Displaying publications 1 - 20 of 82 in total

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  1. Ng Kh, Wong J
    Biomed Imaging Interv J, 2008 Apr;4(2):e21.
    PMID: 21614324 DOI: 10.2349/biij.4.2.21
    Informal discussion started in 1996 and the South East Asian Federation of Organizations for Medical Physics (SEAFOMP) was officially accepted as a regional chapter of the IOMP at the Chicago World Congress in 2000 with five member countries, namely Indonesia, Malaysia, Philippines, Singapore and Thailand. Professor Kwan-Hoong Ng served as the founding president until 2006. Brunei (2002) and Vietnam (2005) joined subsequently. We are very grateful to the founding members of SEAFOMP: Anchali Krisanachinda, Kwan-Hoong Ng, Agnette Peralta, Ratana Pirabul, Djarwani S Soejoko and Toh-Jui Wong.The objectives of SEAFOMP are to promote (i) co-operation and communication between medical physics organizations in the region; (ii) medical physics and related activities in the region; (iii) the advancement in status and standard of practice of the medical physics profession; (iv) to organize and/or sponsor international and regional conferences, meetings or courses; (v) to collaborate or affiliate with other scientific organizations.SEAFOMP has been organizing a series of congresses to promote scientific exchange and mutual support. The South East Asian Congress of Medical Physics (SEACOMP) series was held respectively in Kuala Lumpur (2001), Bangkok (2003), Kuala Lumpur (2004) and Jakarta (2006). The respective congress themes indicated the emphasis and status of development. The number of participants (countries in parentheses) was encouraging: 110 (17), 150 (16), 220 (23) and 126 (7).In honour of the late Professor John Cameron, an eponymous lecture was established. The inaugural John Cameron Lecture was delivered by Professor Willi Kalender in 2004. His lecture was titled "Recent Developments in Volume CT Scanning".
    Matched MeSH terms: Cone-Beam Computed Tomography
  2. Al-Ani O, Nambiar P, Ha KO, Ngeow WC
    Clin Oral Implants Res, 2013 Aug;24 Suppl A100:115-21.
    PMID: 22233422 DOI: 10.1111/j.1600-0501.2011.02393.x
    The mandibular incisive nerve can be subjected to iatrogenic injury during bone graft harvesting. Using cone beam computed tomography (CBCT), this study aims to determine a safe zone for bone graft harvesting that avoids injuring this nerve.
    Matched MeSH terms: Cone-Beam Computed Tomography
  3. Purmal K, Alam MK, Pohchi A, Abdul Razak NH
    PLoS One, 2013;8(12):e84202.
    PMID: 24367643 DOI: 10.1371/journal.pone.0084202
    Intermaxillary (IMF) screws feature several advantages over other devices used for intermaxillary fixation, but using cone beam computed tomography (CBCT) scans to determine the safe and danger zones to place these devices for all patients can be expensive. This study aimed to determine the optimal interradicular and buccopalatal/buccolingual spaces for IMF screw placement in the maxilla and mandible. The CBCT volumetric data of 193 patients was used to generate transaxial slices between the second molar on the right to the second molar on the left in both arches. The mean interradicular and buccopalatal/buccolingual distances and standard deviation values were obtained at heights of 2, 5, 8 and 11 mm from the alveolar bone crest. An IMF screw with a diameter of 1.0 mm and length of 7 mm can be placed distal to the canines (2 - 11 mm from the alveolar crest) and less than 8 mm between the molars in the maxilla. In the mandible, the safest position is distal to the first premolar (more than 5 