ASSIGNMENT

Prepared by:

Sudil Paudyal

B.Sc.MIT 1st year

Roll no.51

Tribhuvan University, Institute Of Medicine

Maharajgunj Medical Campus

Topic: Radiography of

Soft tissue of neck (STN) and

Abdomen

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Soft Tissue of Neck (STN)

GENERAL ANATOMY:

The neck occupies the region between skull and thorax, its upper limit being defined by an imaginary line extending from inferior border of symphysis menti to the external occipital protuberance and its lower limit being defined by a line extending from the suprasternal notch to superior border of the first thoracic vertebra. For radiographic purposes the neck is divided into posterior and anterior portions in accordance with the tissue composition and function of the contained structures.

The portion of neck lying in front of the vertebrae is composed largely of soft tissues, the upper part of respiratory and digestive systems being the principal structures. The thyroid and parathyroid glands and large part of sub maxillary glands, are also located in the anterior portion of neck.

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The thyroid gland consists of two central lobes connected together by a narrow median portion called the isthmus. The gland lies at the front and sides of the upper part of trachea, its lobes reaching from lower third of the thyroid cartilage to the level of first thoracic vertebrae.

The parathyroid glands are small ovoid bodies and are normally four in number- two on each side. They are situated, one above the other on the posterior part of adjacent lobe of thyroid gland.

The pharynx serving as a passage for both food and air is common to the respiratory and digestive systems. It is a musculomembranous, tubular structure situated in front of vertebrae and behind the nose, mouth and larynx. It is approximately 5 inches in length, extending from the undersurface of body of sphenoid bone and the basilar part of the occipital bone inferiorly to the level of disk between the sixth and seventh cervical vertebrae, where it becomes continuous with oesophagus. The pharyngeal cavity is further subdivided into nasal, oral and laryngeal portions. The nasopharynx lies above soft palate. The oropharynx is the portion extending from soft palate to the level of hyoid bone. The base of tongue forms anterior wall of oropharynx. The laryngopharynx lies behind larynx, its anterior wall being formed by the back of larynx and communicates with it by means of the upper laryngeal aperture.

The larynx is organ of voice, and serving as the air passage between pharynx and the trachea, it is also one of the divisions of the respiratory system. It is a movable, tubular structure, broader above than below. It is situated below the root of tongue and in front of the laryngopharynx, where it extends from the level of the superior margin of fourth cervical vertebrae to its junction with the trachea at the level of the

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inferior margin of the sixth cervical vertebrae. The framework of larynx is composed of nine cartilages- three single (epiglottis, thyroid, and cricoid) and three paired (arytenoids, corniculate, cuneiform). The thin leaf shaped epiglottis is situated behind the root of tongue and the hyoid bone. The thyroid cartilage forms the laryngeal prominence, or “Adam’s apple”.

The laryngeal cavity is subdivided into three compartments by two pairs of mucosal folds. The upper pair of folds, called the rima vestibule are known as the false vocal cords. The space above them is called laryngeal vestibule. The lower pair of folds is called the rima glottidis and they are known as true vocal cords. The vocal cords and the rima glottidis make up the vocal apparatus of the larynx and are collectively called the glottis.

RADIOGRAPHY:

Plain radiography is requested to investigate the presence of soft tissue swellings and their effects on the air passages, as well as to locate the presence of foreign bodies or assess laryngeal trauma. The main routinely done projections are described below.

STN- Antero posterior

Indications:

Trauma Foreign body localization

Patient position:

Patient lies supine, with the median sagittal plane adjusted to coincide with the central long axis of the table.

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Chin is raised to show the soft tissues below the mandible and to bring the radiographic baseline to an angle of 20 degrees from the vertical.

Cassette is centered at the level of the fourth cervical vertebra.

Centring of beam:

Central ray is directed 10 degrees cephalic and in the midline at level of fourth cervical vertebra.

Exposure is made on forced expiration.

Radiation protection:

Collimation should be done to include only the area of interest.

Lead apron should be used to cover the lower part of the body.

All the other radiation protection measures that are applied in the department and universally should be applied.

Equipment setting:

Kv mAs FFD mA Film size mS Grid Focus

70 15 100 cm  100 25 X 30 cm  150 No Small

Picture criteria:

The image should demonstrate an area from the occipital bone to the seventh cervical vertebra.

Mandible should not overlap the laryngeal area. Neck should be free of rotation.

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STN-lateral

Indications:

Trauma Foreign body localization

Patient position:

Patient stands or sits with either shoulder against a vertical cassette.

The median sagittal plane of the trunk and head are parallel to the cassette.

The jaw is raised so that the angles of the mandible are separated from the bodies of the upper cervical vertebra.

Immediately before exposure the patient is asked to depress the shoulders forcibly so that their structures are projected below the level of the seventh cervical vertebra.

