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Kazantsev P, Wesolowska P, Bokulic T, Falowska-Pietrzak O, Repnin K, Dimitriadis A, Swamidas J, Izewska J. The IAEA remote audit of small field dosimetry for testing the implementation of the TRS-483 code of practice. Med Phys 2024. [PMID: 38700987 DOI: 10.1002/mp.17109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 03/27/2024] [Accepted: 04/02/2024] [Indexed: 05/05/2024] Open
Abstract
BACKGROUND The TRS‑483, an IAEA/AAPM International Code of Practice on dosimetry of small static photon fields, underwent testing via an IAEA coordinated research project (CRP). Alongside small field output factors (OFs) measurements using active dosimeters by CRP participants, the IAEA Dosimetry Laboratory received a mandate to formulate a remote small field dosimetry audit method using its passive dosimetry systems. PURPOSE This work aimed to develop a small field dosimetry audit methodology employing radiophotoluminescent dosimeters (RPLDs) and radiochromic films. The methodology was subsequently evaluated through a multicenter pilot study with CRP participants. METHODS The developments included designing and manufacturing a dosimeter holder set and the characterization of an RPLD system for measurements in small photon fields using the new holder. The audit included verification of small field OFs and lateral beam profiles for small fields. At first, treatment planning system (TPS) calculated OFs were checked against a reference data set that was available for conventional linacs. Second, calculated OFs were verified through the RPLD measurement of point doses in a machine-specific reference field, 4 cm × 4 cm, 2 cm × 2 cm, and 1 cm × 1 cm, corresponding size circular fields or nearest achievable field sizes. Lastly, profile checks in in-plane and cross-plane directions were done for the two smallest fields by comparing film measurements with TPS calculations at 20%, 50%, and 80% isodose levels. RESULTS RPLD correction factors for small field measurements were approximately unity. However, they influenced the dose determination's overall uncertainty in small fields, estimated at 2.30% (k = 1 level). Considering the previous experience in auditing reference beam output following the TRS-398 Code of Practice, the acceptance limit of 5% for the ratio of the dose determined by RPLD to the dose calculated by TPS, DRPLD/DTPS, was considered adequate. The multicenter pilot study included 15 participants from 14 countries (39 beams). Consistent with the previous findings, the results of the OF check against the reference data confirmed that TPSs tend to overestimate OFs for the smallest fields included in this exercise. All except three RPLD measurement results were within the acceptance limit, and the spread of results increased for smaller field sizes. The differences between the film measured and TPS calculated dose profiles were within 3 mm for most of the beams checked; deviated results revealed problems with TPS commissioning and calibration of the treatment unit collimation systems. CONCLUSION The newly developed small field dosimetry audit methodology proved effective and successfully complemented the CRP OF measurements by participants with RPLD audit results.
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Affiliation(s)
| | - Paulina Wesolowska
- International Atomic Energy Agency, Vienna, Austria
- The Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
| | - Tomislav Bokulic
- International Atomic Energy Agency, Vienna, Austria
- University of Zagreb, Zagreb, Croatia
| | - Olga Falowska-Pietrzak
- International Atomic Energy Agency, Vienna, Austria
- Stockholm University, Stockholm, Sweden
| | - Kostiantyn Repnin
- International Atomic Energy Agency, Vienna, Austria
- Medical University of Vienna, Vienna, Austria
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Dimitriadis A, Kazantsev P, Chelminski K, Titovich E, Naida E, Magnus T, Meghzifene A, Azangwe G, Carrara M, Swamidas J. IAEA/WHO postal dosimetry audit methodology for electron beams using radio photoluminescent dosimeters. Med Phys 2023; 50:7214-7221. [PMID: 37793099 DOI: 10.1002/mp.16776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/02/2023] [Accepted: 09/23/2023] [Indexed: 10/06/2023] Open
Abstract
BACKGROUND Independent dosimetry audits are an important intervention in radiotherapy for quality assurance. Electron beams, used for superficial radiotherapy treatments, must also be tested in dosimetry audits as part of a good quality assurance program to help prevent clinical errors. PURPOSE To establish a new service for IAEA/WHO postal dosimetry audits in electron beams using RPL dosimeters. METHODS A novel postal audit methodology employing a PMMA holder system for RPLDs was developed. The associated correction factors including holder dependence, energy dependence, dose response non-linearity, and fading were obtained and tested in a multi-center (n = 12) pilot study. A measurement uncertainty budget was estimated and employed in analyzing the irradiated dosimeters. RESULTS Holder and energy correction factors ranged from 1.004 to 1.010 and 1.019 to 1.059 respectively across the energy range. The non-linearity and fading correction models used for photon beams were tested in electron beams and did not significantly increase measurement uncertainty. The mean dose ratio ± SD of the multi-center study was 1.001 ± 0.011. The overall uncertainty budget was estimated as ± 1.42% (k = 1). CONCLUSIONS A methodology for IAEA/WHO postal dosimetry audits in electron beams was developed and validated in a multi-center study and is now made available to radiotherapy centers as a routine service.
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Affiliation(s)
- Alexis Dimitriadis
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Pavel Kazantsev
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Krzysztof Chelminski
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Egor Titovich
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Ekaterina Naida
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Talent Magnus
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Ahmed Meghzifene
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Godfrey Azangwe
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Mauro Carrara
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Jamema Swamidas
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
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Grishchuk D, Dimitriadis A, Sahgal A, De Salles A, Fariselli L, Kotecha R, Levivier M, Ma L, Pollock BE, Regis J, Sheehan J, Suh J, Yomo S, Paddick I. ISRS Technical Guidelines for Stereotactic Radiosurgery: Treatment of Small Brain Metastases (≤1 cm in Diameter). Pract Radiat Oncol 2022; 13:183-194. [PMID: 36435388 DOI: 10.1016/j.prro.2022.10.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/10/2022] [Accepted: 10/12/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE The objective of this literature review was to develop International Stereotactic Radiosurgery Society (ISRS) consensus technical guidelines for the treatment of small, ≤1 cm in maximal diameter, intracranial metastases with stereotactic radiosurgery. Although different stereotactic radiosurgery technologies are available, most of them have similar treatment workflows and common technical challenges that are described. METHODS AND MATERIALS A systematic review of the literature published between 2009 and 2020 was performed in Pubmed using the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) methodology. The search terms were limited to those related to radiosurgery of brain metastases and to publications in the English language. RESULTS From 484 collected abstract 37 articles were included into the detailed review and bibliographic analysis. An additional 44 papers were identified as relevant from a search of the references. The 81 papers, including additional 7 international guidelines, were deemed relevant to at least one of five areas that were considered paramount for this report. These areas of technical focus have been employed to structure these guidelines: imaging specifications, target volume delineation and localization practices, use of margins, treatment planning techniques, and patient positioning. CONCLUSION This systematic review has demonstrated that Stereotactic Radiosurgery (SRS) for small (1 cm) brain metastases can be safely performed on both Gamma Knife (GK) and CyberKnife (CK) as well as on modern LINACs, specifically tailored for radiosurgical procedures, However, considerable expertise and resources are required for a program based on the latest evidence for best practice.
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Affiliation(s)
- Diana Grishchuk
- National Hospital for Neurology and Neurosurgery, London, United Kingdom.
| | - Alexis Dimitriadis
- National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Arjun Sahgal
- Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada
| | - Antonio De Salles
- Department of Neurosurgery, University of California, Los Angeles, California
| | - Laura Fariselli
- Radiotherapy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta Milano, Unita di Radiotherapia, Milan, Italy
| | - Rupesh Kotecha
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida
| | - Marc Levivier
- Neurosurgery Service and Gamma Knife Center, Center Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Lijun Ma
- Department of Radiation Oncology, University of California San Francisco, San Francisco, California
| | - Bruce E Pollock
- Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
| | - Jean Regis
- Department of Functional Neurosurgery, La Timone Hospital, Aix-Marseille University, Marseille, France
| | - Jason Sheehan
- Department of Neurologic Surgery, University of Virginia, Charlottesville, Virginia
| | - John Suh
- Department of Radiation Oncology, Cleveland Clinic, Cleveland, Ohio
| | - Shoji Yomo
- Division of Radiation Oncology, Aizawa Comprehensive Cancer Center, Aizawa Hospital, Matsumoto, Japan
| | - Ian Paddick
- National Hospital for Neurology and Neurosurgery, London, United Kingdom
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Shapey J, Kujawa A, Dorent R, Wang G, Dimitriadis A, Grishchuk D, Paddick I, Kitchen N, Bradford R, Saeed SR, Bisdas S, Ourselin S, Vercauteren T. Segmentation of vestibular schwannoma from MRI, an open annotated dataset and baseline algorithm. Sci Data 2021; 8:286. [PMID: 34711849 PMCID: PMC8553833 DOI: 10.1038/s41597-021-01064-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 09/08/2021] [Indexed: 11/08/2022] Open
Abstract
Automatic segmentation of vestibular schwannomas (VS) from magnetic resonance imaging (MRI) could significantly improve clinical workflow and assist patient management. We have previously developed a novel artificial intelligence framework based on a 2.5D convolutional neural network achieving excellent results equivalent to those achieved by an independent human annotator. Here, we provide the first publicly-available annotated imaging dataset of VS by releasing the data and annotations used in our prior work. This collection contains a labelled dataset of 484 MR images collected on 242 consecutive patients with a VS undergoing Gamma Knife Stereotactic Radiosurgery at a single institution. Data includes all segmentations and contours used in treatment planning and details of the administered dose. Implementation of our automated segmentation algorithm uses MONAI, a freely-available open-source framework for deep learning in healthcare imaging. These data will facilitate the development and validation of automated segmentation frameworks for VS and may also be used to develop other multi-modal algorithmic models.