mm) and distal to the second premolar (more than 2 mm). There was a significant difference (p<0.05) between the right and left quadrants. The colour coding 3D template showed the safe and danger zones based on the mesiodistal, buccopalatal and buccolingual distances in the maxilla and mandible.The safest sites for IMF screw insertion in the maxilla were between the canines and first premolars and between the first and second molars. In the mandible, the safest sites were between the first and second premolars and between the second premolar and first molar. However, the IMF screw should not exceed 1.0 mm in diameter and 7 mm in length.
    Matched MeSH terms: Cone-Beam Computed Tomography*
  4. Anderson PJ, Yong R, Surman TL, Rajion ZA, Ranjitkar S
    Aust Dent J, 2014 Jun;59 Suppl 1:174-85.
    PMID: 24611727 DOI: 10.1111/adj.12154
    Following the invention of the first computed tomography (CT) scanner in the early 1970s, many innovations in three-dimensional (3D) diagnostic imaging technology have occurred, leading to a wide range of applications in craniofacial clinical practice and research. Three-dimensional image analysis provides superior and more detailed information compared with conventional plain two-dimensional (2D) radiography, with the added benefit of 3D printing for preoperative treatment planning and regenerative therapy. Current state-of-the-art multidetector CT (MDCT), also known as medical CT, has an important role in the diagnosis and management of craniofacial injuries and pathology. Three-dimensional cone beam CT (CBCT), pioneered in the 1990s, is gaining increasing popularity in dental and craniofacial clinical practice because of its faster image acquisition at a lower radiation dose, but sound guidelines are needed to ensure its optimal clinical use. Recent innovations in micro-computed tomography (micro-CT) have revolutionized craniofacial biology research by enabling higher resolution scanning of teeth beyond the capabilities of MDCT and CBCT, presenting new prospects for translational clinical research. Even after four decades of refinement, CT technology continues to advance and broaden the horizons of craniofacial clinical practice and phenomics research.
    Matched MeSH terms: Cone-Beam Computed Tomography
  5. Ishak MH, Zhun OC, Shaari R, Rahman SA, Hasan MN, Alam MK
    Mymensingh Med J, 2014 Oct;23(4):781-6.
    PMID: 25481601
    This study evaluated the validity of panoramic radiography and cone beam computed tomography (CBCT) in the assessment of mandibular canal and impacted third molar. In this descriptive-analytical study, 58 mandibular third molars from 42 patients who showed a close relationship between impacted third molar and canal on panoramic radiographs were selected. They were then classified into seven radiographic markers in panoramic radiographs (superimposition, darkening of the root, interruption of the white lines, root narrowing, canal diversion, canal narrowing, and also closed distance in OPG <1mm). The groups of markers were further assessed with CBCT to see presence or absence of contact. The three most common markers seen in panoramic images are superimposition, interruption of white line and root darkening. In CBCT, superimposition marker always presented higher frequency of contact with canal compared to non-contact group. There are 31% of teeth presented with interruption of white lines and there are 29.3% of teeth presented with superimposition. About 55.6% and 35.3% of the impacted mandibular third molars which indicated interruption of white lines and superimposition also indicated contact in the CBCT respectively. Presence or absence of radiological sign in panoramic radiography was not properly predict a close relationship with third molar and it is suggested that in case of tooth-canal overlapping, the patient should be referred for CBCT assessment.
