scholarly journals A retrospective comparison of two different immobilization systems for radiotherapy of extremity soft tissue sarcomas and its influence on CTV-PTV margin

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Reham Mohamed ◽  
Muhammad Shuja ◽  
Asaad Al-Hazienh ◽  
Moamen Aly
Keyword(s):  
Lateral Displacement ◽  
Soft Tissue Sarcomas ◽  
Target Volume ◽  
Random Errors ◽  
Setup Errors ◽  
Vector Error ◽  
Retrospective Comparison ◽  
Wide Range ◽  
Pre Treatment ◽  
Radiotherapy Treatment

Abstract Background On account of extremity wide range of movements and difficulty of reproducibility during irradiation of extremity sarcomas, assorted immobilization strategies are employed to eliminate setup errors. The study purpose was to compare the setup errors of the commonly used immobilization tools and to define planning target volume (PTV) margins for each device. Methods A retrospective review comparing Vac-Loc™ and thermoplastic cast (Tcast) was conducted. On radiotherapy treatment, portal imaging was matched with the pre-treatment simulation imaging for both fixation tools. The isocenter shifts and total vector error (TVE) were compared. Random (σ) and systemic errors (Σ) were computed and PTV margins were defined. Results Three hundred seven shifts in each direction measured in 14 patients. Mean displacements for the Vac-Loc™ and Tcast, respectively, were as follow: vertical; -0.01 cm vs. 0.02 cm, longitudinal; 0.03 cm vs. 0.04; lateral; 0.04 cm vs. 0.00 cm and TVE; 0.15 cm vs. 0.17 cm with no significant statistical difference. Random and systemic errors were comparable for both devices. The lateral displacement and rotational random errors were higher Vac-Loc™ compared to Tcast. Overall measured PTV margins were marginally lower for Tcast compared to Vac-Loc™. Conclusion Vac-Loc™ and Tcast are valid options for immobilization with no clear superiority of either device. The marginal advantage of Tcast warrants further prospective studies.

scholarly journals Does the protocol-required uniform margin around the CTV adequately account for setup inaccuracies in whole breast irradiation?

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Jurui Luo ◽  
Zhihai Yin ◽  
Zhen Zhang ◽  
Xiaomao Guo ◽  
Xiaoli Yu ◽  
...  
Keyword(s):  
Intensity Modulated Radiation Therapy ◽  
Patient Characteristics ◽  
Breast Conserving Surgery ◽  
Target Volume ◽  
Tumor Location ◽  
Patient Specific ◽  
Whole Breast Irradiation ◽  
Breast Irradiation ◽  
Setup Errors ◽  
Pre Treatment

Abstract Purpose To use cone-beam computed tomography (CBCT) imaging to determine the impacts of patient characteristics on the magnitude of geometric setup errors and obtain patient-specific planning target volume (PTV) margins from the correlated patient characteristics in whole breast irradiation (WBI). Methods Between January 2019 and December 2019, a total of 97 patients who underwent breast-conserving surgery, followed by intensity-modulated radiation therapy in WBI, were scanned with pre-treatment CBCT for the first three treatment fractions and weekly for the subsequent fractions. Setup errors in the left–right (LR), superior–inferior (SI) and anterior–posterior (AP) directions were recorded and analyzed with patient characteristics—including age, tumor location, body mass index (BMI), chest circumference (CC) and breast volume (BV)—to examine the predictors for setup errors and obtain specific PTV margins. Results A total of 679 CBCT images from 97 patients were acquired for analysis. The mean setup errors for the whole group were 2.32 ± 1.21 mm, 3.71 ± 2.21 mm and 2.75 ± 1.56 mm in the LR, SI and AP directions, respectively. Patients’ BMI, CC and BV were moderately associated with setup errors, especially in the SI directions (R = 0.40, 0.43 and 0.22, respectively). Setup errors in the SI directions for patients with BMI > 23.8 kg/m2, CC > 89 cm and BV > 657 cm3 were 4.56 ± 2.59 mm, 4.77 ± 2.42 mm and 4.30 ± 2.43 mm, respectively, which were significantly greater than those of patients with BMI ≤ 23.8 kg/m2, CC ≤ 89 cm and BV ≤ 657 cm3 (P < 0.05). Correspondingly, the calculated PTV margins in patients with BMI > 23.8 kg/m2, CC > 89 cm and BV > 657 cm3 were 4.25/7.95/4.93 mm, 4.37/7.66/5.24 mm and 4.22/7.54/5.29 mm in the LR/SI/AP directions, respectively, compared with 3.64/4.64/5.09 mm, 3.31/4.50/4.82 mm and 3.29/5.74/4.73 mm for BMI ≤ 23.8 kg/m2, CC ≤ 89 cm and BV ≤ 657 cm3, respectively. Conclusions The magnitude of geometric setup errors was moderately correlated with BMI, CC and BV. It was recommended to set patient-specific PTV margins according to patient characteristics in the absence of daily image-guided treatment setup.