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Affiliation(s)
- Jonathan Shapey
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom.
- Department of Neurosurgery, King's College Hospital, London, United Kingdom.
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London, United Kingdom.
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, United Kingdom.
| | - Aaron Kujawa
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Reuben Dorent
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Guotai Wang
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Alexis Dimitriadis
- Queen Square Radiosurgery Centre (Gamma Knife), National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Diana Grishchuk
- Queen Square Radiosurgery Centre (Gamma Knife), National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Ian Paddick
- Queen Square Radiosurgery Centre (Gamma Knife), National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Neil Kitchen
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, United Kingdom
- Queen Square Radiosurgery Centre (Gamma Knife), National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Robert Bradford
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, United Kingdom
- Queen Square Radiosurgery Centre (Gamma Knife), National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Shakeel R Saeed
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, United Kingdom
- The Ear Institute, University College London, London, United Kingdom
- The Royal National Throat, Nose and Ear Hospital, London, United Kingdom
| | - Sotirios Bisdas
- Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Sébastien Ourselin
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Tom Vercauteren
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
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Kry S, Lye J, Clark C, Andratschke N, Dimitriadis A, Followill D, Howell R, Hussein M, Ishikawa M, Kito S, Kron T, Lee J, Michalski J, Monti A, Reynaert N, Taylor P, Venables K, Xiao Y, Lehmann J. PD-0899 Report dose-to-medium in clinical trials; a consensus from the Global Harmonisation Group. Radiother Oncol 2021. [DOI: 10.1016/s0167-8140(21)07178-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Paddick I, Cameron A, Dimitriadis A. Extracranial dose and the risk of radiation-induced malignancy after intracranial stereotactic radiosurgery: is it time to establish a therapeutic reference level? Acta Neurochir (Wien) 2021; 163:971-979. [PMID: 33325003 PMCID: PMC7966618 DOI: 10.1007/s00701-020-04664-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/01/2020] [Indexed: 11/29/2022]
Abstract
BACKGROUND To measure extracranial doses from Gamma Knife Perfexion (GKP) intracranial stereotactic radiosurgery (SRS) and model the risk of malignancy after SRS for different treatment platforms. METHODS Doses were measured for 20 patients undergoing SRS on a GKP at distances of 18, 43 and 75 cm from the target, corresponding to the approximate positions of the thyroid, breast and gonads respectively. A literature review was conducted to collect comparative data from other radiosurgery platforms. All data was used to calculate the dose to body organs. The National Cancer Institute (NCI) RadRAT calculator was used to estimate excess lifetime cancer risk from this exposure. Five different age groups covering childhood and younger adults were modelled for both sexes. RESULTS Extracranial doses delivered during SRS with the GKP were a median 0.04%, 0.008% and 0.002% of prescription dose at 18 cm, 43 cm and 70 cm from the isocentre respectively. Comparison with the literature revealed that the extracranial dose was lowest from GKP, then linacs equipped with micro-multileaf collimators (mMLC), then linacs equipped with circular collimators (cones), and highest from Cyberknife (CK). Estimated lifetime risks of radiation-induced malignancy in the body for patients treated with SRS aged 5-45 years were 0.03-0.88%, 0.36-11%, 0.61-18% and 2.2-39% for GKP, mMLC, cones and CK respectively. CONCLUSIONS We have compared typical extracranial doses from different platforms and quantified the lifetime risk of radiation-induced malignancy. The risk varies with platform. This should be taken into account when treating children and young adults with SRS. The concept of a therapeutic reference level (TRL), similar to the diagnostic reference level (DRL) established in radiology, is proposed.
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Affiliation(s)
- Ian Paddick
- Queen Square Radiosurgery Centre, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK.
| | - A Cameron
- Bristol Haematology and Oncology Centre, Bristol, BS2 8ED, UK
| | - A Dimitriadis
- Queen Square Radiosurgery Centre, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
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Klinge T, Modat M, McClelland JR, Dimitriadis A, Paddick I, Hopewell JW, Walton L, Rowe J, Kitchen N, Ourselin S. The impact of unscheduled gaps and iso-centre sequencing on the biologically effective dose in Gamma Knife radiosurgery. J Radiosurg SBRT 2021; 7:213-221. [PMID: 33898085 PMCID: PMC8055240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/21/2020] [Indexed: 11/01/2022]
Abstract
PURPOSE Establish the impact of iso-centre sequencing and unscheduled gaps in Gamma Knife® (GK) radiosurgery on the biologically effective dose (BED). METHODS A BED model was used to study BED values on the prescription iso-surface of patients treated with GK Perfexion™ (Vestibular Schwannoma). The effect of a 15 min gap, simulated at varying points in the treatment delivery, and adjustments to the sequencing of iso-centre delivery, based on average dose-rate, was quantified in terms of the impact on BED. RESULTS Depending on the position of the gap and the average dose-rate profiles, the mean BED values were decreased by 0.1% to 9.9% of the value in the original plan. A heuristic approach to iso-centre sequencing showed variations in BED of up to 14.2%, relative to the mean BED of the original sequence. CONCLUSION The treatment variables, like the iso-centre sequence and unscheduled gaps, should be considered during GK radiosurgery treatments.
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Affiliation(s)
- Thomas Klinge
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Dept. Medical Physics and Biomedical Engineering, University College London, London, UK, Centre for Medical Image Computing, Dept. Medical Physics and Biomedical Engineering, University College London, London, UK, School of Biomedical Engineering & Imaging Sciences, King’s College London, London, UK
| | - Marc Modat
- School of Biomedical Engineering & Imaging Sciences, King’s College London, London, UK
| | - Jamie R. McClelland
- Centre for Medical Image Computing, Dept. Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Alexis Dimitriadis
- Queen Square Gamma Knife Centre, National Hospital for Neurology and Neurosurgery, London, UK
| | - Ian Paddick
- Queen Square Gamma Knife Centre, National Hospital for Neurology and Neurosurgery, London, UK
| | | | - Lee Walton
- The National Centre for Stereotactic Radiosurgery, Royal Hallamshire Hospital, Sheffield, UK
| | - Jeremy Rowe
- The National Centre for Stereotactic Radiosurgery, Royal Hallamshire Hospital, Sheffield, UK
| | - Neil Kitchen
- Victor Horsley Department of Neurosurgery, National Hospital Queen Square, UCLH Trust, London, UK
| | - Sébastien Ourselin
- School of Biomedical Engineering & Imaging Sciences, King’s College London, London, UK
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Koriath C, Kenny J, Adamson G, Druyeh R, Taylor W, Beck J, Quinn L, Mok TH, Dimitriadis A, Norsworthy P, Bass N, Carter J, Walker Z, Kipps C, Coulthard E, Polke JM, Bernal-Quiros M, Denning N, Thomas R, Raybould R, Williams J, Mummery CJ, Wild EJ, Houlden H, Tabrizi SJ, Rossor MN, Hummerich H, Warren JD, Rowe JB, Rohrer JD, Schott JM, Fox NC, Collinge J, Mead S. Predictors for a dementia gene mutation based on gene-panel next-generation sequencing of a large dementia referral series. Mol Psychiatry 2020; 25:3399-3412. [PMID: 30279455 PMCID: PMC6330090 DOI: 10.1038/s41380-018-0224-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 06/28/2018] [Accepted: 07/18/2018] [Indexed: 11/09/2022]
Abstract
Next-generation genetic sequencing (NGS) technologies facilitate the screening of multiple genes linked to neurodegenerative dementia, but there are few reports about their use in clinical practice. Which patients would most profit from testing, and information on the likelihood of discovery of a causal variant in a clinical syndrome, are conspicuously absent from the literature, mostly for a lack of large-scale studies. We applied a validated NGS dementia panel to 3241 patients with dementia and healthy aged controls; 13,152 variants were classified by likelihood of pathogenicity. We identified 354 deleterious variants (DV, 12.6% of patients); 39 were novel DVs. Age at clinical onset, clinical syndrome and family history each strongly predict the likelihood of finding a DV, but healthcare setting and gender did not. DVs were frequently found in genes not usually associated with the clinical syndrome. Patients recruited from primary referral centres were compared with those seen at higher-level research centres and a national clinical neurogenetic laboratory; rates of discovery were comparable, making selection bias unlikely and the results generalisable to clinical practice. We estimated penetrance of DVs using large-scale online genomic population databases and found 71 with evidence of reduced penetrance. Two DVs in the same patient were found more frequently than expected. These data should provide a basis for more informed counselling and clinical decision making.
