Physics of Radiology

Primary, physico-chemical radiation reactions are discussed, with emphasis on the formation of free radicals and their subsequent attack of biological macromolecules. The nature of the biologic target is considered. (BBB)

Interaction of radiation with matter

Quality control in diagnostic radiology.

Quality Management in the Imaging Sciences

Quality Control in Diagnostic Imaging

The present study examined the mechanical attributes of 135 conventional diagnostic X-ray machines in Mizoram, India. The purpose of studying the X-ray mechanical parameters, such as congruency, perpendicularity of the central beam, and half-value layer, was to improve the quality of the diagnostic image and reduce the patient dose. A battery-operated portable dosimeter was used to measure output radiation of the X-ray machine. The half-value layer was measured at a constant accelerating potential of 70 kVp and tube load. To measure the congruency and beam alignment perpendicularity, a congruence and alignment tool was used. The survey data were collected between June 2015 and June 2016. The authors followed international standard test procedures, and the results were compared to national and international standards. SPSS Statistics for Windows, Version 17 was used to calculate the mean, range, and standard deviation. The half-value layer ranged from 0.45 to 3.00 mm; the mean half-value layer was 1.60 ± 0.51 SD mm. In comparison with national and international standards, only 27.83% (national) and 15.64% (international) of the machines’ filtration were found to be within acceptable limits. The congruence misalignment of the x-axis varied between 0.50% and 15.30% of the source-to-image distance; for the y-axis, it ranged from 0.50 to 10.90%. When the congruence between the radiation beam and optical field was tested, 80.85% of diagnostic X-ray machines did not meet the prescribed acceptance parameters. When the perpendicularity between the central beam and the image receptor was tested, 69.81% did not meet safety standards.

Qualitative study of mechanical parameters of conventional diagnostic X-ray machines in Mizoram

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.

http://ijmp.mums.ac.ir/article_13968_7d793922f729e39991c05d63157c86f4.pdf

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

The purpose of this research was to measure the radiation level and estimate the dosage at the control panel (CP) and outside the patient entrance door (PED) of diagnostic X-ray installations. This is important for ensuring the safety of workers and the public, particularly in the study area, where there is no proper radiation monitoring service. A water phantom, 10-L fresh water in a plastic container, was used as the source of scattered radiation. Using an ion-chamber survey meter, the stray radiation rate was measured at the CP and outside the PED for both chest and couch missions. The CPs were fully covered by a protective barrier, providing a negligible exposure rate (i.e., 0.07–4.2 mR/h for chest and 0.21–3.8 mR/h for couch). By contrast, installations that did not properly cover the CP showed relatively high exposures (from 18 to 205 mR/h for chest and 2.4–270 mR/h for couch). The radiation rates outside the PED in installations having lead-lined doors were negligibly low; whereas, in installations having no lead-lining, exposure rates reached as high as 95 and 110 mR/h for chest and couch missions, respectively. The occupational doses were well below the Atomic Energy Regulatory Board dose limit (i.e., 40 mR/week). However, excessive doses were observed in public spaces outside the PED, compared with the dose limit for the public (i.e., 2 mR/week).

Evaluation of radiation doses at diagnostic X-ray control panels and outside patient entrance doors in Aizawl district, India

The main objective of the present study is to find out the intensity of radiation attenuated by different types of patient entrance doors (PED) as well as control panel (CP) protective barriers in diagnostic X-ray installations. To measure the intensity of ionizing radiation, ion chamber survey meter was used; all measurements were performed in freeze mode. In setting maximum accelerating potential, minimum tube current and fixed exposure time, a water phantom was exposed through maximum field size. Radiation exposure rates were measured at CPs as well as PEDs with and without barriers. In chest mission, radiation rates with PED ranged from 0.3 µSv/h to 0.7 mSv/h and without PED 0.2 mSv/h to 1.2 mSv/h. At the same time, in couch mission, radiation rates measured behind PED ranged from 0.3 µSv/h to 2.2 mSv/h and 0.03 mSv/h to 2.25 mSv/h in front of PED. All institutions showed higher exposure rates without PED; all types of doors considerably attenuated radiation. Among different types of door, lead-lined door attenuated 99.53% in chest mission and 97.44% in couch mission. While plywood doors attenuated approximately 40% of the incident radiation, it is more or less similar as air does in every half meter away from the phantom. Radiation rates in chest missions with CP barriers ranged from 2 µSv/h to 0.38 mSv/h, while 0.4 mSv/h to 2.35 mSv/h without CP barriers. In couch missions, radiation rates measured with CP barriers varied from 4 µSv/h to 0.6 mSv/h whereas without CP barriers from 0.7 mSv/h to 5 mSv/h. There was a significant difference between radiation measured behind and in front of the CP barriers. Among them, the percentage of attenuation was high in lead and concrete barriers.

Jonathan Lalrinmawia

Papers

Qualitative study of mechanical parameters of conventional diagnostic X-ray machines in Mizoram

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

Evaluation of radiation doses at diagnostic X-ray control panels and outside patient entrance doors in Aizawl district, India

Study on the intensity of radiation attenuated by protective barriers in diagnostic X-ray installations