optimized with max dose-volume histogram (DVH) constraint of 500 cGy to 10% prostheses volume (MDVH). PA techniques contained 6 PA with beam angles that avoid entering each prosthesis. For each patient, other than prostheses constraints, the same Pinnacle VMAT optimization objectives were used. Plans were normalized with PTV D95% = 79.2 Gy prescription dose. Organ-at-risk DVH metrics, monitor units (MUs), conformality, gradient, and homogeneity indices were evaluated for each plan. Mean entrance prosthesis dose was determined in Pinnacle by converting each arc into static beams and utilizing only control points traversing each prosthesis. Plan deliverability was evaluated with SunNuclear ArcCheck measurements (gamma criteria 3%/2 mm) on an Elekta machine. Results: MD and MDVH had similar dosimetric quality, both improved DVH metrics for rectum and bladder compared to PA. Plan complexities among all plans were similar (average MUs: 441-518). Conformality, homogeneity, and gradient indices were significantly improved in MD and MDVH versus PA ( P < .001). Gamma pass rates for MD (99.0 ± 1.2%) and MDVH (99.2 ± 0.99%) were comparable. A significant difference over PA was observed (96.8 ± 1.6%, P < .001). Field-by-field analysis demonstrated 12/20 PA plans resulted in fields with pass rates <95% versus 1/20 plans for MD and none for MDVH. Cumulative mean entrance doses to each prosthesis were 62.9 ± 17.7 cGy for MD plans and 83.4 ± 27.5 cGy for MDVH plans. Conclusion: MD and MDVH plans had improved dosimetric quality and deliverability over PA plans with minimal entrance doses (∼1% of prescription) to each prosthesis and are an improved alternative for bilateral prostheses prostate patients.

Choice of appropriate beam model and gantry rotational angle for low-dose gradient-based craniospinal irradiation using volumetric-modulated arc therapy

2016 ◽  
Vol 16 (1) ◽  
pp. 53-64 ◽  
Author(s):  
Biplab Sarkar ◽  
Anirudh Pradhan
Keyword(s):  
Low Dose ◽  
Volumetric Modulated Arc Therapy ◽  
Craniospinal Irradiation ◽  
Leaf Width ◽  
Beam Model ◽  
Significant Difference ◽  
Arc Therapy ◽  
Prescription Dose ◽  
Flat Beam ◽  
The Impact

AbstractObjectivesWe aimed to assess the impact of advanced multileaf collimator (MLC) models and flattening filter-free (3F) beam in volumetric-modulated arc therapy (VMAT)-based craniospinal irradiation (CSI).MethodsCT scans of five medulloblastoma patients who previously received CSI at our hospital were used for the present study. Patients were planned for a prescription dose of 35 Gy to craniospinal axis. A three-dimensional conformal radiotherapy (3DCRT) plan and a VMAT plan using 1 cm MLC leaf width were generated as the gold standard (reference arm). Test VMAT plans were generated using Agility MLC model (MLC leaf width 5 mm) for various combinations of flattened beam (F) and 3F beam for treating the brain and spine planning target volume (PTV). Organs at risks (OARs) were analysed for dose 5, 50, 75 and 90% volumes, mean dose and maximum dose.ResultsAll 3DCRT plans and VMAT plans were aimed to cover 95% of PTV by at least 95% prescription dose. VMAT demonstrated lesser dose spillage than 3DCRT to body volume minus PTV (NTID: non tumor integral dose) for a dose threshold above 7·5 Gy. For the low-dose range (1–7 Gy), variation between the dose coverage between all VMAT plans (for either spine or brain PTV) was <1%. Intra-VMAT plan dose variation for all OAR’s for all tested parameters was <1 Gy. Average monitor unit (MU) difference among different VMAT plans ranged between 1·52 and 2·13 when normalised to 3DCRT MU. For VMAT plans, flat beam with 1 cm MLC showed the highest MU, whereas Agility MLC with 3F beam had the least MU values for intra-VMAT plans. No statistical significance variation (p) was observed in between reference arm and test arm plans except for mean dose and V107% for PTV spine. When compared between reference arm 3DCRT and test arm VMAT plans. For OAR’s, no statistical difference was observed between reference and test arm VMAT plans.ConclusionsReference arm plans and test arm plans exhibit no statistically significant difference. However, as compared with 3DCRT, VMAT plans are more conformal and produce lesser dose to OAR at the cost of higher delivered MU. 3F beams or finer width MLC’s (width <5 mm) have no advantage over the conventional 1 cm MLC and flat beam except that 3F beams have a shorter beam delivery time. This study demonstrate a significantly lesser spillage dose to NTID/body that of the reported literature, which is attributed to limited rotational arc length used for VMAT plans.

