kVp Meter Research Articles

An Enumeration Survey on Diagnostic X-Ray Generators and Essential Safety Parameters in Mizoram, India

Introduction: Best radiography practice involves operational optimal machine performance, delivering cost-effective healthcare services under appropriate safety conditions for workers and the public. The present study aimed to investigate the safety status of diagnostic X-ray installations in Mizoram, India. Material and Methods: Linearity of time (sec), linearity of current (mA), output reproducibility, table dose (μGy/mAs), peak voltage (kVp) accuracy, and 16 essential safety parameters of 135 X-ray machines were considered in this study. A battery-operated dosimeter and wide-range digital kVp meter were used to measure output radiation and effective peak potential of X-ray tube. Data analysis was performed using SPSS software to obtain the mean, standard deviation, and coefficient of variation. Results: Among different electronic parameters, 59.2% linearity of time, 82.6% linearity of current, 89.7% kVp accuracy, 35.1% output reproducibility, and 92.8% table dose were beyond the acceptable limits. Based on 16 essential safety parameters, it was observed that 98.7% of X-ray machines did not receive proper quality assurance test, 1.9% of the installations employed lead-line patient entrance doors, 46.8% of the machines were operated without any protective barriers and 83.1% of the units were operated without personnel monitoring service. Conclusion: The present study had concluded with more problems than the previous studies in different parts of the world in this regard. Due to the absence of proper quality control (QC) programs, many installations did not follow standard installation guidelines. The authors recommended that proper QC should be implemented by the frequent monitoring of each and every diagnostic X-ray installation.

Validation of kVp measurement using the HVL approach for standard beam qualities for mammography

In mammography imaging, the most common target material used in mammography machines are Molybdenum (Mo) target with Mo filters. In the publication of International Electrotechnical Commission (IEC) 61267, the establishment of mammography beam qualities assembly are given in 3 fixed parameters namely the target material which is Mo, the Mo filter thickness and the tube voltage. While, Mo target with rhodium (Rh) filters combination standard beam qualities were established by the Physikalish-Technische Bundesanstalt (PTB) primary standard Laboratory. The objective of this study is to measure the kVp and HVL ranging from 23-31 kV. Later compare the displayed kilovoltage peak (kVp) on the control panel with the kVp measured using a non-invasive kVp meter and validating them with the HVL measurement. From the results, the kVp dialed and kVp measured shows significant difference by 2-4 kV. The HVL measured for the kVp before and after corrected also shows similar pattern, where the HVL after kVp is correct is almost identical to the standard beam qualities with the difference of 1%. This verifies that the kVp measurement using a non-invasive kVp meter can be validated with just a simple measurement of its HVL for mammography standard beam qualities.

Assessment of peak kilovoltage accuracy in ten selected X-ray centers in Lagos metropolis, South-Western Nigeria: A quality control test to determine energy output accuracy of an X-ray generator

Background: Most X-ray centers recruited for this study admitted that there have been no maintenance checks on the energy output accuracy of their X-ray machines. Most centers complained of recurrent machine breakdown due to poor power supply, while others pointed out that X-ray machine age could be a contributory factor to poor image quality. Aim and Objectives: To determine peak kilovoltage (kVp) accuracy of individual X-ray unit and to compare their values with recommended standards and to further establish if machine age has a significant effect on mean kVp accuracy. Materials and Methods: One dedicated conventional X-ray unit in each of the ten diagnostic centers was used for this study denoted as D 1−D 10 . kVp was measured using a noninvasive Unfors ThinX RAD kVp meter. The kVp accuracy test was carried out by positioning the Unfors ThinX RAD kVp meter at the center of the beam axis of the patient's couch at a focus to image distance of 100 cm. The X-ray machine technical factors were varied by selecting tube potential within the range of 50−120 kVp at a fixed tube current of 20 mA. Data analysis value was done using GraphPad Prism version 5.0 statistics software (GraphPad Software, Inc., San Diego, California, USA). Results: The kVp accuracy test for X-ray units D 1 , D 2 , D 5 , D 6 , D 7 , and D 8 were within an acceptable limit of ±5% at all selected tube potential from 50 to 120 kVp, X-ray units D 2 and D 6 showed accurate compliance at much lower kVp accuracy values. X-ray units D 3 and D 10 were above ±5% accuracy limit at all selected kVp tube potential. No statistically significant differences exist between machine age and mean kVp accuracy (P = 0.770). Conclusion: One-fourth of the total kVp accuracy results were above ±5% limit. Old X-ray machine had higher chances of failed kVp accuracy. Traces of failed test were also noticed in X-ray machines below 5 years.

