Establishing inherent uncertainty in the shifts determined by volumetric imaging

2017 ◽  
Vol 16 (3) ◽  
pp. 258-264
Author(s):  
Upendra Kumar Giri ◽  
Anirudh Pradhan
Keyword(s):  
Linear Accelerator ◽  
Systematic Errors ◽  
Cone Beam ◽  
Random Errors ◽  
Mean Values ◽  
Volumetric Imaging ◽  
X Ray ◽  
Image Quality Control ◽  
The Mean ◽  
Six Degree Of Freedom

AbstractObjectiveThis study was conducted for establishing inherent uncertainty in the shift determination by X-ray volumetric imaging (XVI) and calculating margins due to this inherent uncertainty using van Herk formula.Material and methodsThe study was performed on the XVI which was cone-beam computed tomography integrated with the Elekta AxesseTM linear accelerator machine having six degree of freedom enabled HexaPOD couch. Penta-Guide phantom was used for inherent translational and rotational shift determination by repeated imaging. The process was repeated 20 times a day without moving the phantom for 30 consecutive working days. The measured shifts were used for margins calculation using van Herk formula.ResultsThe mean standard deviations were calculated as 0·05, 0·05, 0·06 mm in the three translational (x, y and z) and 0·05°, 0·05°, 0·05° in the three rotational axes (about x, y, z). Paired sample t-test was performed between the mean values of translational shifts (x, y, z) and rotational shifts. The systematic errors were found to be 0·03, 0·04 and 0·03 mm while the random errors were 0·05, 0·06 and 0·06 mm in the lateral, cranio-caudal and anterio-posterior directions, respectively. For the rotational shifts, the systematic errors were 0·02, 0·03 and 0·03 and the random errors were 0·06, 0·05 and 0·05 in the pitch, roll and yaw directions, respectively.ConclusionOur study concluded that there was an inherent uncertainty associated with the XVI tools, on the basis of these six-dimensional shifts, margins were calculated and recorded as a baseline for the quality assurance (QA) programme for XVI imaging tools by checking its reproducibility once in a year or after any major maintenance in hardware or upgradation in software. Although the shift determined was of the order of submillimetre order, still that shift had great significance for the image quality control of the XVI tools. Every departments practicing quality radiotherapy with such imaging tools should establish their own baseline value of inherent shifts and margins during the commissioning and must use an important QA protocol for the tools.

scholarly journals Analysis of the setup deviations generated in the 6D ExacTrac X-ray system for patients in hypofractionated intracranial radiosurgery treatments

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Maíra Milanelo Vasques ◽  
Victor Augusto Bertotti Ribeiro ◽  
Camila Pessoa Sales ◽  
Ana Paula Vollet Cunha ◽  
Caroline Zeppelini Emiliozzi
Keyword(s):  
Planning Target Volume ◽  
Imaging System ◽  
Systematic Errors ◽  
Target Volume ◽  
Mean Values ◽  
Single Fraction ◽  
X Ray ◽  
The Mean ◽  
Standard Deviations ◽  
Pre Treatment

The purpose of this study was to evaluate the use of the pre-treatment daily imaging system with the Brainlab ExacTrac X-Ray 6D for patients in hypofractionated intracranial treatments and radiosurgery procedures in order to quantify setups errors and review margins used by the institution in the current planning protocol. The deviations generated in the translational and rotational coordinates were given in terms of the mean values and their respective standard deviations. The random and systematic errors were determined through the Stroom and Wang relation and 36 patients treated with intracranial hypofractionated radiosurgery from August 2015 to October 2016 were evaluated. The prescribed dose was 25-30 Gy in 5 fractions for 30 patients and 12-18 Gy in a single fraction for 6 patients. The calculated margin for the planning target volume (PTV) from the deviations analyzed was 1.3mm, consistent with that adopted by the institution. When the correlation between the volume of the PTV, vector and its respective loss of coverage is evaluated and a tendency can be observed for smaller volumes to suffer greater losses in coverage when the isocenters were displaced with the resulting margins. We can suggest that for volumes smaller than 2.6 cm3, margins greater than 1 mm are required in order to guarantee the expected coverage of the PTV. 