scholarly journals Considerations for the verification of volumetric modulated arc therapy-planned dose distributions

2019 ◽  
Vol 3 ◽  
Author(s):  
Lourens Strauss ◽  
William Shaw
Keyword(s):  
Error Detection ◽  
Volumetric Modulated Arc Therapy ◽  
Standard Of Care ◽  
Target Volume ◽  
Pass Rates ◽  
Dose Distributions ◽  
Dose Volume ◽  
Multi Leaf Collimator ◽  
Arc Therapy ◽  
Verification Systems

Background: Volumetric modulated arc therapy (VMAT) is the standard of care for many clinical indications, but should only be considered with proper technical support and quality assurance (QA) in place. Despite the high accuracy of VMAT systems, errors can be present and adequate verification is required. Dosimetric VMAT verification systems have a broadly similar analysis philosophy. However, many factors influence the analyses and the subsequent QA outcome, based on which the plan will pass or fail.Aim: This study investigated various factors that influence the dosimetric impact and detectability of known linac component deviations on VMAT QA, including geometries, tissue densities, gamma criteria and dose–volume differences.Setting: Universitas Hospital (Annex), Bloemfontein, South Africa.Methods: Deliberate multi-leaf collimator (MLC)-bank offsets were introduced on four different VMAT plans of the prostate, nasopharynx and brain. Measured reference dose sets were compared to measured QA results, using the IBA Dolphin© detector and Compass© software for three dosimetric scenarios. Gamma pass rates over a range of criteria from 1%/2-mm to 4%/4-mm in the total volumes and per structure, as well as dose–volume differences were studied.Results: Gamma tests in the total patient/phantom did not sufficiently detect errors. The calculation media did not influence the QA outcome greatly. However, the detection geometry affected the results. Per structure gamma analyses provided superior error detection, although still missed some clinically relevant differences. The addition of dose–volume analyses highlighted several important errors.Conclusion: Volumetric modulated arc therapy using only total volume gamma analyses can easily overlook clinically relevant errors. The choice of gamma criterion is crucial. Verification with at least a per structure gamma test in combination with dose–volume checks is recommended, especially in small target volume cases.

scholarly journals The Therapeutic Value of Volumetric-Modulated Arc Therapy In Advanced Non-Small Cell Lung Cancer Primary Tumors: A Multicenter Retrospective Analysis Based On Propensity Score Matching And Comparison With Intensity-Modulated Radiotherapy

2021 ◽  
Author(s):  
Jie Liu ◽  
Tao Li ◽  
Wang Xiaohu ◽  
Shengfa Su ◽  
Qingsong Li ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Volumetric Modulated Arc Therapy ◽  
Intensity Modulated Radiotherapy ◽  
Small Cell ◽  
Small Cell Lung ◽  
Primary Tumors ◽  
Intensity Modulated ◽  
Dose Volume ◽  
Significant Difference ◽  
Arc Therapy

Abstract Objective:.To explore the feasibility of volumetric-modulated arc therapy (VMAT) instead of intensity-modulated radiotherapy (IMRT) for primary tumors of advanced non–small-cell lung cancer (A-NSCLC). Methods:.We used propensity score matching (PSM) and multicenter retrospective analysis to study the efficacy and toxicity of VMAT technology in radiotherapy for primary tumors of A-NSCLC.We used the chi-squared test to analyze the response rate(RR), local control (LC), acute radiation injury, and dose-volume parameters; the Kaplan–Meier and log-rank tests were used to determine local-regional progression-free survival (LRPFS) and overall survival (OS). Results: LRPFS was significantly prolonged in stage III patients treated with IMRT before PSM (P< .05) and cases of grade 1 or 2 acute radiation esophagitis (RE) or radiation pneumonia(RP) in the IMRT than the VMAT(P< .05), but cases of grade 3 or 4 RE and RP were not significantly different between the groups (P> .05). Before PSM, there was no significant difference in the LRPFS and OS rates of the whole study group and the RR, LC, and stage IV subgroups, respectively (P> .05). After PSM, there was no significant difference in the RR, LC, LRPFS, OS, RP, or RE of patients treated with VMAT and IMRT (P> .05), normal whole-lung (V5, V20, MLD), heart (V30, V40, MHD), and equal dose-volume parameters were significantly lower in the VMAT group (P< .05).Conclusion:.Radiation therapy of A-NSCLC primary tumors using VMAT can achieve a similar efficacy to that of IMRT but with significantly lower low-dose volume parameters of normal tissues and organs; this is true especially in stage N2 cases, where the reduction in radiation damage may be more favorable.