Determination of reference dose levels among selected X-ray centers in Lagos State, South-West Nigeria

Background: With increasing use of diagnostic X-ray machines across Lagos, South-West Nigeria, relevant international bodies have proposed the use of reference dose levels (RDLs) to help manage radiation dose to patients without compromising image quality. Objectives: The purpose of this study was to determine the entrance surface dose (ESD) at third quartile (75 th percentile) in Lagos metropolis for normal adult radiographic examinations and to compare them with national and international established reference dose guidelines. Materials and Methods: One dedicated X-ray unit in each diagnostic center was used for this study denoted as H1-H10. A noninvasive Unfors ThinX RAD kilovoltage (kVp) meter which served as the phantom (mimicked patient) was used for measurements. The ESDs were determined by placing the Unfors ThinX RAD kVp meter on the patient's table bucky at a source to image distance (SID) of 100 cm and at the erect bucky at a SID of 180 cm. The peak tube kVp was varied at different milliampere seconds (mAs). Results : The mean ESD for adult postero-anterior (PA) chest, antero-posterior (AP) Abdomen and (AP) lumbar spine X-ray examination were 0.603, 2.57, and 2.57 mGy, respectively. While the ESD for the third quartile for adult (PA) chest, (AP) abdomen, and (AP) lumbar spine X-ray examination among the ten X-ray centers were 0.93, 2.74, and 2.47 mGy, respectively. Conclusion: Third quartile ESD which translate to RDL for adult (PA) chest examination for this study was higher compared to other national and international RDLs but adult (AP) abdomen and lumbar spine examinations were within accepted national and international range.

P.13 - Calibration of non-invasive KVp meter traceable to voltage measurement standard

P.13 - Calibration of non-invasive KVp meter traceable to voltage measurement standard

Determination of the tube voltage from clinic mammo-graphic system using two types of detectors

The use of X rays for diagnostic radiology is very common and important to Medicine, including mammographic diagnosis focusing decreasing of the doses applied to the patients and preserving high quality of the diagnostic image. A quality control program of the irradiation systems it is necessary to control periodically the performance of the X-ray systems applied in that diagnosis in order to obtain the best results in that diagnosis. The verification of the beam characteristics is made by using standard dosimetric procedures which include the determination of the kilovoltage and the kerma rates for the different radiation qualities applied in the diagnosis. The Instruments Calibration Laboratory (LCI) of IPEN perform calibration in dosemeters used in radiation dosimetry (in diagnostic radiology) for many years and are improving their methodology to attend the actual demand of that equipments used in quality control of that X-radiation systems. The objective of that paper were the measurements of kVp and air kerma produced for one mammographic system of LCI, Model VMI – Graphmammo AF (Philips) using two different measurements systems from PTW (Diavolt) and Radcal (kVp meter) that procedure is just to determine the stability of that system that is used to perform diagnosis in mammography level. The results obtained with the two systems utilized shows good agreement. That measurement can be applied at a routine quality control program of that X-ray system.

Commissioning and quality assurances of the Intrabeam Intra-Operative radiotherapy unit

Purpose: The authors report comprehensive commissioning and quality assurance (QA) procedures for Intrabeam, Intra-Operative radiotherapy (IORT) unit. The Intrabeam system miniature X-ray source is a 50 kV and 40 µA unit. Methods: The authors’ tests include measurements of output, beam deflection, isotropy, kVp and mAs measurements, quality index, isodose, reproducibility, linearity, depth dose verification, and 3D dose distribution. IC ionization chamber and the UNIDOSE dosimeter were used for the output commissioning. Probe adjuster/ionization chamber holder (PAICH) was used to check the mechanical straightness of the probe. For radiation tests, NACP parallel plate chamber, Standard Imaging electrometer, 30 × 30 × 30 cm 3 IAEA water phantom, solid water slabs, EDR-2 Films with RIT software, and ionization based survey meters were used. Unfors Xi platinum edition kVp meter was used to measure the kVp and mAs. Results: In mechanical QA test, X-Beam position (-0.09 mm), Y-Beam position (0.01 mm), and radial position (0.11 mm) errors were within the tolerance level. Isotropy test with PDA, survey meter, ion chamber, and film measurements also produced results within the specifications. Output measurements with PAICH and external chamber measurements were matched. Beam quality, linearity, and reproducibility values were ascertained at 50KV and 40 µA and found to be within limits. Isodose, 3D dose distribution, transverse, and horizontal profiles showed the good isotropy of the source. Conclusion: The authors’ methodology provides comprehensive commissioning and calibration procedures for the Intrabeam system.