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Affiliation(s)
- C Koriath
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - J Kenny
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - G Adamson
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - R Druyeh
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - W Taylor
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - J Beck
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - L Quinn
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - T H Mok
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - A Dimitriadis
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - P Norsworthy
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - N Bass
- UCL Division of Psychiatry, Maple House, University College London, London, UK
| | - J Carter
- UCL Division of Psychiatry, Maple House, University College London, London, UK
| | - Z Walker
- UCL Division of Psychiatry, Maple House, University College London, London, UK
- Essex Partnership University NHS Foundation Trust, Essex, SS11 7XX, UK
| | - C Kipps
- Wessex Neurological Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - E Coulthard
- Institute of Clinical Neuroscience, University of Bristol, Level 1 Learning and Research Building, Bristol, BS10 5NB, UK
| | - J M Polke
- Neurogenetics Laboratory, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - M Bernal-Quiros
- Neurogenetics Laboratory, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - N Denning
- Division of Psychological Medicine & Clinical Neurosciences, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
| | - R Thomas
- Division of Psychological Medicine & Clinical Neurosciences, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
| | - R Raybould
- Division of Psychological Medicine & Clinical Neurosciences, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
| | - J Williams
- Division of Psychological Medicine & Clinical Neurosciences, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
| | - C J Mummery
- Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - E J Wild
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - H Houlden
- Neurogenetics Laboratory, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - S J Tabrizi
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - M N Rossor
- Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - H Hummerich
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - J D Warren
- Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - J B Rowe
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0SZ, UK
- Medical Research Council Cognition and Brain Sciences Unit, Cambridge, CB2 7EF, UK
| | - J D Rohrer
- Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - J M Schott
- Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - N C Fox
- Dementia Research Centre, Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - J Collinge
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK
| | - S Mead
- MRC Prion Unit at UCL, UCL Institute of Prion Diseases, Courtauld Building, London, W1W 7FF, UK.
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Paddick I, Grishchuk D, Dimitriadis A. IntuitivePlan inverse planning performance evaluation for Gamma Knife radiosurgery of AVMs. J Appl Clin Med Phys 2020; 21:90-95. [PMID: 32755072 PMCID: PMC7497913 DOI: 10.1002/acm2.12973] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/04/2020] [Accepted: 06/09/2020] [Indexed: 11/11/2022] Open
Abstract
Purpose To compare planning indices achieved using manual and inverse planning approaches for Gamma Knife radiosurgery of arterio‐venous malformations (AVMs). Methods and materials For a series of consecutive AVM patients, treatment plans were manually created by expert planners using Leksell GammaPlan (LGP). Patients were re‐planned using a new commercially released inverse planning system, IntuitivePlan. Plan quality metrics were calculated for both groups of plans and compared. Results Overall, IntuitivePlan created treatment plans of similar quality to expert planners. For some plan quality metrics statistically significant higher scores were achieved for the inversely generated plans (Coverage 96.8% vs 96.3%, P = 0.027; PCI 0.855 vs 0.824, P = 0.042), but others did not show statistically significant differences (Selectivity 0.884 vs 0.856, P = 0.071; GI 2.85 vs 2.76, P = 0.096; Efficiency Index 47.0% vs 48.1%, P = 0.242; Normal Brain V12(cc) 5.81 vs 5.79, P = 0.497). Automatic inverse planning demonstrated significantly shorter planning times over manual planning (3.79 vs 11.58 min, P < 10−6) and greater numbers of isocentres (40.4 vs 10.8, P < 10−6), with an associated cost of longer treatment times (57.97 vs 49.52 min, P = 0.009). When planning and treatment time were combined, there was no significant difference in the overall time between the two methods (61.76 vs 61.10, P = 0.433). Conclusions IntuitivePlan can offer savings on the labor of treatment planning. In many cases, it achieves higher quality indices than those achieved by an “expert planner”.
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Affiliation(s)
- Ian Paddick
- Queen Square Radiosurgery Centre, National Hospital for Neurology and Neurosurgery, London, UK
| | - Diana Grishchuk
- Queen Square Radiosurgery Centre, National Hospital for Neurology and Neurosurgery, London, UK
| | - Alexis Dimitriadis
- Queen Square Radiosurgery Centre, National Hospital for Neurology and Neurosurgery, London, UK
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Affiliation(s)
- S. Antoniou
- First Department of Internal Medicine, Agios Dimitrios Hospital Thessaloniki, Greece
| | - A. Dimitriadis
- First Department of Internal Medicine, Agios Dimitrios Hospital Thessaloniki, Greece
| | - F. Polydorou
- Laboratory of Microbiology Agios Dimitrios Hospital Thessaloniki, Greece
| | - E. Malaka
- Laboratory of Microbiology Agios Dimitrios Hospital Thessaloniki, Greece
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Affiliation(s)
- S. Antoniou
- CAPD unit “Agios Dimitrios” Hospital Thessaloniki, Greece
| | - D. Syreggelas
- CAPD unit “Agios Dimitrios” Hospital Thessaloniki, Greece
| | | | - A. Dimitriadis
- CAPD unit “Agios Dimitrios” Hospital Thessaloniki, Greece
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Logothetis A, Pantelis E, Zoros E, Pappas EP, Dimitriadis A, Paddick I, Garding J, Johansson J, Kollias G, Karaiskos P. Dosimetric evaluation of the Leksell GammaPlan ™ Convolution dose calculation algorithm. Phys Med Biol 2020; 65:045011. [PMID: 31860889 DOI: 10.1088/1361-6560/ab64b7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The dosimetric accuracy of the Leksell GammaPlan Convolution calculation algorithm was evaluated through comparison with corresponding Monte Carlo (MC) dosimetric results. MC simulations were based on generated sector phase space files for the 4 mm, 8 mm and 16 mm collimator sizes, using a previous comprehensive Gamma Knife Perfexion™ source model and validated using film dosimetry. Test cases were designed for the evaluation of the Convolution algorithm involving irradiation of homogeneous and inhomogeneous phantom geometries mimicking clinical cases, with radiation fields created using one sector (single sector), all sectors with the same (single shot) or different (composite shot) collimator sizes. Dose calculations using the Convolution algorithm were found to be in excellent agreement (gamma pass rate greater than 98%, applying 1%/1 mm local dose difference and distance agreement criteria), with corresponding MC calculations, indicating the accuracy of the Convolution algorithm in homogeneous and heterogeneous model geometries. While of minor clinical importance, large deviations were observed for the voxels laying inside air media. The calculated beam on times using the Convolution algorithm were found to increase (up to 7%) relative to the TMR 10 algorithm currently used in clinical practice, especially in a test case mimicking a brain metastasis close to the skull, in excellent agreement with corresponding MC calculations.
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Affiliation(s)
- A Logothetis
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Athens, Greece
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Shapey J, Wang G, Dorent R, Dimitriadis A, Li W, Paddick I, Kitchen N, Bisdas S, Saeed SR, Ourselin S, Bradford R, Vercauteren T. An artificial intelligence framework for automatic segmentation and volumetry of vestibular schwannomas from contrast-enhanced T1-weighted and high-resolution T2-weighted MRI. J Neurosurg 2019; 134:171-179. [PMID: 31812137 DOI: 10.3171/2019.9.jns191949] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 09/11/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Automatic segmentation of vestibular schwannomas (VSs) from MRI could significantly improve clinical workflow and assist in patient management. Accurate tumor segmentation and volumetric measurements provide the best indicators to detect subtle VS growth, but current techniques are labor intensive and dedicated software is not readily available within the clinical setting. The authors aim to develop a novel artificial intelligence (AI) framework to be embedded in the clinical routine for automatic delineation and volumetry of VS. METHODS Imaging data (contrast-enhanced T1-weighted [ceT1] and high-resolution T2-weighted [hrT2] MR images) from all patients meeting the study's inclusion/exclusion criteria who had a single sporadic VS treated with Gamma Knife stereotactic radiosurgery were used to create a model. The authors developed a novel AI framework based on a 2.5D convolutional neural network (CNN) to exploit the different in-plane and through-plane resolutions encountered in standard clinical imaging protocols. They used a computational attention module to enable the CNN to focus on the small VS target and propose a supervision on the attention map for more accurate segmentation. The manually segmented target tumor volume (also tested for interobserver variability) was used as the ground truth for training and evaluation of the CNN. We quantitatively measured the Dice score, average symmetric surface distance (ASSD), and relative volume error (RVE) of the automatic segmentation results in comparison to manual segmentations to assess the model's accuracy. RESULTS Imaging data from all eligible patients (n = 243) were randomly split into 3 nonoverlapping groups for training (n = 177), hyperparameter tuning (n = 20), and testing (n = 46). Dice, ASSD, and RVE scores were measured on the testing set for the respective input data types as follows: ceT1 93.43%, 0.203 mm, 6.96%; hrT2 88.25%, 0.416 mm, 9.77%; combined ceT1/hrT2 93.68%, 0.199 mm, 7.03%. Given a margin of 5% for the Dice score, the automated method was shown to achieve statistically equivalent performance in comparison to an annotator using ceT1 images alone (p = 4e-13) and combined ceT1/hrT2 images (p = 7e-18) as inputs. CONCLUSIONS The authors developed a robust AI framework for automatically delineating and calculating VS tumor volume and have achieved excellent results, equivalent to those achieved by an independent human annotator. This promising AI technology has the potential to improve the management of patients with VS and potentially other brain tumors.
