DIAGNOSTIC EQUIPMENT
times become twice as long. Gamma Knife treatment length can vary, but for complex cases with multiple lesions the procedure can take several hours. So, it is not logistically feasible for treatments to double in length every five years in terms of management. The planning software for the machines automatically takes the sources’ strength into account when planning treatments, so that clinical staff are aware of when the source is approaching half-life.
Applying for a licence Hospitals looking to introduce a Gamma Knife must apply for a licence to house live radioactive sources on site. This is the same process for brachytherapy equipment, and is in place to ensure that conditions around security and safety are upheld by sites holding active sources. The licence is granted by the Office for Administration of Radioactive Substances Advisory Committee (ARSAC), and includes requirements for tamper-proof doors, and lead-lined shielding for walls etc.
As with many hospitals that deliver
radiation, staff exposure is stringently monitored, with lead-lined PPE in place, just as it is in place with X-ray and LINACs etc. Radiation monitoring for staff in hospitals is an integral part of good practice. It is the core discipline for various roles, including RSOs, Health and Medical Physicists, Radiologists, and Nuclear Medicine Techs. This is because it is important to be acutely aware of exposure rates for staff. However, as the Gamma Knife is self-shielding, radiation is only able to escape during treatment and at the QSRC treatment room, with vinyl indications on the floor marking out the exposure in the area, in line with ARSAC conditions.
Specialised infrastructural requirements Because Gamma Knife requires housing this live radioactive source, hospitals must also meet specialised infrastructural requirements to provide this treatment option, providing sufficient protection
With the equipment being so heavy, the biggest crane in Europe was used for the QSRC installation, which also involved a road closure via Westminster City Council.
from radiation. The QSRC therefore uses specialised CAT4 doors, in line with the safety and security conditions, which not only insulate the radiation, but are designed to withstand 40 minutes of power tools – protecting the cobalt source from theft. A multifaceted team comprised of
architects, engineers, project managers, radiation safety advisors, radiologists, physicians, and chief technicians (who are going to be using the department), should be involved in the planning of a building with lead protection. Generally, due to the small number of facilities that provide this service (which drives volume of work for centres), it is highly desirable to plan the protection of a lead-lined room for the maximum possible load. This means, roughly speaking, that the radiation protection of a general-purpose lead- lined room about 6 x 4 x 3 metres in size calls for a wall thickness in all directions equivalent to 2 mm of lead (from the World Health Organization’s Manual on
Radiation Protection in Hospitals And General Practice, 1975).
Self-shielding devices While these treatment rooms require reinforced floors, prefabricated break-out walls, and lead lining, the Gamma Knife machines are self-shielding. There is thus only exposure risk when the Gamma Knife unit doors are open, during treatment. This means that – in contrast with other radiation medical equipment – such as LINAC machines that require 2 metre thick walls and specific power supply – these rooms only require walls with a thin lead lining. Such requirements are similar to that of a CT room, making Gamma Knife relatively flexible to implement, and presenting an opportunity to convert old CT treatment rooms to house a Gamma Knife.
As the Gamma Knife requires lead shielding in the floors, walls, and ceilings, its installation at the Queen Square Radiosurgery Centre was complex –
INVICTA Professional Engineering Services Paul Harman BEng (Hons), CMgr, IEng MIET, MIHEEM, MAPM Email:
paul.harman@invicta-pes.co.uk
Tel: 07508376191 INVICTA PES is happy to announce that they can provide:
n Authorising Engineer – Ventilation n Authorising Engineer – Pressure Systems n Skilled Person Training (On-site) n Competent Person (Ventilation) Training (on-site) n Design review advice n AHU Compliance Reviews n Board or Trust Compliance Assurance for SHTM and HTM
3 3 3 3 3 3 3
September 2023 Health Estate Journal 73
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120