Dosimetry and kVp standardization for quality assurance of mammography

Breast cancer mortality rates were significantly reduced in Taiwan after achieving early-stage monitoring with mammography screening. This study establishes an appropriate and traceable calibration infrastructure, which offers calibration services for mammography X-ray quality assurance instrumentation, which is performed clinically on a regular basis. The entrance air kerma, HVL, and kVp of mammography equipment with five different target/filter combinations can be taken as adequate indicators for the level of average glandular dose (AGD). The primary dose standard in mammography uses a free-air ionization chamber to estimate the rate of air kerma. Several correction factors were determined by Monte Carlo simulations and experiments. A secondary kVp standard in mammography is in accordance with the IEC 61676 recommendations. The calibration system of kVp meter uses a high-voltage divider, which is traceable to ITRI primary standard in Taiwan. Dose and kVp verifications were conducted by mammography instruments, which were previously calibrated by NIST and PTB. The evaluation results indicate that the capabilities of this irradiation system met the ISO 4037-1 requirements. The expanded uncertainties (k=2) were 1.03% and 1.6% when the mammography X-ray air kerma rate and kVp meter calibration factors were evaluated using ISO GUM. Experimental verification and a comparison with NIST using transfer ionization chambers yielded differences in calibration factors. Comparison with the PTB using kVp meter indicated a less than 1% difference. The results showed that dose and kVp standards were in reasonable agreement with standard uncertainty. The low uncertainties associated with the obtained results in this work show that the standardization employed can be accurately used for calibration of instrument in mammography in Taiwan.

Alara approach: Imaging optimization in radiotherapy

Background The medical physics unit of CORT37 want to implement an ALARA approach in order to optimize the dose for the imaging used in radiotherapy. Objectives Optimize the use of imaging devices with the best compromise between dose and quality image. Materials and methods The CT‘s CTDI has been measured with a pencil-type ionization chamber of 100 mm and a PMMA phantom of 16 and 32 cm. The average CTDI was compared with the values of DRL. The dose has been measured in parallel with the image quality which was evaluated by SNR, noise, spatial resolution and contrast resolution. The phantom used is Catphan 504. The image analysis was done by using Image J and Artiscan software. The dose for a Clinac OBI has been measured using a kVp meter with a DSD equal to 80 cm, and a 19 cm tissue-equivalent thikcness and an aperture of 10 × 10 cm 2 field size. In parallel, image quality has beeb quantified by the TOR18FG phantom. Different clinical protocol acquisitions were compared with each other and DRL. The emitted dose during CBCT acquisition was measured with an aperture of 12 mm, with the same ionization chamber and phantom used for the CT measurments. The image quality was evaluated with the same way as for the CT. A double-blind medical validation of the images (obtained from the patients) washeld before implemeting in clinical routine the optimized protocols. Results and discussions All CT's CTDI values are below the DRL. When comparing the previous CTDI values with the ones after optimization, we obtain dose reduction factors that vary between 1.4 and 3.1. Reduction factors for OBI vary from 0.75 to 45.85, depending on the mode used (radiography or fluoroscopy). The CBCT dosimetric gain has not been quantified, but the parameters have been optimized. All these protocols are now applied in clinical routine. Conclusion Imaging protocols are now optimized.

Calibration of KVp meter used in quality control tests of diagnostic X-ray units

In diagnostic radiology, the tube voltage [peak kilovoltage (kV(p))] is one of the most important parameter affecting both radiation exposure and image contrast. So, an accurate kV(p) meter is necessary to control kV(p) in the medical radiography practice with the overall uncertainty less than ± 5 % according to IEC 61676. Therefore, both invasive and non-invasive calibration methods of kV(p) meter were established and applied to different kinds of commercial quality control instruments for diagnostic radiology. Calibration of kV(p) meter by the invasive method is the most accurate (with uncertainty of 1.67 %, k=2); however, the non-invasive method also provides good results (with uncertainty of 3.12 %, k=2). Due to their detailed design, the commercial kV(p) meters have various responses with X-ray beam, so the working regime of a particular device type must be appropriately selected with a specific X-ray machine used for calibration of kV(p) meter.