    Matched MeSH terms: Cone-Beam Computed Tomography/methods*
  6. Ananda GK, Nambiar P, Mutalik S, Shanmuhasuntharam P
    Surg Radiol Anat, 2015 Nov;37(9):1099-108.
    PMID: 25850735 DOI: 10.1007/s00276-015-1473-0
    With the advent of cone-beam computed tomography (CBCT) for maxillofacial imaging, there has been a paradigm shift from two dimensional panoramic radiography to three dimensional imaging. This study investigated the microanatomy of the maxillary permanent first molar socket and its relationship to the floor of the maxillary sinus, especially for immediate or early implant placement.
    Matched MeSH terms: Cone-Beam Computed Tomography
  7. Al-Amery SM, Nambiar P, Jamaludin M, John J, Ngeow WC
    PLoS One, 2015;10(2):e0117251.
    PMID: 25679505 DOI: 10.1371/journal.pone.0117251
    The maxillary incisive canal connects the roof of the oral cavity with the floor of nasal cavity and has the incisive and nasal foramina respectively at its two opposite ends. Its close proximity with the anterior incisors affects one's ability to place immediate implants in ideal position.
    Matched MeSH terms: Cone-Beam Computed Tomography*
  8. Heng SP, Low SH, Sivamany K
    Indian J Cancer, 2015 Oct-Dec;52(4):639-44.
    PMID: 26960504 DOI: 10.4103/0019-509X.178386
    The purpose of this study is to determine the influence of bladder and bowel preparation protocols on the dose-volume histograms (DVHs) of these organs using the cone beam computed tomography (CBCT)-based intensity modulated radiotherapy (IMRT) treatment planning for prostate cancer patients. The pelvic DVHs of 12 prostate cancer patients were studied using CBCT images obtained immediately before each treatment. Six patients had bladder and bowel preparation protocol whilst the other six patients were the control group. Contoured bladder and rectal volumes on CBCT images were compared with planning computed tomography. All patients were treated with IMRT with 7800 cGy in 39 fractions over 8 weeks. Compared with the patient with bladder preparation protocol, patients without bladder preparation instruction had higher bladder volume and dose variation. The maximum variation in bladder volume was as high as 98% in the control group. Without bowel preparation protocol, the rectal volumes were more variability. Owing to changes in rectal filling on the day of treatment, the maximum variation in rectal volume was as high as + 96%. With bowel preparation protocol, the maximum rectum volume variations were less than 25%. The changes in prostate target dose compared with planning dose were minimal as would be expected from positioning with daily image guidance and gold seed implanted.
    Matched MeSH terms: Cone-Beam Computed Tomography
  9. Al-koshab M, Nambiar P, John J
    PLoS One, 2015;10(3):e0121682.
    PMID: 25803868 DOI: 10.1371/journal.pone.0121682
    INTRODUCTION: Proper imaging allows practitioners to evaluate an asymptomatic tempormandibular joint (TMJ) for potential degenerative changes prior to surgical and orthodontic treatment. The recently developed cone-beam computed tomography (CBCT) allows measurement of TMJ bony structures with high accuracy. A study was undertaken to determine the morphology, and its variations, of the mandibular condyle and glenoid fossa among Malay and Chinese Malaysians.

