Radiographic positioning pdf

 

    Radiographic positioning techniques for the cervical spine We hope having these articles available in a single, easily downloadable PDF format will enhance . Review of Radiographic. Anatomy & Positioning and. Pediatric Positioning. Approved for 5 Category A Credits. American Society of Radiologic. This Manual of Radiographic Technique is for use with the World Health. Organization Basic .. (1) THE POSITION OF THE X-RAY EQUIPMENT. (2) THE .

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    Radiographic Positioning Pdf

    Clark s Positioning in Radiography 12th Edition - Free ebook download as PDF File .pdf), Text File .txt) or read book online for free. MERRILL's Atlas of Radiographic Positioning & Procedures, 13th Ed. - Ebook download as PDF File .pdf), Text File .txt) or read book online. MERRILL's Atlas . Position: strict right lateral decubitus, hip and knee joints bent. Radiography scale at the median level between the gluteal fold. Projection: lateral, perpendicular.

    Moore Chrissie W. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronically or mechanically, including photocopying, recording or any information storage or retrieval system, without either prior permission in writing from the publisher or a licence permitting restricted copying. Whilst the advice and information in this book are believed to be true and accurate at the date of going to press, neither the authors nor the publisher can accept any legal responsibility or liability for any errors or omissions that may be made. In particular but without limiting the generality of the preceding disclaimer every effort has been made to check drug dosages; however it is still possible that errors have been missed. Furthermore, dosage schedules are constantly being revised and new side effects recognized.

    Dose quantity Unit Definition Radiation protection 1 Absorbed dose Gy Energy absorbed in Dose quantities known mass of tissue Organ dose mGy Average dose to specific tissue X-ray examinations provide significant benefits to patients as a Effective dose mSv Overall dose weighted for diagnostic tool, but the use of ionizing radiation also carries a small sensitivity of different risk of causing harm. Some types of Dose—area product Gy. The equivalent dose expressed in Sieverts Sv is found by doses and set DRLs for multiplying the absorbed dose by the quality factor assigned to examinations specific types of radiation.

    For diagnostic X-rays, the quality fac- DRL, dose reference level. The risk also depends on which organs and tissues are irradiated. To take account of this, the tissues are given a weight- ing factor according to their susceptibility to harm from radiation. The effective dose for an Radiograph Entrance surface Dose—area examination expressed in Sv is found by adding up the weighted dose mGy product Gy.

    Skull lateral 1. However, they can be derived using mathematical Thoracic spine AP 3. The models are Lumbar spine AP 6 1. Combining the weighted organ doses gives the Abdomen AP 6 3 effective dose for the given examination conditions.

    Skin doses are Pelvis AP 4 3 usually measured using thermoluminescent dosimeters TLDs or are calculated indirectly from tube output and back-scatter data. Examination Fluoroscopy Dose—area For monitoring the relative patient dose levels for different types time min product Gy. National and local diag- Barium meal 2. Some proposed values are shown in the table here. Barium or water-soluble enema 2. The graphic examinations are substantially lower than the threshold Department of Health DoH is likely to adopt some of these as national needed to cause immediate harmful effects due to cell-killing, such diagnostic reference levels.

    Other threshold or deterministic effects AP, antero-posterior; PA, postero-anterior. Occasionally, skin damage has been seen after complex interventional investigations. For these procedures, it is necessary to manage this type of risk.

    Irradiation of a fetus during organo- genesis could also lead to deterministic effects such as malforma- tions and mental retardation when doses exceed — mGy. Once an exposure resulting in a slight increase in the probability of cancer occurring is justified, then the equipment and protocols used for the exam- in the years following exposure.

    Typically, risks for initial referral to evaluation of the images produced. All members children are two or three times greater than those for average of staff involved in medical exposures have clear responsibilities adults, while risks for elderly people are five times lower than for protecting patients. The duty holders are the referrer, the prac- those for average adults.

    Radiation protection measures reduce titioner who justifies the examination and the operators who this stochastic risk to patients by minimizing the X-ray dose carry out practical aspects of the examination from identifica- used to obtain diagnostic information. In addition to the risk of causing somatic harm to the patient, Responsibility for implementing IRMER falls on employers.

    Irradiating the gonads of patients could potentially harm the duty holders, and set out their responsibilities and the steps their children through the risk of heritable disease. The risk is small they must follow to ensure that the patients are properly protected compared with the natural risks, but using techniques and protec- through the various stages of the examination.

    Implementation tive measures to minimize gonad doses is a sensible and simple includes the need to use written protocols, which should define precaution. Medical exposure legislation Procedures must also focus on issues that need special consid- eration by duty holders because the potential risks may be greater The basic measures for the radiation protection of people under- or the benefits less clear. These include the exposure of children, going medical exposures were contained in the Recom- high-dose examinations, exposure of women who may be preg- mendations of the International Commission on Radiological nant, and exposure for medical research or medicolegal purposes.

    Great Britain imple- to protect patients. For example, an operator carrying out a mented most of the provisions in the directive in the Ionising medical exposure needs to know how to optimize all aspects of Radiations Medical Exposure Regulations IRMER In this case, qualified radiographers patients and others undergoing medical exposures and keeping are the appropriate operators because they have the adequate their doses as low as reasonably practicable ALARP.

    The training to perform these duties. To maintain their competency, requirements of IRMER follow the fundamental principles for practitioners and operators are required to keep up to date with radiation protection: Possible alternatives must be considered techniques through continuing education.

    These may involve: Protection of the patient from any unnecessary primary and scatter radiation should be employed. The gonads should not be in the line of the primary beam for projections other than the abdomen, and therefore careful radiographic technique is essen- tial, e. Special care must be taken to collimate the beam to the area of interest, thus avoiding the unnecessary irradiation of tissue and reducing scatter radiation. When more radiation-sensitive tissues are located in the image-acquisition field, these should be excluded whenever possible, e.