scholarly journals Organ motion in linac-based SBRT for glottic cancer

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Annarita Perillo ◽  
Valeria Landoni ◽  
Alessia Farneti ◽  
Giuseppe Sanguineti
Keyword(s):  
Early Stage ◽  
Displacement Vector ◽  
Thyroid Cartilage ◽  
Three Dimensional ◽  
Target Volume ◽  
Glottic Cancer ◽  
Organ Motion ◽  
Delivery Times ◽  
Significant Difference ◽  
Pre Treatment

Abstract Purpose The purpose of this study is to evaluate inter- and intra-fraction organ motion as well as to quantify clinical target volume (CTV) to planning target volume (PTV) margins to be adopted in the stereotactic treatment of early stage glottic cancer. Methods and materials Stereotactic body radiotherapy (SBRT) to 36 Gy in 3 fractions was administered to 23 patients with early glottic cancer T1N0M0. Patients were irradiated with a volumetric intensity modulated arc technique delivered with 6 MV FFF energy. Each patient underwent a pre-treatment cone beam computed tomography (CBCT) to correct the setup based on the thyroid cartilage position. Imaging was repeated if displacement exceeded 2 mm in any direction. CBCT imaging was also performed after each treatment arc as well as at the end of the delivery. Swallowing was allowed only during the beam-off time between arcs. CBCT images were reviewed to evaluate inter- and intra-fraction organ motion. The relationships between selected treatment characteristics, both beam-on and delivery times as well as organ motion were investigated. Results For the population systematic (Ʃ) and random (σ) inter-fraction errors were 0.9, 1.3 and 0.6 mm and 1.1, 1.3 and 0.7 mm in the left-right (X), cranio-caudal (Y) and antero-posterior (Z) directions, respectively. From the analysis of CBCT images acquired after treatment, systematic (Ʃ) and random (σ) intra-fraction errors resulted 0.7, 1.6 and 0.7 mm and 1.0, 1.5 and 0.6 mm in the X, Y and Z directions, respectively. Margins calculated from the intra-fraction errors were 2.4, 5.1 and 2.2 mm in the X, Y and Z directions respectively. A statistically significant difference was found for the displacement in the Z direction between patients irradiated with > 2 arcs versus ≤ 2 arcs, (MW test, p = 0.038). When analyzing mean data from CBCT images for the whole treatment, a significant correlation was found between the time of delivery and the three dimensional displacement vector (r = 0.489, p = 0.055), the displacement in the Y direction (r = 0.553, p = 0.026) and the subsequent margins to be adopted (r = 0.626, p = 0.009). Finally, displacements and the subsequent margins to be adopted in Y direction were significantly greater for treatments with more than 2 arcs (MW test p = 0.037 and p = 0.019, respectively). Conclusions In the setting of controlled swallowing during treatment delivery, intra-fraction motion still needs to be taken into account when planning with estimated CTV to PTV margins of 3, 5 and 3 mm in the X, Y and Z directions, respectively. Selected treatments may require additional margins.

scholarly journals Focusing of Particles in a Microchannel with Laser Engraved Groove Arrays

Biosensors ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 263
Author(s):  
Tianlong Zhang ◽  
Yigang Shen ◽  
Ryota Kiya ◽  
Dian Anggraini ◽  
Tao Tang ◽  
...  
Keyword(s):  
Open Space ◽  
Lateral Displacement ◽  
Reynolds Numbers ◽  
Secondary Flows ◽  
Particle Sedimentation ◽  
Nanoparticle Separation ◽  
Wide Range ◽  
Fs Laser ◽  
Channel Bottom ◽  
Myoblast Cells

