1. Fast screen-film
combinations (e.g. rare earth)
2. Low attenuation (e.g.
carbon fiber) materials for cassette fronts, antiscatter grid interspacing.
3. Constant potential
generators with appropriate kilovoltage.
4. Appropriate beam
filtration (minimum 2.5 mm Al for general radiography).
5. Specialized equipment for
mammography and pediatrics
6. Pulsed and frame-hold
(image storage) fluoroscopy equipment.
7. Digital radiography
equipment.
8. Dose-area product meter to
monitor patient exposure.
(B) Some dose-saving techniques:
1. Use smallest possible
field size and good collimation.
2. Collimate to exclude
radiosensitive organs (gonads, breasts and eyes).
3. When gonads lie outside
the primary beam, make distance between the edge of the field and the gonads as
large as possible.
4. Shield breasts, eyes, and
gonads unless the area of interest would be masked. Dose to ovary can be halved
and that to testes reduced by a factor of 20.
5. Use largest practicable
focus to skin distance: never less than 30 cm, especially in mobile
radiography.
6. Position the patient
carefully. Reduce the dose to the female breast and, in skull radiography, to
the eye by postero-anterior projection. Minimize the gap between patient and
film-screen.
7. Use compression of patient
where possible.
8. Use non-grid techniques
when examining children and small adults.
9. Keep film reject rate due
to all causes down to 5%. Check the factors before exposure. Quality assurance,
particularly of automatic processors, is important.
10. In fluoroscopy use the minimal field size and minimal
screening time essential for good diagnosis.
11. Use zoom or small field techniques, which require a
higher dose rate, with discretion.
(C) High-risk examinations:
(C) High-risk examinations:
1. Keep pediatric radiation
doses to an absolute minimum consistent with adequate diagnosis as children up
to the age of 10 years are believed to be 3-4 times more radiosensitive than
adults.
2. In pelvimetry: use MRI or
CT scanography where possible; otherwise use fast rare earth screens and carbon
fiber components.
3. Mammography is not
generally performed on women younger than 50 years unless there is a family
history of breast cancer or the patient has related symptoms.
4. In CT scanning, take the
minimum number of slices, position the patient to avoid the eyes and other
critical organs; reduce milliamperage if appropriate, e.g. for the chest.
5. Patients who are or might
be pregnant.
6. Interventional radiology needs care
to avoid skin reactions;
use pulsed and frame-hold
systems: minimize screening times.
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