    Typical gonad shields with sheet of lead rubber for gonad protection Protection from scattered radiation is employed by the intelli- gent use of lead protective materials protecting the gonads and should be employed regularly in extremity radiography.

    In order to reduce repeat images, the use of foam pads, sand- bags and other immobilizing devices should be used to ensure that the patient is immobilized and in a position that is as com- fortable as possible. The shortest exposure time should be selected to avoid movement unsharpness. IRMER requires employers to have a written procedure for this. If a woman of childbearing age is, or cannot be certain Examples of immobilization devices that she is not, pregnant, then direct irradiation of the abdomen and pelvis should be avoided.

    The only exception to this rule is when those justifying the procedure in conjunction with the referring clinician can state that there are overriding clinical rea- sons for the requested examination to proceed.

    In such cases, all steps must be taken to minimize the number of exposures and the absorbed dose per exposure. Examinations of regions other than the abdomen and pelvis may proceed, provided there is good beam collimation and lead protection of the abdomen and pelvis. Handbook of Skeletal Radiology, 2nd edn. St Louis: Hand Fractures and dislocation of metacarpals Postero-anterior basic Anterior oblique basic Serious injury or foreign bodies Lateral basic Antero-posterior alternate Pathology e.

    The best possible radiographs are essential, because decisions about injuries, especially of the elbow and the wrist, affect future dexterity, employment and earnings of the patient. The importance of registering the correct right or left marker at the time of the exposure cannot be overemphasized; neither can the importance of recording the correct patient identification and date of the examination. To ensure maximum radiation protection, the patient should be seated at the side or end of the table with the lower limbs and gonads away from the primary beam, i.

    More than one pro- jection can be recorded on the cassette provided that lead-rubber is used to mask off the parts of the cassette not being used. The limb should be immobilized by the use of non-opaque pads within the radiation field and sandbags outside the field.

    It is important to remember that the patient will be able to keep the limb still only if it is in a comfortable and relaxed position. For examination of the forearm, elbow and humerus, the shoulder, elbow and wrist should be in a plane parallel to the cassette. With the cassette on the table, this means that the shoulder, elbow and wrist will be at the same horizontal level, i. If possible use a cassette with high-resolution screens. A lead-rubber mask may be used to mask off the half of the film not in use.

    Postero-anterior radiograph showing fractures of fourth and fifth metacarpals. Middle Fingers digits 2—5 3 Ring Index 4 2 Distal. Little Phalanges Middle 5. Thumb digit 1 Inter- phalangeal joints 1 Proximal. Proximal 3 5th phalanx 2 4 metacarpo- phalangeal 5 joint 1. Metacarpals Carpo-metacarpal 1—5 joints.

    Normal anterior oblique radiograph of left hand. Normal postero-anterior radiograph, both hands Postero-anterior radiograph of both hands showing severe erosive disease. It can also be used to demonstrate a fracture of the base of the fifth metacarpal. Radiation protection If it has been necessary to position the patient facing the table, it is essential to provide radiation protection for the lower limbs and gonads.

    This may be achieved by placing a lead-rubber sheet on the table underneath the cassette to attenuate the primary beam. It may also be used to demonstrate a fracture or dislocation of the carpal bones. Radiological considerations Lateral radiograph of hand with foreign body marker. It is often necessary to image adjacent fingers, e. If this is the case, then care should be taken to avoid superimposition, particularly in the lateral projection, by fully extending one finger and partly flex- ing the other.

    A non-opaque foam pad is used to support the finger not in contact with the cassette. Note In cases of severe trauma, when the fingers cannot be flexed, it may be necessary to take a lateral projection of all the fingers superimposed, as for the lateral projection of the hand, but cen- Normal lateral radiograph of ring and little fingers tring over the proximal inter-phalangeal joint of the index finger.

    Lateral radiograph of Lateral radiograph of little middle finger showing a finger showing dislocation of the fracture of the middle distal interphalangeal joint phalanx. In the case of a suspected foreign body in the thenar eminence, a postero-anterior projection is used to maintain the relationship with adjacent structures. A lead-rubber mask may be used to mask off the half of the cassette not in use.

    The hand may be slightly rotated to ensure that the second, third and fourth metacarpals are not superimposed on the base of the first metacarpal. Normal antero-posterior radiograph of thumb. Radiological considerations Fracture of the base of the first metacarpal through the joint surface may be associated with dislocation due to the pull of the abductor and extensor tendons of the thumb.

    In contrast, a frac- ture that does not transgress the articular surface does not dis- locate and does not have the same significance Rolando fracture. The projections may also be used to demonstrate other carpal bones, as indicated below. For scaphoid fractures, three projections are normally taken: Styloid Styloid process process of radius of ulna Normal postero-anterior radiograph of scaphoid in ulnar deviation Radio-carpal Radio-ulnar joint joint.

    The hand should remain adducted in ulnar deviation. Normal anterior oblique radiograph of scaphoid. Posterior oblique radiograph of wrist Normal posterior oblique radiograph of wrist. It carries a high risk of delayed Shaft of radius Shaft of avascular necrosis of the distal pole, which can cause severe dis- ulna ability. If suspected clinically, the patient may be re-examined after 10 days of immobilization, otherwise a technetium bone scan or magnetic resonance imaging MRI may offer imme- diate diagnosis.

    Lateral radiograph of wrist showing dislocation of the lunate. The lunate Normal lateral radiograph of wrist bone is rotated and anteriorly displaced. The flexor reti- naculum is attached to the two medial prominences the pisiform and the hook of the hamate and to the two lateral prominences the tubercle of the scaphoid and the tubercle of the trapezium.

    The median nerve along with the flexor tendons pass through the tunnel, and any swelling here can cause compression of the median nerve, giving rise to the carpal tunnel syndrome. Radiographic examination of the bony part of the tunnel is by an axial projection to demonstrate the medial and lateral prom- inences and the concavity.