Novel methods for demonstrating osseointegration of hydroxylapatite-coated titanium hip prostheses

1991 ◽  
Vol 49 ◽  
pp. 34-35 ◽  
Author(s):  
P. Frayssinet ◽  
J. Hanker ◽  
D. Hardy ◽  
B. Giammara
Keyword(s):  
Hip Prosthesis ◽  
Ethanol Concentration ◽  
Bone Matrix ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Hip Prostheses ◽  
Cellular Inclusions ◽  
Microscopic Studies ◽  
Diamond Saw ◽  
Plasma Sprayed

Prostheses implanted in hard tissues cannot be processed for electron microscopic examination or microanalysis in the same way as those in other tissues. For these reasons, we have developed methods allowing light and electron microscopic studies as well as microanalysis of the interface between bone and a metal biomaterial coated by plasma-sprayed hydroxylapatite(HA) ceramic.An HA-coated titanium hip prosthesis (Corail, Landos, France), which had been implanted for two years, was removed after death (unrelated to the orthopaedic problem). After fixation it was dehydrated in solutions of increasing ethanol concentration prior to embedment in polymethylmethacrylate(PMMA). Transverse femur sections were obtained with a diamond saw and the sections then carefully ground to a thickness of 200 microns. Plastic-embedded sections were stained for calcium with a silver methenamine modification of the von Kossa method for calcium staining and coated by carbon. They have been examined by back-scatter SEM on an ISI-SS60 operated at 25 KV. EDAX has been done on cellular inclusions and extracellular bone matrix.

Analysis of 18F-FDG uptake patterns in PET for diagnosis of septic and aseptic loosening after total hip arthroplasty

2003 ◽  
Vol 42 (06) ◽  
pp. 234-239 ◽  
Author(s):  
T. Mumme ◽  
P. Reinartz ◽  
D. Wirtz ◽  
F. U. Niethard ◽  
U. Büll ◽  
...  
Keyword(s):  
Aseptic Loosening ◽  
Femoral Component ◽  
Hip Prosthesis ◽  
Prosthetic Infection ◽  
Clinical Value ◽  
Septic Loosening ◽  
Hip Prostheses ◽  
Fdg Uptake ◽  
Positron Emission ◽  
Painful Hip

Summary Aim: Identification of typical patterns for fluorodeoxyglucose (FDG) uptake in positron emission tomography (PET) to detect aseptic loosening of hip prosthesis (ace-tabular and/or femoral component) and prosthetic infection. Methods: 18 patients with painful hip prosthesis underwent PET using a dedicated full ring scanner after application of 200-300 MBq FDG. The interface between bone and surrounding soft tissue or bone as displayed on coronal slices was divided into 12 segments in accordance with the classifications of Delee and Gruen. FDG uptake in each of the segments was scored (0-3) by two independent observers. Intraoperative findings were regarded as the gold standard. Results: After surgical revision 14 acetabular components and 9 femoral components were found to be loose and prosthetic infection was present in 7 prostheses. Loosening of the acetabular component was correlated to enhanced uptake in the middle of the acetabular interface, while loosening of the femoral component was correlated to enhanced uptake in the proximal and middle segment of the lateral femoral interface and the proximal segment of the medial femoral interface. A similar pattern was found in prosthetic infection with high uptake along the middle portion of the lateral fe-moral interface. In 6 of 7 infected prostheses loosening of the acetabular and of the femoral component was present. Taking the typical uptake patterns as criteria for loosening and grade 3 uptake as an additional criterion for septic loosening the accuracy of PET imaging in the detection of loosening of the acetabular or the femoral component and of prosthetic infection was 72, 78 and 89%, respectively. Conclusion: This pilot study presents FDG-PET as a promising diagnostic tool for patients with painful hip prostheses. Its clinical value should be evaluated in a larger patient population.

scholarly journals Volumetric Modulated Arc Radiotherapy for Early Stage Non-Small-Cell Lung Carcinoma: Is It Better Than the Conventional Static Beam Intensity Modulated Radiotherapy?