검출기 측정방법에 따른 PAE값의 변화

본 연구는 검출기 측정방법에 따라 관전압 정확도 검사결과인 PAE값이 어떻게 달라지는지 알아보고자 한다. 실험방법으로는 측정거리와 X선관 각도, 방향에 따른 PAE값의 변화실험에서는 초점과 측정기간의 거리를 100cm, 80cm, 60cm에 위치시킨 상태에서 관전압지시치는 70kVp, X선관 각도는 음극, 양극측으로 <TEX>$5^{\circ},\;10^{\circ},\;15^{\circ},\;20^{\circ},\;25^{\circ},\;30^{\circ}$</TEX>로 맞추어 측정하고, 관전압지시치에 따른 PAE값의 변화실험에서는 관전압 60kVp, 70kVp, 80kVp, 90kVP, 100kVp를 설정하고 소초점과 대초점을 전환하며 측정하였다. 측정거리와 X선관 각도, 방향에 대한 PAE값의 결과를 보면 100cm일 경우에는 음극측에서 전체적으로 PAE값이 높게 나타났으며 80cm, 60cm일 경우에는 양극측에서 높게 나타났다. PAE값의 변동율은 100cm일 경우 음, 양극측 모두 안정적으로 나타났으며 80cm, 60cm일 경우에는 불균형적으로 나타났다. 관전압지시치에 따른 PAE값의 결과로는 대초점보다는 소초점이 높게 나타났으며, 지시치가 클수록 높게 나타났다. 오차 범위는 지시치가 클수록 적게 나타났다. The aim of this study is to investigate PAE, as the result of the test of kVp accuracy, according to detector measurement method. Based on the indicated value of 70kVp, each distance between a focus and a kVp meter was 100cm, 80cm and 60cm and the angle of X-ray tube was set on <TEX>$5^{\circ},\;10^{\circ},\;15^{\circ},\;20^{\circ},\;25^{\circ},\;30^{\circ}$</TEX>. Each indicated value, 60kVp, 70kVp, 80kVp, 90kVp and 100 kVp, was used compare Small focus with Large focus. As a result, PAE on the side of cathode was higher than it on the side of anode in the case of 100cm and PAE on the side of anode was higher in the case of 80cm and 60cm. The coefficient rate was stable both the side of cathode and anode in the case of 100cm and it was fluctuated in the case of 80cm and 60cm. PAE in the case of Small focus was higher than Large focus and it was disproportionate to an indicated value. Error rate was in inverse proportion to the indicated value.

SU-GG-I-82: Performance Assessment of X-Ray QA Instruments Used in Mammography

Purpose: To establish the calibration standard of dose and kVp meter for performance assessment of mammography X‐ray QA instrumentation and to evaluate the uncertainty and the impact of X‐ray spectrum variation in different beam qualities. Method and Materials: The accuracy of instruments calibration forms the first step to determine the quality control trains in national survey. The primary standard for dose and kVp meter for X‐ray beams was obtained from a free air ionization chamber and high voltage divider. The uncertainty analysis followed the method recommended by the ISO Guide. The beams qualities were at 23–35kVp produced by Mo target X‐ray sets with 30 μm Mo filtration and Rh target X‐ray with 29 μm Rh filtration. Dose verification was conducted by mammographyionization chambers which were previously calibrated by the NIST. Three different techniques were compared: spectrum end‐point direct measurements, calibrated non‐invasive kVp devices and the calibrated voltage divider technique. Results: Acceptable agreement (difference within 1%) was obtained in the mammography X‐ray range. Agreement among these methods was good with a difference less than 1% for all beam qualities. The uncertainty estimates results of the dose and voltage values calculated respectively from the measured spectra and voltage divider technique are less than 3% for voltage range of 23–35 kV. Conclusions: This technique is capable of providing quality services required by quality assurance standards in mammography, namely, the indicated values should be within 5% of the delivered values. The low uncertainties associated with the obtained results in this work pointed out that the method employed can be accurately used for calibration of instrument in mammography. The performance characteristics of dosimeters and non‐invasive kVp meters were determined for annual calibration in an attempt to ascertain the likely performance of instruments in routine use.

