検索結果

評価の指標線量は空気カーマ

1.2 Quantities and Units

The recommended quantity for shielding design calculations for x rays is air kerma ( K ), defined as the sum of the initial kinetic energies of all the charged particles liberated by uncharged particles per unit mass of air, measured at a point in air (ICRU, 1998a).

放射線の防護量はNCRP report147でも実効線量

The recommended radiation protection quantity for the limitation of exposure to people from sources of ionizing radiation is effective dose (E), defined as the sum of the weighted equivalent doses to specific organs or tissues [i.e., each equivalent dose is weighted by the corresponding tissue weighting factor for the organ or tissue (wT)] (NCRP, 1993).

実効線量はそのまま指標として使えない（日本でも同じ考え方）

1.4 Shielding Design Goals for Medical X-Ray Imaging Facilities and Effective Dose

It is not practical to base shielding design directly on E, since E cannot be measured directly.
Therefore, for the purposes of this Report, the shielding design goals are stated in terms of K (in milligray) at the point of nearest occupancy beyond the barrier.

管理区域の線量限度は、実効線量としては日本と米国は同じであるが（5mSv）、米国ではそれをそのまま空気カーマに適用している（日本とは異なる考え方）

1.4.1 Controlled Areas

To achieve both recommendations, this Report recommends a fraction of one-half of that E value, or 5 mSv y^–1, and a weekly shielding design goal (P) of 0.1 mGy air kerma (i.e., an annual air-kerma value of 5 mGy) for controlled areas. The P value adopted in this Report would allow pregnant radiation workers continued access to their work areas.

非管理区域境界の線量限度は、米国と日本は同じく、1mSvを担保するという考え方であるが、米国は週単位の設定となっている

1.4.2 Uncontrolled Areas

This recommendation can be achieved for the medical radiation facilities covered in this Report with a weekly shielding design goal of 0.02 mGy air kerma (i.e., an annual air-kerma value of 1 mGy) for uncontrolled areas.