NSW HOSPITAL AND UNIVERSITY RADIATION SAFETY
OFFICERS GROUP (HURSOG)
GUIDE TO RADIOIODINE THERAPY FACILITY DESIGN This document is a connsus statement produced by a working party of HURSOG, to aid in the design and construction of radioiodine therapy facilities (treatment rooms and radioactive waste tanks). The members of the working party were : Jocelyn Towson (Royal Prince Alfred Hospital), Richard Smart (St. George Hospital), Brenda Walker (Prince of Wales Hospital), Lee Collins (Westmead Hospital), and Mark Gilbert (post-graduate student, Uni. Western Sydney).
Edit by chf.
1. Workload Data
131
1. The vast majority of treatments involve I - as iodide for thyroid carcinoma, with MIBG (for phaeochromocytoma), lipiodol (for hepatocellular carcinoma) and as iodide (for thyrotoxicosis) being less frequent us.
1.2 Administered activity, typical workload and length of stay :
Iodide4-6 GBq (Ca)1-4 per week 3 days
1 GBq (toxicosis)5/year 6 days
MIBG8 GBq1/year 6 days
Lipiodol 1 GBq10/year 3 days
1.3 Waste volume80 litres /day/person, bad on 10 litre flush, 8 flushes per day. NB. This does NOT include shower/handbasin waste - if this to be stored, then the volume per day will be much higher, and advice should be taken from the hydraulic engineers.
1.4 Activity discharged to wage This can be calculated as the maximum activity prent in a delay tank at any time using an assumption of 80% discharge over 3 days. The amount is less for toxic patients, but so is the administered activity.
Usage Maximum Expected Tank Activity
1 room, 1 patient/week
2 x average administered activity
1 room,
2 patients/week
3 x average administered activity
2 rooms, 1 patient/week each 4 x average administered activity
2 rooms, 2 patients/week each 6 x average administered activity
___________________________________________________________________________
1.5 Discharge Limits In the abnce of any current NSW EPA requirements, the
NH&MRC requirement of a maximum 20 times the ALI per week, irrespective of discharge
131
volume, should be ud. For I this is 16 MBq / week.
1.6 Tank volume From the above information, the necessary tank volume (each tank) for any situation can be calculated.
2. Radioactive Waste Tank Design
2.1 Material Preferably (and cheapest), reinforced concrete at approx. 2.35 gm/cc. Precast structures may be advisable.
2.2 Wall Thickness Only radioisotope in the outer 20 cm or so of fluid requires shielding (due to absorption in the water). Using an integrated do limit of 1 mSv / year, depending on the occupancy, the minimum wall thickness should be 120 mm, and the maximum would be 200 mm. A propod additional design constraint of 0.3 would reduce the basic design do from 1 mSv/year to 0.3 mSv/year, and would thus change the values.
2.3 Lining A smooth impermeable membrane on the inside of the tank is mandatory. Epoxies such as Sikagard-63 or Epires are suitable. The membrane thickness should be 1-3 mm.
2.4 Sump A sump must be provided. There should be a manual drain valve, or a parate submersible pump available to empty the tank at the sump.
2.5 Spill Precautions To guard against spillage, particularly during pumping or tank overflow, either a hob high enough to contain a spill of the entire contents of one tank, or a gutter connected to the wer is required. Installation of a moisture detector in the floor to alert to the prence of a spill is strongly recommended, particularly where control of the tank system is remotely located. Any propod alternative method of preventing spread of contamination must be approved by the Radiation Control Section, EPA.
2.6 Level Indicators Indicators of tank content level are required, preferably giving a continuous indication (as oppod to t levels). Suitable types are :
Conductivity nsors - can be stepped in many intervals
Ultrasonic level nsor - continuous detection, and recommended.
Float switches - pret levels only, and least suitable.
2.7 Macerator (Mutrator)It must be assumed that there are solids in the waste (apart from faeces, which will turn into sludge). To minimi the effects of the :
* Tanks should be as maintenance-free as possible. Macerator and pumps could be on the outside o
f tanks, or submerged. If submersible pumps must be ud, they should be of the grinder-type, eg. Piranha 12/2 and placed in the sump.
___________________________________________________________________________
* Can either u during pumpout or on recirculating basis
* The macerator system should be parate to allow regular u - pumpout can be
either a parate pump circuit or via a valve on the macerator circuit
2.8 Maintenance Need to prepare a maintenance/operation manual for the tank system.
2.9 Baffles Advice should be taken from hydraulic engineers as to any need for baffles in the tanks, and their construction.
2.10 Pipework Pipes should be cast iron from the patient’s room to the tanks if they must withstand pressure, otherwi PVC should be ud. In any ca PVC should be ud in and around tanks. Physical damage protection for PVC pipes may be needed. Cast iron pipes if ud should have smooth interior walls to avoid clogging. Deadspaces in pipework must be minimid, especially between the diverter (to direct flow to a particular tank) and the tank inlet.
2.11 Valves Advice needed as to what type and the actuation method - price and reliability will be main issues.
2.12 Sludge Sewage sludge should be handled by the macerator or during flush/clean procedures (if ud).
2.13 Flushing A parate flush water supply is required outside the tanks. A direct input to each tank is preferable, but non-return valves will be required. Water authorities may prohibit any direct connection to water supplies, and a nearby ho can be ud.
