Positioning Technique For The Ventrodorsal Radiographic Study Of The Avian Coelom

Precut strips of paper tape, as described for the laterolateral radiographic study of the coelom, are prepared. For the ventrodorsal projection, the bird is placed on the positioning device in dorsal recumbency. The neck is placed in the guillotine and the head is adjusted to the straight rostrocaudal position. Further gentle traction is applied to the bird's body by extending the pelvic limbs slightly caudally and securing them with gauze to the positioning device's cleats. The wings are fully and symmetrically extended laterally and secured with paper tape. Two pieces of tape are crossed at the carpal region of each wing. The sternum (keel) is palpated to confirm that it is superimposed on the vertebral column. Positions of the extremities (legs and wings) are also evaluated for bilateral symmetry. Metallic "R" and "L" markers should be placed on the radiographic cassette indicating the laterality of the patient (Figure 1-5).

POSITIONING TECHNIQUE FOR THE MEDIOLATERAL RADIOGRAPHIC STUDY OF THE AVIAN THORACIC EXTREMITY (WING)

Positioning the body for a mediolateral radiographic study of the thoracic extremity (wing) is similar to the ventrodorsal coelomic study and results in both wings having a mediolateral projection. In contrast, the mediolateral view of the wing with the bird in lateral recumbency requires positional modification to reduce superimposition of the wings, and only the nonde-pendent wing results in a true mediolateral view; the dependent wing results in a lateromedial view. When the patient is positioned in dorsal recumbency, the mediolateral radiographic study of the wing is preferred over the lateromedial study of the wing (which would require the patient to be in ventral recumbency) because of decreased object film distance (OFD). Positioning the patient for the mediolateral radiographic study of the wing requires that the patient be placed in dorsal recumbency and the body placed to the edge of the cassette so that the entire wing of interest will be included on the radiographic image (Figure 1-6). If the body of the bird is placed on the center of the radiographic cassette, the film size might be insufficient to include the entire wing. Birds with large wing spans may require that the wing be positioned diagonally across the film cassette to maximize the length of the x-ray field.

POSITIONING TECHNIQUE FOR THE CAUDOCRANIAL RADIOGRAPHIC STUDY OF THE AVIAN THORACIC EXTREMITY (WING)

Lateral or supine (dorsal recumbency) positioning of the patient produces similar radiographic images of the wing (i.e., lateromedial and mediolateral). It is therefore necessary to make a caudocranial image of the wing, which is the orthogonal projection of the mediolateral and lateromedial studies. Positioning the avian patient for the caudocranial projection of the wing presents a unique challenge to the technician or veterinarian. To facilitate patient positioning and decrease the chance of iatrogenic fractures, many avian patients require anesthesia or sedation to make the orthogonal caudocranial projection of the wing. The bird is held in an inverted position with the head directed toward the floor and the long axis of the bird's body perpendicular to the surface of the x-ray table. This results in a caudocranial projection of the wing. The leading edge of the wing is placed on the

Avian Radiography Wing Caudocranial View

Figure 1-4 Positioning technique for the laterolateral radiographic study of the avian coelom. The bird is placed in right lateral recumbency on the positioning device, and the guillotine device is applied to the neck. The bird's body is then gently moved cau-dally to extend the neck. Further gentle traction is applied to the bird's body by extending the pelvic limbs slightly caudally and securing them with gauze to the positioning device's cleats. The wings are then secured to the positioning device in full extension using radiolucent tape. Rotation of the bird's body can result if excessive pressure is applied to the upper wing when it is secured to the positioning device. All extremities (wings and legs) are positioned so that they are superimposed on their contralateral extremity. This helps to minimize rotation of the bird's body. The x-ray beam (+) is centered on the middle portion of the body, and the x-ray beam field (dotted lines) includes the entire bird for small birds. For medium and large birds, the x-ray field includes the body, proximal extremities, and caudal cervical regions. A metallic "R" marker is placed on the radiographic cassette indicating that the right side is dependent.

cassette and the wing is extended manually while the body or legs are held with the other hand.The appropriate metallic "R" or "L" marker is placed on the radiographic cassette indicating whether the radiographic image is of the right or left wing, respectively (Figure 1-7). A lead apron and gloves are worn for the procedure. The technician's hands should not be in the primary x-ray beam. This caudocranial projection is more difficult to make with direct digital radiology units because it may not be possible to move the x-ray sensor (located under the table top) to the edge of the table. In contrast, the craniocaudal projection of the wing is not practical because the length of the flight feathers precludes close apposition of the bones of the wing with the radiographic cassette. In addition, craniocaudal positioning of the wing results in increased OFD, thereby degrading image quality.