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Vincent Wing Cheung Wu ◽  
Man In Pun ◽  
Cho Pan Lam ◽  
To Wing Mok ◽  
Wah Wai Mok
Keyword(s):  
Early Stage ◽  
Small Cell Lung Carcinoma ◽  
Volumetric Modulated Arc Therapy ◽  
Intensity Modulated Radiotherapy ◽  
Small Cell ◽  
Small Cell Lung ◽  
Cell Lung Carcinoma ◽  
Intensity Modulated ◽  
Significant Difference ◽  
Arc Therapy

This study compared the performance of volumetric modulated arc therapy (VMAT) techniques: single arc volumetric modulated arc therapy (SA-VMAT) and double arc volumetric modulated arc therapy (DA-VMAT) with the static beam conventional intensity modulated radiotherapy (C-IMRT) for non-small-cell lung carcinoma (NSCLC). Twelve stage I and II NSCLC patients were recruited and their planning CT with contoured planning target volume (PTV) and organs at risk (OARs) was used for planning. Using the same dose constraints and planning objectives, the C-IMRT, SA-VMAT, and DA-VMAT plans were optimized. C-IMRT consisted of 7 static beams, while SA-VMAT and DA-VMAT plans consisted of one and two full gantry rotations, respectively. No significant difference was found among the three techniques in target homogeneity and conformity. Mean lung dose in C-IMRT plan was significantly lower than that in DA-VMAT plan P=0.04. The ability of OAR sparing was similar among the three techniques, with no significant difference in V20, V10, or V5 of normal lungs, spinal cord, and heart. Less MUs were required in SA-VMAT and DA-VMAT. Besides, SA-VMAT required the shortest beam on time among the three techniques. In treatment of early stage NSCLC, no significant dosimetric superiority was shown by the VMAT techniques over C-IMRT and DA-VMAT over SA-VMAT.

Improving Tribological Characteristics of Hip Prostheses Using Biocompatible Nanocoatings

2013 ◽  
Vol 741 ◽  
pp. 67-72 ◽  
Author(s):  
Gheorghe I. Gheorghe ◽  
Liliana Laura Badita
Keyword(s):  
Hip Prosthesis ◽  
Protective Coatings ◽  
Scratch Resistance ◽  
Hip Prostheses ◽  
Force Microscopy ◽  
Tin Coatings ◽  
Femoral Heads ◽  
Before And After ◽  
Tin Thin Films ◽  
Steel Substrates

Total hip prosthesis (THP) is the most success of the 20th century in orthopaedic biomedical engineering. However due to difficult conditions within the human body its durability is generally limited to 15-16 years. THP is a bio-tribosystem, on which many mechanical, thermal, chemical and biological factors act. This paper presents the results of an analysis regarding the topography and tribological parameters of femoral heads structures before and after TiN coating. We report on the synthesis of TiN thin films on steel substrates by pulsed laser deposition (PLD) method for improving the mechanical characteristics of the structures. Adhesion resistance of the coating on the sub-layer was evaluated by scratching tests accompanied by Optical Microscopy (OM), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). As a principal result, this work points out that TiN protective coatings deposited by PLD technique with the maximum number of pulses can represent an alternative technology to ensure adhesion and scratch resistance of TiN coatings on femoral heads.

scholarly journals Treatment planning comparison of volumetric modulated arc therapy with Trilogy and Halcyon for bilateral breast cancer

2021 ◽  
Author(s):  
Tao Sun ◽  
Xiutong Lin ◽  
Guifang Zhang ◽  
Qingtao Qiu ◽  
Chengqiang Li ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Treatment Planning ◽  
Volumetric Modulated Arc Therapy ◽  
Bilateral Breast Cancer ◽  
Planning System ◽  
Skin Dose ◽  
Delivery Time ◽  
Dose Volume ◽  
Arc Therapy ◽  
The Mean