scholarly journals Height difference between the vestibular and palatal walls and palatal width: a cone beam computed tomography approach

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
P. López-Jarana ◽  
C. M. Díaz-Castro ◽  
A. Falcão ◽  
C. Falcão ◽  
J. V. Ríos-Santos ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Bone Thickness ◽  
Height Difference ◽  
Mean Values ◽  
The Mean ◽  
Maxilla And Mandible ◽  
Palatal Bone ◽  
Two Parameters

Abstract Background The objective of this study was to measure two parameters involved in tri-dimensional implant planning: the position of the buccal and palatal bone wall and the palatal thickness. Methods Cone beam computed tomography (CBCT) images (Planmeca ProMax 3D) of 403 teeth (208 upper teeth and 195 lower teeth) were obtained from 49 patients referred to the Dental School of Seville from January to December 2014. The height difference between the palatal and buccal walls was measured on the most coronal point of both walls. The thickness of the palatal wall was measured 2 mm from the most coronal point of the palatal wall. Results The mean values in the maxilla were 1.7 ± 0.9 mm for central and lateral incisors, 2.2 ± 1.7 mm for canines, 1.6 ± 0.9 mm for premolars and 1.9 ± 1.5 mm for molars. In the lower jaw, the mean values were 1.3 ± 0.8 mm for incisors, 1.7 ± 1.2 mm for canines, 2.3 ± 1.3 mm for premolars, and 2.6 ± 1.7 mm for molars. In the upper jaw, more than 55% of maxillary teeth (excluding second premolars and molars) presented mean height differences greater than 1 mm. In the mandible, more than 60% of incisors showed a buccal bone thickness of 1 mm from the apical to lingual aspect. All teeth except the second premolar presented a buccal wall located more than 1 mm more apically than the lingual bone wall. Conclusions The buccal bone wall is located more apically (greater than 1 mm) than the palatal or lingual table in most of the cases assessed. The thickness of the palatal or lingual table is also less than 2 mm in the maxilla and mandible, except in the upper canines and premolars and the lower molars.

scholarly journals The correlation between the three-dimensional radiolucency area around the crown of impacted maxillary canines and dentigerous cysts

2020 ◽  
Vol 49 (4) ◽  
pp. 20190402
Author(s):  
Junliang Chen ◽  
Dongmei Lv ◽  
MingXia Li ◽  
Wei Zhao ◽  
Yun He
Keyword(s):  
Cone Beam Ct ◽  
Dentigerous Cyst ◽  
Three Dimensional ◽  
Cone Beam ◽  
Hard Tissue ◽  
Mean Values ◽  
Dentigerous Cysts ◽  
Impacted Canine ◽  
The Mean ◽  
Surgical Operations

This study aimed to reveal the correlation between the radiolucency area around the crown of impacted maxillary canines and dentigerous cysts using cone beam CT (CBCT). CBCT data were obtained from patients with impacted maxillary canines. Three points of five areas (tooth cusp area and buccal, lingual, mesial and distal areas of the crown) were randomly selected, and the distance between the point and the surrounding hard tissue was measured respectively. The mean values were recorded as the radiolucency area. These results were compared with the occurrence of dentigerous cysts during surgery. 58 patients with 76 impacted maxillary canines were included. 14 of the 76 impacted canines were accompanied by cysts (18.42%). With the increase in the thickness of the radiolucency area, the incidence of cysts was significantly increased (p < 0.05). No cysts were found in the compacted canines with 0–1 mm thickness of the radiolucency area. The highest incidence (71.43%) was observed in canines with 3–4 mm thickness of the radiolucency area. This study found that the thickness of the radiolucency area around the crown of the maxillary impacted canine was closely related to the occurrence of dentigerous cysts. CBCT can be used to estimate the occurrence possibility of dentigerous cyst and guide surgical operations.