    This examination is requested less often nowadays due to improved electrophysiological techniques and the advent of MRI, which gives far better anatomical information. A lead- rubber sheet can be used to mask the half of the cassette not in use.

    An additional oblique projection may also be undertaken to provide further information. When carrying out radiographic examinations of the radius and ulna, it is important to bear in mind the movements that occur at the joints of the upper limb.

    The hand can be rotated from the palm facing the table to the palm at right-angles to the table with little or no rotation of the ulna. In this movement, Method 1 the upper end of the radius rotates about its long axis while the lower end rotates around the lower end of the ulna, carrying the hand with it. The hinge formed by the trochlear surface of the humerus and the trochlear notch of the ulna prevents rotation of the ulna unless the humerus rotates.

    If, therefore, the wrist is positioned for a postero-anterior projection and then moved into the pos- ition for the lateral simply by rotating the hand, we will obtain two projections of the radius but the same projection of the ulna. To achieve two projections at right-angles of both the radius and the ulna, the two positions must be obtained by rotating the humerus not simply the hand through 90 degrees, i.

    Thus, there are basically two methods of positioning the wrist Method 2 for a radiographic examination of the lower end of radius and ulna, but only one of these will give two projections of both the radius and the ulna. Method 1 The forearm remains pronated and the change in position from that for the postero-anterior projection to that for the lateral is achieved by rotation of the hand.

    In this movement, only the radius, and not the ulna, rotates, giving two projections at right- angles to each other of the radius but the same projection each time for the ulna. Of the two bones, the radius is the more frequently injured, so this positioning method can be used to demonstrate the injury, provided that the patient can rotate the hand.

    Very often, the patient cannot rotate the hand, so the second method must be used. Method 2 The change in position is achieved by rotation of the humerus.

    Because the humerus rotates, so does the ulna. This method Almost identical projections of the ulna produced by using the postero- anterior projection, and method 1 for the lateral projection.

    Note the therefore gives us two projections at right-angles to each other orientation of the fracture of the distal ulna remains the same of the radius and the ulna. Increased exposure factors will be necessary to penetrate the plaster, and the resultant image will be of reduced contrast.

    Postero-anterior radiograph of Postero-anterior radiograph of wrist wrist through conventional plaster through light-weight plaster. Normal anterior oblique radiograph of wrist. To obtain an additional projection of the lower end of the ulna, it is necessary to rotate the humerus see Wrist, lateral — method 2, p. One manifestation of lunate dislocation is an increased gap between it and the scaphoid, which will be missed if the wrist is rotated on the postero- anterior projection.

    To change the projection of the ulna, the arm must be rotated as shown in the three photographs above. The antero-posterior projection with the forearm supinated demonstrates the radius and ulna lying side by side. Both projections are normally acquired on one film, with the half of the film not in use being shielded with by lead rubber. Note The postero-anterior projection of the forearm with the wrist pronated is not satisfactory because, in this projection, the radius is superimposed over the ulna for part of its length.

    Example of incorrect technique — the radius is superimposed in the postero-anterior projection. Essential image characteristics Normal basic lateral radiograph of forearm. In Galeazzi fracture there is a fracture of the radius with dislocation of the distal ulna, while in Monteggia fracture there is fracture of the ulna with dislocation of the head of the radius.

    In forearm frac- ture, therefore, both ends of both bones, as well as the prox- imal and distal radio-ulnar joints, must be demonstrated.

    Radiographs of the forearm showing Galeazzi fracture. For many examinations, the patient will be seated at the table with the shoulder lowered, so that the upper arm, elbow and forearm are on the same horizontal level. In changing the position from that for the lateral projection to that for the antero-posterior projection, the humerus must be rotated through 90 degrees to make sure that two projections at right-angles are obtained of the humerus as well as the ulna and radius.

    Alternatively, if the limb cannot be moved, two projections at right-angles to each other can be taken by keeping the limb in the same position and moving the tube through 90 degrees between projections. For the lateral projection, the central ray should pass parallel to a line joining the epicondyles of the humerus. For the antero- posterior projection, the central ray should pass at right-angles Supracondyalar ridge to this line.

    In some instances, tube angulation will be necessary. If the patient cannot extend the elbow fully, modified pos- Epicondyles itioning is necessary for the antero-posterior projection. Olecranon Shaft of humerus Special care should be taken with the child suffering from a process Trochlear surface supracondylar fracture of the humerus, when basic projections should not be attempted.

    Capitulum Basic lateral and antero-posterior projections can be taken on the Head of radius same cassette using lead rubber to mask off each half of the cas- Coronoid sette in turn. For each projection, care should be taken to place the process elbow in the centre of the half of the film being used, so that the Trochlear Tuberosity two projections of the joint are at the same eye level when viewed. Shaft of ulna. Notes Antero-posterior radiograph of elbow. In such cases, no attempt should be made to extend the elbow joint, and a modified technique must be employed.

    Antero-posterior — partial flexion If the patient is unable to extend the elbow fully, the positioning for the antero-posterior projection may be modified. For a general survey of the elbow, or if the main area of interest is the proximal end of the radius and ulna, then the posterior aspect of the forearm should be in contact with the cassette.

    If the main area of interest Normal antero-posterior radiograph of elbow is the distal end of the humerus, however, then the posterior aspect of the humerus should be in contact with the cassette.

    If the elbow is immobilized in the fully flexed position, then an axial projection must be used instead of the antero-posterior projection. In both of the above cases, some superimposition of the bones will occur. However, gross injury and general alignment can be demonstrated. Antero-posterior radiograph of elbow in partial flexion. In either of these cases, the bones of the forearm will be super- imposed on the humerus.

    Direction and centring of the X-ray beam Axial radiograph of elbow — upper arm in contact with the cassette. Axial radiograph of elbow — arm in plaster cast with upper arm in contact with the cassette.

