Optimisation of Varian TrueBeam head, thorax and pelvis CBCT based on patient size

Abstract Purpose: The aim of this study was to optimise patient dose and image quality of Varian TrueBeam cone beam computed tomography (CBCT) pelvis, thorax and head and neck (H&N) images based on patient size. Methods: An elliptical phantom of small, medium and large size was designed representative of a local population of pelvis, thorax and H&N patients. The phantom was used to establish the relationship between image noise, CT and CBCT exposure settings. Using this insight, clinical images were optimised in phases and the image quality graded qualitatively by radiographers. At each phase, the time required to match the images was recorded from the record and verify system. Results: Average patient diameter was a suitable metric to categorise patient size. Phantom measurements showed the power relationship between noise and CBCT exposure settings of value −0·15, −0·35 and −0·43 for thorax, pelvis and H&N, respectively. These quantitative phantom measurements provided confidence that phased variation of ~±20% in mAs should result in clinically usable images. Qualitative assessment of almost 2000 images reduced the exposure settings in H&N images by −50%, thorax images by up to −66% and pelvis images by up to −80%. These optimised CBCT settings did not affect the time required to match images. Findings: Varian TrueBeam CBCT mAs settings have been optimised for dose and image quality based on patient size for three treatment sites: pelvis, thorax and H&N. Quantitative phantom measurements provided insight into the magnitude of change to implement clinically. The final optimised exposure settings were determined from radiographer qualitative image assessment.

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Can the BMI-Based Dose Regimen be Used to Reduce Injection Activity and to Obtain a Constant Image Quality in Oncological Patients by 18F-FDG Total-Body PET/CT Imaging?

10.21203/rs.3.rs-402099/v1 ◽

2021 ◽

Author(s):

Jie Xiao ◽

Haojun Yu ◽

Xiuli Sui ◽

Yan Hu ◽

Cao Yanyan ◽

...

Keyword(s):

Image Quality ◽

Dose Regimen ◽

Qualitative Assessment ◽

Acquisition Time ◽

Quadratic Relation ◽

Patient Cohort ◽

Oncological Patients ◽

Pet Ct ◽

Patient Size ◽

Total Body

Abstract Purpose PET image quality is influenced by the patient size according to the current guideline. The purpose was to propose an optimized dose regimen to yield a constant image quality independent of patient size to meet the clinical needs.Methods A first patient cohort of 78 consecutives for oncological patients (59.7±13.7 years) who underwent a total-body PET/CT scan were retrospectively enrolled to develop the regimen. The patients were equally distributed in four BMI groups according to WHO criteria. The liver SNR (Signal noise ratio, SNRL) was obtained through manually drawing ROIs and normalized (SNRnorm) by the injected activity and acquisition time. And fits of SNRnorm against different patient-dependent parameters were performed to determine the best correlating parameter and fit method. A qualitative assessment on image quality was performed using a 5-point Likert scale to determine the acceptable threshold of SNRL. And thus, an optimized regimen was proposed and validated by a second patient cohort with prospectively enrolled 38 oncological patients. Results The linear fit showed SNRnorm was the strongest correlation (R2 = 0.69) with the BMI than other patient-dependent parameters. The qualitative assessment revealed a SNRL of 14.0 as a threshold to achieve a sufficient image quality. The optimized dose regimen was determined as a quadratic relation with BMI: Injected activity = 39.2 MBq/(-0.03*BMI+1.49)2. In the validation study, the SNRL no longer decreased with the increase of BMI. There was no significant difference of the image quality, the SNRL, between different BMI groups (p > 0.05). In addition, the injected activity was reduced by 75.6±2.9 %, 72.1±4.0 %, 67.1±4.4 % and 64.8±3.5 % compared to the first cohort for the four BMI groups, respectively.Conclusion The study recommended a quadratic relation between the 18F-FDG injected activity and the patient’s BMI and propose a regimen for total-body PET imaging. In the regimen, the image quality can maintain in a constant level independent of patient size and meet the clinical requirement even with a reduced injected activity.

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Comparison of CT image quality between the AIDR 3D and FIRST iterative reconstruction algorithms: an assessment based on phantom measurements and clinical images

Physics in Medicine and Biology ◽

10.1088/1361-6560/ac0391 ◽

2021 ◽

Author(s):

Stephanie M Leon ◽

Edmond A Olguin ◽

Colin J Schaeffer ◽

Catherine A Olguin ◽

Nupur Verma ◽

...

