The baby is positioned supine on cassette, with the median sagittal plane adjusted perpendicular to the middle of the cassette, ensuring that the head and chest are straight and shoulders and hips are level.
The head may need a covered sandbag support on either side. A 10 degree foam pad should be placed under the shoulders to avoid a lordotic projection ant to lift the chin and prevent it obscuring the lung apices.
Arms should be on either side, separated slightly from the trunk to avoid being included in the radiation field and to avoid skin crease artifacts, which can mimic pneumothoraces.
Arm can be immobilized with Velcro bands and/or sandbags.
BABY REQUIRING HOLDING
Positioned is similar to that described for the sleeping baby and can be performed by a single assistant with the following adaption.
The arms should be held flexed on either side of the head.
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Arms should not be extended fully, as this can cause lordotic images.
When needed, legs should be held together and flexed at the knees.
DIRECTION AND CENTERING OF THE X-RAY BEAM
No single centering point is advised. Centre the beam to the midline of the cassette. The central ray is directed vertically, or angled 5-10 degrees caudally if the baby is completely flat, to avoid projecting the chin over the lung apices. Contact maximum FFD should be used. Although some incubators have cassette under the baby is recommended as routine, to avoid magnification and change of exposure factors.
ESSENTIAL IMAGE CHARACTERISTICS
Peak inspiration to include 8-9 posterior ribs (4-5 anterior ribs). No rotation. Medial ends of the clavicles should overlap the tranverse processes of the spine symmetrically, or anterior ribs ends should be equidistant from the spine. No tilting or lordosis. Medial ends of the clavicles should overlie the lung apices. Superior/anterior coning should be from vertical trachea to T12/L1, including the diaphragms. Lateral coning should include both shoulders and ribs but not beyond the proximal third of the humeri. Reproduction of the vascular pattern in the central two-third of the lungs. Reproduction of the trachea and major bronchi. Visually sharp reproduction of the diaphragm and costrophenic angles. Reproduction of the spine and paraspinal structures. Visualization of retrocardiac lung and mediastinum Visually sharp reproduction of the skeleton.
COMMON FAULTS AND REMEDIES
Classically, the port hole of the incubator must not overlie the chest. All extraneous tubes and wires should be repositioned away from the chest area. Exposure should be made in inspiration. Watching for full distension of the baby's avdomen rather than the chest best assesses this. Expiratory images mimic parenchymal lung disease. Arms should not be extended fully above the head, as this will lead to a lordotic position. Lordotic images show anterior rib ends pointing upwards, and the lung bases are obscured by the diaphragm. The head must be supported to avoid the chin lolling forward and obscuring the upper chest. Minimal exposures of less than 0.02s should be used to avoid motion artifact. Rotated images should be avoided, as this can cause misinterpretation of mediastinal shift and lung translucency. The separate ossification centres of the sternum, projected over the lungs can also cause confusion. As in all radiographs, but particularly in neonatal work, where the name label is large compared with the size of the image, the label should not obscure any of the anatomical detail. Taking a radiograph when a baby is crying should be avoided, as this can cause overexpansion of the lungs, which may mimic pathology. Overexposures of neonatal chest radiographs will result in loss of lung detail.
If the baby is intubated, great care must be taken not to dislodge the endotracheal tube. Even small movements of the head can result in significant movement of the tip, this should lie in the lower third of the trachea, approximately between T1 and carina. An umbilical arterial catheter (UAC) follows the umbilical artery down inferiorly to either internal iliac artery and then via the iliac to the aorta. This catheter is usually finer and more radio-opaque than an umbilical venous catheter (UVC). The former should idelly be placed with its tip in the mid-thoracic aorta between T4 and T9, which avoids the risk of causing thrombosis if the tip is opposite the origins of any of the abdominal vessels. Some UACs can be left with their tips in the lower abdominal aorta if there has been difficulty with advancing them. The UVC passes directly upwards through the ductus venosus in the liver and should lie with its tip in the IVC or right atrium. If lines are only faintly radio-opaque, then 0.5ml of non-ionic intravenous contrast (iodine 200mg/ml) can be used for opacification
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Minimal handling and the avoidance of heat loss from any incubator are essential. Babies are very vulnerable to infection, and therefore strict hygiene rules and hand-washing are paramount. All the cassette and foam pads inserted into an incubator should be washable. Experienced nursing help in immobilization technique is invaluable. All preparation of the x-ray equipment should be performed before placing the x-ray cassette under the baby.