SU-GG-T-34: Xoft Axxent Electronic Brachytherapy System: A Clinical Implimentation Experience

Purpose: To clinically implement Xoft's Axxent electronic brachytherapy (EBT) system for partial breast irradiation and develop quality assurance standards. Method and Materials: A Xoft Axxent controller unit was tested with a single EBT source tube. The source kVp was measured using diagnostic radiology equipment: Rad Cal 90‐10 kVp Meter and Barracuda MPD. The dose contribution from tube warm‐up and the linearity of delivered dose were measured with Standard Imaging'sHDR 1000 Plus well chamber and MAX 4000electrometer. The controller's timer reproducibility and accuracy were tested. An anthropomorphic breast phantom of in‐house design simulated a clinical environment during radiation exposure surveys. Exposure measurements were collected using a Rad Cal 90‐10 pancake and Victoreen 450 Bionization chambers for various positions and shielding conditions. System interlocks and mechanical accuracy were also tested. Results: Our tests demonstrated a standard deviation of 1.32% in linearity and 1.59% in constancy of measured Air Kerma Strength. The average difference between measured and expected kVp was 2.18%. The average dose resulting from source warm‐up was found to be equivalent to 2.65 seconds of treatment time. Exposure levels ranged from 23 R/h (at the unshielded phantom's surface) to less than 0.3 mR/h (at 1 meter from the source with 1.5 mm Pb shielding). The timer was found to be both accurate and reproducible. Additional testing of interlocks successfully reproduced results observed during acceptance testing.Conclusion: Our commissioning method accurately characterizes the typical performance of a Xoft Axxent EBT system. A policy of using mobile shielding equivalent to 1.5 mm Pb was established for our clinical procedures. While the radiation source is patient specific, the performance of the controller for a given source should be characterized as a necessary part of annual quality assurance.

Study of Radiation Dose and Device Quality for Diagnostic X-ray Units

Digital kVp meter, ion chamber, and x-ray films were used to study the tube voltage, beam output, and dose distribution for 29 x-ray units. Of which 14 units are equipped with single phase power supply and 15 with inverter frequency power supply. The experimental results show that the dose is dependent on tube voltage, tube current, field size except beyond 20×20cm2, exposure distance, and heel effect. The relationship between dose and tube voltage and exposure distance as well is non-linear, while that between dose and tube current is linear. The non-uniform and non-symmetric dose distribution depends on the heel effect of the x-ray beam. The measured voltage deviating from the default value may reach -2.4% to -9.1% depending on the power supply system used. The dose delivered from the units with inverter frequency power supply is 1.64 times higher than that with single phase power supply.

X‐ray spectroscopy in mammography with a silicon PIN photodiode with application to the measurement of tube voltage

In this work a silicon PIN photodiode was employed in mammographic x-ray spectroscopy under clinical and nonclinical conditions. Measurements have been performed at a constant potential tungsten anode tube, adapted in this work with molybdenum filters to produce a beam like that used in mammography, and at a clinical equipment with a molybdenum anode tube by using an additional aluminum filtration. The corrected x-ray spectra were in full agreement with those generated by theoretical models published in the literature and agree well with those measured with a CdZnTe detector for tube voltages less than 30 kV. The half value layer and the relative exposure values calculated from the corrected silicon PIN photodiode spectra were in agreement with those measured with an ionization chamber. These results indicate that a silicon PIN photodiode are very suitable for mammographic x-ray spectroscopy. As an application, the voltage (kV) applied to mammographic x-ray equipment has been measured through the evaluation of the spectra high energy cut off. Uncertainties evaluated for the voltage values calculated from the measured spectra are less than 0.13% for voltages in the range 20-35 kV. The low uncertainties associated with the obtained results in this work point out that the method employed can be accurately used for calibration of noninvasive mammographic kVp meters.

Determination of the voltage applied to x-ray tubes from the bremsstrahlung spectrum obtained with a silicon PIN photodiode.

This work describes a methodology for the obtainment of the electron accelerating potential (kVp) applied to an x-ray tube, through the determination of the end point of the energy spectrum of the radiation emitted by the tube. The measurements have been performed utilizing alternatively two silicon PIN photodiodes, directly irradiated by the x-ray beam. Both were operated at room temperature, with low bias, so avoiding the drawbacks presented by photomultiplier tubes and germanium detectors. The energy calibration of the system was performed with X- and gamma-emitter radioactive sources, which makes the method absolute. Each kVp value was determined by means of a linear regression in the end of the spectrum, to give, simultaneously, a good fit of the straight line to the experimental data and a low standard deviation for the kVp value. Results of the measurements carried out with an x-ray tube connected to a three-phase generator, using additional filtration between 1.5 and 4.0 mm of Cu, are presented. This filtration was used in order to minimize the contribution of low energy photons and to reduce pulse pile-up. Errors determined for the values of kVp are between 0.06 and 0.16 kV, in the potential range from 50 to 100 kV. As an example, the methodology has been applied in the verification of the secondary calibration of a voltage divider, utilized, by its turn, in the tertiary calibration of noninvasive kVp meters. All intrinsic sources of errors involved in the process are discussed and evaluated.