Keyword(s):

Image Quality ◽

Iterative Reconstruction ◽

Ct Image ◽

Reconstruction Algorithms ◽

Clinical Images ◽

Phantom Measurements ◽

Ct Image Quality

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Evaluation of image quality at the detector’s edge of dedicated breast positron emission tomography

EJNMMI Physics ◽

10.1186/s40658-020-00351-6 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Yoko Satoh ◽

Utaroh Motosugi ◽

Masamichi Imai ◽

Yoshie Omiya ◽

Hiroshi Onishi

Keyword(s):

Image Quality ◽

Chest Wall ◽

Clinical Studies ◽

Breast Imaging ◽

Phantom Study ◽

Breast Lesions ◽

Clinical Images ◽

Dedicated Breast Pet ◽

Pet Ct ◽

Significant Difference

Abstract Background Using phantoms and clinical studies in prone hanging breast imaging, we assessed the image quality of a commercially available dedicated breast PET (dbPET) at the detector’s edge, where mammary glands near the chest wall are located. These are compared to supine PET/CT breast images of the same clinical subjects. Methods A breast phantom with four spheres (16-, 10-, 7.5-, and 5-mm diameter) was filled with 18F-fluorodeoxyglucose solution (sphere-to-background activity concentration ratio, 8:1). The spheres occupied five different positions from the top edge to the centre of the detector and were scanned for 5 min in each position. Reconstructed images were visually evaluated, and the contrast-to-noise ratio (CNR), contrast recovery coefficient (CRC) for all spheres, and coefficient of variation of the background (CVB) were calculated. Subsequently, clinical images obtained with standard supine PET/CT and prone dbPET were retrospectively analysed. Tumour-to-background ratios (TBRs) between breast cancer near the chest wall (close to the detector’s edge; peripheral group) and at other locations (non-peripheral group) were compared. The TBR of each lesion was compared between dbPET and PET/CT. Results Closer to the detector’s edge, the CNR and CRC of all spheres decreased while the CVB increased in the phantom study. The disadvantages of this placement were visually confirmed. Regarding clinical images, TBR of dbPET was significantly higher than that of PET/CT in both the peripheral (12.38 ± 6.41 vs 6.73 ± 3.5, p = 0.0006) and non-peripheral (12.44 ± 5.94 vs 7.71 ± 7.1, p = 0.0183) groups. There was no significant difference in TBR of dbPET between the peripheral and non-peripheral groups. Conclusion The phantom study revealed poorer image quality at < 2-cm distance from the detector’s edge than at other more central parts. In clinical studies, however, the visibility of breast lesions with dbPET was the same regardless of the lesion position, and it was higher than that in PET/CT. dbPET has a great potential for detecting breast lesions near the chest wall if they are at least 2 cm from the edge of the FOV, even in young women with small breasts.

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Feasibility and accuracy of the automated software for dynamic quantification of left ventricular and atrial volumes and function in a large unselected population

European Heart Journal - Cardiovascular Imaging ◽

10.1093/ehjci/jeaa356.356 ◽

2021 ◽

Vol 22 (Supplement_1) ◽

Author(s):

G Italiano ◽

G Tamborini ◽

V Mantegazza ◽

V Volpato ◽

L Fusini ◽

...

Keyword(s):