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Affiliation(s)
- Jonathan Shapey
- 1Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London
- 2Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London
- 3School of Biomedical Engineering & Imaging Sciences, King's College London, United Kingdom
| | - Guotai Wang
- 1Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London
- 3School of Biomedical Engineering & Imaging Sciences, King's College London, United Kingdom
- 4School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Reuben Dorent
- 3School of Biomedical Engineering & Imaging Sciences, King's College London, United Kingdom
| | - Alexis Dimitriadis
- 6Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, London
| | - Wenqi Li
- 3School of Biomedical Engineering & Imaging Sciences, King's College London, United Kingdom
| | - Ian Paddick
- 5Queen Square Radiosurgery Centre (Gamma Knife) and
| | - Neil Kitchen
- 2Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London
- 5Queen Square Radiosurgery Centre (Gamma Knife) and
| | - Sotirios Bisdas
- 6Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, London
| | - Shakeel R Saeed
- 2Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London
- 7The Ear Institute, University College London; and
- 8The Royal National Throat, Nose and Ear Hospital, London, United Kingdom
| | - Sebastien Ourselin
- 3School of Biomedical Engineering & Imaging Sciences, King's College London, United Kingdom
| | - Robert Bradford
- 2Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London
- 5Queen Square Radiosurgery Centre (Gamma Knife) and
| | - Tom Vercauteren
- 3School of Biomedical Engineering & Imaging Sciences, King's College London, United Kingdom
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Alyahyawi A, Dimitriadis A, Jafari S, Lohstroh A, Alanazi A, Alsubaie A, Clark C, Nisbet A, Bradley D. Thermoluminescence measurements of eye-lens dose in a multi-centre stereotactic radiosurgery audit. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2018.08.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Dimitriadis A, Paddick I. A novel index for assessing treatment plan quality in stereotactic radiosurgery. J Neurosurg 2018; 129:118-124. [DOI: 10.3171/2018.7.gks18694] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 07/26/2018] [Indexed: 12/14/2022]
Abstract
OBJECTIVEStereotactic radiosurgery (SRS) is characterized by high levels of conformity and steep dose gradients from the periphery of the target to surrounding tissue. Clinical studies have backed up the importance of these factors through evidence of symptomatic complications. Available data suggest that there are threshold doses above which the risk of symptomatic radionecrosis increases with the volume irradiated. Therefore, radiosurgical treatment plans should be optimized by minimizing dose to the surrounding tissue while maximizing dose to the target volume. Several metrics have been proposed to quantify radiosurgical plan quality, but all present certain weaknesses. To overcome limitations of the currently used metrics, a novel metric is proposed, the efficiency index (η50%), which is based on the principle of calculating integral doses: η50% = integral doseTV/integral dosePIV50%.METHODSThe value of η50% can be easily calculated by dividing the integral dose (mean dose × volume) to the target volume (TV) by the integral dose to the volume of 50% of the prescription isodose (PIV50%). Alternatively, differential dose-volume histograms (DVHs) of the TV and PIV50% can be used. The resulting η50% value is effectively the proportion of energy within the PIV50% that falls into the target. This value has theoretical limits of 0 and 1, with 1 being perfect. The index combines conformity, gradient, and mean dose to the target into a single value. The value of η50% was retrospectively calculated for 100 clinical SRS plans.RESULTSThe value of η50% for the 100 clinical SRS plans ranged from 37.7% to 58.0% with a mean value of 49.0%. This study also showed that the same principles used for the calculation of η50% can be adapted to produce an index suitable for multiple-target plans (Gη12Gy). Furthermore, the authors present another adaptation of the index that may play a role in plan optimization by calculating and minimizing the proportion of energy delivered to surrounding organs at risk (OARη50%).CONCLUSIONSThe proposed efficiency index is a novel approach in quantifying plan quality by combining conformity, gradient, and mean dose into a single value. It quantifies the ratio of the dose “doing good” versus the dose “doing harm,” and its adaptations can be used for multiple-target plan optimization and OAR sparing.
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Murata G, Tzamaloukas A, Voudiklari S, Dimitriadis A, Balaskas EV, Nicolopoulou N, Dombros N. Estimating Urea Clearance in Patients on Continuous Ambulatory Peritoneal Dialysis: A Multivariate Analysis. Int J Artif Organs 2018. [DOI: 10.1177/039139889802100909] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The purpose of this study was to determine if Kt/V urea in continuous ambulatory peritoneal dialysis (CAPD) could be estimated by a multivariate model based upon simple clinical observations. The study included 439 clearance studies in 301 CAPD patients followed in 8 dialysis centers. Weekly urea clearance, 24 h urine volume and 24 h drain volume were normalized to body water by the formulae of Watson (Kt/V, UV/V, and DV/V respectively). Adequate dialysis was defined as Kt/V ≥2.0 weekly. Subjects at 2 units were used to derive the models, while others were used for model validation. Stepwise multiple linear regression was performed on the derivation set (DS) to identify the clinical variables that correlated with Kt/V. The model was then used to estimate Kt/V for the validation set (VS). In the DS, 110 clearance studies were performed in subjects with residual renal function. Multiple linear regression showed that weekly Kt/V was defined by the expression: Kt/V = 1.48 + 24.1 (UV/V) + 2.92(DV/V) - 0.049 (serum creatinine) (r=0.750, p<0.001). In 204 VS studies, the correlation between estimated and measured Kt/V was 0.633. There were marked differences in the proportion of adequately dialyzed patients when Kt/V estimated from the formula shown was <2.0, between 2.0 and 2.3, and >2.3 weekly (7.9%, 54.7% and 79.7%, respectively; p<0.001). In the 33 studies done in DS anuric patients, regression analysis showed the following: Kt/V = 0.46 + 2.59 (DV/V) + 0.009(age) (r=0.562; p = 0.003). In 92 VS studies in anuric subjects, there was strong correlation between estimated and measured Kt/V (r=0.740). Again, there were marked differences in the frequency of adequate dialysis in anuric patients with estimated Kt/V <2.0, between 2.0 and 2.3, and >2.3 weekly (8.1%, 68.8%, and 100%, respectively; p<0.001). The risk of low Kt/V can be estimated by multivariate linear models requiring only simple clinical measurements.
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Affiliation(s)
- G.H. Murata
- Veterans Affairs Medical Center and the University of New Mexico School of Medicine, Albuquerque, New Mexico - USA
| | - A.H. Tzamaloukas
- Veterans Affairs Medical Center and the University of New Mexico School of Medicine, Albuquerque, New Mexico - USA
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Dimitriadis A, Palmer AL, Thomas RAS, Nisbet A, Clark CH. Adaptation and validation of a commercial head phantom for cranial radiosurgery dosimetry end-to-end audit. Br J Radiol 2017; 90:20170053. [PMID: 28452563 DOI: 10.1259/bjr.20170053] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE To adapt and validate an anthropomorphic head phantom for use in a cranial radiosurgery audit. METHODS Two bespoke inserts were produced for the phantom: one for providing the target and organ at risk for delineation and the other for performing dose measurements. The inserts were tested to assess their positional accuracy. A basic treatment plan dose verification with an ionization chamber was performed to establish a baseline accuracy for the phantom and beam model. The phantom and inserts were then used to perform dose verification measurements of a radiosurgery plan. The dose was measured with alanine pellets, EBT extended dose film and a plastic scintillation detector (PSD). RESULTS Both inserts showed reproducible positioning (±0.5 mm) and good positional agreement between them (±0.6 mm). The basic treatment plan measurements showed agreement to the treatment planning system (TPS) within 0.5%. Repeated film measurements showed consistent gamma passing rates with good agreement to the TPS. For 2%-2 mm global gamma, the mean passing rate was 96.7% and the variation in passing rates did not exceed 2.1%. The alanine pellets and PSD showed good agreement with the TPS (-0.1% and 0.3% dose difference in the target) and good agreement with each other (within 1%). CONCLUSION The adaptations to the phantom showed acceptable accuracies. The presence of alanine and PSD do not affect film measurements significantly, enabling simultaneous measurements by all three detectors. Advances in knowledge: A novel method for thorough end-to-end test of radiosurgery, with capability to incorporate all steps of the clinical pathway in a time-efficient and reproducible manner, suitable for a national audit.
