EQUIPMENT PERFORMANCE EVALUATION
DENTAL RADIOGRAPHIC UNIT
25 TAC ?289.232(i)(7)(A) Facility Name: _____________________________________ Registration No.:__________________ Date: __________________
Service Company: __________________________________ Service Company Registration No.: _________________________
Survey Instrument Used: ____________________________ ? Exposed sensor/detector ? Enclosed sensor/detector
Instrument Calibration Date: _______________ Technician Signature: _____________________________________________
X-RAY UNIT IDENTIFICATION (FROM CONTROL PANEL) Manufacturer: _______________________________________________________________ Location/Room: ______________ Model No.: ________________________________________ Serial No.:____________________________________________
TIMER ACCURACY ( ) Pass ( ) Fail Regulation –The accuracy of the timer shall meet the manufacturer’s specifications. If the manufacturer’s specifications are not obtainable, the timer accuracy shall be ?10 percent of the indicated time with the testing performed at 0.5 second. (See 25 TAC ?289.232(i)(6)(H)(i) )
SELECT ONE: ? Manufacturer’s specifications which are _____________________________________ OR
? Intraoral units ?10 % tolerance with testing performed at 0.5 second (500 milliseconds)
? Panoramic units ?10% tolerance with testing performed at ________________seconds Document time used for testing: __________msec; OR __________pulses; OR __________seconds Perform four measurements: 1. _______________ 2. _______________ 3. ______________ 4. _______________
EXPOSURE REPRODUCIBILITY ( ) Pass ( ) Fail Regulation –When all technique factors are held constant, the coefficient of variation of exposures for both manual and AEC systems shall not exceed 0.05. (See 25 TAC ?289.232(i)(6)(I) ) (See pages 3 and 4 for instructions.)
Technique factors selected: _______mA _______kVp _______time
S = estimated standard deviation of the population Perform four measurements: 1/2 2n??s1( - X)i X 1.___________ mR C = = ???X= mean value of observations in sample n-1XXi=1????= ith observation in sample 2. ___________mR X1/2i2 n N = number of observations in sample ??s1( - X) 3. ___________mR Coefficient of variation: XiC = = ?? (Must not exceed .05) _______________ ? 4. ___________mR n-1XXi=1????
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KVP TEST ( ) Pass ( ) Fail Regulation – If the registrant possesses the manufacturer’s kilovolt peak specifications, the radiation machine shall meet
those specifications. Otherwise, the measured kVp shall be accurate to within ?10 percent of the indicated setting at no less than
three points over the usual operating range of the machine. (For units with fewer than three fixed kVp settings, the units shall be
checked at those settings.) (See 25 TAC ?289.232(i)(6)(J) ) EQUIPMENT PERFORMANCE EVALUATION - DENTAL UNIT Serial No. _____________________________ SELECT BELOW: ((Measured kVp – Indicated kVp) ? Indicated kVp) x 100 = % Deviation ((Measured kVp - Indicated kVp) ?Indicated kVp) x 100 = % of Deviation
? Manufacturer’s specifications which are ___________________________________ OR
? ?10% of the indicated setting used 1. Indicated kVp _________ Measured kVp _________ Deviation _________% 2. Indicated kVp _________ Measured kVp _________ Deviation _________% 3. Indicated kVp _________ Measured kVp _________ Deviation _________% 4. Indicated kVp _________ Measured kVp _________ Deviation _________% TUBE STABILITY ( ) Pass ( ) Fail Regulation –The tube shall remain physically stable during exposures. In cases where tubes are designed to move during exposure the registrant shall assure proper and free movement of the unit. (See 25 TAC ? 289.232(i)(6)(K) ) For intraoral machines only: For panoramic and cephalometric machines only: Tube stable in all orientations? Yes ( ) No ( ) Free movement where designed? Yes ( ) No ( )
COLLIMATION ( ) Pass ( ) Fail Regulation– 25 TAC ?289.232 (i)(6)(L) Field limitation shall meet the requirements of 25 TAC ?289.232(i)(11)(B) and 25 TAC ?289.232(i)(12) Intraoral: Minimum source to skin distance (SSD) ___________ cm X-ray field size at tip of cone ___________ cm Field size ? to 7cm if the minimum SSD is 18cm or more; ? to 6cm if the minimum SSD is less than 18 cm Panoramic: Image receptor slit size: (Circle inch or centimeter) Transverse _______in/cm Vertical _______ in/cm X-ray field size: Transverse _______in/cm Vertical _______ in/cm X-ray field misalignment at image receptor slit: Transverse _______in/cm Vertical _______ in/cm (Misalignment cannot exceed 0.0 inches in the transverse axis and 0.5 inches in the vertical axis.) Cephalometric: Source to image distance (SID) __________ in/cm (Misalignment must not exceed 2% of the SID) Image receptor size: __________ in/cm X __________ in/cm Measured x-ray field size: __________ in/cm X __________ in/cm X-ray field misalignment: __________ in/cm X __________ in/cm ENTRANCE EXPOSURE (EE) ( )Pass ( ) Fail
Regulation – The in-air exposure limits for an average adult intraoral bite wing examination shall not exceed 450 mR for 60
kVp and above; 600 mR for less than 60 kVp. (See 25 TAC ?289.232(i)(6)(M) ) (See page 5 for instructions.)
