Radiological safety status and quality assurance audit of medical X-ray diagnostic installations in India.
Bottom Line: A QA kit consisting of a kVp Test-O-Meter (ToM) (Model RAD/FLU-9001), dose Test-O-Meter (ToM) (Model 6001), ionization chamber-based radiation survey meter model Gun Monitor and other standard accessories were used for the required measurements.The present study on the radiological safety status of diagnostic X-ray installations may be a reasonably good representation of the situation in the country as a whole.The study contributes significantly to the improvement of radiological safety by the way of the steps already taken and by providing a vital feed back to the national regulatory body.
Affiliation: Atomic Energy Regulatory Board, India.
We conducted a radiological safety and quality assurance (QA) audit of 118 medical X-ray diagnostic machines installed in 45 major hospitals in India. The main objective of the audit was to verify compliance with the regulatory requirements stipulated by the national regulatory body. The audit mainly covered accuracy check of accelerating potential (kVp), linearity of tube current (mA station) and timer, congruence of radiation and optical field, and total filtration; in addition, we also reviewed medical X-ray diagnostic installations with reference to room layout of X-ray machines and conduct of radiological protection survey. A QA kit consisting of a kVp Test-O-Meter (ToM) (Model RAD/FLU-9001), dose Test-O-Meter (ToM) (Model 6001), ionization chamber-based radiation survey meter model Gun Monitor and other standard accessories were used for the required measurements. The important areas where there was noncompliance with the national safety code were: inaccuracy of kVp calibration (23%), lack of congruence of radiation and optical field (23%), nonlinearity of mA station (16%) and timer (9%), improper collimator/diaphragm (19.6%), faulty adjustor knob for alignment of field size (4%), nonavailability of warning light (red light) at the entrance of the X-ray room (29%), and use of mobile protective barriers without lead glass viewing window (14%). The present study on the radiological safety status of diagnostic X-ray installations may be a reasonably good representation of the situation in the country as a whole. The study contributes significantly to the improvement of radiological safety by the way of the steps already taken and by providing a vital feed back to the national regulatory body.
No MeSH data available.
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Mentions: Table 2 gives the acceptance criteria of major QA tests that were performed on various X-ray machines. For the verification of the accelerating potential (kVp), tube current values from 15 mAs to 20 mAs and target-to-detector distance (TDD) of 50 cm were used. The kVp ranges verified include kVp values from 55 kVp to 100 kVp (i.e., 60, 70, 80/81, 90, and 100). The difference between the kVp set on the control panel (CP) and measured by RAD/FLU kVp meter was determined for ensuring the acceptance criteria of ±5 kVp. For assessing the linearity of tube current (mA station), TDD of 100 cm, accelerating potential from 70 kVp to 80 kVp, and exposure time of 0.1 second were used. For assessing the linearity of timer, TDD of 100 cm, accelerating potential from 60 kVp to 70 kVp, and tube current of 100 mA to 150 mA were used. The air kerma was measured at different mAs values and the ratio of air kerma to mAs was obtained to determine the coefficient of linearity (CoL) to verify the compliance with the acceptance criteria (CoL < 0.1). For testing the congruence of radiation and optical field we used the congruence tool manufactured by BARC; a photographic film of 10 inches × 12 inches was exposed at target-to-film distance (TFD) of 100 cm for exposure settings 10 mAs to 12 mAs at 60 kVp. The total filtration of the X-ray tube was verified by estimating the Half-Value Layer (HVL). For this purpose, a dose ToM (model 6001) and five aluminium (Al) filters (sheets) of thickness 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm, respectively, were used. Dose ToM was kept at 100 cm from the X-ray target and the radiation field collimated to dose ToM size. The first exposure was made at frequently used kVp and about 30 mAs without any filter interposed. Then, an Al filter of 1 mm was placed over the dose ToM and the exposure was measured. Subsequently, the thickness of the Al filter was increased in steps from 1 mm to 5 mm. Each time, three measurements of exposure were taken. After completion of measurements, a curve was plotted with the μGy/mAs reading on the Y-axis and the Al filter thickness in mm on the X-axis. Half value layer (HVL) of the X-ray beam at the given kVp was evaluated in terms of Al thickness in mm from the graph. The total tube filtration was determined based on the available nomograms showing the relation between HVL and total filtration of the X-ray beam. A minimum total filtration of at least 2.5 mm of Al was observed in all the cases. The output of X-ray machines in terms of values of air kerma-free in air at 150 cm TDD, 58 kVp (mean value), and 14 mAs (mean value) is shown in Figure 2.
No MeSH data available.