Study of the quality assurance of conventional x-ray units at medical city in Baghdad

الملخص EN

The primary goal of a radiology quality assurance (QA) program is to ensure adequate clinical diagnostic information together with low possible radiation exposure for patient (ALARA principle).This can be achieved by optimum operating parameters such as kVp,entrance skin dose(ESD), linearity of tube current ,time of exposure and the filtration .

Six conventional X-ray unitsin medical city at Baghdad from different origins and different manufacturing time were studied.

The patient entrance surface dose air kerma (ESD) is the quantity currently recommended for patient dose assessment and for comparing patient dose levels with diagnostic reference levels in general radiography.

The mean (ESD), were measured for different organ using ionization chamber (Dosimax ,Unfors) andthermo luminance dosimeter (TLD).

The ESD doses were compared with other recommended data.

It is found that the measured values were greater than recommended values for most x-ray units.

TLD readingwashigher than average value of ionization chamber because the scattering of radiation inpatient body, the scattering coefficient were in the range between (1.1 – 1.05).The voltage stability for the unit was tested for three units(A, B & C) and found the percentage of voltage ripple to unit (B &C) is (3.79) and (4.856) respectively and for units A was 11.4.

The current and exposure time were assess and found that this relationship is linear for the units (B&C) but not for the unit (A) .

HVL of aluminum were (2.6, 2.8) for tube B and C, respectively.

HVL is exceeding the minimum value, passed above 2.3 mm Al at 70 KeV.

This is within the accepted value of IAEA, but HVL for unit A was 0.5 which is less than the recommended value.