Fluke Biomedical 76-414 - Manual (Page 10)

Nuclear Associates 76-414-4150
Operators Manual
2-4
2) Dose information . The following dose information obtained by using the CT dosimetry phantom.
For any CT x-ray system designed to image both the head and body, separate dose information shall
be provided for each application. All dose measurements shall be performed with the CT dosimetry
phantom placed on the patient couch or support device without additional attenuating materials
present.
(i) The CTDI at the following locations in the dosimetry phantom:
(a) Along the axis of rotation of the phantom.
(b) Along a line parallel to the axis of rotation and 1.0 centimeter interior to the surface of the
phantom with the phantom positioned so that CTDI is the maximum obtainable at this depth.
(c) Along lines parallel to the axis of rotation and 1.0 centimeter interior to the surface of the
phantom at positions 90, 180, and 270 degrees from the position in paragraph (c)(2)(i)(b) of
this section. The CT conditions of operation shall be the typical values suggested by the
manufacturer for CT of the head or body. The location of the position where the CTDI is
maximum as specified in paragraph (c)(2)(i)(b) of this section shall be given by the
manufacturer with respect to the housing of the scanning mechanism or other readily
identifiable feature of the CT x-ray system in such a manner as to permit placement of the
dosimetry phantom in this orientation.
(ii) The CTDI in the center location of the dosimetry phantom for each selectable CT condition of
operation that varies either the rate or duration of x-ray exposure. This CTDI shall be presented
as a value that is normalized to the CTDI in the center location of the dosimetry phantom from
paragraph (c)(2)(i) of this section, with the CTDI of paragraph (c)(2)(i) of this section having a
value of one. As each individual CT condition of operation is changed, all other independent
CT conditions of operation shall be maintained at the typical values described in paragraph
(c)(2)(i) of this section. These data shall encompass the range of each CT condition of operation
stated by the manufacturer as appropriate for CT of the head or body. When more than three
selections of a CT condition of operation are available, the normalized CTDI shall be provided, at
least, for the minimum, maximum, and mid-range value of the CT condition of operation.
(iii) The CTDI at the location coincident with the maximum CTDI at 1 centimeter interior to the surface
of the dosimetry phantom for each selectable peak tube potential. When more than three
selections of peak tube potential are available, the normalized CTDI shall be provided, at least,
for the minimum, maximum, and a typical value of peak tube potential. The CTDI shall be
presented as a value that is normalized to the maximum CTDI located at 1 centimeter interior to
the surface of the dosimetry phantom from paragraph (c)(2)(i) of this section, with the CTDI of
paragraph (c)(2)(i) of this section having a value of one.
(iv) The dose profile in the center location of the dosimetry phantom for each selectable nominal
tomographic section thickness. When more than three selections of nominal tomographic section
thicknesses are available, the information shall be provided, at least, for the minimum, maximum,
and midrange value of nominal tomographic section thickness. The dose profile shall be
presented on the same graph and to the same scale as the corresponding sensitivity profile
required by paragraph (c)(3)(iv) of this section.
(v) A statement of the maximum deviation from the values given in the information provided
according to paragraph (c)(2) (i), (ii), (iii), and (iv) of this section. Deviation of actual values may
not exceed these limits.