Effective doses in four-dimensional computed tomography for lung radiotherapy planning.

The recent broad adoption of 4-D computed tomography (4DCT) scanning in radiotherapy has allowed the accurate determination of the target volume of tumors by minimizing image degradation caused by respiratory motion. Although the radiation exposure of the treatment beam is significantly greater than that of CT scans used for treatment planning, it is important to recognize and optimize the radiation exposure in 4DCT from the radiological protection point of view. Here, radiation exposure in 4DCT was measured with a 16 multidetector CT. Organ doses were measured using thermoluminescence radiation dosimeter chips inserted at respective anatomical sites of an anthropomorphic phantom. Results were compared with those with the helical CT scan mode. The effective dose measured for 4DCT was 24.7 mSv, approximately four times higher than that for helical CT. However, the increase in treatment accuracy afforded by 4DCT means its use in radiotherapy is inevitable. The patient exposure in the 4DCT could be of value by clarifying the advantage of the treatment planning using 4DCT.

Dietary iodine and bromine intakes in Ukrainian subjects.

Dietary iodine and bromine intakes in Ukrainian subjects were estimated in relation to the health effects on inhabitants after the Chernobyl accident. Two hundred and eighty-six total diets were collected from twenty-five regions for Ukrainians by a duplicate portion study. Iodine and bromine were rapidly determined by inductively coupled plasma mass spectrometry after chemical separation. The range, median, and geometric mean of iodine intakes were 2.86-698, 44.7, and 48.1 microg per person per day, respectively. Those of bromine were 0.627-16.9, 2.97, and 2.92 mg per person per day, respectively. Daily intakes of both elements in Ukrainians were lower than previously reported values. The iodine intake in areas contaminated by the Chernobyl accident was lower than that in non-contaminated areas. The low iodine intake in both areas would be related to the high prevalence of goiters throughout the whole country. The low bromine intakes indicated Ukrainians were not exposed to bromine-containing foods.

Feasibility study of glass dosimeter postal dosimetry audit of high-energy radiotherapy photon beams.

INTRODUCTION: The characteristics of a glass dosimeter were investigated for its potential use as a tool for postal dose audits. Reproducibility, energy dependence, field size and depth dependence were compared to those of a thermoluminescence dosimeter (TLD), which has been the major tool for postal dose audits worldwide. MATERIALS AND METHODS: A glass dosimeter, GD-302M (Asahi Techno Glass Co.) and a TLD, TLD-100 chip (Harshaw Co.) were irradiated with gamma-rays from a (60)Co unit and X-rays from a medical linear accelerator (4, 6, 10 and 20 MV). RESULTS: The dosimetric characteristics of the glass dosimeter were almost equivalent to those of the TLD, in terms of utility for dosimetry under the reference condition, which is a 10 x 10 cm(2) field and 10 cm depth. Because of its reduced fading, compared to the TLD, and easy quality control with the ID number, the glass dosimeter proved to be a suitable tool for postal dose audits. Then, we conducted postal dose surveys of over 100 facilities and got good agreement, with a standard deviation of about 1.3%. CONCLUSIONS: Based on this study, postal dose audits throughout Japan will be carried out using a glass dosimeter.

Dietary iodine intake in residents of northwestern regions of ukraine contaminated by the chernobyl accident.

Daily iodine intake in Ukrainian subjects of northwestern regions was estimated in relation to the health effects on inhabitants after the Chernobyl accident. Total diets were collected from 106 locations for children and adult males by a duplicate portion study. Iodine was rapidly determined by inductively coupled plasma mass spectrometry after chemical separation. Iodine concentration on a dry basis for Ukrainians was 0.11 microg g(-1) and the daily iodine intake was in the range of 2.80-372 microg per person. The median, geometric mean, and standard deviation were 28.1, 32.7, and 2.51 microg, respectively. The yearly trend of the intake had almost no change. Regional differences would be expected to exist among the 10 areas of the Ukraine, but no clear differences appeared in the present findings. Daily iodine intake in Ukrainians was lower than the recommended dietary intake (RDI) allowance (150 microg), and its lack would be related to the high prevalence of goiter in the country.