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Affiliation(s)
- Alexis Dimitriadis
- 1 Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK.,2 Department of Medical Physics, Royal Surrey County Hospital NHS Foundation Trust, Guildford, UK.,3 Radiation Dosimetry Group, National Physical Laboratory, Teddington, UK
| | - Antony L Palmer
- 1 Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK.,4 Medical Physics Department, Portsmouth Hospitals NHS Trust, Portsmouth, UK
| | - Russell A S Thomas
- 3 Radiation Dosimetry Group, National Physical Laboratory, Teddington, UK
| | - Andrew Nisbet
- 1 Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK.,2 Department of Medical Physics, Royal Surrey County Hospital NHS Foundation Trust, Guildford, UK
| | - Catharine H Clark
- 1 Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK.,3 Radiation Dosimetry Group, National Physical Laboratory, Teddington, UK
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Dimitriadis A, Thomas R, Palmer A, Eaton D, Lee J, Patel R, Silvestre Patallo I, Nisbet A, Clark C. OC-0540: A national cranial stereotactic radiosurgery end-to-end dosimetry audit. Radiother Oncol 2017. [DOI: 10.1016/s0167-8140(17)30980-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Karavasilis E, Dimitriadis A, Gonis H, Pappas P, Georgiou E, Yakoumakis E. DOSE COEFFICIENTS FOR LIVER CHEMOEMBOLISATION PROCEDURES USING MONTE CARLO CODE. Radiat Prot Dosimetry 2016; 172:409-415. [PMID: 26656074 DOI: 10.1093/rpd/ncv492] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 10/24/2015] [Accepted: 10/28/2015] [Indexed: 06/05/2023]
Abstract
The aim of the present study is the estimation of radiation burden during liver chemoembolisation procedures. Organ dose and effective dose conversion factors, normalised to dose-area product (DAP), were estimated for chemoembolisation procedures using a Monte Carlo transport code in conjunction with an adult mathematical phantom. Exposure data from 32 patients were used to determine the exposure projections for the simulations. Equivalent organ (HT) and effective (E) doses were estimated using individual DAP values. The organs receiving the highest amount of doses during these exams were lumbar spine, liver and kidneys. The mean effective dose conversion factor was 1.4 Sv Gy-1 m-2 Dose conversion factors can be useful for patient-specific radiation burden during chemoembolisation procedures.
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Affiliation(s)
- E Karavasilis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str. Goudi, Athens 11527, Greece
| | - A Dimitriadis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str. Goudi, Athens 11527, Greece
| | - H Gonis
- Radiology Department, Laiko Hospital of Athens, 17 Ag. Thoma Str. Goudi, Athens 11527, Greece
| | - P Pappas
- Radiology Department, Laiko Hospital of Athens, 17 Ag. Thoma Str. Goudi, Athens 11527, Greece
| | - E Georgiou
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str. Goudi, Athens 11527, Greece
| | - E Yakoumakis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str. Goudi, Athens 11527, Greece
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Tzamicha E, Dimitriadis A, Tsalafoutas I, Georgiou E, Tsapaki V, Yakoumakis E. Glandular dose in digital mammography: Monte carlo method using voxel phantoms. Phys Med 2016. [DOI: 10.1016/j.ejmp.2016.07.225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Nisbet A, Dimitriadis A, Palmer A, Clark C. EP-1560: Is EBT-XD film suitable for linac and Gamma Knife radiosurgery dosimetry verification and audit? Radiother Oncol 2016. [DOI: 10.1016/s0167-8140(16)32810-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
OBJECTIVE To investigate and benchmark the current clinical and dosimetric practices in stereotactic radiosurgery (SRS) in the UK. METHODS A detailed questionnaire was sent to 70 radiotherapy centres in the UK. 97% (68/70) of centres replied between June and December 2014. RESULTS 21 centres stated that they are practising SRS, and a further 12 centres plan to start SRS by the end of 2016. The most commonly treated indications are brain metastases and acoustic neuromas. A large range of prescription isodoses that range from 45% to 100% between different radiotherapy centres was seen. Ionization chambers and solid-water phantoms are used by the majority of centres for patient-specific quality assurance, and thermoplastic masks for patient immobilization are more commonly used than fixed stereotactic frames. The majority of centres perform orthogonal kilovoltage X-rays for localization before and during delivery. The acceptable setup accuracy reported ranges from 0.1 to 2 mm with a mean of 0.8 mm. CONCLUSION SRS has been increasing in use in the UK and will continue to increase in the next 2 years. There is no current consensus between SRS centres as a whole, or even between SRS centres with the same equipment, on the practices followed. This indicates the need for benchmarking and standardization in SRS practices within the UK. ADVANCES IN KNOWLEDGE This article outlines the current practices in SRS and provides a benchmark for reference and comparison with future research in this technique.
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Affiliation(s)
- Alexis Dimitriadis
- 1 Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK.,2 Department of Medical Physics, Royal County Hospital NHS Foundation Trust, Guildford, UK.,3 Radiation Dosimetry Group, National Physical Laboratory, Teddington, Middlesex, UK
| | - Karen J Kirkby
- 4 Manchester Academic Science, Institute of Cancer Sciences, University of Manchester, Manchester, UK.,5 The Christie NHS Foundation Trust, Manchester, UK
| | - Andrew Nisbet
- 1 Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, UK.,2 Department of Medical Physics, Royal County Hospital NHS Foundation Trust, Guildford, UK
| | - Catharine H Clark
- 2 Department of Medical Physics, Royal County Hospital NHS Foundation Trust, Guildford, UK.,3 Radiation Dosimetry Group, National Physical Laboratory, Teddington, Middlesex, UK
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Palmer AL, Dimitriadis A, Nisbet A, Clark CH. Evaluation of Gafchromic EBT-XD film, with comparison to EBT3 film, and application in high dose radiotherapy verification. Phys Med Biol 2015; 60:8741-52. [DOI: 10.1088/0031-9155/60/22/8741] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Yakoumakis E, Tzamicha E, Dimitriadis A, Georgiou E, Tsapaki V, Chalazonitis A. Dual-energy contrast-enhanced digital mammography: patient radiation dose estimation using a Monte Carlo code. Radiat Prot Dosimetry 2015; 165:369-372. [PMID: 25836682 DOI: 10.1093/rpd/ncv098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Mammography is a standard procedure that facilitates breast cancer detection. Initial results of contrast-enhanced digital mammography (CEDM) are promising. The purpose of this study is to assess the CEDM radiation dose using a Monte Carlo code. EGSnrc MC code was used to simulate the interaction of photons with matter and estimate the glandular dose (Dg). A voxel female human phantom with a 2-8-cm breast thickness range and a breast glandular composition of 50 % was applied. Dg values ranged between 0.96 and 1.45 mGy (low and high energy). Dg values for a breast thickness of 5.0 cm and a glandular fraction of 50 % for craniocaudal and mediolateral oblique view were 1.12 (low energy image contribution is 0.98 mGy) and 1.07 (low energy image contribution is 0.95 mGy), respectively. The low kV part of CEDM is the main contributor to total glandular breast dose.
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Affiliation(s)
- E Yakoumakis
- Medical Physics Department, University of Athens, Athens, Greece
| | - E Tzamicha
- Medical Physics Department, University of Athens, Athens, Greece
| | - A Dimitriadis
- Medical Physics Department, University of Athens, Athens, Greece
| | - E Georgiou
- Medical Physics Department, University of Athens, Athens, Greece
| | - V Tsapaki
- Medical Physics Department, Konstantopoulio General Hospital of Nea Ionia, Attiki, Greece
| | - A Chalazonitis
- Radiology Department, Alexandra General Hospital, Athens, Greece
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Yakoumakis E, Dimitriadis A, Gialousis G, Makri T, Karavasilis E, Yakoumakis N, Georgiou E. Evaluation of organ and effective doses during paediatric barium meal examinations using PCXMC 2.0 Monte Carlo code. Radiat Prot Dosimetry 2015; 163:202-209. [PMID: 24876338 DOI: 10.1093/rpd/ncu174] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Radiation protection and estimation of the radiological risk in paediatric radiology is essential due to children's significant radiosensitivity and their greater overall health risk. The purpose of this study was to estimate the organ and effective doses of paediatric patients undergoing barium meal (BM) examinations and also to evaluate the assessment of radiation Risk of Exposure Induced cancer Death (REID) to paediatric patients undergoing BM examinations. During the BM studies, fluoroscopy and multiple radiographs are involved. Since direct measurements of the dose in each organ are very difficult if possible at all, clinical measurements of dose-area products (DAPs) and the PCXMC 2.0 Monte Carlo code were involved. In clinical measurements, DAPs were assessed during examination of 51 patients undergoing BM examinations, separated almost equally in three age categories, neonatal, 1- and 5-y old. Organs receiving the highest amounts of radiation during BM examinations were as follows: the stomach (10.4, 10.2 and 11.1 mGy), the gall bladder (7.1, 5.8 and 5.2 mGy) and the spleen (7.5, 8.2 and 4.3 mGy). The three values in the brackets correspond to neonatal, 1- and 5-y-old patients, respectively. For all ages, the main contributors to the total organ and effective doses are the fluoroscopy projections. The average DAP values and absorbed doses to patient were higher for the left lateral projections. The REID was calculated for boys (4.8 × 10(-2), 3.0 × 10(-2) and 2.0 × 10(-2) %) for neonatal, 1- and 5-y old patients, respectively. The corresponding values for girl patients were calculated (12.1 × 10(-2), 5.5 × 10(-2) and 3.4 × 10(-2) %).