Technique factors, for intraoral bite wing examination only, selected: kVp ________ mA(s) ________ time ________
Source to Skin Distance (SSD) _____ in/cm Source to Detector Distance (SDD) _____ in/cm
Tip of cone is positioned ? inch or less from surface of instrument housing or detector. Yes ( ) N o ( )
? Calculated Measurement OR ? Direct Measurement EE: mR Detector Meas. __________mR Rad Insp EPE Dent-1 (July 2006) Page 2 of 5
EXPOSURE REPRODUCIBILITY CALCULATIONS
1/22n??s1( - X)Xi
C = = ???
C = coefficient of variation
s = estimated standard deviation of the population
X = mean value of observations in sample
= ith observation in sampleXi
n = number of observations in sample
In this example, the exposures are considered to be reproducible.
The four (n) exposures () measured 409 mR, 387 mR, 391 mR, and 410 mR. Xi
STEP 1 Determine the mean value (X) of the four exposures taken.
(409 mR + 387 mR + 391 mR + 410 mR) ? 4 = 399.25 mR
STEP 2 Find the difference between each exposure and the mean value (disregard sign).
409.00 mR 387.00 mR 391.00 mR 410.00 mR
-399.25 mR -399.25 mR -399.25 mR -399.25 mR
9.75 mR 12.25 mR 8.25 mR 10.75 mR
STEP 3 Square each of the differences
229. = 95.0612. = 150.06 7525
2210. = 115.568. = 68.06 7523
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STEP 4 Divide each number by 3 (n-1) and add the results
95.06 - 3 = 31.88
150.06 - 3 = 50.02
68.06 - 3 = 22.69
115.56 - 3 = 38.85
STEP 5 For s, determine the square root of the above number
143.11 = 11.96
STEP 6 Divide s by the mean value () x
11.9629 - 399.25 = .0299 = c = the coefficient of variation
STEP 7 If c=0.05 or less, the exposures are considered to be reproducible
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ENTRANCE EXPOSURE (EE) CALCULATIONS
EXAMPLE – (DENTAL – BITE WING)
SENSOR/DECTECTOR ENCLOSED WITHIN A HOUSING
2SDD?? EE = mR (MEASURED) x ??SSD??
EE = entrance exposure
mR (MEASURED) = indicated exposure
SDD = source (target) to enclosed detector distance
SSD = source to surface (skin) distance
For this example only: SDD = 24 cm. SSD = 21 cm.
Detector = 2cm. below housing surface Measurement = 374 mR
(Verify that all units of measurements are the same – either inches or centimeters)
STEP 1 Set the control panel with the technique factors (kVp, mA, time) that the facility uses
for an average person intraoral bite wing examination.
STEP 2 Measure the SSD. To obtain an accurate EE, have the operator position the tube over the
detector housing as if they were positioning a patient. Measure from the target to the
housing surface. (21 cm.)
STEP 3 Measure the SDD. Place the tip of the cone 1.5 cm. or less from the housing surface.
Measure from the target to the surface of the housing and add the predetermined distance
of the detector below the surface.
22 cm.+2 cm. = 24 cm.
STEP 4 Divide the SDD by the answer in Step 2.
24 ? 21 = 1.143
STEP 5 Square the answer in Step 4.
1.143 x 1.143 = 1.307
STEP 6 Multiply the measurement reading in mR by the answer in Step 5.
374 x 1.307 = 489 mR
STEP 7 Compare the answer in Step 6 to the regulatory limits of 450 mR when 60 kVp or above
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