    METHODS: CBCT was used to assess 200 joints in 100 subjects (mean age, 30.5 years). i-CAT CBCT software and The Mimics 16.0 software were employed to measure the volume, metrical size, position of each condyle sample and the thickness of the roof of the glenoid fossa (RGF).

    RESULTS: No significant gender differences were noted in thickness of the RGF and condylar length; however condylar volume, width, height and the joint spaces were significantly greater among males. With regards to comparison of both TMJs, the means of condylar volume, width and length of the right TMJ were significantly higher, while the means of the left condylar height and thickness of RGF were higher. When comparing the condylar measurements and the thickness of RGF between the two ethnic groups, we found no significant difference for all measurements with exception of condylar height, which is higher among Chinese.

    CONCLUSION: The similarity in measurements for Malays and Chinese may be due to their common origin. This information can be clinically useful in establishing the diagnostic criteria for condylar volume, metrical size, and position in the Malaysian East Asians population.

    Matched MeSH terms: Cone-Beam Computed Tomography/methods*
  10. Al-Jaf, Nagham, Rohaya Megat Abdul Wahab, Mohamed Ibrahim Abu Hassan
    Compendium of Oral Science, 2015;2(1):14-20.
    MyJurnal
    Objectives: To assess interradicular spaces of maxilla and mandible in subjects with class I sagittal skeletal relationship as an aid for miniscrew placement. Materials and Methods: The study was carried out using cone-beam computed tomography (CBCT) images of 47 adult subjects with class I skeletal relationship. Interradicular spaces were obtained at the alveolar processes from first premolar to second molar at 2 different vertical levels (6 and 8mm) from the cementoenamel junction (C.E.J). Results: In the maxilla, the highest inter-radicular space existed between second premolar and first molar. In the mandible, the highest interradicular space existed between first and second molar. All mandibular measurements were higher than their respective maxillary measurement. Generally, availability of interradicular space increases apically in both arches, but the difference is not significant. In the maxilla, male subjects’ measurement were significantly higher at 8 mm level between second premolar and first molar and between first and second molar Conclusions: Interradicular spac-es in the maxillary and mandibular alveolar spaces are available for miniscrew placement. In both arches, a more apical location provides more interradicular space. However, careful planning is needed to avoid sinus perforation.
    Matched MeSH terms: Cone-Beam Computed Tomography; Spiral Cone-Beam Computed Tomography
  11. Mustafa A, Lung CY, Mustafa NS, Mustafa BA, Kashmoola MA, Zwahlen RA, et al.
    Clin Oral Implants Res, 2016 Mar;27(3):303-9.
    PMID: 25393376 DOI: 10.1111/clr.12525
    OBJECTIVES: To investigate the effect of eicosapentaenoic acid (EPA)-coated Ti implants on osteoconduction in white New Zealand rabbit mandibles.

    MATERIAL AND METHODS: Sandblasted and cleansed planar titanium specimens with a size of 5 × 5 × 1 mm were coated on one side with 0.25 vol% eicosapentaenoic acid (EPA). The other side of the specimens was kept highly polished (the control side). These specimens were inserted in rabbit mandibles. Twelve rabbits were randomly assigned into three study groups (n = 4). The rabbits were sacrificed at 4, 8, and 12 weeks. The harvested specimens with the implants were assessed for new bone formation on both sides of the implant using CBCT, conventional radiographs, and the biaxial pullout test. The results were statistically analyzed by a nonparametric Kruskal-Wallis test and Friedman's test as multiple comparisons and by Brunner-Langer nonparametric mixed model approach (R Software).

    RESULTS: A significant osteoconductive bone formation was found on the EPA-coated Ti implant surface (P < 0.05) at 8 weeks when compared to the polished surface (control). Biaxial pullout test results showed a significant difference (P < 0.05) after 8 and 12 weeks with a maximum force of 243.8 N, compared to 143.25 N after 4 week.

    CONCLUSION: EPA implant coating promoted osteoconduction on the Ti implant surfaces, enhancing the anchorage of the implant to the surrounding bone in white New Zealand rabbits.

    Matched MeSH terms: Cone-Beam Computed Tomography
  12. Wan Hassan WN, Othman SA, Chan CS, Ahmad R, Ali SN, Abd Rohim A
    Am J Orthod Dentofacial Orthop, 2016 Nov;150(5):886-895.
    PMID: 27871715 DOI: 10.1016/j.ajodo.2016.04.021
    INTRODUCTION: In this study we aimed to compare measurements on plaster models using a digital caliper, and on 3-dimensional (3D) digital models, produced using a structured-light scanner, using 3D software.

    METHODS: Fifty digital models were scanned from the same plaster models. Arch and tooth size measurements were made by 2 operators, twice. Calibration was done on 10 sets of models and checked using the Pearson correlation coefficient. Data were analyzed by error variances, repeatability coefficient, repeated-measures analysis of variance, and Bland-Altman plots.

    RESULTS: Error variances ranged between 0.001 and 0.044 mm for the digital caliper method, and between 0.002 and 0.054 mm for the 3D software method. Repeated-measures analysis of variance showed small but statistically significant differences (P <0.05) between the repeated measurements in the arch and buccolingual planes (0.011 and 0.008 mm, respectively). There were no statistically significant differences between methods and between operators. Bland-Altman plots showed that the mean biases were close to zero, and the 95% limits of agreement were within ±0.50 mm. Repeatability coefficients for all measurements were similar.

    CONCLUSIONS: Measurements made on models scanned by the 3D structured-light scanner were in good agreement with those made on conventional plaster models and were, therefore, clinically acceptable.