Machine Learning ◽

Atrial Fibrillation ◽

Image Quality ◽

Normal Subjects ◽

Left Ventricular ◽

Systolic Volume ◽

Unselected Population ◽

Lv Volumes ◽

Time Required ◽

2D Images

Abstract Funding Acknowledgements Type of funding sources: None. Objective. Preliminary studies showed the accuracy of machine learning based automated dynamic quantification of left ventricular (LV) and left atrial (LA) volumes. We aimed to evaluate the feasibility and accuracy of machine learning based automated dynamic quantification of LV and LA volumes in an unselected population. Methods. We enrolled 600 unselected patients (12% in atrial fibrillation) clinically referred for transthoracic echocardiography (2DTTE), who also underwent 3D echocardiography (3DE) imaging. LV ejection fraction (EF), LV and LA volumes were obtained from 2D images; 3D images were analysed using Dynamic Heart Model (DHM) software (Philips) resulting in LV and LA volume-time curves. A subgroup of 140 patients underwent also cardiac magnetic resonance (CMR) imaging. Average time of analysis, feasibility, and image quality were recorded and results were compared between 2DTTE, DHM and CMR. Results. The use of DHM was feasible in 522/600 cases (87%). When feasible, the boundary position was considered accurate in 335/522 patients (64%), while major (n = 38) or minor (n = 149) borders corrections were needed. The overall time required for DHM datasets was approximately 40 seconds, resulting in physiologically appearing LV and LA volume–time curves in all cases. As expected, DHM LV volumes were larger than 2D ones (end-diastolic volume: 173 ± 64 vs 142 ± 58 mL, respectively), while no differences were found for LV EF and LA volumes (EF: 55%±12 vs 56%±14; LA volume 89 ± 36 vs 89 ± 38 mL, respectively). The comparison between DHM and CMR values showed a high correlation for LV volumes (r = 0.70 and r = 0.82, p < 0.001 for end-diastolic and end-systolic volume, respectively) and an excellent correlation for EF (r= 0.82, p < 0.001) and LA volumes. Conclusions. The DHM software is feasible, accurate and quick in a large series of unselected patients, including those with suboptimal 2D images or in atrial fibrillation. Table 1 DHM quality Adjustment Feasibility Good Suboptimal Minor Major Total of patients (n, %) 522/600 (87%) 327/522 (62%) 195/522 (28%) 149/522 (29%) 38/522 (6%) Normal subjects (n, %) 39/40 (97%) 23/39 (57%) 16/39 (40%) 9/39 (21%) 1/39 (3%) Atrial Fibrillation (n, %) 59/73 (81%)* 28/59 (47%) 31/59 (53%) 15/59 (25%) 6/59 (10%) Valvular disease (n, %) 271/312 (87%) 120/271 (%) 151/271 (%) 65/271 (24%) 16/271 (6%) Coronary artery disease (n, %) 47/58 (81%)* 26/47 (46%) 21/47 (37%) 16/47 (34%) 5/47 (11%) Miscellaneous (n, %) 24/25 (96%) 18/24 (75%) 6/24 (25%) 5/24 (21%) 3/24 (12%) Feasibility of DHM, image quality and need to adjustments in global population and in each subgroup. Abstract Figure 1

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Design and Construction of Cervix Phantom for Brachytherapy Dose Assessment Procedure for Clinical Application

International Journal of Scientific Research in Science Engineering and Technology ◽

10.32628/ijsrset173488 ◽

2017 ◽

pp. 106-109

Author(s):

Justice Avevor ◽

Issahaku Shirazu ◽

Samuel Nii Adu Tagoe ◽

J. H. Amuasi ◽

J. J. Fletcher

Keyword(s):

Clinical Application ◽

Excellent Result ◽

Dose Assessment ◽

Internal Diameter ◽

Cylindrical Shape ◽

Assessment Procedure ◽

External Diameter ◽

Actual Patient ◽

Average Patient ◽

Patient Size

An important point to consider in a brachytherapy dosimetry study is the design of an appropriate phantom size in calculations or experimental measurements. Perspex sheets of various size and thickness are used to design the cervix phantom. The aim of the study is to design and construct cervix phantom to mimic the pelvic segment of a standard adult human patients undergoing Brachytherapy. This is to allow assessment of dose to cervix and the surrounding tissues during cervix Brachytherapy. The methodology include; first phantom design where physical dimensions of the phantom were determined from a sampling of 30 patients’ cases to simulate an average patient size. Secondly, construction of phantom with fabricated cylindrical shape, composed of 6 mm Perspex sheets, and the assembly enclosed with the 4 mm Perspex sheet. The result of the constructed phantom had lateral separation of 34 cm, an anterior and posterior separation of 27 cm; with length of 33 cm. The Perspex pieces were glued to each other with Trichloromethane (chloroform) at room temperature. Chloroform dissolves the Perspex (PMMA), and when applied to the surfaces of the Perspex sheets, the surfaces stick together after the chloroform dries up. In forming the surface of the phantom, the 4 mm Perspex sheet was oven heated to a temperature of 140?C to make the sheet malleable. One end of the phantom was made thicker than the other end by gluing another 6 mm Perspex sheet such that the thickness of that particular end of the phantom was 12 mm. A hole of diameter 6.5 cm, which was a little bit posterior to the phantom, was created central to the 12 mm end of the phantom. The opening created was covered by 11 x 11 cm2 and 12 mm Perspex slab which was formed by gluing two 6 mm sheets together. A hole of diameter 5 cm was also made central to the cover created, such that the centre of this hole matches that of the hole on the end of the phantom. A 2.4 cm thick ring with internal diameter of 5 cm and external diameter of 6 cm was fabricated from 2.4 cm Perspex slab, which was formed from gluing four pieces of 6 mm Perspex sheets together. The fabricated ring was mounted on the 11 x 11 cm2 cover created such that the internal walls of the ring and that of the hole in the cover matches. The ring was then glued to the cover using the chloroform. The built phantom simulate actual patient anatomy and produce an excellent result to be use for clinical application.

