Okla. Admin. Code § 310:281-11-13

Current through Vol. 42, No. 7, December 16, 2024

Section 310:281-11-13 - Fluoroscopic x-ray systems and spot-film devices except radiation therapy simulators

(a)Limitation of useful beam.

(1)Primary barrier.

(A) The fluoroscopic imaging assembly shall be provided with a primary protective barrier which intercepts the entire cross section of the useful beam at any source-to-image receptor distance (SID).

(B) The x-ray tube used for fluoroscopy shall not produce x-rays unless the barrier is in position to intercept the useful beam and the imaging device is in place and operable.

(2)X-Ray field.

(A) Means shall be provided for stepless (continuous) adjustment of the field size.

(B) The minimum field size at the greatest SID shall be equal to or less than 5 centimeters by 5 centimeters.

(C) Neither the length nor the width of the x-ray field in the plane of the image receptor shall exceed that of the visible area of the image receptor by more than 3 percent of the SID. The sum of the excess length and the excess width shall be no greater than 4 percent of the SID.

(D) Spot-film devices shall meet the following additional requirements:

(i) Means shall be provided between the source and the patient for adjustment of the x-ray field size in the plane of the film to the size of that portion of the film which has been selected on the spot-film selector.

(ii) Such adjustment shall be automatically accomplished except when the x-ray field size in the plane of the film is smaller than that of the selected portion of the film.

(iii) The total misalignment of the edges of the x- ray field with the respective edges of the selected portion of the image receptor along the length or width dimensions of the x-ray field in the plane of the image receptor shall not exceed 3 percent of the SID when adjusted for full coverage of the selected portion of the image receptor.

(iv) The sum, without regard to sign of the misalignment along any 2 orthogonal dimensions, shall not exceed 4 percent of the SID.

(v) The center of the x-ray field in the plane of the film shall be aligned with the center of the selected portion of the film to within 2 percent of the SID.

(E) Compliance with 310:281-11-13(a)(2) is determined with the beam axis perpendicular to the plane of the image receptor.

(b)Activation of the fluoroscopic tube. X-ray production in the fluoroscopic mode shall be controlled by a device which requires continuous pressure by the fluoroscopist for the entire time of the exposure (dead-man switch). When recording serial fluoroscopic images, the fluoroscopist shall be able to terminate the x-ray exposures at any time, but means may be provided to permit completion of any single exposure of the series in process.

(c)Exposure rate limits:

(1)Entrance Exposure Rate Allowable Limits.

(A) Fluoroscopic equipment provided with automatic exposure rate control mode (no manual mode) shall not be operable at any combination of tube potential and current that will result in an exposure rate in excess of 2.6 mC/kg (10 roentgens) per minute at the point where the center of the useful beam enters the patient, except:

(i) During recording of fluoroscopic images; or

(ii) When an optional high level control is provided. When so provided, the equipment shall not be operable at any combination of tube potential and current which will result in an exposure rate in excess of 2.6 mC/kg (10 roentgens) per minute at the point where the center of the useful beam enters the patient unless the high level control is activated. Special means of activation of high level controls shall be required. The high level control shall only be operable when continuous manual activation is provided by the operator. A continuous signal audible to the fluoroscopist shall indicate that the high level control is being employed.

(B) Fluoroscopic equipment (manual mode only) not provided with automatic exposure rate control shall not be operable at any combination of tube potential and current that will result in an exposure rate in excess of 2.6 mC/kg (10 roentgens) per minute at the point where the center of the useful beam enters the patient, except:

(i) During recording of fluoroscopic images; or

(ii) When an optional high level control is activated. The high level control shall only be operable when continuous manual activation is provided by the operator. A continuous signal audible to the fluoroscopist shall indicate that the high level control is being employed.

(C) Fluoroscopic equipment, provided with both automatic exposure rate control and manual modes, shall not be operable at any combination of tube potential and current that shall result in an exposure rate in excess of 2.6 mC/kg (10 roentgens) per minute in either mode at the point where the center of the useful beam enters the patient, except:

(i) During recording of fluoroscopic images; or

(ii) When the mode or modes have an optional high level control, in which case the mode or modes shall not be operable at any combination of tube potential and current that results in an exposure rate in excess of 2.6 mC/kg (10 roentgens) per minute at the point where the center of the useful beam enters the patient, unless the high level control is activated. Special means of activation of high level controls shall be required. The high level control shall only be operable when continuous manual activation is provided by the operator. A continuous signal audible to the fluoroscopist will indicate that the high level control is being employed.

(D) Any fluoroscopic equipment manufactured after May 19, 1995 which can exceed 1.3 mC\kg (5 roentgens) per minute shall be equipped with an automatic exposure rate control. All entrance exposure rates are limited to 2.6 mc/kg (10 roentgens) per minute with an upper limit of 5.2 mC/kg (20 roentgens) per minute when the high level control is activated.

