Diagnostic reference levels [DRLs] for routine X-ray examinations in Lorestan province, Iran

In diagnostic radiology there are two reasons for measuring or estimating radiation doses to patients. Firstly measurements provide a means for setting and checking standards of good practice as an aid to the optimization of patient protection. Secondly estimates of the absorbed dose to tissue and organs in the patients. A total of 2382 patients were studied to calculate the Entrance Surface Air Kerma [ESAK] following seven radiographic examinations including: chest [PA, Lat], lumbar spines [AP, Lat], pelvis [AP], abdomen [AP], skull [PA, Lat], thoracic spine [AP, Lat] and cervical spines [AP, Lat]. The ESAKs values were measured according to x- ray tube output, optimized exposure parameters and body thickness [tp] for each technique. The parameters such as, 1st quartile, mean, median, 3rd quartile, minimum, maximum and standard deviation of each ESAK values are reported and compared to NRPB guide levels. The results showed that the ESAKs values in the lumbar spines and chest X-ray examinations were 30% above the guide levels. However, for the pelvis [AP], skull [PA] and abdomen [AP] examinations, these values were below than those reported by the NRPB. Periodic quality control and monitoring the technical performance of radiographers might effectively improve the image quality and eventually reducing the dose received by patients

Lessons learnt from errors in radiotherapy centers

The purpose of this work is to discover and analyze errors and incidents in some radiotherapy centers, and to introduce methods that could reduce their occurrences, especially those which had happened due to the use of improper and inadequate equipment. This work is a first step toward clarifying the role of education in a risk-conscious culture, and changing the attitude of radiotherapy staff when they are working under encouraging conditions that remove barriers for reporting errors. For the present study clinical investigation, the data of 6000 patients were checked. They were treated at a few radiotherapy centers during one year. Patients were treated by linear accelerator or cobalt machine, photon or electron beams. A purposely designed check list was used for error data collection. Incidents were discovered by manual check at different steps of treatment. By highlighting frequency of occurrence, further investigation for preventing error repetition can be possible. Eighty five incidents were reported by Technologists, fifty four were reported by Physicists, and twenty six events were pointed out by Radiation Oncologists. About fifty percent of total 165 detected events were classified as treatment field errors. Geometrical misses in treatment field have the highest probability for both photon and electron beams. Incident prevention considering likelihood of individual event can be possible when using facilities like record-and-verification [R and V] system and electronic-portal-image-device [EPID], taking seriously QA, defining and implementing layers of defense in depth, and making an organized system for reporting and analyzing errors

Experimental and Monte Carlo studies on the response of CR-39 detectors to Am-Be neutron spectrum

The Poly-Allyl Diglycol Carbonate [PADC] detector is of particular interest for development of a fast neutron dosimeter. Fast neutrons interact with the constituents of the CR-39 detector and produce H, C and 0 recoils, as well as [n, a] reaction. These neutron- induced charged particles contribute towards the response of CR-39 detectors. Material and Electrochemical etching was used to enlarge track diameter which was made by low energy recoil protons. Before electrochemical etching, a chemical etching was performed for 1 hour. The responses were also calculated by Monte Carlo simulations, using MCNPX code in different energy bins considering H, C and O recoils. The total registered efficiency and partial contributions of the efficiency, due to interactions with each constituent of CR-39, were calculated. The optimized condition of etchant was obtained to be 6N KOH 15kV.cm[1], and 6 hours etching time. The obtained results show that track efficiency of CR-39 was a function of incident neutron energy. The tracks caused by O and C recoil nuclei were negligible for neutron energies lower than 1 MeV. At neutron energies lower than 1 MeV, only recoil protons would have sufficient energy to leave visible tracks. But, O and C recoils had important contributions in overall response of PADC at neutron energies of few MeV. The efficiency of a CR-39 based dosemeter could be calculated by MCNPX code and the results were in a good agreement with experimental results in energy range of [241]Am - Be bare source and [241]Am-Be was softened with a spherical polyethylene moderator of radius of 20 cm