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Affiliation(s)
- E Yakoumakis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str, Goudi, Athens 11527, Greece
| | - A Dimitriadis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str, Goudi, Athens 11527, Greece
| | - G Gialousis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str, Goudi, Athens 11527, Greece Medical Physics Department, IASO Hospital, 37-39 Kifissias Str., Maroussi, Athens 15123, Greece
| | - T Makri
- Radiological Imaging Department, Ag.Sofia Hospital, Lebadias and Thibon, Goudi, Athens 11527, Greece
| | - E Karavasilis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str, Goudi, Athens 11527, Greece
| | - N Yakoumakis
- Department of Radiology, Aretaieion Hospital University of Athens, 76 Vas Sophias Avenue, Athens 11528, Greece
| | - E Georgiou
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str, Goudi, Athens 11527, Greece
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Dimitriadis A, Hussein M, Jafari S, Kirkby K, Nisbet A, Clark C. EP-1658: Does the delivery technique impact the effect of respiratory motion in stereotactic ablative body radiotherapy? Radiother Oncol 2014. [DOI: 10.1016/s0167-8140(15)31776-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Yakoumakis E, Tzamicha E, Dimitriadis A, Georgiou E, Tsapaki V, Chalazonitis A. Dual-energy contrast-enhanced digital mammography: Glandular dose estimation using Monte Carlo Code and voxel phantom. Phys Med 2014. [DOI: 10.1016/j.ejmp.2014.07.291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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30
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Karavasilis E, Dimitriadis A, Gonis H, Pappas P, Georgiou E, Yakoumakis E. Effective dose in percutaneous transhepatic biliary drainage examination using PCXMC2.0 and MCNP5 Monte Carlo codes. Phys Med 2014; 30:432-6. [PMID: 24374260 DOI: 10.1016/j.ejmp.2013.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 12/09/2013] [Accepted: 12/10/2013] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVES To estimate the organ equivalent doses and the effective doses (E) in patient undergoing percutaneous transhepatic biliary drainage (PTBD) examinations, using the MCNP5 and PCXMC2 Monte Carlo-based codes. METHODS The purpose of this study is to estimate the organ doses to patients undergoing PTBD examinations by clinical measurements and Monte Carlo simulation. Dose area products (DAP) values were assessed during examination of 43 patients undergoing PTBD examination separated into groups based on the gender and the dimensions and location of the beam. RESULTS Monte Carlo simulation of photon transport in male and female mathematical phantoms was applied using the MCNP5 and PCXMC2 codes in order to estimate equivalent organ doses. Regarding the PTBD examination the organ receiving the maximum radiation dose was the lumbar spine. The mean calculated HT for the lumbar spine using the MCNP5 and PCXMC2 methods respectively, was 117.25 mSv and 131.7 mSv, in males. The corresponding doses were 139.45 mSv and 157.1 mSv respectively in females. The HT values for organs receiving considerable amounts of radiation during PTBD examinations were varied between 0.16% and 73.2% for the male group and between 1.10% and 77.6% for the female group. E in females and males using MCNP5 and PCXMC2.0 was 5.88 mSv and 6.77 mSv, and 4.93 mSv and 5.60 mSv. CONCLUSION The doses remain high compared to other invasive operations in interventional radiology. There is a reasonable good coincidence between the MCNP5 and PCXMC2.0 calculation for most of the organs.
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Affiliation(s)
- E Karavasilis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str., Goudi, 11527 Athens, Greece.
| | - A Dimitriadis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str., Goudi, 11527 Athens, Greece
| | - H Gonis
- Medical Physics Department, Laiko Hospital of Athens, 17 Ag. Thoma Str., Goudi, 11527 Athens, Greece
| | - P Pappas
- Radiology Department, Laiko Hospital of Athens, 17 Ag. Thoma Str., Goudi, 11527 Athens, Greece
| | - E Georgiou
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str., Goudi, 11527 Athens, Greece
| | - E Yakoumakis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str., Goudi, 11527 Athens, Greece
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Yakoumakis E, Dimitriadis A, Makri T, Karlatira M, Karavasilis E, Gialousis G. Verification of radiation dose calculations during paediatric cystourethrography examinations using MCNP5 and PCXMC 2.0 Monte Carlo codes. Radiat Prot Dosimetry 2013; 157:355-362. [PMID: 23765072 DOI: 10.1093/rpd/nct150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The estimation of the radiological risk in the case of children is of particular importance due to their enhanced radiosensitivity when compared with that of adult patients. The purpose of this study is to estimate the organ and effective doses of paediatric patients undergoing micturating cystourethrography examinations. Since direct measurements of the dose in each organ are very difficult, dose-area products of 90 patients undergoing cystourethrography examinations were recorded and used with two Monte Carlo codes, MCNP5 and PCXMC2.0, to assess the organ doses in these procedures. The organs receiving the highest radiation doses were the urinary bladder (ranging from 1.9 mSv in the newborn to 4.7 mSv in a 5-y old patient) and the large intestines (ranging from 1.5 mSv in the newborn to 3.1 mSv in the 5-y old patient). For all ages the main contributors to the total organ or effective doses are the fluoroscopy projections compared with the radiographs. There was a reasonable agreement between the dose estimates provided by PCXMC v2.0 and MCNP5 for most of the organs considered in this study. In special cases, there were systematic disagreements in organ doses such as in the skeleton, gonads and oesophagus due to the anatomical differences between patient anatomic models employed by the two codes.
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Affiliation(s)
- E Yakoumakis
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str. Goudi 11527, Athens, Greece
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Giofkos C, Fiorakis C, Vlahaki K, Dimopoulos N, Dimitriadis A, Psarra V, Mitsonis C, Valavanis P, Choidas S. P-1226 - Association of clinical and sociodemographic characteristics with duration of hospitalization in patients with schizophrenia. Eur Psychiatry 2012. [DOI: 10.1016/s0924-9338(12)75393-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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Dimitriadis A, Smith F, Mavrogenis AF, Pope MH, Papagelopoulos PJ, Karantanas A, Hadjipavlou A, Katonis P. Effect of two sitting postures on lumbar sagittal alignment and intervertebral discs in runners. Radiol Med 2011; 117:654-68. [DOI: 10.1007/s11547-011-0748-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 04/26/2011] [Indexed: 10/15/2022]
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Gialousis G, Dimitriadis A, Yakoumakis E. Monte Carlo estimation of dose difference in lung from 192Ir brachytherapy due to tissue inhomogeneity. Radiat Prot Dosimetry 2011; 147:287-290. [PMID: 21831865 DOI: 10.1093/rpd/ncr337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Lung brachytherapy using high-dose rate (192)Ir technique is a well-established technique of radiation therapy. However, many commercial treatment planning systems do not have the ability to consider the inhomogeneity of lung in relation to normal tissue. Under such circumstances dose calculations for tissues and organs at risk close to the target are inaccurate. The purpose of the current study was to estimate the dose difference due to tissue inhomogeneity using the Monte Carlo simulation code MCNP-5. Results showed that there was a relative sub dosage by treatment planning systems calculations in neighbouring tissues around the radioactive source due to inhomogeneity ignorance. The presence of lung instead of normal tissue resulted in an increase in relative dose, which approached 8 % at 4-cm distance from the source. Additionally, the relative increase was small for the lung (2.1 %) and larger for organs at risk such as the heart (6.8 %) and bone marrow (7.6 %).
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Affiliation(s)
- G Gialousis
- Medical Physics Department, IASSO Hospital, 37-39 Kifissias Str, Maroussi 15123, Athens, Greece.