    A lead-rubber sheet may be used to mask off the area of the cassette not currently in use. The elbow is positioned as for the lateral elbow. The hand is then moved through different degrees of rotation, enabling visu- alization of small fissure fractures through the head of the radius. The forearm is immobilized using a sandbag. Lateral radiograph of elbow for head of Lateral radiograph of elbow for head of Lateral radiograph of elbow for head of radius — palm at right angles to the table radius — palm in contact with the table radius — palm facing away from the trunk.

    Normal Fracture radial head Oblique radiographs of elbow to show proximal radio-ulnar joint Ulnar groove — axial The ulnar groove through which the ulnar nerve passes lies between the medial epicondyle and the medial lip of the trochlear of the humerus and is a possible site for ulnar nerve compression.

    A modified axial projection with the elbow joint fully flexed demonstrates the groove and any lateral shift of the ulna, which would lead to tightening of the ligaments overlying the ulnar nerve.

    It is seen as an elevation of the fat pads anteriorly and posteriorly see below and requires a good lateral projection with no rota- tion. It may be an important clue to otherwise occult fracture of the radial head or a supracondylar fracture of the humerus.

    Recognition of their absence requires knowledge of when and where they should be seen. Antero-posterior radiograph of elbow showing vertical fracture of the head of the radius. Lateral radiograph of elbow showing elevation of anterior and Lateral radiograph showing dislocation of the elbow posterior fat pads.

    Lateral radiograph showing fracture through the olecranon process, with displacement due to triceps muscle pull. Antero-posterior radiograph of elbow showing avulsion injury of the lateral epicondyle. The and blood vessels. The arm is gently extended backwards from the shoulder. The patient is rotated forwards until the elbow is clear of the rib cage but still in contact with the cassette, with the line joining the epicondyles of the humerus at right-angles to the cassette.

    Direction and centring of the X-ray beam Method 1. Demon- stration of the position of the condyles in relation to the ante- rior cortical line of the humeral shaft may be crucial and demands a true lateral image.

    Antero-posterior radiograph in Antero-posterior radiograph in full flexion showing supracondylar partial flexion showing supracondylar fracture fracture. To reduce the risk of patient move- ment, exposures are made on arrested respiration. The radio- radiograph of humerus humerus graphic technique is similar except that a horizontal central ray is used but additional care should be taken to ensure that the patient is immobilized adequately, as described below.

    Lateral — erect If the arm is immobilized in order to obtain a true lateral pro- jection, i. This has the disadvan- tage that the ribs and lungs will be superimposed on the humerus, obscuring details of the injury and signs of healing and adding to the radiation dose to the patient. The position described, although not fully at right-angles to the antero-posterior projection, avoids this superimposition. Antero-posterior radiograph Lateral radiograph of the of humerus showing a humerus in the same patient fracture of the proximal shaft Position of patient and cassette of the humerus.

    It transmits the tendon of the long head of the biceps. The beam is collimated to the humeral head. Two projections at right-angles are necessary: Movement of the arm may be limited, and the technique may need to be modified accordingly. Where possible, the supporting sling should be removed. Depending on the condition of the patient, the examination may be undertaken with the patient erect, providing adequate immobilization is used, supine on the X-ray table, or, in cases of multiple trauma, on a trolley.

    The exposure is made on arrested respiration. If the patient is supine, a sandbag should be placed over the forearm. Antero-posterior radiograph of neck of humerus taken erect to show fracture of the neck of the humerus. If the patient is able to abduct the arm, then a supero-inferior projection is recommended with the patient sitting at the end of the X-ray table.

    Alternatively, if the patient is lying on a trolley, then an infero-superior projection is acquired. If, however, the arm is fully immobilized, then an alternative lateral oblique as for the lateral scapula may be taken.

    Lateral — supero-inferior This projection can be taken even when only a small degree of abduction is possible. It is important that no attempt should be made to increase the amount of movement that the patient is able or willing to make.

    Supero-inferior projection for neck of humerus, showing healing angulated fracture of proximal shaft of humerus. Lateral oblique This projection is used when the arm is immobilized and no abduction of the arm is possible. A vertical Bucky technique may be necessary to improve image quality. The most girdle can be carried out with the patient supine on the X-ray superior of these is the supraspinatus, which traverses the sub- table or trolley, but in most cases it will be more comfortable for acromial tunnel between the undersurface of the acromion and the patient to sit or stand with the back of the shoulder in con- the upper surface of the humerus to reach its insertion.

    The erect position affords ease of position- Impingement is a common orthopaedic problem occurring when ing, allows the head of humerus to be assessed more accurately for the subacromial space is compromised by degenerative disease, potential impingement syndrome, and can sometimes demonstrate often exacerbated by congenital anomalies of the acromion.

    The a lipohaemarthrosis where there is a subtle intra-articular fracture. Radiological signs are non-specific, but radio- The central ray can be directed caudally after centring to the graphs help to assess the width of the subacromial space and coracoid process so that the primary beam can be collimated to the shape of the acromion. It is important that projections of the the area under examination. Rotation of the patient or incorrect size must be large enough to cover the whole of the shoulder angulation of the beam can obscure the signs.

    When localized areas are being exam- Tendinitis inflammation may cause visible calcification and ined, however, e. The calcification can be obscured by can be used for large patients; however, the increased contrast poor technique. The width of this joint space is a marker of When examining the shoulder joint, it is important to check on the severity and progression of disease, and obtaining a projec- the position of the head of the humerus by palpating and posi- tion along the joint line is therefore crucial.

    When the Posterior dislocation is uncommon. Signs on the AP image may line joining the epicondyles is parallel to the tabletop or vertical be no more than subtle loss of the normal congruity between cassette , the humerus is in position for an antero-posterior pro- the glenoid and humeral articular surfaces; therefore, if this is jection of the head of the humerus. To judge the degree of rotation suspected, an axial projection is particularly important.