    Matched MeSH terms: Cone-Beam Computed Tomography
  13. Marroquin Penaloza TY, Karkhanis S, Kvaal SI, Nurul F, Kanagasingam S, Franklin D, et al.
    J Forensic Leg Med, 2016 Nov;44:178-182.
    PMID: 27821308 DOI: 10.1016/j.jflm.2016.10.013
    Different non-invasive methods have been proposed for dental age estimation in adults, with the Kvaal et al. method as one of the more frequently tested in different populations. The purpose of this study was to apply the Kvaal et al. method for dental age estimation on modern volumetric data from 3D digital systems. To this end, 101 CBCT images from a Malaysian population were used. Fifty-five per cent were female (n = 55), and forty-five percent were male (n = 46), with a median age of 31 years for both sexes. As tomographs allow the observer to obtain a sagittal and coronal view of the teeth, the Kvaal pulp/root width measurements and ratios were calculated in the bucco-lingual and mesio-distal aspects of the tooth. From these data different linear regression models and formulae were built. The most accurate models for estimating age were obtained from a diverse combination of measurements (SEE ±10.58 years), and for the mesio-distal measurements of the central incisor at level A (SEE ±12.84 years). This accuracy, however is outside an acceptable range in for forensic application (SEE ±10.00 years), and is also more time consuming than the original approach based on dental radiographs.
    Matched MeSH terms: Cone-Beam Computed Tomography*
  14. Moghbel M, Mashohor S, Mahmud R, Saripan MI
    EXCLI J, 2016;15:500-517.
    PMID: 28096782 DOI: 10.17179/excli2016-473
    Segmentation of the liver from Computed Tomography (CT) volumes plays an important role during the choice of treatment strategies for liver diseases. Despite lots of attention, liver segmentation remains a challenging task due to the lack of visible edges on most boundaries of the liver coupled with high variability of both intensity patterns and anatomical appearances with all these difficulties becoming more prominent in pathological livers. To achieve a more accurate segmentation, a random walker based framework is proposed that can segment contrast-enhanced livers CT images with great accuracy and speed. Based on the location of the right lung lobe, the liver dome is automatically detected thus eliminating the need for manual initialization. The computational requirements are further minimized utilizing rib-caged area segmentation, the liver is then extracted by utilizing random walker method. The proposed method was able to achieve one of the highest accuracies reported in the literature against a mixed healthy and pathological liver dataset compared to other segmentation methods with an overlap error of 4.47 % and dice similarity coefficient of 0.94 while it showed exceptional accuracy on segmenting the pathological livers with an overlap error of 5.95 % and dice similarity coefficient of 0.91.
    Matched MeSH terms: Cone-Beam Computed Tomography
  15. Kanagasingam S, Lim CX, Yong CP, Mannocci F, Patel S
    Int Endod J, 2017 May;50(5):417-426.
    PMID: 27063209 DOI: 10.1111/iej.12650
    AIM: To compare the diagnostic accuracy of periapical radiography (PR) and cone beam computed tomography (CBCT) in detecting apical periodontitis (AP) using histopathological findings as a reference standard.

    METHODOLOGY: Jaw sections containing 67 teeth (86 roots) were collected from unclaimed bodies due for cremation. Imaging was carried out to detect AP by digital PR with a central view (DP group), digital PR combining central with 10˚ mesially and distally angled (parallax) views (DPS group) and CBCT scans. All specimens underwent histopathological examination to confirm the diagnosis of AP. Sensitivity, specificity and predictive values of PR and CBCT were analysed using rater mean (n = 5). Receiver-operating characteristic (ROC) analysis was carried out.

    RESULTS: Sensitivity was 0.27, 0.38 and 0.89 for DP, DPS and CBCT scans, respectively. CBCT had specificity and positive predictive value of 1.0 whilst DP and DPS had specificity and positive predictive value of 0.99. The negative predictive value was 0.39, 0.44 and 0.81 for DP, DPS and CBCT scans, respectively. Area under the curve (AUC) for the various imaging methods was 0.629 (DP), 0.688 (DPS), and 0.943 (CBCT).