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35
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Neocleous A, Yakoumakis E, Gialousis G, Dimitriadis A, Yakoumakis N, Georgiou E. Dosimetry using Gafchromic XR-RV2 radiochromic films in interventional radiology. Radiat Prot Dosimetry 2011; 147:78-82. [PMID: 21733864 DOI: 10.1093/rpd/ncr272] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Patient dose measurements of local entrance dose to the skin have been carried out using radiochromic film (Gafchromic XR-RV2) in a sample of interventional procedures. The major aim of the work was to measure patient entrance dose from such examinations using Gafchromic XR-RV2. Forty-five various interventional procedures (including nefrostomies and urinary stenting, biliary stenting and percutaneous transhepatic biliary drainage (PTBD) and aorta stent grafting) were evaluated. Maximum entrance doses were 537 ± 119 mGy in nephrostomies, 943 ± 631 mGy in biliary stenting and PTBD and 2425 ± 569 mGy in aorta stent grafting. Results indicate that all patients undergoing aorta stent grafting received skin dose above 1500 mGy, which means that there is an increasing potential to suffer radiation-induced skin injuries. The film provides dose mapping, the position of the skin area with highest dose and can be used for immediate qualitative and as well as for quantitative assessment of patient skin dose.
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Affiliation(s)
- A Neocleous
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str, Goudi, 115 27 Athens, Greece.
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Dimitriadis A, Gialousis G, Makri T, Karlatira M, Karaiskos P, Georgiou E, Papaodysseas S, Yakoumakis E. Monte Carlo estimation of radiation doses during paediatric barium meal and cystourethrography examinations. Phys Med Biol 2010; 56:367-82. [DOI: 10.1088/0031-9155/56/2/006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Yakoumakis E, Karlatira M, Gialousis G, Dimitriadis A, Makri T, Georgiou E. Effective dose variation in pediatric computed tomography: dose reference levels in Greece. Health Phys 2009; 97:595-603. [PMID: 19901594 DOI: 10.1097/01.hp.0000363840.78169.1b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Computed tomography provides high-resolution imaging of the human body. However, it contributes mainly to the doses on the population. Additionally, the fact that children are two to three times more sensitive to the x rays compared to the adults results in the increased need of taking action for the reduction of the dose regarding the computed tomography examinations. The first part of this paper presents the results of an investigation on the variation of doses to children while the second part compares those results with the European standards. This project took place in twelve hospitals distributed throughout the country. The weighted computed dose-index and the dose length product were calculated for four different age-categories (namely 0, 1, 5 and 10-year-old) and for the three most often examinations (brain, thorax and abdomen). Effective dose values were estimated using coefficients and patients' data. The measurements showed that only a few hospitals are taking into account the protocols regarding the age of the children. As a result, many patients receive high doses without this being necessary. Thus, reducing dose methods should be adapted in order to improve the optimization of this high dose modality.
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Affiliation(s)
- E Yakoumakis
- Medical Physics Department, Medical School, University of Athens, Mikras Asias, Goudi 11527 Athens, Greece
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38
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Papadopoulou PL, Patsikas MN, Charitanti A, Kazakos GM, Papazoglou LG, Karayannopoulou M, Chrisogonidis I, Tziris N, Dimitriadis A. The Lymph Drainage Pattern of the Mammary Glands in the Cat: A Lymphographic and Computerized Tomography Lymphographic Study. Anat Histol Embryol 2009; 38:292-9. [DOI: 10.1111/j.1439-0264.2009.00942.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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39
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Renner S, Dimitriadis A, Voronov L, Havey R, Carandang G, McIntosh B, Carson C, Ty D, Patwardhan A. 010 Restoration of intervertebral disc mechanics after endplate deformity reduction using structural kyphoplasty. J Neurointerv Surg 2009. [DOI: 10.1136/jnis.2009.000851j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Abstract
OBJECTIVE In juvenile nasopharyngeal angiofibroma (JNA), analysis of tumor extension and blood supply is useful for controlling intraoperative bleeding and helps in determining the appropriate surgical approach. The purpose of this study was to evaluate angiographic findings and the efficacy and benefits of preoperative embolization of JNA. PATIENTS AND METHODS Twenty-one male patients with JNA (mean age 13.3 years) were included in this study. The tumors were embolized with particles of gel foam. Surgical removal was achieved through transantral approach (n=2), lateral rhinotomy (n=13), midfacial degloving (n=4), and endonasally (n=2). RESULTS The blood supply was exclusively homolateral in 18 patients, deriving mainly from the external carotid artery, and bilateral in three. There were no connections between the branches of the internal and external carotid arteries. Intratumoral embolization was achieved in all patients. No major complications occurred. Mean blood loss during surgery was 560 ml. The recurrence rate was 14%. CONCLUSION Preoperative angiographic evaluation and embolization of JNA are important tools for planning surgical approach. Embolization reduces significantly the intraoperative blood loss, minimizes the need of blood transfusion, and makes resection easier.
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Affiliation(s)
- C Giavroglou
- Radiologisches Institut der Aristoteles-Universität Thessaloniki, AHEPA-Hospital, Griechenland
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41
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Arvanitakis M, Koustiani G, Gantzarou A, Grollios G, Tsitouridis I, Haritandi-Kouridou A, Dimitriadis A, Arvanitakis C. Staging of severity and prognosis of acute pancreatitis by computed tomography and magnetic resonance imaging-a comparative study. Dig Liver Dis 2007; 39:473-82. [PMID: 17363349 DOI: 10.1016/j.dld.2007.01.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 01/02/2007] [Accepted: 01/18/2007] [Indexed: 02/07/2023]
Abstract
BACKGROUND Determination of severity of acute pancreatitis is important to determine prognosis. AIMS (1) the staging of acute pancreatitis by computed tomography and magnetic resonance imaging, (2) the correlation of computed tomography and magnetic resonance severity indices and 3) the correlation of magnetic resonance severity index with C-reactive protein, Ranson score, duration of hospitalization and clinical outcome. PATIENTS Thirty-five patients (median age: 64 (27-89)) were studied. Twenty-two patients had biliary acute pancreatitis. METHODS The following examinations were conducted: (1) computed tomography 48 h, 7 and 30 days after admission, (2) magnetic resonance imaging 7 and 30 days after admission, (3) C-reactive protein and 4) Ranson score. Clinical outcome was determined on a scale 0-3 (0: remission, 1: local complications, 2: systemic complications, 3: death). RESULTS Six of 35 patients (17%) had necrotizing acute pancreatitis. Fifteen of 35 patients (43%) had severe acute pancreatitis according to Ranson criteria. A significant correlation was noted between magnetic resonance severity index and C-reactive protein (r=0.419, p<0.005), Ranson score (r=0.431, p<0.05), duration of hospitalization (r=0.497, p<0.01) and clinical outcome (r=0.420, p<0.05). Comparison of the imaging methods showed a significant correlation between magnetic resonance severity index and computed tomography severity index (r=0.887, p<0.01). CONCLUSION Magnetic resonance imaging is of comparable diagnostic and prognostic value with computed tomography in the staging of acute pancreatitis.
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Affiliation(s)
- M Arvanitakis
- Department of Gastroenterology, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium.
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Abstract
The aim of the study presented here was to use faeces from 41 gastroenteritis outbreaks (130 specimens) in Victoria, Australia, to evaluate the sensitivity and specificity of the RIDASCREEN norovirus enzyme immunoassay (EIA) kit relative to reverse transcription-polymerase chain reaction and/or electron microscopy. Seven specimens known to contain sapovirus, adenovirus, astrovirus and rotavirus were also tested. For single-specimen diagnosis the kit gave a specificity and sensitivity of 47% and 71%, respectively; altering the positivity cut-off to give a specificity of 73% reduced the sensitivity to 44%. Thus, the kit cannot be recommended for single-specimen diagnosis. One specimen containing adenovirus but not norovirus was identified as non-specifically positive by the EIA kit. If the criterion used for outbreak positivity was at least one EIA-positive specimen per outbreak, the kit's outbreak sensitivity was 94% but the outbreak specificity was only 60%.
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Affiliation(s)
- A Dimitriadis
- Victorian Infectious Diseases Reference Laboratory, 10 Wreckyn Street, North Melbourne, Victoria, 3051, Australia
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Papapolychroniadis C, Kaimakis D, Giannoulis K, Berovalis P, Karamanlis E, Haritanti A, Leukopoulos A, Kokkonis G, Masoura OM, Dimitriadis A, Giala M, Harlaftis N. A case of mucinous adenocarcinoma arising in long-standing multiple perianal and presacral fistulas. Tech Coloproctol 2005; 8 Suppl 1:s138-40. [PMID: 15655599 DOI: 10.1007/s10151-004-0136-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Chronic anal fistulas are not rare; however, the development of a carcinoma in long-standing, perianal fistulas is rare. We describe a case of an 85-year-old man with multiple, recurring, perianal fistulas, extending to the natal cleft. The patient underwent en bloc resection of the fistulas which were in direct continuity with the middle rectum. Histological examination revealed a mucinous colonic adenocarcinoma. Abdominal CT and colonoscopy revealed an extramural residual rectal mass. The patient refused a radical colorectal operation. Three years later, because of fistula recurrence, he underwent loop sigmoidostomy and radical en bloc excision of the perianal fistula and rectum, with immediate reconstruction by bilateral gluteal flaps. The patient was discharged on the 12th postoperative day, refusing adjuvant radiotherapy. We present this rare malignant entity, successfully treated by staged operations and without any adjuvant therapy.
