First TB Prevalence Study - the X-Ray Component

Transcription

1 15 th ISRRT World Congress Durban International Convention Centre Durban South Africa First TB Prevalence Study - the X-Ray Component Euniace M.P. Bandio Principal Radiographer and Tutor School of Radiography - Institute of Allied Health Sciences Muhimbili University of Health and Allied Sciences Overview Basic Facts about TB, Burden nationally and Globally The Survey TB Detection Why have a survey (rationale of such surveys) Imaging Truck Equipment Image acquisition Archiving Interpretation Radiation safety Etiology of TB Tuberculosis or TB, is a disease caused by Mycobacterium tuberculosis complex, Includes 5 species M. tuberculosis (up to 95% of TB cases) M. bovis (including BCG strain) bovine tuberculosis via GI tract (milk) M. africanum M. microti microti (vole bacillus) M. canetti canetti TB can attack any part of the body, but the lungs are the most common target. Forms of TB Disease TB can attack any part of the body Pulmonary TB (common target) Extra pulmonary TB Miliary TB Global burden of TB, /3 of world s s population infected (One infection every second) 8.2 million new cases, 80% in 22 high-burden countries 75% of TB pts in developing countries are in economically productive age group (15-50 yrs) About 2 million occur in sub-saharan Africa No estimate Estimated Global TB incidence rates, 2000 Tuberculosis kills 2 million people each year. 98% of these deaths occur in the developing world Africa >300 /100,000 The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. Global Tuberculosis Control. WHO Report WHO/CDS/TB/

2 Global burden #2 It is estimated that between 2000 and 2020 nearly 1 billion people will be newly infected 200 million people will get sick, and 35 million will die from TB - if control is not further strengthened Re-emergence of TB: Factors Poverty, overcrowding, and poor hygiene HIV epidemic Delays in diagnosing TB Incomplete treatment of infectious TB cases Increased population rates Inadequate political commitment Inadequate funding for TB control until recent Clinical presentation of TB/HIV infected patients In the pre HIV era: 80-85% 85% of all MTB infection was in the form of PTB Up to 15% in the form of EPTB 5% as a combined EPTB+PTB In the HIV era MTB presents as pulmonary disease in 60-70% EPTB in more than 50-60% The Survey it self The Survey will have four main components namely The Survey teams (two field teams and Central teams including Administrative, Radiology and Laboratory) Local Support teams to be recruited in clusters Survey trucks (two trucks supported by two four wheel cars) Survey Units including X-Ray X and Laboratory Equipment Important issues about The Survey Anticipated Trucks Movement Estimated to cover the whole of Tanzania through a representation of 40 Clusters of which the primary clustering is by District, in this case 40 out of 110 Districts in all 25 Regions will be covered Estimated that 60,000 subjects will be met in a restricted period of the study which is one year Two teams including of three Radiographers in each team and two radiographers on the standby team Three Survey Radiologists will be based at the Centre at MUHAS 2

3 TB detection Sputum microscopy Tuberculin Roentgen/Imaging Culture Molecular biology Sensitivity of X-ray, smear microscopy, culture Chest X-ray X, sputum smear examination and culture of all subjects with abnormal X-ray. X High sensitivity. 82% in a study from India, 86% in prevalence surveys held by the WHO in sub-saharan Africa in the 1950s, 95% in surveys in Korea Symptom screening Chest X-ray screening Sensitivity of symptom screening North Arcot District, India 1989 (Datta et al 2001 ) Sensitivity of chest X-ray screening in TB prevalence surveys any TB symptom sub-saharan Africa, 1950s South Africa 1977 cough India 1989* 0% 20% 40% 60% 80% 100% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% all bacillary+abacillary all bacillary smear+ culture+ smear+ *symptomatic cases only Case detection Screening of all participants Rationale prevalence survey Cavities Any TB symptom? Abnormal chest X-ray? Infiltrates Fever No Yes Yes No Chest pain Interstitial abnormalities Dyspnoea Night sweats Weight loss Diagnosing of all suspects Two sputum samples detailed interview Pleural effusion Pulmonary nodules Hilar/mediastinal lymphadenopathy Coughing up blood ZN staining in field TB case Culture at CTRL Provides an estimate of prevalence of pulmonary TB needed to estimate the current case detection rate Identifies efforts needed to reach WHO targets Identifies gaps in case detection 3