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Appropriate Patient Selection at Abdominal Dual-Energy CT Using 80 kV: Relationship between Patient Size, Image Noise, and Image Quality

Radiology ◽

10.1148/radiol.10092016 ◽

2010 ◽

Vol 257 (3) ◽

pp. 732-742 ◽

Cited By ~ 115

Author(s):

Luís S. Guimarães ◽

Joel G. Fletcher ◽

William S. Harmsen ◽

Lifeng Yu ◽

Hassan Siddiki ◽

...

Keyword(s):

Image Quality ◽

Patient Selection ◽

Dual Energy ◽

Image Noise ◽

Dual Energy Ct ◽

Patient Size

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Effect of different contrast administration protocols on contrast enhancement and image quality in CT scan

10.21203/rs.2.16817/v1 ◽

2019 ◽

Author(s):

Noor Ruhaya Ibrahim ◽

Noor Khairiah A. Karim ◽

Ibrahim Lutfi Shuaib ◽

Noor Diyana Osman ◽

Salwah Hashim ◽

...

Keyword(s):

Image Quality ◽

Contrast Enhancement ◽

Hounsfield Unit ◽

Fixed Time ◽

Qualitative Assessment ◽

Contrast Administration ◽

Contrast Volume ◽

Significant Difference ◽

Group A ◽

Group B

Abstract Objective The aim of this study is to compare the effect of different contrast administration protocols practiced in Advanced Medical and Dental Institute, Universiti Sains Malaysia (Group A) and Hospital Pulau Pinang, Malaysia (Group B), on contrast enhancement and image quality in computed tomography scan. The two protocols were fixed time delay (FTD) with fixed volume (FV), and automatic bolus tracking (ABT) with weight based volume (WBV) contrast administration. Quantification of contrast enhancement’s magnitude in four different anatomical structures was measured in Hounsfield Unit (HU) and based on 5-point scale (1=poor, 5=excellent), the images were rated qualitatively.Results Mean enhancement values of all structures in Group B was higher compared to Group A (p = < 0.001). Mean of quality rating between the two groups was statistically not significant (p = 0.185). There was a weak correlation between HU values and administered contrast volume (r = 0.152). It can be concluded that FTD with FV protocol is non inferior to ABT with WBV protocol as it yielded higher degree of contrast enhancement. There was no significant difference between the two protocols in term of qualitative assessment although ABT with WBV protocol had higher mean grading in image quality.

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Inexpensive, realtime tele-ultrasound using a commercial, web-based video streaming device

Journal of Telemedicine and Telecare ◽

10.1258/jtt.2012.110112 ◽

2012 ◽

Vol 18 (4) ◽

pp. 185-188 ◽

Cited By ~ 9

Author(s):

Yannis M Paulus ◽

Noel P Thompson

Keyword(s):

Image Quality ◽

Video Streaming ◽

Delay Time ◽

Qualitative Assessment ◽

Web Based ◽

Grey Scale ◽

Standard Resolution ◽

Ultrasound System

We have devised an inexpensive, web-based tele-ultrasound system using commercially-available video streaming equipment. We examined the spatial and grey scale resolution, and the delay time of the system. The receiving PC was tested at various distances from the transmitting site, from 3.2 km to 4828 km. Standard resolution targets and echocardiography movie strips recorded on DVDs were used to assess the image quality. A qualitative assessment was made by an expert sonographer. As the distance between the transmitter and the receiver increased, the scan smoothness decreased and the delay increased. At a distance of 3.2 km the delay was 2–3 s, and at 4828 km it was 10–15 s. The delay was short enough to allow realtime guidance of the scanning technician by telephone. The system allows inexpensive, readily available, realtime tele-ultrasonography.

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