2.14 Radiation Monitors Monitors give a gross estimate of tank activity only. They can be placed either in the roof of each tank (inside a waterproof container such as PVC pipe) or in the recirculating pump line if installed. The latter can be calibrated to give an approximate tank activity. Geiger-type monitors are sufficient for this purpo.
2.15 Control System Components of the control system should be :
* Volume/level detection stages-empty
-warning when approaching full eg. 75%
-alarm to switch tanks at 90%
-major alarm at 100%
* When both tanks full, either the toilet flush water must be automatically shut off
(mains pressure flush only), or the drain pumps run slowly or intermittently to maintain the level of the tank ready to be emptied at full. See also 2.16.
* The EPA prefers manual changeover of tanks (when one tank is filled), but this could be automatic (assuming the other tank is empty at the time - if not there must be no
atttempt at changeover).电脑网速慢怎么解决
___________________________________________________________________________
* Emptying of the decayed tank must be manually controlled.
* If discharge is restricted by the concentration of radionuclide, it may be preferable to u a puld pumpout, where the pump could operate for say 5 minutes per hour.
Although this would reduce the required storage volume, advice must be taken as to
the feasibility of this approach.
* Valves should be briefly exercid regularly to avoid jamming
2.16 Emergency Diversion A backup valve should be included to divert wage direct to the main in the event of failure of the tank systems. From the radiation safety point of view, direct discharge of waste in an emergency is far preferable to hazards due to buildup of radioactive waste in pipes or storage of urine in the ward.
2.17 Signage Advice should be taken from the radiation safety officer as to what signs are required. Generally radiation warning signs should be displayed on pipework, tanks, access doors, pumps etc.
关于美术的名言3. Room Design
3.1 Source Term (activity in patient). The following assumes an effective half life of 24 hours.
* Assuming an effective half life of 24 hours, and an administered activity of 6GBq, the source term per patient is 9 GBq-days, eg. for a length of stay of three days, the
continuous activity per patient for calculation purpos is 3 GBq.
Thus, for example, using 6GBq dos :
Usage Source Term (GBq-days)
1 room, 1 patient/week9
1 room,
2 patients/week18
2 rooms, 1 patient/week each9 per room
2 rooms, 2 patients/week each18 per room
* Assume each room will be ud for 2 patients per week (worst ca)
* Assume no patient lf-attenuation (incread scatter may balance out any
attenuation)
-
1.5怎么取消电脑屏幕保护
* The distance factor for a distributed source can be taken to be r (fitting data from Table 11.4.1 of the Radiation Health Handbook, revid edition, 1992, the actual
-1.6
relationship is 0.91 r ). Beyond 3 metres the normal inver square law can be ud.
131-1-1
* The do rate constant for I can be taken to be 60 µSv.hr.GBq @ 1 metre (there
___________________________________________________________________________
is a range of data quoted in the literature, from 51 to 76)
3.2 Occupancies U the standard NCRP 1/0.25/0.0625 levels instead of the AS2243
values.
3.3 Design Do
中药材种植
* Source positions to be assumed to be :
Barrier adjacent to bed- 1 m from barrier
Other barriers- centre of treatment room
Special cas- as appropriate
* Dos to be calculated at 0.5 m from barriers.
* For areas accessible to the public, u a weekly do limit of 1/50 of annual limit (1 mSv), ie. 20µSv/week
Suggested design dos :
**
Adult patient bedroom 40 µSv/week
Paediatric patient bedroom20 µSv/week
Staff and public areas20 µSv/week
**
For adult patient bedrooms a further occupancy factor of 0.5 has been ud assuming a maximum likely stay of 6 months in beds in adjacent rooms. Other values may be ud when the actual occupancy is
known.
A propod additional design constraint of 0.3 would change the basic design do
from 1 mSv/year to 0.3 mSv/year, and would thus change the above values.
3.4 Toilets Toilet flush should be approx. 10 litres. Where dual flush toilets are installed, the low volume flush (eg. 6 litres) should NOT be ud due to possibility of blockages with infrequent u. For ea of decontamination, toilets should be wall mounted. Spare toilet rolls must be kept with the toilet.
3.5 Doors It is preferable to avoid heavy lead shielded doors. Ideally, there should be a vestibule (area with very low occupancy, off traffic areas) leading to the room entry door. If there is direct access from a corridor, a mobile/fixed lead shield may be needed.
欣赏造句>枸杞能提高性功能吗
3.6 Ventilation Special ventilation of treatment bedrooms is NOT required.
3.7 Room Layout The treatment area should preferably contain :
* bedroom, approx. 3.5 x 4.5 m
* bathroom with shower and toilet (bearing in mind the space which may be required
___________________________________________________________________________
for assisted toiletting)
* Indirect entry
* Storage areas for decontamination kit, cleaning items etc. This can be located so as to provide a buffer to occupied areas.
* Storage space for linen, food waste and general waste
Public access to windows, adjoining balconies etc. must be limited.
pr倒放
羊水混浊3.8 Walls, Floors, Furniture The EPA Guidelines for Premis in which Radioactive Substances are Kept or Ud contain requirements for surfaces, and must be followed in order for the treatment room to be registerable under the Radiation Control Act. Bathroom flooring should be of a non-slip type, but must remain easily decontaminated.
___________________________________________________________________________