How Accurate is Qcbed ? -- the Case of Rutile (TiO2)

2001 ◽  
Vol 7 (S2) ◽  
pp. 368-369
Author(s):  
B. Jiang ◽  
J. Friis ◽  
J.C.H. Spence
Keyword(s):  
Systematic Errors ◽  
Mean Value ◽  
Order Structure ◽  
Data Sets ◽  
X Ray ◽  
Silicon Crystals ◽  
Structure Factors ◽  
The Mean ◽  
Mott Formula ◽  
Better Than

An accuracy of better than 1% is needed to measure the changes in charge density due to bonding. Here we report an accuracy up to 0.025% (random error) obtained in rutile crystal structure factors measurement by QCBED. This error is the standard deviation in the mean value obtained from ten data sets. Systematic errors may be present. Figure 1 gives an example of the (200) refinement results. Table 1 lists several low order structure factor refinement results. The accuracy of the measured electron structure factors was 0.1-0.2% but after conversion to x-ray structure factors, the accuracy for low orders improved due to the Mott formula [1] For (110) and (101) reflections, the accuracy in x-ray structure factors became 0.025% and 0.048% respectively. This accuracy is equivalent to that of the X-ray single crystal Pendellosung method on silicon crystals [2].The experiments were done on a Leo 912 Omega TEM.

scholarly journals Articular Eminence Inclination, Height, and Condyle Morphology on Cone Beam Computed Tomography

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Dilhan İlgüy ◽  
Mehmet İlgüy ◽  
Erdoğan Fişekçioğlu ◽  
Semanur Dölekoğlu ◽  
Nilüfer Ersan
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Mean Value ◽  
Cone Beam ◽  
Articular Eminence ◽  
Age And Gender ◽  
Mean Values ◽  
The Mean ◽  
And Gender ◽  
The Relationship

Aim. The aim of the present study was to examine the relationship between articular eminence inclination, height, and thickness of the roof of the glenoid fossa (RGF) according to age and gender and to assess condyle morphology including incidental findings of osseous characteristics associated with osteoarthritis (OA) of the temporomandibular joint (TMJ) using cone beam computed tomography (CBCT).Materials and Methods. CBCT images of 105 patients were evaluated retrospectively. For articular eminence inclination and height, axial views on which the condylar processes were seen with their widest mediolateral extent being used as a reference view for secondary reconstruction. Condyle morphology was categorized both in the sagittal and coronal plane.Results. The mean values of eminence inclination and height of males were higher than those of females (P<0.05). There were significant differences in the RGF thickness in relation to sagittal condyle morphology. Among the group of OA, the mean value of the RGF thickness for “OA-osteophyte” group was the highest (1.59 mm), whereas the lowest RGF values were seen in the “OA-flattening.”Conclusion. The sagittal osteoarthritic changes may have an effect on RGF thickness by mechanical stimulation and changed stress distribution. Gender has a significant effect on eminence height (Eh) and inclination.

scholarly journals Study of the pterigidal canal (vidian canal) through images of cone beam computer tomography.

2020 ◽  
Vol 23 (3) ◽  
Author(s):  
Fernanda Fritoli Marcondes Santana ◽  
Marcos Paulo Motta Silveira ◽  
Pedro Jacy Santos Diamantino ◽  
Karolina Aparecida Castilho Fardim ◽  
Luiz Roberto Coutinho Manhães Júnior ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Close Contact ◽  
Close Relation ◽  
Cone Beam ◽  
Inferior Wall ◽  
Mean Values ◽  
Vidian Canal ◽  
Foramen Rotundum ◽  
The Mean ◽  
The Right