    CONCLUSIONS: All imaging techniques had similar specificity and positive predictive values. Additional parallax views increased the diagnostic accuracy of PR. CBCT had significantly higher diagnostic accuracy in detecting AP compared to PR, using human histopathological findings as a reference standard.

    Matched MeSH terms: Cone-Beam Computed Tomography*
  16. Koh KK, Tan JS, Nambiar P, Ibrahim N, Mutalik S, Khan Asif M
    J Forensic Leg Med, 2017 May;48:15-21.
    PMID: 28407514 DOI: 10.1016/j.jflm.2017.03.004
    Forensic odontology plays a vital role in the identification and age estimation of unknown deceased individuals. The purpose of this study is to estimate the chronological age from Cone-Beam Computed Tomography (CBCT) images by measuring the buccal alveolar bone level (ABL) to the cemento-enamel junction and to investigate the possibility of employing the age-related structural changes of teeth as studied by Gustafson. In addition, this study will determine the forensic reliability of employing CBCT images as a technique for dental age estimation. A total of 284 CBCT images of Malays and Chinese patients (150 females and 134 males), aged from 20 years and above were selected, measured and stages of age-related changes were recorded using the i-CAT Vision software. Lower first premolars of both left and right side of the jaw were chosen and the characteristics described by Gustafson, namely attrition, secondary dentine formation and periodontal recession were evaluated. Linear regression analysis was performed for the buccal bone level and the R values obtained were 0.85 and 0.82 for left and right side respectively. Gustafson's characteristics were analysed using multiple regression analysis with chronological age as the dependent variable. The results of the analysis showed R values ranged from 0.44 to 0.62. Therefore it can be safely concluded that the buccal bone level highly correlated with the chronological age and is consequently the most suitable age-related characteristic for forensic age estimation.
    Matched MeSH terms: Cone-Beam Computed Tomography
  17. Qabbani AA, Razak NHA, Kawas SA, Sheikh Abdul Hamid S, Wahbi S, Samsudin AR
    J Craniofac Surg, 2017 Jun;28(4):e318-e325.
    PMID: 28230596 DOI: 10.1097/SCS.0000000000003569
    The aim of this study was to determine the efficacy of immediate implant placement with alveolar bone augmentation on socket preservation following atraumatic tooth extraction and comparing it with a tooth alveolar socket that was allowed to heal in a conventional way.Twenty medically fit patients (8 males and 12 females aged between 18 and 40 years) who needed noncomplicated tooth extraction of mandibular premolar teeth were divided randomly and equally into 2 groups. In Group I, the empty extraction socket was left untreated and allowed to heal in a conventional way. In Group II, the immediate implant was placed and the gap between the implant and the inner buccal plate surface of the socket wall was filled with lyophilized bovine bone granules and the wound was covered with pericardium membrane. The patients were followed up clinically and radiologically for regular reviews at 1 week, 3 months, and 9 months postoperative. Cone beam computerized tomography images of the alveolar ridge and socket were analyzed to determine the structural changes of the alveolar ridge. Resonance frequency analysis was measured at 9 months for Group II to assess the degree of secondary stability of the implants by using Osstell machine.A significant difference of bone resorption of 1.49 mm (confidence interval, CI 95%, 0.63-2.35) was observed within the control group at 3 months, and 1.84 mm (P ≤ 0.05) at 9 months intervals. No significant changes of bone resorption were observed in Group II. Comparison between groups showed a highly significant difference at 3 months; 2.56 mm (CI 95% 4.22-0.90) and at 9 months intervals; 3.2 mm (CI 95%, 4.70-1.62) P ≤ 0.001 between Group I and II. High resonance frequency analysis values were observed at 9 months postoperative in Group II.In conclusion, the insertion of immediate implants in fresh extraction sockets together with grafting the circumferential gap between the bony socket wall and the implant surface with bovine bone granules was able to preserve a greater amount of alveolar ridge volume when compared with an extraction socket that was left to heal in a conventional way.