Accurate collimation of the x-ray beam using light beam diaphragm with additional lead masking within the primary field balance on top of incubator. It is the radiographer's responsibility to ensure that the holder's hands are not in the direct beam. The abdomen should be included on a chest radiography only if assessment of catheters or relevant pathology is present. In this case, male gonads should be protected. All mobile equipment on SCBU should have short-exposure capability to allow kVp selection of over 60 kV as a dose reduction measure. If this is not possible, then additional filtration can be considered, but this can affect the quality of the image. An accurate exposure chart according to infant weight should be available. All mobile equipment should have a dose area product meter.
CHEST: POST-NEONATAL ANTERO-POSTERIOR SUPINE PROJECTION
The antero-posterior([supine) projection is performed as an alternative to the erect position when the latter is not possible. Special attention is required when imaging a baby's chest. With
the chest being conical in shape, positioning a baby supine with the back against a cassette results in a lordotic projection, with the clavicles projected above the apices and a large part of
the lower lobes superimposed on the abdomen. The heart also appears foreshortened. In a correct projection, the anterior rib ends will be projected inferiorly to the posterior rib ends, and the clavicles will be seen superimposed on the lung apices. This can be accomplished either by leaning the baby forward or by angling the X-ray tube caudally, or both. The projection is often performed as part of a mobile X-ray examination on children of all ages. A cassette size is selected depending on the size of the child.
POSITION OF PATIENT AND CASSETTE
The child is positioned supine on the cassette, with the upper edge positioned above the lung apices. When examining a baby, a 15-degree foam pad is positioned between the thorax and the cassette (thick end under the upper thorax) to avoid a lordotic projection. A small foam
pad is also placed under the child's head for comfort. The median sagittal plane is adjusted at right-angles to the middle of the cassette. To avoid rotation, the head, chest and pelvis are straight. The child's arms are held, with the elbows flexed, on each side of the head. A suitable appliance, e.g. Bucky band or Velcro band, is secured over the baby's abdomen and sandbags are placed next to the thighs to prevent rotation.
DIRECTION AND CENTERING THE X-RAY BEAM
The vertical central beam is directed at right-angles to the middle of the cassette at the level of T8 (mid-sternum). For babies with a very hyperinflated barrel chest (due to bronchiolitis or asthma), the tube is also angled five to 10 - degrees caudally to avoid a lordotic projection.
Care should be taken not to have the lung apices being obscured by the chin.
Lead-rubber coverage of the abdomen in immediate proximity to beam is recommended.
COMMON FAULTS AND REMEDIES
Tilted, with clavicles above the lung apices. This lordotic projection results in the lower lobes of the lungs being obscured by the diaphragms. Pneumonia and other lung pathology can be missed. See Position of patient and cassette for how to correct this fault.
CHEST: POST-NEONATAL LATERAL PROJECTION
This supplementary projection is undertaken to locate the position of an inhaled or swallowed foreign body, to evaluate middle lobe pathology or to localize opacities demonstrated on the postero-anterior/antero-posterior projection. A 24 X 30-cm cassette is selected.
POSITION OF PATIENT AND CASSETTE
The patient is turned to bring the side under investigation towards the cassette. The median sagittal plane is adjusted parallel to the cassette. The outstretched arms are raised above the head and supported. The mid-axiilary line is coincident with the middle of the cassette, and the cassette is adjusted to include the apices and the inferior lobes.
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DIRECTION AND CENTERING X-RAY BEAM
Direct the vertical central ray at right-angles to the middle of the cassette in the mid-axillary line. Exposure is made on peak inspiration.
