Analysis of dose measurement other than the radiation protection during the radiographic examination
© Kim et al.; licensee Springer. 2014
Received: 4 April 2014
Accepted: 28 April 2014
Published: 17 May 2014
The study measured the dose on body regions that were not shielded to protect from radiation exposure during the general procedure, with the goal of providing basic radiation dose data for radiological technologists who perform the radiographic examination.
Materials and methods
Shooting parts with the phantom were similar to human tissues using general shooting equipment in the general examination room. The scattered rays were measured with the ion chamber. The hand received the highest average radiation dose and the kidney the lowest. The same pattern was evident for the average equivalent dose. The available daily shooting was highest in the anterior/posterior skull, followed by the posterior/anterior chest, abdomen, anterior/posterior spine and extremities.
The daily available numbers for the eye were lower than other body regions (6-times, 4-times, 26-times, 3-times and 121-times) and the numbers on the foot were higher than for other regions (73-times, 48-times, 263-times, 39-times and 702-times).
Radiation should be thoroughly blocked by the apron to protect the radiological technologist from the radiation exposure, the proper distance from the irradiation source should be maintained exposure is inevitable and the exposure dose and working environment shall be regularly assessed to ensure minimal exposure dose of the radiological technologist in accordance with the International Commission on Radiological Protection recommendation.
Radiation-based interventional procedures and diagnostic examinations have increased in use, which has increased the exposure dose of medical staff, radiation officials and patients (Hwang et al. 2011). In Korea, diagnostic X-ray examinations have become increasingly popular; natural and artificial radiation exposure accounts for 81% and 19% of the total exposure, respectively. Radiation exposure associated with diagnostic radiology accounts for about 17% of the total radiation exposure and 92% of the the artificial radiation exposure. A management system at the national level would be helpful in decreasing the exposure of patients and in the assessment of the radiological dose for the patients (Korea Institute of Nuclear Safety 2005).
The medically-based radiological dose limit for patients has been established internationally (ICRP Publication 60 1991). The radiological dose received by patients during X-ray examination depends on the body region being examined and the policy of the medical institution/country performing the examination. The individual radiological dose is based on the type of radiographic examination and the institution/country (Lee et al. 2009). International organizations including the International Atomic Energy Agency (IAEA) and the International Commission on Radiological Protection (ICRP) proposed a recommended dose and reference level for medical diagnostic exposure of staff and patients ((IAEA 1996); (ICRP 2002)). The ICRP 60 recommended individual exposure dose for radiological personnel is <50 mSv annually or 100 mSv every 5 years (Health and Welfare Enforcement Ordinance 2001). To achieve the 5-year exposure level, exposure should not exceed 5 mSv/quarter or 20 mSv/year. A radiological technologist performs the examination while wearing personal protection equipment. However, the existing equipment only covers the abdomen and genitals. General shooting mainly consists of the extremities, chest, skull, abdomen and spine. This study measured the dose on the body parts not protected from radiation exposure during the general shooting, with the goal of providing basic data concerning radiation exposure.
Also, the daily number of shooting available for each part was calculated based on the ICRP 60 recommendation(3) with the measured result.
The dose comparison for each part during the examination was analyzed and compared by the ANOVA test using SPSS 18.0 software (SPSS win 18.0, Chicago, USA) and a p-value < 0.05 indicated significance.