4 Primary objective To estimate in a nationwide representative survey the prevalence of pulmonary TB amongst the adult population of the United Republic of Tanzania as a basis for estimation of the current case detection rate and as a baseline measurement for subsequent surveys The Imaging Part Chest X-Ray X is one of the major components of the prevalence survey due to the fact that: All subjects/clients will have to go through the Chest X-ray X except pregnant mothers and patients on treatment as is indicated in the chart, It is taking the highest capital cost of the study, estimated at over USD.400,000.= Work load It is planned that everyday 150 subjects will be attended, within 10 days working at the cluster, 1500 subjects will be attended. This is a workload of a big radiology department per day per year This means with a 9 hours working day, each subject receives an approximate of 3.5 minutes per subject, time well below the standard service time to patients, this will mean adjusting working hours to accommodate the workload and thank God for the Technology to be used Organising our work Truck acquisition and fabrication X-Ray Equipment Image acquisition and recording system Image Interpretation and archiving More on the work Radiation safety procedures Other SOPs Truck acquisition and fabrication Isuzu NQR66R is a truck of choice with several advantages including: Length can afford near to 6metres Width can go to 2.3 metres 5 tones required for the working Truck Truck continues Truck fabrication will be supervised by the Equipment supplier of which it will include the following core inclusions: An 11kW generator which will run the mobile Imaging centre Al electrical installations and insulations Radiation proofing using Lead/Iron sheets 4

5 X-Ray Equipment The X-Ray X unit selected is a Philips Unit Practix 400 of which some of the Important specifications are including: 40 kw, some small fixed units are 20 30kW kv range kV Maximum current 400mA Time from 1ms 5.3s Maximum field 43 x 43 cm Image and Image Acquisition Image acquisition will be in the form not very familiar Computed Radiography imaging will replace convention film processing In calculation of costs and work burden with conventional film processing, it was agreed that though seems new technology it is the most appropriate technology to use. The Philips PCR Eleva S unit being constructed especially for the study was a preferred one due it different scanning format and robustness unit made for mobile work Image acquisition continues Films will be replaced by digital images archived on the CD-Rom and read from a Computer screen Images will be acquired through Imaging plates read by the CR Unit There will be no X-Rays X to read in hardcopies, yet better images will prevail (it is our hope this will be first CR imaging in Tanzania Gvt work) The Philips PCR Eleva S CR Unit 5

6 Image Interpretation Interpretation of Images as prescribed in the protocol will be in two stages: Interpretation in the field by field Radiographers, just to identify or classify normal and abnormal X-X Rays (any abnormality) Interpretation at the Central unit which will be done by Survey Radiologists, here a special format will be designed to be followed by all survey Radiologists All those classified abnormal will constitute to the TB suspect Interpretation continues Field Radiographers will be trained for pattern recognition this will enable them to have more concentration on lesions mostly related to TB Application training will be conducted for both Survey Radiographers and Radiologists There will also be training of all survey teams on most of survey duties Image Archiving Images will be archived on CDs, and with the software available for the Digital Unit, over 100 Images will be archived on one CD-Rom, in other software only Images can be archived (especially Chest X-Ray) X Images will be sent to central (at MUHAS- Radiology Department) after every cluster In the protocol it was stipulated to re-read read selected images of normal status and all of abnormal, with this technology all films will be re-read read Radiation Safety Radiation safety procedures: Issues around Truck fabrication with Radiation safety In collaboration with the NTLP and NIMR, the TAEC has been contacted to discuss the truck construction as related to Radiation safety and issues around ethical stand on mass Radiography The Truck will be masked with Radiation proof walls surrounding the working rooms probably with lead sheets/iron sheets Working rooms construction are planned that staff and subjects will enter Truck through different entrances to avoid accidental exposure radiation safety continues Safety for Truck staff and community All Truck staff will be monitored for Radiation using Thermo-Luminescence Dosimeters (TLDs) to be negotiated from Tanzania Atomic Energy Commission (TAEC) All subjects will be provided with gonad protection during the procedure All assisting persons will be provided with lead aprons Issues related to Pregnant women It is mentioned in the protocol that pregnant women and patients currently on TB treatment will be excluded from X-RaysX Every child bearing age will be asked of her LMP and any possibility of being pregnant All pregnant (or those suspecting) will be excluded in the X-Ray X part of the study Where women will not be sure, UPT will be advised, this is cheap as compared to other methods to determine pregnancy 6

7 Major Challenges: New Technology Enormous number of clients to serve in a day through 40 weeks in the filed Possibility of pregnancy New look in technology and service Commitment Where are we now: Ethical Clearance granted Is planned to start September or October 2008 Trucks are being constructed and hopeful in June the Trucks will be installed with equipment Hopping to start recruitment and training very soon Most of all funds are available Collaborating Institutions: National Tuberculosis and Leprosy Programme (NTLP) of the MOHSW the United Republic of Tanzania National Institute for Medical Research (NIMR) Muhimbili University of Health and Allied Sciences (MUHAS) formally MUCHS KNCV Tuberculosis Foundation, The Hague, the Netherlands Institute of Tropical Medicine, Antwerp, Belgium Thank you for your kind attention Asante kunisikiza 7