    Detailed examination of the entire shoulder mechanism would The image appearance is affected significantly by the posture require multiple projections. The practitioner must therefore be of the patient.

    If the patient leans back into the cassette, adopt- familiar with the reasons for examination to ensure selection of ing a lordotic stance, then the head of humerus will overlie the the appropriate projections to address the clinical problem.

    Conversely, if the patient leans forward, the Ultrasound in experienced hands is a valuable tool for assess- head of humerus becomes projected inferiorly, appearing to be ment of the shoulder, especially for rotator cuff tears. It may be subluxated. It As in all other skeletal examinations, radiographs showing good is often easier to obtain than magnetic resonance imaging MRI , bone detail are required to demonstrate minor fractures and bone although it cannot image the glenohumeral joint.

    Radiological considerations Unenhanced computed tomography CT has a role in assess- ing the severity of complex fractures around the shoulder. The rounded humeral head articulates with a rather flat glenoid to For recurrent dislocations, accurate imaging of the bony gle- maximize the possible range of movement at the joint. The stabil- noid and labrum, the capsule and glenohumeral ligaments, as ity of the joint is maintained by the cartilage of the glenoid labrum, well as the rotator cuff is needed.

    Cross-sectional imaging MRI ligaments, and the tendons of the rotator cuff. The rotator cuff is or CT with arthrography is often required. An avulsion fracture of the greater tuberosity is often seen only on the axial projection. Modified projections may be undertaken to demonstrate the anterior portion of the acromion process in cases of suspected shoulder impingement syndrome.

    These projections may be undertaken with the patient seated or standing, provided that adequate immobilization is used. If the patient is obese, then the use of a grid cassette or Bucky may improve the contrast of the image but will result in an increased radiation dose. Normal antero-posterior radiograph of shoulder. The beam can then be directed caudally and collimated. A curved cassette, if available, can be used to reduce the OFD. If only Normal supero-inferior image of the limited abduction is possible, the cassette may be supported shoulder on pads to reduce the OFD.

    Some tube angulation, towards the palm of the hand, may be necessary to coincide with the plane of the glenoid cavity. No attempt should be made to increase the amount of abduction that the patient is able and willing to make.

    Essential image characteristics Normal infero-superior radiograph of the shoulder. Note The most common type of dislocation of the shoulder is an anterior dislocation, where the head of the humerus displaces below the coracoid process, anterior to the glenoid cavity. Much rarer is a posterior dislocation.

    In some instances, although the antero-posterior projection shows little or no evidence of a pos- terior dislocation, it can always be demonstrated in an infero- superior or supero-inferior projection of the shoulder.

    Axial radiograph of the shoulder showing posterior dislocation. Routine projections described above are frequently unsatisfac- tory because the anterior portion of the acromion is superim- posed on the body of the acromion. If the antero-posterior projection is undertaken with the X-ray beam angled 30 degrees caudally, the anterior part of the acromion is projected infer- iorly to the body of the acromion and is visualized more clearly.

    A modified lateral projection outlet view with degree caudal angulation may also be undertaken. The medial and lateral epicondyles of the distal humerus should be parallel to the cassette.

    Antero-posterior radiograph of shoulder outlet showing normal undersurface of acromion incidental calcification of the supraspinatus tendon. The body of the scapula is now at right-angles to the cassette, and the scapula and the proximal end of the humerus are clear of the rib cage.

    Normal radiograph of lateral shoulder outlet. The horizon- tal central ray can now pass through the joint space parallel to the glenoid cavity of the scapula. Often, such patients present on a trolley in the emergency situation. If the patient cannot be moved, then the cassette tray under the trol- ley can be used. A line join- cassette, and the scapula and the proximal end of the ing the medial and lateral borders of the scapula is now at humerus are clear of the rib cage.

    The affected arm will be immobilized, usually in a collar and cuff support. It is important that accurate assessment of the glenohumeral joint is possible from the resultant image in order that an avul- sion fracture from around the glenoid rim is demonstrated clearly. Poor positioning technique may be the result of the following:. This has the effect that the coronal plane is often tilted towards the unaffected side. Antero-posterior — 25 degrees caudad.

    In the case of recur- rent posterior dislocation, the defect will be on the anterior part of the head. In each case, this is where the dislocated head of the humerus impacts on the glenoid rim. The radiographic examination for recurrent dislocation of the shoulder requires a projection of the glenoid cavity for signs of fracture affecting the inferior rim Bankart lesion as well as differ- ent projections of the head of the humerus to demonstrate the defect.

    It is important to remember that the angle formed between the epicondyles of the humerus and the cassette indicates the degree of rotation of the humerus.

    To judge the rotation of the humerus by the position of the hand can be very misleading. Projections may be selected from the following:. Antero-posterior lateral humerus If the patient is able to cooperate fully, these projections may be taken erect. If not, the patient is positioned supine to reduce the risk of movement. Note Antero-posterior shoulder showing anterior dislocation To improve image quality and reduce radiation dose, careful collimation of the beam is employed.

    Note To improve image quality and reduce radiation dose, careful collimation of the beam is employed. Infero-superior This will give a second projection of the glenoid cavity as well as a further projection of the head of the humerus. Normal infero-superior radiograph of shoulder. Greater tuberosity Superior angle of the scapula Calcified tendons 3 of the humerus Spine of the Most tendon pathology is best demonstrated by MRI or ultra- Infraspinatus scapula sound.

    Calcification does not show well on MRI and calcific tendonitis is thus best depicted by plain radiographs or ultra- Teres minor Medial border sound. The radiographic technique is described below. The tendons affected are those of the supraspinatus, subscapularis, infraspinatus, and rarely teres minor muscles.

    The illustration shows the origins, courses and insertions of most of these muscles. The supraspinatus muscle has its origin in the supraspinatus fossa on the posterior aspect of the scapula superior to the spine of the scapula.