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Centring of the beam:

The horizontal central ray is directed to a point vertically below the mastoid process at the level of the prominence of the thyroid cartilage through the fourth cervical vertebra.

Radiation protection:

Collimation should be done to include only the area of interest. Lead apron should be used to cover the lower part of the body. All the other radiation protection measures that are applied in the

department and universally should be applied.

Equipment setting:

Kv mAs FFD mA Film size mS Grid Focus

70 15 100 cm  100 25 X 30 cm  150 No Small

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Picture criteria:

The soft tissues should be demonstrated from the skull base to the root of the neck (C7).

Radiograph should allow clear visualization of the laryngeal cartilage and any possible foreign body.

Shoulders should not superimpose the trachea.

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ABDOMEN

GENERAL ANATOMY:

The abdomen is the portion of trunk lying below the diaphragm and bounded by pelvic bones inferiorly. In order to describe the location of organs or an area, the abdomen is divided either into four quadrants or nine regions.

The abdomen is divided into four quadrants by a transverse and a mid sagittal plane that intersect at the umbilicus. The quadrants are named Right Upper Quadrant (RUQ), Right Lower Quadrant (RLQ), Left Upper Quadrant (LUQ), and Left Lower Quadrant (LLQ). Dividing the abdomen into four quadrants is useful in describing the locations of various abdominal organs.

The abdomen can be divided into nine regions by using four planes; two transverse and two vertical planes.

The upper transverse plane, called the transpyloric plane, is midway between suprasternal notch and symphysis pubis, approximately midway between the upper border of xiphisternum and umbilicus. Posteriorly, it passes through the body of the first lumbar vertebra; anteriorly, it passes through the tips of the right and left ninth costal cartilages. The lower transverse plane, called the transtubercular plane, is at the level of tubercles of the iliac crest anteriorly and near the upper border of the fifth lumbar vertebra posteriorly.

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The two parasagittal (vertical) planes are at right-angles to the two transverse planes. They run vertically, passing through a point midway between the anterior superior iliac spine and the symphysis pubis on each side.

These planes divide the abdomen into nine regions centrally from above to below epigastric, umbilical and hypogastric regions and laterally from above to below right and left hypochondriac, lumbar and iliac regions.

The principal structures of abdominal cavity are peritoneum, liver, gall bladder, pancreas, spleen, stomach, intestines, kidneys, ureters and major blood vessels.

The peritoneum is a double walled, membranous sac which lines the abdominal cavity. The outer layer of peritoneum closely adheres to the abdominal walls and to the undersurface of the diaphragm. The inner layer forms folds called the mesentery or omenta which serve to support the visceral organs in position. The narrow space between the two layers is called the peritoneal cavity.

RADIOGRAPHY:

Preparation:

Careful preliminary preparation of the intestinal tract is important in radiologic investigation of the abdominal viscera. In the presence of non acute conditions, the preparation can consist of any combination of controlled diet,

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laxative or enemas. The preparation ordered is generally determined by the medical facility in which the examination is to be performed. The emergency patients need not perform the preparation.

Exposure technique:

In examinations of the abdomen without a contrast medium, it is necessary to obtain maximum soft tissue differentiation throughout its different regions. Because of the wide range in thickness of the abdomen and the delicate differences in physical density between the contained viscera, it is necessary to use a more critical exposure technique than is required to demonstrate the difference in density between an opacified organ and the structures adjacent to it. The exposure factors should thus be adjusted to produce a radiograph with moderate gray tones and less black and white contrast. A sharply demonstrated outline of the psoas muscles, lower borer of liver, kidneys ribs and spinous processes of the lumbar vertebra are the best criteria for judging the quality of an abdominal radiograph.

Immobilization:

One of the prime requisite in abdominal examinations is the prevention of movement, both voluntary and involuntary. To prevent muscle contraction the patient must be adjusted in a comfortable position so that he can relax. A compression band may be applied across the abdomen for immobilization but not compression. The exposure should be made 1-2 sec after suspension of respiration to allow involuntary movement of viscera to subside.

Radiographic projections:

Radiography of the abdomen may include one or more radiographic projections. The most commonly performed is the Antero-posterior supine abdomen projection, often called a KUB (so named because it includes the kidneys, ureters and bladder). Projections used to complement the AP supine

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may include AP erect and/or a lateral decubitus (the left lateral is generally preferred). Both projections are useful in assessing the abdomen in cases of falling down of abdominal viscera and in determining air fluid levels. Other projections may include a lateral abdominal image using a horizontal beam taken with the patient lying in the dorsal decubitus body position. These projections are described below.

Abdomen-supine (KUB):

Indications:

Bowel gas patterns in obstruction Perforation Renal pathology Control or preliminary films for contrast studies Aortic Aneurysm To detect calcification or abnormal gas collection

Patient position:

The patient lies supine on the table with the median sagittal plane at right angles.