ESSENTIAL IMAGE CHARACTERISTICS
Peak inspiration ( six anterior ribs above the diaphragm ). Whole chest from C7 to L1. Sternum and spine to be included and to be true lateral. Visualization of whole trachea and major bronchi. Visually sharp reproduction of the whole of both domes of the diaphragm. Reproduction of the hilar vessels. Reproduction ofthe sternum and the thoracic spine.
CINCINNATE FILTER DEVICE
The use of this filter device is employed in cases of suspected inhaled foreign body when an antero-posterior image of the chest is acquired with the child lying supine. The Cincinnati filter is composed of 2mm of aluminium, 0.5 mm of copper and 0.4 mm of tin inserted into the collimator box so that the copper layer is towards the -X-ray tube. Exposures used are in the range of 125-140kVp and 10-16mAs, using a cassette and grid system. On the exposed radiograph, bone detail is effected to a considerable degree, allowing soft tissue and air interfaces in the mediastinum and adjacent lung to be seen. The trachea and proximal
bronchial anatomy are demonstrated well. A CT scout scanogram can be considered as an alternative. Careful handling is always advisable in children suspected to have an inhaled foreign body, as dislodgement can result in total airway obstruction.
ABDOMEN : ANTERO-POSTERIOR
POSITION OF PATIENT AND CASSETTE
The child lies supine on the x-ray table or, in the case of a neonate, in the incubator, with the median sagittal plane of the trunk at right-angles to the middle of the cassette. To ensure that the chils is not rotated, the anterior superior iliac spines should be equidistant from the cassette. The cassette should be large enough to include the symphysis pubis and the diaphragm.
DIRECTION AND CENTERING THE X-RAY BEAM
The vertical central ray is directed to the centre of the cassette.
All acute abdominal radiographs should include the diaphragm and lung bases. Lower-lobe pneumonia can often masquerade as acute abdominal pain. Radiograph for the renal tract can have more lateral coning, and a fizzy drink may be used to distend the stomach with air, thus displacing residue in the tranverse colon and better demonstrating the renal areas. Collimation is as for adults, but babies' and infants' abdomens tend to be rounder; therefore, slightly wider lateral cones are required.
ESSENTIAL IMAGES CHARACTERISTICS
Antero-posterior projection for whole abdomen is that abdomen to include diaphragm, lateral abdominal walls and ischial tuberosities. Pelvis and spine should be straight, with no rotation. Reproduction of properitoneal fat illnes consistent with age. Visualization of kidney and psoas outlines consistent with age and bowel content. Visually sharp reproduction of the bones.
COMMON FAULTS AND REMEDIES
Usually inadequate coning but occasionaily too tight coning excludes the diaphragm. Male gonads not protected. Careful technique is needed to address these problems.
Optimization of abdominal radiographs includes using a lowerdose technique, e.g. no grid and a very fast image acquisition system, in the assessment of examinations such as chronic constipation and swallowed foreign body is recommended. Serial images in the latter are not necessary. All boys should have testicular protection. Radiographs of the renal tract can be more collimated laterally . Although it has been demonstrated that a postero-anterior abdominal technique results in a lower dose , a supine technique with male gonad protection is preferred in children. In supine neonates who cannot be moved, a horizontal beam lateral should be taken from the left to reduce the dose to the liver .
Unlike adults, erect images are rarely required or justified. Left lateral decubitus images may be required in cases of suspected necrotizing enterocolitis. In this projection, with the
patient lying on the left side, free gas will rise, to be located between the lateral margin of the liver and the right abdominal wall. Lateral projections may demonstrate Hirschprung's disease
or a retroperitoneai tumour in some rare cases. Abdominal ultrasound has replaced radiography in many conditions. In non-specific abdominal pain, radiographic abnormality is
unlikely to be demonstrated in the absence of one of the following: loin pain, haematuria, diarrhoea, palpable mass, abdominal distension or suspected inflammatory bowel disease.