(E) Compliance with the requirements of OAC 310:281- 11-13 is determined as follows:

(i) If the source is below the x-ray table, then the exposure rate is measured 1 centimeter above the tabletop or cradle:

(ii) If the source is above the x-ray table, the exposure rate shall be measured at 30 centimeters above the tabletop with the end of the beam- limiting device or spacer positioned as closely as possible to the point of measurement;

(iii) For a c-arm type of fluoroscope, then the exposure rate is measured 30 centimeters from the input surface of the fluoroscopic imaging assembly, with the source positioned at any available SID, provided that the end of the beam-limiting device or spacer is no closer than 30 centimeters from the input surface of the fluoroscopic imaging assembly;

(iv) For a lateral type fluoroscope, the exposure rate is measured at a point 15 centimeters for the centerline of the x-ray table and in the direction of the x-ray source with the end of the beam-limiting device or spacer positioned as closely to the point of measurement. If the tabletop is movable, it shall be positioned as closely as possible to the lateral x-ray source, with the end of the beam-limiting device or spacer no closer than 15 centimeters to the centerline of the x-ray table.

(2)Periodic Measurements. Periodic measurements of the entrance exposure rate shall be performed by a qualified expert for both typical and maximum values as follows (Materials should be placed in the useful beam to protect the imaging system when conducting these periodic measurements.):

(A) Such measurements shall be made annually or after any maintenance of the system which might affect the exposure rate;

(B) Measurement results must be kept where any fluoroscopist may have ready access to such results while using the fluoroscope, and include the following information:

(i) stated in coulombs per kilogram (roentgens) per minute;

(ii) include the technique factors used in determining such results;

(iii) The name of the individual performing the measurements; and

(iv) the date the measurements were performed.

(C) Conditions of periodic measurement of typical entrance exposure rate are as follows:

(i) The measurements shall be made under the conditions that satisfy the conditions of OAC 310:281-11-13(c)(1)(E);

(ii) The kVp, mA, and/or other selectable parameters shall be adjusted to those settings typical of clinical use on a 23 cm thick abdominal patient;

(iii) The x-ray system that incorporates automatic exposure rate control shall have sufficient attenuative material placed in the useful beam to produce a milliamperage and/or kilovoltage to satisfy the conditions of OAC 310:281-11- 13(c)(2)(C)(ii);

(D) Conditions of periodic measurement of maximum entrance exposure rate are as follows:

(i) The measurement shall be made under the conditions that satisfy 310:281-11-13(c)(1)(E);

(ii) The kVp, mA and/or other selectable parameters shall be adjusted to those settings which give the maximum entrance exposure rate;

(iii) The x-ray system(s) that incorporates automatic exposure control shall have sufficient attenuative material placed in the useful beam to produce the maximum entrance exposure rate of the system.

(d)Barrier transmitted radiation rate limits.

(1)Primary barrier transmission. The exposure rate due to transmission through the primary protective barrier with the attenuation block in the useful beam combined with radiation from the image intensifier shall not exceed 2 milliroentgens per hour for each roentgen per minute exposure rate. Measurements shall be made at 10 centimeters from any accessible surface of the fluoroscopic imaging assembly beyond the plane of the image receptor.

(2)Measuring compliance of barrier transmission.

(A) The exposure rate due to transmission through the primary protective barrier combined with radiation from the image intensifier is determined by measurements averaged over an area of 100 square centimeters with no linear dimension greater than 20 centimeters.

(B) If the source is below the tabletop, then the measurement is made with the input surface of the fluoroscopic imaging assembly positioned 30 centimeters above the tabletop.

(C) If the source is above the tabletop and the SID is variable, then the measurement is made with the end of the beam-limiting device or spacer as close to the tabletop as it can be placed, provided that it shall not be closer than 30 centimeters.

(D) Movable grids and compression devices shall be removed from the useful beam during the measurement.

(E) The attenuation block shall be positioned in the useful beam 10 centimeters from the point of measurement of entrance exposure rate and between this point and the input surface of the fluoroscopic imaging assembly.

(F) The collimator shall be fully open when the measurement is made.

(e)Indication of potential and current. During fluoroscopy and cinefluorography, the kV and the mA shall be continuously indicated at the control panel and/or the fluoroscopist's position.

(f)Source-to-Skin distance. The SSD shall not be less than:

(1) 38 centimeters on all stationary fluoroscopes,

(2) 30 centimeters on all mobile fluoroscopes, and

(3) 20 centimeters for image intensified fluoroscopes used for specific surgical application.

(g)Fluoroscopic timer.

(1) Means shall be provided to preset the cumulative on-time of the fluoroscopic x-ray tube. The maximum cumulative time of the timing device shall not exceed 5 minutes without resetting.

(2) A signal audible to the fluoroscopist shall indicate the completion of any preset cumulative on-time. Such signal will continue to sound while x-rays are produced until the timing device is reset.

(h)Radiation therapy simulation systems. If a radiation therapy simulation system complies with (1) and (2) of this subsection, then it is exempt from all the requirements of 310:281-11-13(a), (c), (d), and (g) provided that:

(1) such systems are designed and used in such a manner that no individual other than the patient is in the x-ray room during periods of time when the system is producing x-rays; and

(2) systems which do not meet the requirements of 310:281- 11-13(g) are provided with a means of indicating the cumulative time that an individual patient has been exposed to x-rays. Procedures shall require in such cases that the timer be reset between examinations.

Okla. Admin. Code § 310:281-11-13

Added at 8 Ok Reg 3503, eff 8-15-91 (emergency); Added at 9 Ok Reg 1643, eff 5-29-92; Amended at 21 Ok Reg 1037, eff 5-13-04; Amended at 27 Ok Reg 2512, eff 7-25-10

Amended by Oklahoma Register, Volume 38, Issue 24, September 1, 2021, eff. 9/11/2021