    Its tendon passes beneath the acromion process then over the upper posterior part of the shoulder joint, to be inserted into the highest of the three impressions of the greater tuberosity. The infraspinatus muscle has its origin in the infraspinatus fossa on the posterior surface of the scapula inferior to the spine of the scapula. Its tendon glides over the posterior border of the acromion and then passes behind the capsule of the shoulder joint, to be inserted into the middle impression of the greater tuberosity of the humerus.

    The teres minor muscle has its origin on the lateral border of the scapula and its tendon passes behind the lower part of the capsule of the shoulder joint, to be inserted into the lowest of the three impressions of the greater tuberosity of the humerus and to the shaft just distal to this lowest impression. The subscapularis muscle has its origin in the subscapularis fossa on the deep anterior surface of the scapula and its tendon crosses the shoulder joint anteriorly, to be inserted into the lesser tuberosity of the humerus.

    The recommended projections for each of the tendons are given in the table below remember ultrasound is very effective in localizing calcification and may also give information about the soft tissue of the tendon. No rotation arm in position 1. The line joining the medial and lateral epi- condyles of the humerus is now perpendicular to the vertical cassette holder. The palm of the hand faces forward, with the lateral epicondyle facing backwards. The line joining the medial and lateral epicondyles of the humerus should be perpendicular to the vertical Medial rotation arm in position 2 cassette holder.

    Lateral rotation arm in position 3. No rotation arm in position 1 Medial rotation arm in position 2 Lateral rotation arm in position 3. In certain circumstances, subluxation of the joint may be confirmed with the patient holding a heavy weight. The posterior aspect of the shoulder being exam- ined is placed in contact with the cassette, and the patient is then rotated approximately 15 degrees towards the side being examined to bring the acromioclavicular joint space at right- angles to the film.

    The normal difference between the sides should be less than 2—3 mm Manaster Weight-bearing antero-posterior projection Normal antero-posterior radiograph of acromioclavicular joint. Subluxation may be difficult to diag- nose in the standard antero-posterior image, because the width of the joint can be variable and may look widened in a normal joint.

    Antero-posterior radiograph of acromioclavicular joint showing subluxation. The postero- anterior position also reduces the radiation dose to the thyroid and eyes, an important consideration in follow-up fracture images. Alternatively, the patient may be supine on the table or trolley for the antero-posterior projection in which immobility and move- ment are considerations. Note Exposure is made on arrested respiration to reduce patient Postero-anterior radiograph of clavicle showing comminuted fracture movement.

    Antero-posterior supine radiograph of clavicle showing fracture. Antero-posterior supine radiograph of clavicle showing a pathological fracture through a sclerotic metastasis. In cases of acute injury, it is more comfortable for the patient to be examined in the erect position.

    Some holders allow forward-angulation of the cassette of 15 degrees towards the shoulder. This reduces the distortion caused by the cranially projected central beam.

    Note Supine infero-superior radiograph of clavicle showing early healing of a fracture If the cassette cannot be pressed well into the side of the neck, then the medial end of the clavicle might not be included on the cassette. In this case, with the central ray again angled 45 degrees cranially, the central ray is first centred to the sternoclavicular joint of the affected side and then the tube is rotated until the central ray is directed to the centre of the clavicle. Oblique ray passing through Sternoclavicular joints 3 left sternoclavicular joint In an antero-posterior or postero-anterior projection, the verte- bral column will be superimposed on, and obscure, the sternoclav- Oblique ray passing through right sternoclavicular joint icular joints, hence an oblique projection is required to show the Normal ray joint space clear of the vertebral column.

    An oblique projection is chosen that will bring the joint space as near as possible at Scapula Humerus right-angles to the film. Both sides may be imaged for comparison.

    Note Superimposed lung detail may be reduced by asking the patient to breathe gently during the exposure. Semi-prone alternate Alternatively, the patient may be examined in the semi-prone position. Starting with the patient prone, the side not being examined is raised from the table until the median sagittal plane is at 45 degrees to the table, with the joint being examined in the midline of the table.

    The centring point is to the raised side, 10 cm from the midline at the level of the fourth thoracic vertebra. Alternatives include ultrasound, CT especially with three-dimensional or multiplanar reconstructions and MRI. Radiograph of normal right Radiograph of normal left sternoclavicular join sternoclavicular joint. Posterior subluxation compromises the airway. Radiograph of normal sternoclavicular joints in lateral projection.

    When the shoulders are pressed back, the medial bor- ders for the scapulae are parallel to and near the vertebral col- umn, so that most of the scapula would be superimposed on the thoracic cage in the antero-posterior projection of the scapula. With the arm in full medial rotation, the scapula glides laterally over the ribs, allowing more of the body of the scapula to be shown clearly against the rib cage.

    Antero-posterior basic — erect The scapula can be shown on the antero-posterior basic survey projection of the shoulder but with the arm in medial rotation. It is preferable for the patient to be examined in the erect pos- ition when there is suspected injury as it is more comfortable. There may also be underlying rib fractures. Note Oblique Normal A long exposure time may be chosen and the patient allowed to ray ray continue quiet breathing during the exposure, so that images of overlying lung and rib are blurred in cases of non-trauma.

    This can be checked by pal- Normal lateral radiograph of pating the medial and lateral borders of the scapula near the scapula inferior angle. CT may be very useful for complete evalu- ation, in particular the multiplanar reconstruction facility, Shaft of the once a fracture has been detected. Additionally, the process is demonstrated in the axial supero-inferior and infero-inferior projections of the shoulder see pp. Note This projection will also demonstrate the acromioclavicular joint of the same side free from overlaying structures.

    Normal antero-posterior radiograph of coracoid process Normal supero-inferior radiograph of the shoulder demonstrating the coracoid process. Reference Manaster BJ The position of the foot relates to the direction of rotation. This will produce internal rotation of the hip joint. This will produce external rotation of the hip joint. A lead-rubber mask is used to mask off each half of the cassette not in use.