The average irradiation dose for a single shooting
0.82 ± 0.23
0.08 ± 0.02
0.42 ± 0.13
0.52 ± 0.18
0.31 ± 0.17
5.33 ± 1.28
0.06 ± 0.01
2.72 ± 0.52
2.41 ± 0.65
0.82 ± 0.21
16.52 ± 2.35
0.14 ± 0.06
13.34 ± 2.01
10.34 ± 1.65
2.91 ± 0.82
33.82 ± 6.52
0.48 ± 0.15
16.66 ± 2.56
17.58 ± 2.98
4.36 ± 1.25
40.32 ± 7.65
0.52 ± 0.09
21.05 ± 3.02
22.12 ± 3.23
5.46 ± 1.67
The average equivalent irradiation dose for a single shooting
7.19 ± 2.01
0.70 ± 0.17
3.68 ± 1.14
4.56 ± 1.57
2.71 ± 1.49
46.74 ± 11.22
0.52 ± 0.08
23.85 ± 4.56
21.13 ± 5.70
7.19 ± 1.84
144.88 ± 20.60
1.22 ± 0.82
116.99 ± 17.62
90.68 ± 14.47
25.52 ± 7.19
296.60 ± 87.18
4.20 ± 1.31
146.10 ± 22.45
154.17 ± 26.13
38.23 ± 10.96
353.60 ± 67.09
4.56 ± 0.78
184.60 ± 26.48
193.99 ± 28.32
47.88 ± 14.64
At the time of the establishment of the first safety management system for the diagnostic radiation exposure of field workers by the Ministry of Health and Welfare of Korea, the number of affected personnel was 12,652. However, by 2008, the number of workers had increased almost 4-times to 47,823. The increase reflected the upgrade of the medical welfare and the greater interest in healthcare, which prompted more diagnostic radiology examinations. This increase is expected to continue (Korea Food & Drug Administration 2008). Radiation exposure has increased along with the increase in the number of examinations. The historical ratio between natural radiation and artificial radiation (85:15) has markedly changed, and is now 1:1. The increased frequency of radiographic examinations has been documented ((Brenner & Hall 2007); (Tubiana et al. 2009); (International Agency for Research on Cancer 2000); (Archer and Wagner 2000)). While the exposure dose of patients has been amply researched, only a handful of studies have addressed the exposure dose for radiological technologists.
The current study measured the dose on regions of the body that are not typically shielded by radiation protection equipment for the radiological technologist during general shooting. The hand was measured highest (7.19 ± 2.01 uSv) for the extremity test, 46.74 ± 11.22 uSv for the chest AP, 144.88 ± 20.60 uSv for the skull AP, 296.60 ± 87.18 uSv for the abdomen supine and 353.60 ± 67.09 uSv for the spine AP. Even though the daily dose was low, the accumulation over several years may not be ignored.
In a 1982 report, the United Nations Scientific Committee on the Effects of Atomic Radiation judged that there was no dangerous cause of death, except cancer under low-dose radiation (United Nations Scientific Committee on the Effects of Atomic Radiation 1982). However, a subsequent series of animal tests indicated a more substantial role of radiation. This idea was bolstered by recent data from survivors of the atomic bomb explosions in Japan near the conclusion of World War II. However, a report published in 2010 stated that the cataract was related to the low-dose radiation exposure and that radiation exposure should be restricted to research for the cardiovascular diseases (United Nations Scientific Committee on the Effects of Atomic Radiation 2010). Also, the Biological Effects of Ionizing Radiation VII report summary showed that the fetus under the radiation more than 10 mGy in the uterus increased the childhood cancer and indicated the excess risk of 6% per Gy (Doll & Wakeford 1997). Sodickson et al. (Sodickson et al. 2009) reported that 33% of patients who received more than five CT examinations in 22 years and 15% of 31,462 patients were under the effective dose higher than 100 mSv. The expected rate of cancer occurrence was 0.7%. (Brenner et al. 2001) estimated that the lifetime cancer mortality risk was 0.18% for a single abdominal computed tomography (CT) for a 1-year old infant and the number of cancer-related deaths could reache 5 million cases from 600,000 abdominal and head CT for a year.
Studies reporting an increased cancer prevalence rate and the relationship of low-dose radiation exposure have focused on the increase in the radiation exposure for the medical use. The exposure dose for radiological technologists has rapidly increased. The effects of repeated low-dose exposure require study.
Radiation should be thoroughly blocked by the apron to protect the radiological technologist from radiation exposure. Furthermore, a technologist-patient distance judged to be safe should be maintained if exposure is inevitable. Finally, the exposure dose and working environment should be regularly assessed to help decrease the exposure dose of the radiological technologist in accordance with the ICRP recommendation.
Ki-Youl Kim and Jae-Hwan Cho are co-first authors.
“This work was supported in part by the Soonchunhyang University Research Fund”.
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