Continuous microfluidic focusing of particles, both synthetic and biological, is significant for a wide range of applications in industry, biology and biomedicine. In this study, we demonstrate the focusing of particles in a microchannel embedded with glass grooves engraved by femtosecond pulse (fs) laser. Results showed that the laser-engraved microstructures were capable of directing polystyrene particles and mouse myoblast cells (C2C12) towards the center of the microchannel at low Reynolds numbers (Re < 1). Numerical simulation revealed that localized side-to-center secondary flows induced by grooves at the channel bottom play an essential role in particle lateral displacement. Additionally, the focusing performance proved to be dependent on the angle of grooves and the middle open space between the grooves based on both experiments and simulation. Particle sedimentation rate was found to critically influence the focusing of particles of different sizes. Taking advantage of the size-dependent particle lateral displacement, selective focusing of micrometer particles was demonstrated. This study systematically investigated continuous particle focusing in a groove-embedded microchannel. We expect that this device will be used for further applications, such as cell sensing and nanoparticle separation in biological and biomedical areas.

scholarly journals Conventional 3D staging PET/CT in CT simulation for lung cancer: impact of rigid and deformable target volume alignments for radiotherapy treatment planning

2011 ◽  
Vol 84 (1006) ◽  
pp. 919-929 ◽  
Author(s):  
G G Hanna ◽  
J R Van Sörnsen De Koste ◽  
K J Carson ◽  
J M O'Sullivan ◽  
A R Hounsell ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Treatment Planning ◽  
Target Volume ◽  
Radiotherapy Treatment Planning ◽  
Pet Ct ◽  
Ct Simulation ◽  
Radiotherapy Treatment

Etiology of Ventricular Septal Defects: An Epidemiologic Approach

PEDIATRICS ◽  
1985 ◽  
Vol 76 (5) ◽  
pp. 741-749
Author(s):  
Thomas B. Newman
Keyword(s):  
The United States ◽  
Incidence Rates ◽  
Identical Twins ◽  
Random Errors ◽  
Ventricular Septal Defects ◽  
Metabolic Disturbances ◽  
Cardiac Morphogenesis ◽  
Septal Defects ◽  
Wide Range ◽  
History Of

To investigate the recent 150% increase in the reported incidence of ventricular septal defects (VSDs) in the United States, the epidemiology of ventricular septal defects was examined. The apparent incidence of VSDs is highly dependent on case finding methods, and more complete diagnosis and reporting probably account for the increase in reported incidence. Variations in case ascertainment also account for the small differences in incidence in studies from different places. The several known risk factors for VSD, including a family history of congenital heart disease and exposure to certain drugs, infectious agents, and maternal metabolic disturbances, explain few cases. Incidence rates are similar in different races and seasons and are unrelated to maternal age, birth order, sex, and socioeconomic status. VSDs occur naturally in a wide range of mammals and in birds, which also have four-chambered hearts. Despite identical genes and similar prenatal environments, the concordance rate in identical twins is only about 10%. The consistency of incidence among individuals with widely differing genes and environments and the frequency of discordance in identical twins suggest that VSDs often occur as random errors in development, at a frequency largely determined by the complexity of normal cardiac morphogenesis. This hypothesis has two major implications: many VSDs are not preventable and parents need not feel responsible for VSDs in their children.

scholarly journals Paradigmaváltás szükségessége a sugárterápiában

2015 ◽  
Vol 156 (44) ◽  
pp. 1763-1768
Author(s):  
Árpád Mayer ◽  
Csilla Katona ◽  
Róbert Farkas ◽  
Zsuzsa Póti
Keyword(s):  
Spinal Cord ◽  
Radiation Injury ◽  
Volumetric Modulated Arc Therapy ◽  
Target Volume ◽  
Intensity Modulated ◽  
The Past ◽  
Arc Therapy ◽  
Intracranial Metastases ◽  
The Status ◽  
Radiotherapy Treatment

The status and indications of radiotherapy have significantly changed in the past decade because novel techniques, radiobiological research and major advances in informatics have made better local control possible. Using supplemented marking of the target volume with computer tomography based other image-making methods adapted made it possible to define the tumor and intact surrounding tissues more precisely. With novel radiotherapy techniques the dosage of the homogenity and the covering in the target volume can be raised optimally, especially with intensity modulated arc radiotherapy (volumetric modulated arc therapy) without causing radiation injury or damage to intact surrounding tissues. Furthermore, with novel techniques and target volume marking, new indications have appeared in clinical practice and besides sterotactic radiotherapy for intracranial metastases, the extracranial so-called oligometastic conditions can be maintained close to a curative state (or in remission) for many years. Among these, perhaps the most striking is the stereotactic radiotherapy treatment of liver, lung and spinal cord metastases in one or more fractions, for which the indispensable condition is the image or respiratory guided technique. Orv. Hetil., 2015, 156(44), 1763–1768.