    Dorsi-plantar basic To ensure the tarsal and tarso-metatarsal joints are demonstrated, the foot is X-rayed with the foot flat on the cassette and with the X-ray tube angled 15 degrees cranially. Alternatively, the foot is raised on a degree non-opaque pad using a vertical central beam. The angulation compensates for the inclination of the longitudinal arch and reduces overshadowing of the tarsal bones.

    Proximal phalanx. Head of talus Calcaneum Medial malleolus of tibia Lateral malleolus of fibula. Note A wedge filter can be used to compensate for the difference in Normal dorsi-plantar radiograph of foot tissue thickness.

    These may give rise to con- fusion with small avulsion injuries. This should not be confused with a fracture, which usually runs transversely. Radiographs showing normal fifth metatarsal ossification centre on the left, and fracture base fifth metatarsal on right arrow. It may also be used to demonstrate a fracture or dislocation of the tarsal bones, or base of metatarsal fractures or dislocation. Normal lateral radiograph of foot Note A metal marker placed over the puncture site is commonly used to aid localization of the foreign body.

    Longitudinal Cuboid Head of Sesamoid Proximal and distal plantar arch 5th metatarsal bone of phalanges of the the hallux hallux. Both feet are examined for comparison. Dorsi-plantar — erect This projection can be used to show the alignment of the metatarsals and phalanges in cases of hallux valgus.

    Both forefeet are taken for comparison. Normal erect lateral projection of foot. A lateral projection is taken for fractures of the hallux phalanx. A lead-rubber mask can be used to mask off each half of the cassette not in use.

    This cassette may be supported on a degree pad. Normal dorsi-plantar projection of all toes. Collimated dorsi-plantar oblique projection of fifth toe, showing fracture of the proximal phalanx.

    A bandage is placed around the remaining toes pro- Lateral basic — hallux vided that no injury is suspected and they are gently pulled forwards by the patient to clear the hallux. First metatarsal-phalangeal sesamoid bones The sesamoid bones are demonstrated on the lateral foot projec- tion. However, when requested specifically, a modified lateral and an axial projection may be necessary for further demonstration.

    Textbook of Radiographic Positioning and Related Anatomy

    Axial Position of patient and cassette There is a choice of two positions for this projection: The foot is raised on a support and the cassette is sup- ported vertically and well into the instep. A horizontal beam is used in this case. The hallux is then dorsiflexed with the aid of a bandage and held by the patient. The cassette is raised on a support and positioned firmly against the instep. Lateral projection of first metatarsal Normal axial projection of first sesamoids, note exostosis on metatarsal sesamoids medial sesamoid.

    A lead-rubber mask can be used to mask off the half of the film not in use. The limb is rotated medially approximately 20 degrees until the medial and lateral malleoli are equidistant from the cassette. Tibia Fibula. Ankle joint Tibiofibular synchondrosis.

    Trochlear surface dome of the talus. The lower edge of the cassette is positioned just below the plantar aspect of the heel. Investigation of the injury should therefore cover both areas. Stress projections may clarify this problem and ultrasound or MRI may be useful. These injuries frequently require Tibia surgical fixation. Fibula Ankle joint Promontory of tibia Trochlear surface Lateral of talus malleolus Navicular Posterior tubercle Medial of talus cuneiform.

    This also applies to those patients from the fracture clinic with below-knee plaster casts. In the latter case, for conventional film processing, radio- graphy cassettes with standard-speed screens are used because of the increase in radiation dose necessary to penetrate the cast. The horizontal techniques described can be undertaken only in X-ray rooms that have the capability of lowering the ceiling tube suspension sufficiently to centre the X-ray beam on the ankle joint.

    A non-opaque angled pad is placed against the medial border of the foot and sandbags are placed at each side of the leg for support. Note If the foot remains straight, there will be overshadowing of the tibio-fibular joint combined with a vertical central ray. The Note lower edge of the cassette is placed just below the plantar If there is no internal rotation of the foot, then the distal fibula aspect of the heel.

    Although these projections may be done in the department, they are now Ankle joint 4 commonly done in theatre using a mobile image intensifier. Stress projections for subluxation Stress is applied to the joint by medical personnel, usually an orthopaedic surgeon. The degree of stress applied is viewed and recorded. A lead-rubber mask may be used to mask off each half of the film not in use. Note This projection is used to demonstrate calcaneal spurs.

    For com- parison, a radiograph of both heels in the lateral position may be necessary. The appearance rarely obscures a fracture and should rarely, if ever, require projections of the contralateral side for assessment. In the calcaneum, this results in an apparent lucency in Fracture of the calcaneum Calcaneal spur the central area. This should not be mistaken for pathology. If significant, they are usually ill-defined and clinically tender. Ultrasound may help in their assessment.

    Computed tomography CT is very useful for the complete evaluation of complex calcaneal frac- tures, especially utilizing the direct coronal plane, multipla- nar and three-dimensional reconstructions. Axial projection of calcaneum showing comminuted fracture. The projections undertaken with the articulations demonstrated are shown in the table below, with matching images also given. Lateral oblique — degree Middle and posterior articulations caudal tilt Dorsi-plantar oblique.

    Dorsi-plantar oblique Anterior articulation degree oblique — medial Posterior articulation from an with degree cranial tilt anterior direction degree oblique — lateral Posterior articulation from a lateral with degree cranial tilt direction.

    Posterior Lateral oblique degree caudal tilt articular surface. Middle articular surface. Radiograph showing effect of degree Radiograph showing effect of degree Radiograph showing effect of degree angulation angulation angulation. A cas- sette fitted with standard intensifying screens is chosen that is large enough to accommodate the entire length of the tibia and fibula.

