Why its done
Chest x-ray is used to diagnose cancer, tuberculosis (MTB) and other lung diseases, and disorders of the mediastinum and bony thorax. The chest x-ray provides a record of the sequential progress or development of a disease. It can also be use to give valuable information about the condition of the heart, lungs, GI tract, and thyroid gland
How to prepare
No special preparation is required. However, the patient will be informed of the purpose and procedure process for the test. There there should be no discomfort. Pregnancy should be screened or at least inform of the last menstrual period.
The is an increased risk of fetal teratogenicity. The ould be a vasovagal response (hypotension, bradycardia) when instructed on breath-holding.
There should be a normal appearing and normally positioned chest, bony thorax (all bones present, aligned, symmetrical, and normally shaped), soft tissues, mediastinum, lungs, pleura, heart, and aortic arch.
How its done
The patient is positioned sitting or standing upright in front of the x-ray machine, with arms held slightly out from the sides, chest expanded, and shoulders pressed forward. The x-ray film is placed against the anterior chest. For lateral views, the patientwill stand with arms raised from the shoulders. The film is placed against the right or left side of the chest. The patient is asked to hold very still and takes in a deep breath and hold as radiographs are taken. For portable x-rays, the patient is positioned sitting in a high-Fowler’s position, and the portable x-ray machine is moved into place in front of the chest for the radiographic exposure onto the plate positioned behind the back and chest.
The chest x-rays do provide records of progress or development of a disease. X-rays must be done after the insertion of chest tubes or subclavian catheters to determine their anatomic position as well as to detect possible pneumothorax related to the insertion procedure. A postbronchoscopy chest x-ray is done to ensure there is no pneumothorax following a biopsy. In addition, the position of other devices such as nasogastric or enteric feeding tubes can be determined and adjusted if necessary. Abnormal chest x-ray results indicate the following lung conditions: Presence of foreign bodies, aplasia, atelectasis, coccidioidomycosis, hypoplasia, lung or liver cysts, pneumonia( bronchopneumonia, lobar, aspiration, or viral ), brucellosis, abscess ( lung or liver), middle lobe syndrome, pneumothorax, pleural effusion, pulmonary tuberculosis, sarcoidosis, and pneumoconiosis (eg, asbestosis).
Westermark’s sign (indicates decreased lung vascularity, sometimes thought to suggest pulmonary embolus)
Abnormal conditions of the bony thorax include the following: Hemivertebrae, Bone destruction or degeneration, Heart enlargement, kyphosis, Osteoarthritis, Osteomyelitis, Scoliosis, and Trauma.
Factors affecting results
- Misinterpretation of a chest x-ray is possible because of tumor, post-operative changes, massive pulmonary emboli, false ventricular aneurysm and esophageal varices. Knowledge of the patient’s history is importanten.
- Clothing, jewelry, and metal objects cause shadows on the film.
- Movement during the procedure obscures the clarity of the picture.
- Poor patient positioning makes x-rays difficult to interpret.
- Overexposure or underexposure results in inadequate visualization.
- The experience of the radiologist in interpreting the films affects the accuracy and outcome of the findings.