Abstract Background: The Halcyon is a new machine from the Varian company. The purpose of this study was to evaluate the dosimetry of the Halcyon in treatment of bilateral breast cancer with volumetric modulated arc therapy. Methods: On CT images of 10 patients with bilateral breast cancer, four Halcyon plans with different setup fields were generated, and dosimetric comparisons using Bonferroni’s multiple comparisons test were conducted among the four plans. Whole and partial arc plans on the Trilogy and the Halcyon, referred to as T-4arc, T-8arc, H-4arc and H-8arc, were designed. The prescription dose was 50 Gy in 2-Gy fractions. All plans were designed with the Eclipse version 15.5 treatment planning system. The dosimetric differences between whole and partial arc plans in the same accelerator were compared using the Mann-Whitney U test. The better Halcyon plan was selected for the further dosimetric comparison of the plan quality and delivery efficiency between the Trilogy and the Halcyon. Results:Halcyon plans with high‐quality megavoltage cone beam CT setup fields increased the Dmean, D2 and V107 of the planning target volume (PTV) and the V5 and Dmean of the heart, left ventricle (LV) and lungs compared with other Halcyon setup plans. The mean dose and low dose volume of the heart, lungs and liver were significantly decreased in T-8arc plans compared to T-4arc plans. In terms of the V5, V20, V30, V40 and Dmean of the heart, the V20, V30, V40 and Dmean of the LV, the V30, V40, Dmax and Dmean of the left anterior descending artery (LAD), and the V5 and V40 of lungs, H-8arc was significantly higher than H-4arc (p<0.05). Compared with the Trilogy’s plans, the Halcyon’s plans reduced the high-dose volume of the heart and LV but increased the mean dose of the heart. For the dose of the LAD and the V20 and V30 of lungs, there was no significant difference between the two accelerators. Compared with the Trilogy, plans on the Halcyon significantly increased the skin dose but also significantly reduced the delivery time. Conclusion: For the Halcyon, the whole-arc plans have more dosimetric advantages than partial-arc plans in bilateral breast cancer radiotherapy. Although the mean dose of the heart and the skin dose are increased, the doses of the cardiac substructure and other OARs are comparable to the Trilogy, and the delivery time is significantly reduced.

The Porous-Coated Anatomic (PCA) Total Hip Prosthesis

1994 ◽  
Vol 4 (2) ◽  
pp. 69-74
Author(s):  
P. Farsetti ◽  
R. Caterini ◽  
V. Barletta ◽  
A. E. Guarnieri ◽  
E. Ippolito
Keyword(s):  
Hip Prosthesis ◽  
Bone Ingrowth ◽  
Gluteus Medius ◽  
Radiographic Examination ◽  
Total Hip Prosthesis ◽  
Rating Score ◽  
Hip Prostheses ◽  
Total Hip ◽  
Total Hip Prostheses

Thirty uncemented porous-coated anatomic (PCA) total hip prostheses were implanted in 27 patients. The average age at the time of surgery was 54 years, and the average follow-up was 4.5 years. The average hip rating score was 88 points. Three patients had thigh pain at follow-up and fifteen had a mild limp, related to a weakness of the gluteus medius and minimus. On radiographic examination, we observed a good bone ingrowth of the implant in all patients. No aseptic loosening was radiographically demonstrated. No relationship was found between pain in the thigh and the various radiographic parameters studied (ra-diodense lines, sclerosis, varus position of the stem).

A Survey of Neurological Surgery Residency Program Mentorship Practices Compared to Accreditation Council for Graduate Medical Education Resident Outcome Data

Neurosurgery ◽  
2019 ◽  
Vol 87 (5) ◽  
pp. E566-E572 ◽  
Author(s):  
Nickalus R Khan ◽  
Pamela L Derstine ◽  
Andrew J Gienapp ◽  
Paul Klimo ◽  
Nicholas M Barbaro
Keyword(s):  
Medical Education ◽  
Graduate Medical Education ◽  
Scholarly Activity ◽  
Pass Rates ◽  
Mentorship Program ◽  
Accreditation Council ◽  
Graduate Medical ◽  
Significant Difference ◽  
Survey Results ◽  
Mentorship Programs

Abstract Mentorship can be a powerful and life-altering experience during residency training, but there are few articles discussing mentorship models within neurosurgery. In this study, we surveyed US neurosurgical department mentorship practices and linked them to resident outcomes from the Accreditation Council for Graduate Medical Education (ACGME), including resident survey responses, board pass rates, and scholarly activity. A 19-question survey was conducted from October to December 2017 with the assistance of the Society of Neurological Surgeons. De-identified data were then obtained from the ACGME and correlated to these results. Out of 110 programs, 80 (73%) responded to the survey and gave informed consent. The majority (65%) had a formal mentorship program and assigned mentor relationships based on subspecialty or research interest. Barriers to mentorship were identified as time and faculty/resident “buy-in.” Mentorship programs established for 5 or more years had superior resident ACGME outcomes, such as board pass rates, survey results, and scholarly activity. There was not a significant difference in ACGME outcomes among programs with formal or informal/no mentorship model (P = .17). Programs that self-identified as having an “unsuccessful” mentorship program had significant increases in overall negative resident evaluations (P = .02). Programs with well-established mentorship programs were found to have superior ACGME resident survey results, board pass rates, and more scholarly activity. There was not a significant difference among outcomes and the different models of formal mentorship practices. Barriers to mentorship, such as time and faculty/resident “buy-in,” are identified.

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