Performance assessment of patient dosimetry services and X-ray quality assurance instruments used in diagnostic radiology

Experiences of the Regional Radiation Physics and Protection Service (RRPPS) in performance assessment of diagnostic X-ray QA instrumentation and on-patient dosemeters are recounted. Issues relating to the provision of realistic and reproducible reference conditions for calibrated X-irradiations are considered and summary statistics from test measurements of dose and kVp meters are provided. For both dose and kVp meters it is indicated that as many as 25% of instruments used in routine use in the U.K. may require some adjustment before they can truly be said to be performing as the manufacturer intended. Results from intercomparison exercises for patient dosimetry services are also discussed. It is apparent that, for those centres participating in the exercise, dose assessments are generally being obtained to within a bias and a relative standard deviation of less then 10%.

Short communication: kilovoltage measurement with rhodium target and filters on mammography X-ray machines.

X-ray machines used for mammography have, until recently, almost exclusively employed molybdenum (Mo) as anode material and filtration. In the UK, the RMI model 232 kVp meter is used extensively for the measurement of kilovoltage on such equipment. This unit is provided with switchable internal calibration only for molybdenum and molybdenum, or tungsten and aluminium, as anode and filtration, respectively. However, rhodium (Rh) has recently been introduced for filtration with either a molybdenum or rhodium anode in mammography equipment but, as yet, calibration facilities are not available for rhodium spectra. In this work, appropriate corrections for readings obtained with the RMI 232 kVp meter are derived for use with rhodium as filtration material with either molybdenum or rhodium anode material. An intercomparison between measurements made with four RMI model 232 kVp meters and nine IGE DMR X-ray sets was undertaken. The reproducibility of the instruments was confirmed and measurements of tube potential made on each of the X-ray sets pooled. Measurements were made from a nominal 25-35 kVp using Mo/Mo, Mo/Rh and Rh/Rh target/filter combinations. Corrections for readings obtained with Mo/Rh and Rh/Rh were produced by comparison with readings obtained with Mo/Mo, assuming stability of tube potential between anodes. The results are compared with data recently produced by the manufacturer of the meter.

In-Field Testing of a New Instrument for Quality Control in Mammography

Routine quality control procedures for mammography need a periodical testing of the X ray units. The checks of kVp accuracy, mA linearity, exposure reproducibility and HVL consistency require several instruments (non-invasive kVp meter, dosemeter, absorbers, etc.) and a lot of time. The use of a new instrument for a quick and easy measurement of kVp ripple, HVL, exposure time and incident air kerma is presented. The instrument, composed of an X ray probe and a portable computer, allows the evaluation of the above parameters in a single shot. Two mammographic units have been routinely tested measuring kVp, HVL, exposure time and incident air kerma. The evaluation has been performed exposing the probe during the execution of a performance phantom radiograph. The relationships between the fluctuations of the measured parameters are compared with the limiting values proposed by CEC guidelines. Correlation analysis of the whole data set allows malfunctioning identification. The instrument works properly and is very useful in quality control activity.

In-Field Testing of a New Instrument for Quality Control in Mammography

Routine quality control procedures for mammography need a periodical testing of the X ray units. The checks of kVp accuracy, mA linearity, exposure reproducibility and HVL consistency require several instruments (non-invasive kVp meter, dosemeter, absorbers, etc.) and a lot of time. The use of a new instrument for a quick and easy measurement of kVp ripple, HVL, exposure time and incident air kerma is presented. The instrument, composed of an X ray probe and a portable computer, allows the evaluation of the above parameters in a single shot. Two mammographic units have been routinely tested measuring kVp, HVL, exposure time and incident air kerma. The evaluation has been performed exposing the probe during the execution of a performance phantom radiograph. The relationships between the fluctuations of the measured parameters are compared with the limiting values proposed by CEC guidelines. Correlation analysis of the whole data set allows malfunctioning identification. The instrument works properly and is very useful in quality control activity.