A very fast film/screen system should be used in chronic cases. A study of colonic transit time may also be requested. The patient swailows 30 radio-opaque plastic pellets and an antero-posterior radiograph with the child in the supine position is performed at day 5 following ingestion. If pellets are not present on day 5, this is normal. If there is a general delay in colonic transit, then the pellets will be distributed throughout the colon. If the pellets are grouped in the sigmoid/rectum, then there is poor evacuation. A medium-speed screen/film system is used in children under two years of age when Hirschprung's disease is suspected. All images should allow adequate assessment of the spine.
Suspected swallowed foreign body
The initial radiograph should be with a fast-speed screen/film system to include the neck and upper abdomen. The radiograph should demonstrate the mandible to iliac crests. Lead protection should be used. The most likely sites of hold-up are the neck, midoesophagus
where the left main bronchus crosses the oesophagus, and at the gastro-oesophageal junction. If a foreign body is demonstrated in the neck or chest, a lateral radiograph should be taken to confirm position. If history is less than four hours and the foreign body is in the oesophagus, the child should be given a fizzy drink, kept erect and an antero-posterior radiograph repeated in 30 minutes to see whether the foreign body has been dislodged. If history is greater than four hours, the patient should be kept nil by mouth and referred for consideration of physical removal. lf no foreign body is demonstrated, no further radiographs are required unless the patient returns with symptoms of abdominal pain and vomiting. A supine abdominal radiograph
should then be performed. Parents should always be advised to return if any of these symptoms develop, but pressure to obtain serial radiographs of foreign bodies passing through the abdomen should be resisted strongly, as this involves unnecessary exposure without any
added benefit. In cases of lead acid or mercury batteries, the radiographs are acquired as described above. However, if the battery is still in the stomach, then it can react with gastric acid. Therefore, the child is normally given metoclopramide and the abdominalradiograph repeated in 24 hours. If the battery is still in the stomach, surgical referral is normally advised.
Open pins and needles are occasionally swallowed. Surprisingly, most pass unhindered if they are beyond the oesophagus; therefore, the same radiographs are indicated as above. If a swallowed foreign body is suspected to be radiolucent, then a contrast study may be indicated. NB: the use of a metal detector in determining the presence of a metal object in the abdomen may reduce the need for unnecessary irradiation of a child (Arena and Baker 1990, Ryan and
Suspected necrotizing enterocolitis
An antero-posterior supine abdominai radiograph is obtained, with the legs and arms held in a similar position to that described for the neonatal chest radiograph in a nonsleeping
infant. The abdomen is normally distended in these cases. Care must be taken not to collimate within the margins of the abdomen. If a perforation is suspected, an antero-posterior (left lateral decubitus) projection is selected using a horizontal beam, with the child lying in the lateral position. The right side of the patient is positioned uppermost, as it is easier to demonstrate free air around the liver. The patient should be kept in this position for a few minutes before the radiograph is taken to allow the air to rise. If the infant is too ill to be moved, then a lateral (dorsal decubitus) projection is preferred, using a horizontal beam, with
the tube directed to the left side of the abdomen to reduce the dose to the liver. This requires less exposure than the antero-posterior projection. Lead protection should be used for boys.
Suspected diaphragmatic hernia. A combined antero-posterior chest and abdomen radiograph is recommended. lmperforate anus (prone invertogram). A lateral (ventral decubitus) projection is selected using a horizontal beam. This allows intraluminal air to rise and fill the most distal bowel to assess the leve1 of atresia. Radiography should not be performed less than 24 hours after birth. Position of patient and cassette. The infant should be placed in the proper position, with the pelvis and buttocks raised on a triangular covered foam pad or rolled-up nappy. The infant should be kept in this position for approximately 10-1 5 minutes. The cassette is supported vertically against the lateral aspect of the infant's pelvis, and adjusted parallel to the median sagittal plane. Direction and centering of the X-ray beam. The horizontal central ray is directed to the centre of thecassette.
A lead marker is taped to the skin in the anatomical area where the anus would normally be sited. The distance between this and the most distal air-filled bowel can then be measured.