The pelvis is adjusted so that the anterior superior iliac spines are equidistant from the table.

The cassette is placed longitudinally and positioned so that the symphysis pubis is included on the film.

The arms placed alongside the trunk or above the head.

Centring of beam:

The vertical central ray is directed approximately at the level of a point 1 cm below the line joining the iliac crests.

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Radiation protection:

Strict application of the “pregnancy rule” or the “ten day rule” is important in females of the child bearing age.

For males, the correct size of gonad protection should be selected and applied carefully so that the gonads are shielded and pelvic region not obscured with lead.

Equipment setting:

Kv mAs FFD mA Film size mS Grid Focus

65 36 100 cm  300 35 X 43 cm  0.12 Yes Large

Picture criteria:

The image should cover whole of abdomen to include diaphragm to symphysis pubis.

Soft tissue gray tones should demonstrate Lateral abdominal wall and the

properitoneal fat layer. Psoas muscle, lower border of liver

and the kidneys. Ribs and spinous processes of the

lumbar vertebra. The whole of the urinary tract should be visualized. The bowel pattern should be demonstrated with minimal

unsharpness.

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Abdomen – Erect

Indications:

Trauma over abdomen

Suspected GI perforation

Abdominal malignancy

Intestinal obstruction

Patient position:

The patient stand with their back against the vertical bucky.

The median sagittal plane is adjusted at right angles and coincident with the midline of the table.

The pelvis is adjusted so that the anterior superior iliac spines are equidistant from the table.

Centring of beam:

The horizontal central ray is directed perpendicular to midpoint at the level of iliac crests.

Radiation protection: The pregnancy rule or the rule of ten should be followed. Gonad shielding should be used.

Equipment setting:

Kv mAs FFD mA Film size mS Grid Focus

70 36 100 cm  300 35 X 43 cm  0.12 Yes Large

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Picture criteria:

The area from dome of diaphragm to symphysis pubis should be included without rotation.

Lateral abdominal wall and properitoneal fat should be visualized.

Psoas muscle, lower border of liver and kidney shadows should be visualized.

Vertebra should be in center of film. Side identification marker should be placed properly.

Abdomen Lat. Decubitus

Lateral decubitus is done instead of abdomen erect if patient is unable to stand or sit.

Indications:

Abdominal perforation Intestinal obstruction Abdominal malignancy

Patient position:

The patient lies in left side with elbows and arms flexed so that hands can rest near the patients head.

The cassette is positioned transversely in vertical bucky or a grid cassette is kept behind the patient

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vertically against the posterior aspect of the trunk, with its upper border high enough to project above the right lateral abdominal and thoracic walls.

Exposure is made on arrested respiration.

Centring of beam:

The central ray is directed perpendicular to midpoint at the level of iliac crest with x-ray tube horizontally.

Radiation protection:

Strict application of the “pregnancy rule” or the “ten day rule” is important in females of the child bearing age.

For males, the correct size of gonad protection should be selected and applied carefully so that the gonads are shielded and pelvic region not obscured with lead.

Equipment setting:

Kv mAs FFD mA Film size mS Grid Focus

70 36 100 cm  300 35 X 43 cm  0.12 Yes Large

Picture criteria:

Lung area above dome of diaphragm should be included.

Lateral abdominal wall and properitoneal fat should be visualized.

Psoas muscle, lower border of liver and kidney shadows should be visualized.

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Patient should not be rotated.

Lateral dorsal decubitus (supine):

Occasionally, the patient cannot sit or even be rolled on to the side, in which case the patient remains supine and a lateral projection is taken using a horizontal central ray.

Indications:

Abdominal perforation Intestinal obstruction Abdominal malignancy

Patient position: The patient lies supine, with

the arms raised away from the abdomen and thorax.

A grid cassette is supported vertically against the patient’s side, to include the thorax to the level of mid-sternum and as much of the abdomen as possible.

Alternatively, when using a trolley, the patient may be positioned against a vertical Bucky.

Centring of the beam:

The horizontal central ray is directed to the lateral aspect of the trunk so that it is at right-angles to the cassette and centred to it.

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Radiation protection:

Strict application of the “pregnancy rule” or the “ten day rule” is important in females of the child bearing age.

For males, the correct size of gonad protection should be selected and applied carefully so that the gonads are shielded and pelvic region not obscured with lead.

Equipment setting:

Kv mAs FFD mA Film size mS Grid Focus

70 36 100 cm  300 35 X 43 cm  0.12 Yes Large

Picture criteria:

Lung area above dome of diaphragm should be included without motion.

Abdominal contents should be seen with soft tissue gray tones.

Patient should be elevated so entire abdomen is demonstrated.

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References:

1. Clark’s positioning in radiography, 12th edition2. Merrill’s atlas of radiographic positions and radiologic procedures,

12th edition3. Encyclopedia of radiography

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