Radiation risk from chest, abdomen and pelvis computed tomography investigations

Estimation of cancer risks due to chest radiotherapy treatment planning computed tomography (CT) simulations

The objective of our study was to determine organ doses to estimate the lifetime attributable risk (LAR) of cancer incidence related to chest tomography simulations for Radiotherapy Treatment Planning (RTTP) using patient-specific information. Patient data were used to calculate organ doses and effective dose. The effective dose (E) was calculated by two methods. First, to calculate effective dose in a standard phantom, the collected dosimetric parameters were used with the ImPACT CT Patient Dosimetry Calculator and E was calculated by applying related correction factors. Second, using the scanner-derived Dose Length Product, LARs were computed using the US National Academy of Sciences (BEIR VII) model for age- and sex-specific risks at each exposure. DLP, CTDI_vol, and scan length were 507 ± 143 mGy.cm, 11 ± 4 mGy, and 47 ± 7 cm, respectively. The effective dose was 10 ± 3 mSv using ImPACT patient dosimetry calculator software and 9 ± 2 mSv using the scanner-derived Dose Length Product. The LAR of cancer incidence for all cancers, all solid cancers and leukemia were 65 ± 29, 62 ± 27, 7 ± 2 cases per 100,000 individuals, respectively. Radiation exposure from the usage of CT for radiotherapy treatment planning (RTTP) causes non-negligible increases in lifetime attributable risk. The results of this study can be used as a guide by physicians to implement strategies based on the As Low As Reasonably Achievable (ALARA) principle that lead to a reduction dose without sacrificing diagnostic information.

Effective dose and radiation risk under 640-slice abdominal computed tomography examination without contrast medium injection

BACKGROUND

Medical imaging plays a crucial role in modern medicine. In order to provide fast and accurate medical diagnosis, computed tomography (CT) is a commonly used tool in radiological examinations, and 640-slice CT is the most advanced CT imaging modality.

OBJECTIVE

To evaluate the radiation dose and the risk under 640-slice abdominal CT examination.

METHODS

Examinations were performed using a 640-slice CT scanner on an Alderson-Rando anthropomorphic phantom. The used scanning acquisition parameters were the same as those used on abdominal examination without contrast medium injection in clinical practice. To measure the absorbed doses, optically stimulated luminescence dosimeters (OSLDs) were put into liver, stomach, bladder, gonads, colon, small intestine, bone marrow, and skin.

RESULTS

According to the 1990 Recommendations of the International Commission on Radiological Protection (ICRP Publication 60), the calculated effective doses received from this examination were 0.90 mSv in males and 0.89 mSv in females. According to the 2007 Recommendations of the International Commission on Radiological Protection (ICRP Publication 103), the calculated effective dose received from this examination was 0.83 mSv in both sexes.

CONCLUSIONS

Radiation doses obtained from the abdominal 640-slice CT examination are lower than the yearly cumulative doses received from natural radiation, revealing there is no deterministic effect and radiation risk is relatively low; therefore, this CT examination is considered safe.

Senior interventional cardiologists are exposed to higher effective doses than other staff members

Those working in interventional cardiology are exposed to varying radiation doses during diagnostic and interventional procedures. The work presented in this paper aimed to monitor the effective doses received by different categories of medical staff members practicing interventional cardiology procedures including senior cardiologists, junior cardiologists, anesthetists and nurses. Thermo-luminescence dosimeter (TLD) badges that consisted of lithium fluoride doped with magnesium and titanium were used to quantify radiation doses. Measurements were performed with the dosimeters mounted under and above leaded aprons worn by medical staff. The results revealed that the effective doses to senior cardiologists were the highest compared to those to other participating staff members, due to their position close to the X-ray tube. The average daily effective doses for senior cardiologists, junior cardiologists, anesthetists and nurses were higher for dosimeters located above the aprons than those for dosimeters located under the aprons. Above the apron, the average effective doses accumulated during the study period were 0.44 ± 0.06, 0.34 ± 0.05, 0.29 ± 0.03 and 0.29 ± 0.04 mSv, respectively; whereas, under the apron, they were 0.20 ± 0.02, 0.18 ± 0.02, 0.17 ± 0.02 and 0.18 ± 0.02, respectively. Also, the fluoroscopy time was correlated with the dose acquired, especially for senior cardiologists. It is concluded that doses to senior cardiologists are quite high, and that many variables can affect staff exposure such as distance, direction, procedure and skills.