scholarly journals Efficacy of Synthetic Pesticides Against Thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae) on Okra Abelmoschus esculentus (L.) Moench

2021 ◽  
Vol 13 (9) ◽  
pp. 148
Author(s):  
Hira Mannan ◽  
Qurban Ali Nahiyoon ◽  
Jilian Li
Keyword(s):  
Insect Pests ◽  
Thrips Tabaci ◽  
Abelmoschus Esculentus ◽  
Vegetable Crops ◽  
Vegetable Crop ◽  
Agronomic Crops ◽  
Wide Range ◽  
Field Efficacy ◽  
Synthetic Pesticides ◽  
Pre Treatment

Okra (Abelmoschus esculentus L.) is an essential vegetable crop with good nutritional significance. Insect pests are the major threat for poor production of the okra crop. Thrips of vegetable crops are known to be serious pests on a wide range of fruit, vegetable, flower, and agronomic crops. The present field study was carried out to know the efficacy of different insecticides (acetamiprid 19% weightable water (ww), lambda 25% ww, colarphipare 32% ww, lambda 2.5% ww and abamectin 1.3% ww) against Thrips, Thrips tabaci (Lindeman) on okra crop during the year 2019, and observations against T. tabaci (Lindeman) were recorded after 24 hrs, 48 hrs, 72 hrs and 07 days of each spray in all the treatments. The pre-treatment count of thrips on okra was non-significant (P &gt; 0.05); while the evaluated efficacy of different insecticides against thrips was significant (P &lt; 0.01). It was noted that all the insecticides showed their highest efficacy after 7 days of spray and acetamiprid 19% weightable water (ww) was more efficient to combat the T. tabaci as compared to other pesticides that produced field efficacy of 73.92 and 74.91% against thrips after 7 days of 1st and 2nd spray respectively. Abamectin, 1.3% ww, was reasonably successful, yielding 53.81 and 56.66% field efficacy against T. tabaci (Lindeman) after 7 days of first and second spray. Also, moderately effective was colarphipare 32% ww, which developed field effectiveness of 56.41 and 61.49% against T. tabaci (Lindeman) after 7 days of first and second spray, respectively.

scholarly journals ACTIVE INVOLVEMENT OF RADIOLOGIST IN RADIATION ONCOLOGY PRACTICE

2021 ◽  
Vol 10 (4) ◽  
pp. 3199-3201
Author(s):  
Anurag A. Luharia
Keyword(s):  
Radiation Oncology ◽  
Normal Tissue ◽  
Radiation Treatment ◽  
Imaging Modality ◽  
Tumour Volume ◽  
Target Volume ◽  
Ct Images ◽  
Radiotherapy Planning ◽  
Internal Target Volume ◽  
Radiotherapy Treatment

Advancements in Radiation Oncology from conventional to 3D conformal radiotherapy treatment demands expertise in many steps of radiation planning, the horizon of radiologist is now expanded by many folds and made radiologist as a integral part of the Radiation Oncology Department. A critical aspect of radiotherapy treatment planning (RTP) is determining how to deliver the required radiation dosage to cancer cells while minimising the exposure to normal tissue for which the prerequisite is identification and accurate delineation of tumour volume as well as normal structure resulted in an increase in the therapeutic ratio by reducing complication associated with normal tissue and allowing for higher target dosage and better local control. In modern radiotherapy CT images are the standard set of imaging modality required for the radiotherapy planning along with it many other modalities like MRI, PET or DSA are used by superimposing on original CT images in order to contour or delineate the structures defined by International Commission on Radiation Units and Measurements in Reports 50, 62 and 71 (ICRU) for radiotherapy planning which comprise of Gross tumour volume, clinical target volume, planning target volume, irradiated volume, Internal target volume and the normal structures as Organ at risk. It is self-evident that the contribution of a radiologist with a thorough knowledge of the development of these new modalities is critical for optimising the potential of these novel modes of radiation treatment delivery.

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