Objective: The aim of this study was to evaluate the pterygoid canal (PC) by Cone Beam Computed Tomography (CBCT), establishing its configuration and proximity with anatomical structures. Material and Methods: We evaluated 398 CBCT exams, all from a public University radiology clinic archive. Four parameters were evaluated: single or double PC, distance between PC and the inferior part of the sphenoid sinus (SS), ratio of PC and SS and the distance between the PC and the foramen rotundum. Results: It was observed that most of the PC of the sample presented simple morphology, the most frequent type of relationship between the PC and the SS on both sides was the close contact with the wall. Among the cases that there were some distances between the PC and the inferior wall of the SS, the mean of this distance did not exceed 3.20 mm, being the left side (3.03 mm) slightly closer than the right (3.20 mm). Finally, the distances between the PC and the corresponding Foramen Rotundum are presented with mean values of 5.87 mm for the right side and 6.31 mm for the left side. Conclusion: CBCT examination is of paramount importance for PC identification; once in the studied sample, the mean values found evidence the close relation between the PC and the SS.KeywordsCone beam computed tomography; Endonasal approach; Vidian canal.

scholarly journals Custom Focal Trough in Cone-Beam Computed Tomography Reformatted Panoramic Versus Digital Panoramic for Mental Foramen Position to Aid Implant Planning

2020 ◽  
Vol 10 ◽  
pp. 34
Author(s):  
Khaled Beshtawi ◽  
Emad Qirresh ◽  
Mohamed Parker ◽  
Shoayeb Shaik
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Mental Foramen ◽  
Reference Points ◽  
Cone Beam ◽  
Vertical Position ◽  
Linear Measurements ◽  
Mean Values ◽  
The Mean ◽  
High Level

Objectives: To compare the linear measurements from digital panoramic (DP) radiographs and cone-beam computed tomography (CBCT) volumes for the localization of the mental foramen (MF). Material and Methods: Thirty-one patients with panoramic and CBCT radiographs depicted on the same machine were analyzed. The vertical and horizontal positions of the MF were compared by the differences in distances measured from reference points to the boundaries (tangents) of the MF in digital panoramic (DP) and CBCT reformatted panoramic (CRP) views. The vertical position of MF was also analyzed on CBCT oblique coronal views (CORO) and compared with its corresponding distances on DP and CRP views. Results: Statistically significant differences (P < 0.05) were found in all compared measurements between CRP and DP views. In addition, the vertical distance (Y1) compared between DP, CRP, and CORO views also showed a statistically significant measurement discrepancy in the mean distance (P < 0.000) with the highest mean difference of 1.59 mm (P < 0.05) was attained from Y1 (DP-CORO). Inter- and intra-examiner analysis indicated a high level of agreement for all measurements. Conclusion: The mean values of discrepancies in measurements between DP and CRP views for horizontal and vertical linear measurements were clinically tolerable. Nevertheless, significant differences in the vertical MF position were detected between the panoramic views (DP, CRP) and the coronal views (CORO). This implies that the use of coronal view measurements during implant planning might reduce the risk of neurovascular injuries.

scholarly journals Second Root Canal in Mandibular Incisors: an Ex Vivo Cone-Beam Computed Tomography (CBCT) Study

2018 ◽  
Vol 22 (1) ◽  
pp. 38-42
Author(s):  
Maria Elpida Kalaitzoglou ◽  
Eleni Kantilieraki ◽  
Charalampos Beltes ◽  
Christos Angelopoulos ◽  
Panagiotis Beltes
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Root Canal ◽  
Ex Vivo ◽  
Cone Beam ◽  
Mean Values ◽  
Root Canals ◽  
The Mean ◽  
Type 3 ◽  
Mandibular Incisors