POSITIONING TECHNIQUE FOR THE MEDIOLATERAL RADIOGRAPHIC STUDY OF THE AVIAN PELVIC LIMB (LEG)

Mediolateral radiographic images of the pelvic limbs are made with the patient in right lateral recumbency for the right leg and left lateral recumbency for the left leg. Mediolateral projections are preferred to the lateromedial projections of the pelvic limbs because the OFD is less with the mediolateral projection. Positioning and securing the leg of interest are similar as described for the laterolateral radiographic projection of the coelom, except the contralateral leg is rotated dorsal and pulled caudally to minimize superimposition on the leg of interest. Placement of the bird on the positioning device, application of the guillotine to the neck, and circum ferential application of bandage gauze around the distal aspects of tarsometatarsi facilitate application of traction on both legs for positioning purposes. The appropriate metallic "R" or "L" marker is placed on the radiographic cassette indicating whether the radiographic image is of the right or left leg, respectively (Figure 1-8).

POSITIONING TECHNIQUE FOR THE CRANIOCAUDAL RADIOGRAPHIC STUDY OF THE AVIAN PELVIC LIMB (LEG)

Craniocaudal radiographic images of the pelvic limbs are made with the patient in a supine (dorsal recumbency) position. Cra-niocaudal projections of the pelvic limb are optimal as a result of the reduction in OFD. Positioning and securing the leg of interest are similar as described for ventrodorsal radiographic projection of the coelom. Placement of the bird on the positioning device, application of the guillotine to the neck, and circumferential application of bandage gauze around the distal aspect of the tarsometatarsus facilitate application of traction on the leg of interest. The appropriate metallic "R" or "L" marker is placed on the radiographic cassette indicating whether the radiographic image is of the right or left leg, respectively (Figure 1-9).

POSITIONING TECHNIQUES FOR THE MEDIOLATERAL AND DORSOPLANTAR RADIOGRAPHIC STUDIES OF THE AVIAN DISTAL PELVIC EXTREMITY (FOOT)

Mediolateral and dorsoplantar radiographic studies of the foot are made with the patient in the lateral and supine positions, respectively. The mediolateral projection is preferred over the lateromedial study because of decreased OFD. Positioning

Figure 1-5 Positioning technique for the ventrodorsal radiographic study of the avian coelom.

The bird is placed on the positioning device in dorsal recumbency. The neck is placed in the guillotine, and gentle traction is applied to the bird's body by extending the pelvic limbs slightly caudally and securing them with gauze to the positioning device's cleats. The wings are secured to the positioning device in full extension using radiolucent tape. Two strips of tape are crossed at the carpal region of each wing. The x-ray beam (+) is centered midline on the caudal portion of the sternum, and the x-ray beam field (dotted lines) includes the coelom, head, and extremities for small birds. For medium and large birds, the x-ray field includes the body, proximal extremities, and caudal cervical regions. Metallic "R" and "L" markers are placed on the radiographic cassette indicating the laterality of the patient.

Avian Radiograph

Figure 1-5 Positioning technique for the ventrodorsal radiographic study of the avian coelom.

The bird is placed on the positioning device in dorsal recumbency. The neck is placed in the guillotine, and gentle traction is applied to the bird's body by extending the pelvic limbs slightly caudally and securing them with gauze to the positioning device's cleats. The wings are secured to the positioning device in full extension using radiolucent tape. Two strips of tape are crossed at the carpal region of each wing. The x-ray beam (+) is centered midline on the caudal portion of the sternum, and the x-ray beam field (dotted lines) includes the coelom, head, and extremities for small birds. For medium and large birds, the x-ray field includes the body, proximal extremities, and caudal cervical regions. Metallic "R" and "L" markers are placed on the radiographic cassette indicating the laterality of the patient.

techniques are similar as described for the pelvic limb radiographic examinations, but the positioning device is not utilized and the foot is secured directly to the film cassette with paper tape. Special attention is paid to separating the digits of the foot to minimize superimposition of the digits. For both projections the toes are spread apart and individual digits secured with individual pieces of radiolucent tape. On the mediolateral view of the foot, superimposition of the phalanges makes it difficult to count them. When interpreting the radiographs, counting the phalanges aids in the identification of the specific digit (i.e., the number of phalange bones in each digit is one greater than the number of the digit itself). Radiopaque numeral markers can be placed adjacent to the digits to help identify them on the radiographs. The markers are taped to the surface of the film cassette with radiolucent tape (Figures 1-10 and 1-11).

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Responses

  • Evelyn
    When taking a vetrodorsal xray of a bird in dorsal recumbancy the beam is centered over what?
    4 years ago
  • hobson
    Where is the beam centered when taking a whole body ventrodorsal view of a bird?
    2 years ago

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