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Photo 6.4 Lead blinds protecting windows (Photograph courtesy of Connolly Hospital, Blanchardstown) 6.3.5 Staff areas in X‐ray room A protective screen, or shielded console area, must be provided for staff at the control panel in an X‐ray room. Protective screens are typically custom designed and the location, size and shape will involve collaboration between the equipment manufacturer, the user and the RPA. The final design should be approved by the RPA before installation. The screen should ideally be located in a position adjoining the staff entrance and should be angulated so that that primary radiation and first scatter cannot enter directly the area behind it (see Chapter 3). In addition, there should not be an unprotected direct line of sight from the patient or X‐ray tube to the operator behind the screen or to a loaded cassette or CR plate inside the control booth. The exposure hand switch should be located so that the operator must remain behind the screen during operation. This is generally achieved if the exposure switch is located at a distance of more than 1 m from the edge of the screen (NCRP, 2004). The screen should be fixed in position and should be of an adequate size to allow the required number of people work behind it. Mobile screens should not be used in fixed installations (Health Canada, 1999, WHO 1975) with the possible exception of DXA and dental facilities. General X‐ray room screens are commonly 2-2.5 m in length with an additional wing of length 0.6-1.0 m for room sizes of approximately 33 m 2 (see Chapter 3). The dimensions and location must be approved by the RPA, prior to installation. Screens are generally longer in fluoroscopy, interventional and CT rooms than in general X‐ray rooms. This allows for the increased ancillary equipment and accommodates the larger number of people who may be in attendance (NHS, 2001). 82 The Design of Diagnostic Medical Facilities where Ionising Radiation is used
For general rooms, the lead equivalence of the screen is typically 2 mm although 3-4 mm or more may be required for angiography suites and multi-slice CT installations. The minimum height should be 2 m (BIR, 2000). The upper half is generally transparent and made of lead glass or lead acrylic to permit the operator to have a panoramic view of the room, good visibility of the patient, the X‐ray tube, warning lights on equipment (where fitted) and the doors. The design must ensure integrity at the joints between the panel sections, and the panels and lead glass (see Appendix E, Fig. E.7). Joints should be adequately shielded and the lead glass sheets/panels should be overlapped by 30-40 mm (BIR, 2000) or protected by a shielded joint (Photo 6.5). The screen should be marked with the lead equivalent thickness. Exceptionally, in some rooms a mirror may be necessary to enable the operator to view entrance doors, which may be out of direct sight. In addition to protecting the operator, the console may sometimes be required to protect unused films in cassettes or CR plates. If this is the case, it must be taken into consideration when specifying the lead equivalence. Photo 6.5 Lead plywood on lead lined batons Lead Lead (Photographs courtesy of Wardray Premise Ltd) The control panel/operator’s console effectively becomes a separate room in CT and interventional suites (see Sections 3.4.2 and 3.5). The operator(s) then view the room through a panoramic window composed of lead glass or acrylic as described above. The window frames must be shielded and there must be sufficient overlap of the shielding between the window and window frames and between the window frames and the wall as described above (see Appendix E, Fig. E.7). There will normally be a door leading from the operator’s room to the controlled area which must be protected as described in Section 6.3.3. In designing operator areas or rooms a number of operational aspects have a strong influence on the level of shielding required. If access to these areas is restricted to occupationally exposed workers the design constraint of 1 mSv per year can be used. This is likely to be the case in a general radiography room. If, on the other hand, the area is to be used as a general consultation, teaching, cardiac monitoring and reporting area, non-designated staff will regularly be in attendance. This will often be the case with CT and interventional suites. In such cases the design constraint for a member of the public, 0.3 mSv per year must be used (see The Design of Diagnostic Medical Facilities where Ionising Radiation is used 83
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RPII 09/01 The Design of Diagnostic
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Foreword The original Code of Pract
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4. Nuclear medicine 35 4.1 Introduc
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1. Legal and administrative framewo
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e made as soon as possible. It shou
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It should be noted that it is the u
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Records should be kept as they will
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2. Identify the persons (staff and
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3.1.3 Computed Tomography (CT) CT a
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Photo 3.2: Interventional X‐ray r
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3.3 Radiography rooms 3.3.1 General
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X Figure 3.2: Dedicated chest room
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Figure 3.4: DXA room Operator’s c
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Figure 3.5b: A dental radiography s
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Radiation shielding calculations fo
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There are large variations in the s
Page 34 and 35: e assessed by the RPA as part of th
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Page 38 and 39: It is recognised worldwide that the
Page 40 and 41: The operator console should be loca
Page 42 and 43: Figure 4.3: A possible layout for a
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Page 46 and 47: uptake probe and associated equipme
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Page 56 and 57: Table 5.4: Workload data from NCRP
Page 58 and 59: 5.2.4 Primary radiation A barrier i
Page 60 and 61: The primary beam will be attenuated
Page 62 and 63: 1 χ = ln αγ B −γ 1+ + β α
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Page 66 and 67: R D(t) = . t D(0) × t Equation 5.8
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Page 72 and 73: Example 4: Dental X‐ray room (BIR
Page 74 and 75: Example 6: Shielding required for a
Page 76 and 77: 6. Some practical considerations 6.
Page 78 and 79: 6.1.4 Brick There are many types of
Page 80 and 81: Walls are generally shielded to ful
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Page 90 and 91: ICRP. 2007. Recommendations of the
Page 92 and 93: Appendices Appendix A: Dose limits
Page 94 and 95: Appendix C: Radiation transmission
Page 96 and 97: Figure C.1: Transmission of primary
Page 98 and 99: Figure C.5: 2 mm lead equivalent th
Page 100 and 101: Table D.3: Physical properties & ef
Page 102 and 103: Appendix E: Schematic diagrams of r
Page 104 and 105: Figure E.7: Shielding around the ed
Page 106 and 107: Figure F. 3: Sample radiation warni
Page 108 and 109: Notes 106 The Design of Diagnostic
Page 110: Notes 108 The Design of Diagnostic
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