    The limb is rotated medially until the medial and lateral malleoli are equidistant from the cassette. Both images should to the middle of the cassette. Radiological considerations This pair of bones constitutes a ring. As for other bony rings, a fracture at one site may be associated with a fracture elsewhere.

    If a fracture of one of the pair is seen, with overlap or shortening, then the entire length of both bones must be demonstrated. The affected limb is rotated to centralize the patella between the femoral condyles, and sandbags are placed against the ankle to help maintain this position. If the central ray is not perpendi- Normal antero-posterior radiograph cular to the long axis of the tibia, then the anterior and posterior margins of the tibial plateau will be separated widely and assess- ment of the true width of the joint space will be difficult.

    Although the relationship of the patella to the sur- Medial femoral rounding structures can be assessed the trabecular pattern of condyle Lateral tibial the femur is superimposed. Therefore, this projection is not Intercondylar plateau ideal for demonstrating discrete patella bony abnormalities.

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    Anterior and posterior tibial spines Tibia Fibula. With the knee flexed at 90 degrees, a patella in normal position Patello-femoral joint will lie between two parallel lines drawn along the anterior Patella Knee joint and posterior surfaces of the femur.

    This may Lateral Tibial spines permit a clearer view of the patello-femoral articulation. Effect of over rotation Effect of under rotation. Additional projections Further projections are used to demonstrate fracture of the patella and the intercondylar notch. Stress views may also be taken in suspected ligamental tears. Ultrasound may also be useful in this clinical situation. Lateral — horizontal beam Horizontal beam lateral showing depressed fracture of tibial plateau arrows and lipohaemarthrosis arrowheads.

    This projection replaces the conventional lateral in all cases of gross injury and suspected fracture of the patella. Horizontal beam. Horizontal beam lateral showing distal femoral fracture.

    Any such deformity will be accentuated when weight bearing, which more closely resembles the real-life situ- ation. It is commonly requested to assess alignment prior to joint replacement, as narrowing of one side to the joint space more than the other will produce varus or valgus tilt. Both knees may be included for comparison.

    Radiographic Evaluation

    Stress projections for subluxation Stress projections of the knee joint are taken to show subluxation due to rupture of the collateral ligaments. Although these projec- tions may be done in the department, they are now commonly done in theatre using a mobile image intensifier. Stress is applied to the joint by medical personnel, usually an orthopaedic surgeon.

    Its significance varies according to the clinical setting. Causes include infection, haemorrhage and arthritis, but it may also be a marker of occult fracture, e.

    Lipohaemarthrosis occurs when a fracture passes into the marrow-containing medullary space. Good technique horizontal beam is used. Ultrasound may only if exposed properly i. If clinically be useful if confirmation is required. Projections of the suspected, then a skyline view maybe requested.

    The optimum retro-patellar joint spacing occurs when the knee is flexed approximately 30—45 degrees. Further flexion pulls the patella into the intercondylar notch, reducing the joint spacing; as flexion increases, the patella tracks over the lateral femoral condyle.

    The most common principle used is reflection at grazing incidence angles, either using total external reflection at very small angles or multilayer coatings. Other principles used include diffraction and interference in the form of zone plates , refraction in compound refractive lenses that use many small X-ray lenses in series to compensate by their number for the minute index of refraction, Bragg reflection off of a crystal plane in flat or bent crystals.

    X-ray beams are often collimated or reduced in size using pinholes or movable slits typically made out of tungsten or some other high- Z material. Narrow parts of an X-ray spectrum can be selected with monochromators based on one or multiple Bragg reflections off of crystals.

    X-ray spectra can also be manipulated by having the X-rays pass through a filter optics. This will typically reduce the low energy part of the spectrum, and possibly parts above absorption edges of the elements used for the filter. Focusing optics[ edit ] Analytical X-ray techniques such as X-ray crystallography, small-angle X-ray scattering, wide-angle X-ray scattering , X-ray fluorescence, X-ray spectroscopy and X-ray photoelectron spectroscopy all benefit from high X-ray flux densities on the samples being investigated.

    This is achieved by focusing the divergent beam from the X-ray source onto the sample using one out of a range of focusing optical components. This is also useful for scanning probe techniques such as scanning transmission X-ray microscopy and scanning X-ray fluorescence imaging.

    Polycapillary optics[ edit ] A polycapillary lens for focusing X-rays Polycapillary lenses are arrays of small hollow glass tubes that guide the X-rays with many total external reflections on the inside of the tubes. Polycapillary optics are achromatic and thus suitable for scanning fluorescence imaging and other applications where a broad X-ray spectrum is useful. They collect X-rays efficiently for photon energies of 0. Polycapillary optics cannot image more than one point to another, so they are used for illumination and collection of X-rays.

    Main article: Zone plate Zone plates consist of a substrate with concentric zones of a phase-shifting or absorbing material with zones getting narrower the larger their radius. The zone widths are designed so that a transmitted wave gets constructive interference in a single point giving a focus. Zone plates are highly chromatic and usually designed only for a narrow energy span, making it necessary to have monochromatic X-rays for efficient collection and high-resolution imaging.

    Compound refractive lenses[ edit ] Main article: Compound refractive lens Since refractive indices at x-ray wavelengths are so close to 1, the focal lengths of normal lenses get impractically long. To overcome this lenses with very small radii of curvature are used, and they are stacked in long rows so that the combined focusing power gets appreciable.

    Since the refractive index depends strongly on X-ray wavelength, these lenses are highly chromatic and the variation of the focal length with wavelength must be taken into account for any application. Reflection[ edit ] Several designs have been used in X-ray telescopes based on grazing incidence reflection: the Kirkpatrick-Baez design and a few of designs by Wolter Wolter I-IV The basic idea is to reflect a beam of X-rays from a surface and to measure the intensity of X-rays reflected in the specular direction reflected angle equal to incident angle.

    It has been shown that a reflection off a parabolic mirror followed by a reflection off a hyperbolic mirror can lead to the focusing of X-rays.