    Matched MeSH terms: Cone-Beam Computed Tomography/methods
  18. Lim D, Parumo R, Chai MB, Shanmuganathan J
    J Oral Implantol, 2017 Jun;43(3):228-231.
    PMID: 27996585 DOI: 10.1563/aaid-joi-D-16-00172
    Displacement of dental implants into the maxillary sinus is a rare complication. This article presents a case of displaced dental implant into maxillary sinus. Retrieval of the dental implant from left maxillary sinus was performed via endoscopic sinus surgery. This case highlighted a delayed referral of a 53-year-old male by a general dental practitioner for management of a dislodged dental implant into the left maxillary antrum. The implant was dislodged during placement of a healing abutment 4 months after implant insertion to replace missing 25. Cone beam computerized tomography revealed the displaced implant was located at the ostium of the left nose. A sudden change in sinonasal pressure when the patient took a deep breath during the procedure may have created a negative pressure and suction effect causing the implant to be dislodged and embedded at the ostium. In view of its position, a referral to an otorhinolaryngologist was made for endoscopic removal of the displaced implant. This case also highlighted the need for inter disciplinary cooperation in the management of such a complication for the best interest of the patients.
    Matched MeSH terms: Cone-Beam Computed Tomography
  19. Cheng CS, Jong WL, Ung NM, Wong JHD
    Radiat Prot Dosimetry, 2017 Jul 01;175(3):357-362.
    PMID: 27940494 DOI: 10.1093/rpd/ncw357
    This work evaluated and compared the absorbed doses to selected organs in the head and neck region from the three image guided radiotherapy systems: cone-beam computed tomography (CBCT) and kilovoltage (kV) planar imaging using the On-board Imager® (OBI) as well as the ExacTrac® X-ray system, all available on the Varian Novalis TX linear accelerator. The head and neck region of an anthropomorphic phantom was used to simulate patients' head within the imaging field. Nanodots optically stimulated luminescent dosemeters were positioned at selected sites to measure the absorbed doses. CBCT was found to be delivering the highest dose to internal organs while OBI-2D gave the highest doses to the eye lenses. The setting of half-rotation in CBCT effectively reduces the dose to the eye lenses. Daily high-quality CBCT verification was found to increase the secondary cancer risk by 0.79%.
    Matched MeSH terms: Cone-Beam Computed Tomography*
  20. Khalil A, Faisal A, Ng SC, Liew YM, Lai KW
    J Med Imaging (Bellingham), 2017 Jul;4(3):037001.
    PMID: 28840172 DOI: 10.1117/1.JMI.4.3.037001
    A registration method to fuse two-dimensional (2-D) echocardiography images with cardiac computed tomography (CT) volume is presented. The method consists of two major procedures: temporal and spatial registrations. In temporal registration, the echocardiography frames at similar cardiac phases as the CT volume were interpolated based on electrocardiogram signal information, and the noise of the echocardiography image was reduced using the speckle reducing anisotropic diffusion technique. For spatial registration, an intensity-based normalized mutual information method was applied with a pattern search optimization algorithm to produce an interpolated cardiac CT image. The proposed registration framework does not require optical tracking information. Dice coefficient and Hausdorff distance for the left atrium assessments were [Formula: see text] and [Formula: see text], respectively; for left ventricle, they were [Formula: see text] and [Formula: see text], respectively. There was no significant difference in the mitral valve annulus diameter measurement between the manually and automatically registered CT images. The transformation parameters showed small deviations ([Formula: see text] deviation in translation and [Formula: see text] for rotation) between manual and automatic registrations. The proposed method aids the physician in diagnosing mitral valve disease as well as provides surgical guidance during the treatment procedure.
    Matched MeSH terms: Cone-Beam Computed Tomography
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