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Affiliation(s)
- C Papapolychroniadis
- 1st Propedeutical Department of Surgery, Aristotle University, AHEPA Hospital, Thessaloniki, Greece.
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Papapolychroniadis C, Kaimakis D, Fotiadis P, Karamanlis E, Stefopoulou M, Kouskouras K, Dimitriadis A, Harlaftis N. Perforated diverticulum of the caecum. A difficult preoperative diagnosis. Report of 2 cases and review of the literature. Tech Coloproctol 2005; 8 Suppl 1:s116-8. [PMID: 15655592 DOI: 10.1007/s10151-004-0129-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Perforation of a solitary caecal diverticulum is a rare cause of acute abdomen and an uncommon differential diagnosis for acute appendicitis. Nine hundred cases have been described since Potiers' first description of perforated caecal diverticulum in 1912. METHODS We describe 2 cases of perforated diverticulum of the caecum. The first patient was a 50-year-old man diagnosed by subsequent histology, and the second a 77-year-old woman diagnosed intra-operatively. Radiography, ultrasound and CT scan of the abdomen pointed at the diagnosis in the second case. A right hemicolectomy was performed. RESULTS There were no complications, apart from a transient faecal fistula in the first patient managed conservatively. In both patients histology revealed a perforated caecal diverticulum. CONCLUSIONS The surgeon must be familiar with the diagnosis and management of this rare, inflammatory benign caecal entity.
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Goller JL, Dimitriadis A, Tan A, Kelly H, Marshall JA. Long-term features of norovirus gastroenteritis in the elderly. J Hosp Infect 2005; 58:286-91. [PMID: 15564004 DOI: 10.1016/j.jhin.2004.07.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2003] [Accepted: 06/14/2004] [Indexed: 11/17/2022]
Abstract
Noroviruses are important pathogens in both sporadic cases and outbreaks of gastroenteritis in humans. Noroviruses can affect individuals of all ages in a variety of settings, but are a particularly important cause of gastroenteritis in aged-care facilities. The relationship between clinical symptoms and norovirus excretion and the possible role of asymptomatic carriage of norovirus in the elderly are poorly understood. This study examined symptoms and norovirus excretion in elderly individuals associated with a norovirus outbreak in an aged-care facility. Ten individuals aged 79-94 years were recruited for the study. Nine were symptomatic and one was an asymptomatic contact who subsequently developed gastroenteritis. The 10 participants were interviewed regarding their clinical symptoms between two and six times over a three-week study period. One or more sequential faecal samples were collected from all participants over the same period and tested by reverse transcription-polymerase chain reaction for the presence of norovirus. Norovirus was detected in faecal samples from all 10 study participants and was commonly detected in formed stools. In the nine symptomatic participants, acute symptoms such as diarrhoea and vomiting had largely resolved by the third or fourth day of illness, but non-specific symptoms such as headache, thirst and vertigo could persist for as long as 19 days. Both acute and non-specific symptoms appeared to resolve and recur in some participants. The median excretion time for norovirus was 8.6 days (range 2-15 days) in symptomatic participants (N=5). There was no general relationship between the duration of norovirus excretion and the duration of either acute or non-specific symptoms. A faecal sample collected from the asymptomatic contact the day before gastroenteritis symptoms began was positive for norovirus, demonstrating prodromal excretion of norovirus. The results of this study indicate that infection control guidelines should consider both long-term excretion and prodromal excretion of norovirus, and the possibility that formed stools can contain norovirus. Furthermore, the care of elderly individuals recovering from a norovirus infection should take long-term non-specific clinical symptoms into account.
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Affiliation(s)
- J L Goller
- Victorian Infectious Diseases Reference Laboratory, 10 Wreckyn Street, North Melbourne, Victoria 3051, Australia
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46
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Abstract
A polymerase chain reaction-based approach was used to study the expression of Wnt genes in human colon carcinoma tissue and normal colon mucosa. In a number of cases Wnts 2, 4, 5a, 6 and/or 7a were found to be more highly expressed in colon carcinoma tissue compared to surrounding normal-appearing mucosa from the same patients. Wnts 4, 5a, 6 and 7a, but not 2, were also found to be expressed in colon cancer cell lines. The increased levels of expression of these Wnt genes in tumor tissue may indicate their possible involvement in human colon tumorigenesis.
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Affiliation(s)
- A Dimitriadis
- School of Life Sciences and Technology, Victoria University, Werribee Campus, P.O. Box 14428, City MC, VIC 8001, Melbourne, Australia
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Abstract
Three patients with hyperprolactinemia due to pituitary adenomas (two patients) or empty sella (one patient) and osteopenia are described. Their ages at presentation ranged from 8 to 17 years. Each patient was treated with cabergoline. Serum prolactin levels became normal in all patients within one month. Bone density and pubertal stage improved after 12 months of treatment.
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Drevelengas A, Kalaitzoglou I, Destouni E, Skordalaki A, Dimitriadis A. Bilateral Sertoli cell tumor of the testis: MRI and sonographic appearance. Eur Radiol 1999; 9:1934. [PMID: 10602982 DOI: 10.1007/s003300050954] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Daniilidis J, Vlachtsis K, Ferekidis E, Dimitriadis A. Intrasphenoidal encephalocele and spontaneous CSF rhinorrhoea. Rhinology 1999; 37:186-9. [PMID: 10670035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Intrasphenoidal encephalocele is a rare clinical entity. In the international literature only 16 cases have been reported up today, with female predominance. Clinically they manifest at middle and advanced ages (40-67 years), when spontaneous CSF rhinorrhoea or recurrent meningitis occurs. We present our case, a 46 years old female, who had CSF rhinorrhoea from the right vestibule for 10 months. The diagnosis was based on the history and the high-resolution brain and skull base CT-scanning in conjunction with opaque fluid injection in the subarachnoidal space through a lumbar puncture. She was successfully treated with an operation, through an endonasal trans-ethmoid microendoscopic approach, using the Draf and Stammberger technique. We discuss the pathogenesis of the intrasphenoidal encephalocele, the existence of small occult defects in the skull base, which cause, at the middle and advanced ages, CSF fistula with spontaneous CSF rhinorrhoea and/or recurrent meningitis. Finally we emphasize the advantages of the endonasal surgical approach for the treatment of this condition.
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Affiliation(s)
- J Daniilidis
- Department of Otorhinolaryngology of the Aristotelian University of Thessaloniki, AHEPA Hospital, Greece
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Murata GH, Tzamaloukas AH, Voudiklari S, Dimitriadis A, Balaskas EV, Nicolopoulou N, Dombros N. Estimating urea clearance in patients on continuous ambulatory peritoneal dialysis: a multivariate analysis. Int J Artif Organs 1998; 21:515-20. [PMID: 9828056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The purpose of this study was to determine if Kt/V urea in continuous ambulatory peritoneal dialysis (CAPD) could be estimated by a multivariate model based upon simple clinical observations. The study included 439 clearance studies in 301 CAPD patients followed in 8 dialysis centers. Weekly urea clearance, 24 h urine volume and 24 h drain volume were normalized to body water by the formulae of Watson (Kt/V, UV/V and DV/V respectively). Adequate dialysis was defined as Kt/V > or = 2.0 weekly. Subjects at 2 units were used to derive the models, while others were used for model validation. Stepwise multiple linear regression was performed on the derivation set (DS) to identify the clinical variables that correlated with Kt/V. The model was then used to estimate Kt/V for the validation set (VS). In the DS, 110 clearance studies were performed in subjects with residual renal function. Multiple linear regression showed that weekly Kt/V was defined by the expression: Kt/V=1.48 + 24.1 (UV/V) + 2.92(DV/V) - 0.049 (serum creatinine) (r=0.750, p<0.001). In 204 VS studies, the correlation between estimated and measured Kt/V was 0.633. There were marked differences in the proportion of adequately dialyzed patients when Kt/V estimated from the formula shown was <2.0, between 2.0 and 2.3, and >2.3 weekly (7.9%, 54.7% and 79.7%, respectively; p<O.001). In the 33 studies done in DS anuric patients, regression analysis showed the following: Kt/V=0.46 + 2.59 (DV/V) + O.009(age) (r=0.562; p=0.003). In 92 VS studies in anuric subjects, there was strong correlation between estimated and measured Kt/V (r=0.740). Again, there were marked differences in the frequency of adequate dialysis in anuric patients with estimated Kt/V <2.0, between 2.0 and 2.3, and >2.3 weekly (8.1%, 68.8%, and 100%, respectively; p<0.001). The risk of low Kt/V can be estimated by multivariate linear models requiring only simple clinical measurements.
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Affiliation(s)
- G H Murata
- Veterans Affairs Medical Center and the University of New Mexico School of Medicine, Albuquerque 87108, USA
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