2 How to obtain a good quality chest radiography (1) 3 aspects are very important for good quality:The penetrating power of the x-ray beam (adjustment of x-ray tube voltage )The x-ray tube current (milliampere)The exposure time adjustment
3 How to obtain a good quality chest radiography (2) The adjustment of the x-ray tube voltage controls the contrast: the difference of density levels of the different organs and tissues in the thoraxThe x-ray tube current and the exposure time controls the intensity of x-ray beams
4 How to obtain a good quality chest radiography (3) Adjustment of voltageHigh voltage: a range of 100 /120 kV: optimal contrast between lungs and bones, and good visualisation of mediastinum and vesselsExposure time<0.05 seconds: decrease of motion artefact caused by the beating of the heart or respiratory movement
5 How to obtain a good quality chest radiography (4) A long distance between the tube focus and the film improves the image clarityand decreases the geometric blur
6 How to obtain a good quality chest radiography (5) Other criteriaQuality of the x-ray grid: the flat metallic plate with very narrow lead trips close to the film: increase in the image clarity and reduction of the scattered radiation from the patientGood quality electrical power supplyEfficient and frequent maintenance of x-ray equipmentQuality of films and good conditions of storageGood screen-film systemGood techniques for x-ray film processing (developing, rinsing, fixing, washing and drying procedure). If possibleautomatic film processor.
7 What about digital X ray system?(1) (Direct Digitalised System) composed with:Electronic flat-panel X ray detectorHigh resolution grayscale diagnostic displayHigh performance computer
8 What about digital X ray system ?(2) Avantages:-feasible imaging quality adjusted by computer processing-easy and quick image processing-X-ray film and its processing procedures in dark room no more needed.-Lower dose radiation- imaging transmission and intepretation via internet to referent radiologist is easily possibleDisadvantages:- Costly initial investment (61000 to $)- Significant trainning in digital technology needed for the radiological technicians and costly running maintenance
9 Possible compromise with computed radiography (CR system) digital radiography using a Photo‐stimulable Phosphor plate (PSP, also called Imaging Plate, IP) enclosed in a cassette as a detector, instead of a film‐screen.The IP is then introduced into a CR Reader which reads the film and converts the recorded signal into a digital grey scale imageSame avantages than digitalised systemLower cost than DR system, because can be used with the existing X ray equipment. Only a CR reader and CR cassette reader (with Imaging Plates) need to be purchased..
10 Basic radiographic views: Postero-anterior viewLateral viewAdditional/supplementary view:radiography in expirationradiography in supine and lateral positionBack view (antero-posterior view)Opacification of the oesaphagus
11 The thorax is composed of: Bone (vertebrae, ribs, scapula…). The main component is calcium, which absorbs the x-ray considerably: the bone image is very opaque (white on the radiography)Blood and soft tissue (heart, mediastinum, vessels). The absorption of x-rays is less complete than bones: the image is less opaque (light grey)Fat tissue. the absorption of x-rays is lower: the image is dark grey.Air (in lungs) which does not absorb the x-ray at all. The image of the lungs is black
12 Picture of 4 different solutions on a chest x-ray film calciumwateroilAir
17 Same patient with deep inspiration Poor inspiration False opacity of the inferior lobesAdequate inspiration if you can count9 posterior or 6 anterior parts of ribs over the diaphragm
18 PA is the correct view false cardiomegaly AP versus PA view clavicles are high and horizontalThe x-ray beam is antero posteriorSame patient with correctpostero-anterior x-ray beamincidencePA is the correct viewThe technician should specify the position of the patient if AP view
19 The heart outline is bigger on D2 ( bird’s-eye view of the patient)
20 Correct standing or sitting position for chest radiography
21 Standing or sitting position not always easy to obtain…
22 If the patient is insupine position (too illto stand up), the cardiacoutline and mediastinumis enlarged. The scapulamay be on the lung field.The chest x-ray haspoor quality for analysis
23 The technician should specify the patient position if supine Standing patient withpostero-anterior X ray beamPatient in supine positionThe technician should specify the patient position if supine
24 Dark film Lighy film no detail visible in the lung area Under penetrationNo detail visiblein the mediastinum area.
25 Correct density and good contrast: - Pulmonary vessels visible in the lungs, behind the diaphragmand behind the heartPara-aortic line visible- Vertebra visible behind the mediastinum
26 Conditions for adequate contrast / density Correct x-ray factor (Kv, Mas, exposure time)Good conditions of developing and good quality of processing chemicalsCorrect temperature of developercorrect quality of filmIn case of digitalised or computerised system, imaging quality is adjusted by computer processing and the 3 last conditions are no more needed.
27 Exact front view : the vertical line connecting the spinous process of thoracic vertebrae is in the middle of the two sterno-claviculars joints.
30 Chest x-ray: to ensure top quality deep inspirationadequate contrast / densitycorrect position of the patient (exact front view)x-ray beam in postero anterior view (the patient is standing)
31 Process for analysis of the chest radiography: the check list Verification of name and dateClinical history and findingsVerification of the factors for good qualityAssess-thoracic wall and thoracic skeleton- mediastinum- each lung field, one after the otherDo not skip any item in the checklist !
63 The pulmonary vena are not physiologiccally visible RSPVLPSVL ARIPVL VThe pulmonary vena are not physiologiccally visible
64 Mediastinum linesX ray beam crossing thorax and mediastinum meets in some places pleural thickness, producing images on the CXR like lines defining mediastinum lines…
65 Too complicated And not so usefull… Mediastinum lines 1. Sub clavicle arterial line2. Posterior mediastinum line3. Brachio cepahalic vena line4. para-azygos line5. Anterior mediastinum line6. Descending aortic line7. Right and left paravertébral line8. Inferior veina cava line9. para-œsophageal line10. para-trachéal lineToo complicatedAnd not so usefull…6
66 Three of them are really important. Right paratracheal lineAorto pulmonary linePara-aortic lineThree of them are really important.