SummaryBackground/Aim: To analyze the internal morphology of mandibular incisors with two root canals using cone-beam computed tomography (CBCT). Material and Methods: 289 (143 central and 146 lateral) extracted intact mandibular incisors were radiographed for detection of a second root canal. The teeth presenting a second root canal were imaged with CBCT and evaluated regarding: root canal type, the distance of the cementoenamel junction (CEJ) to the bifurcation of the canals and the distance of the canal fusion to the apical foramen (in teeth in which canals rejoined). Results: Out of 143 central and 146 lateral mandibular incisors, 41 (28.7%) and 44 (30.1%) teeth respectively showed a second root canal. Types II, III, V and an additional type to Vertucci’s classification were identified. Type III was the most prevalent and presented in 30 (73.2%) central and 34 (77.3%) lateral mandibular incisors with two root canals. The mean values of the distance of the CEJ to the canal bifurcation were 4.2 mm and 4.0 mm for central and lateral mandibular incisors respectively. The mean values of the distance of the canal fusion to the apical foramen 5.5 mm and 5.1 mm for central and lateral mandibular incisors respectively. Conclusions: Mandibular incisors with two root canals mainly present with Vertucci’s Type 3 canal configuration. The canal bifurcation was identified mostly at the coronal and middle thirds of the root, while the canal fusion occurred in the middle third of the root.

Commissioning experience of the X-ray volume imaging system of an image-guided radiotherapy capable linear accelerator

2020 ◽  
pp. 1-6
Author(s):  
Payal Raina ◽  
Susanta Kumar Sahoo
Keyword(s):  
Linear Accelerator ◽  
Imaging System ◽  
Test Results ◽  
Image Guided Radiotherapy ◽  
Volumetric Imaging ◽  
X Ray ◽  
Image Guided ◽  
Volume Imaging ◽  
Quality Registration ◽  
Acceptance Tests

Abstract Aim: An image-guided radiotherapy capable linear accelerator was installed at our hospital which is equipped with an X-ray volumetric imaging (XVI) system. The aim of this study was to describe the results of acceptance tests which were carried out on the XVI facility to verify the manufacturer’s specification. Materials and methods: The commissioning test had six elements: system safety, geometric accuracy, image quality, registration and correction accuracy, X-ray tube and generator performance, and quality assurance (QA) procedures. Results: We had satisfactory results for all the tests. The system passed the safety testes, and the agreement of isocentres was found to be within the tolerance limit. Imaging quality was acceptable. Registration and correction accuracy was tasted with indigenously developed phantom and positioned accurately at isocentre. X-ray tube and generator test results showed that the tube was performing properly. Findings: The described tests represent that the performance of the system is maintained at acceptable levels.

A modified single breath method for estimation of cardiac output in humans at rest and during exercise

1987 ◽  
Vol 72 (4) ◽  
pp. 437-441 ◽  
Author(s):  
Y. M. H. Al-Shamma ◽  
R. Hainsworth ◽  
N. P. Silverton
Keyword(s):  
Cardiac Output ◽  
Normal Subjects ◽  
Random Errors ◽  
O2 Uptake ◽  
Mean Values ◽  
Single Breath ◽  
Expired Gas ◽  
The Mean ◽  
Rest And Exercise ◽  
Single Breath Method

1. This study was undertaken to determine the accuracy of a modification of a single breath method for estimation of cardiac output. The technique incorporated a single rebreathing stage followed by a prolonged expiration. Cardiac output was determined from the O2 uptake and the instantaneous changes in O2 and CO2 in the expired gas during the prolonged expiration. 2. The mean values and the random errors (determined from the differences between pairs of estimates) of cardiac outputs in normal subjects at rest and exercise were 5.42 and ± 0.60 litres/min (2 sd, 60 pairs) and 14.1 and ±1.8 litres/min (40 pairs). 3. Larger random errors were obtained in a group of cardiac patients but, except in hypoxic patients, the mean values obtained by the single breath and the direct (Fick) methods were almost identical. 4. We conclude that our modification of the single breath method is simple to use and sufficiently reliable for use in humans both at rest and during steady states of light exercise.

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