Re: Geiger Counter at Home?

[Guest guest]

zxcvb2318 wrote:

> Even after spending 1-2 days in the hospital for an RAI, I gather

> that one must be careful at home for the next 1-2 weeks. One post

> said that she covered everything in plastic wrap. I'm not up for

> that but I do want to be careful. Since the iodine can be easily

> cleaned up, it strikes me that it would be really useful to go over

> your room with a geiger counter after you " cooled off " . It would

> have to have adequate sensitivity. Has anybody ever done this?

> Where would you get such a thing? How expensive is it?

Steve -

A few members that I know of have bought Geiger counters for home use and

entertainment (see the comments of one, at the end).

Ian has written several letters about them, copied below.

-

NYC

BTW - I assume you've read the collection of post ablation precautions (msg

#18077)? There are almost as many versions and variations of precautions

as there are low iodine diets. But covering everything in plastic is

generally not necessary.

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There are two parts to a geiger counter, the detector (geiger)

and the electronics.

Geigers come in very many types. The main ones are:

Normal. More or less like a cigar or small fluorescent bulb.

General purpose and comparatively cheap.

Thin end-window. Usually like a tin can of almost any size. One flat side

is

covered by a VERY thin membrane which allows penetration by very soft beta

particles. Used for decontaminating rooms after RAI therapy.

Energy-compensated. These are used for dose-rate measurement. Their

sensitivity depends on size and some tiny ones exist. These are suitable

for

measuring the radiations from large therapy doses. These are the detectors

built in to the 'pocket bleeper' types of radiation detector.

You can't usually swap different detectors onto the different counter

systems

because the electronics need to be adjusted each time.

Geigers have a limited dynamic range. They have an intrinsic count (perhaps

1

count per second) and a maximum count rate (perhaps 1000 counts per

second).

This means that it can only be used usefully from, say 3cps to 600cps - a

dynamic range of 200:1. If a low sensitivity one is chosen to measure

600mCi

then it will not be useful below about 3mCi, so you'll have to use a

different geiger.

[... and ...]

Geiger tubes come in many variants. The ones Dr mentions have been

optimised for one particular job, but of the many types available there are

two which are of interest for use with 131I.

1) Thin end-window or thin side-wall types are made with part of the

body of the detector as thin as possible, to maximise the sensitivity to

beta

particles. These are particularly good at looking for contamination and are

probably the ones Dr is referring to. They are not suitable for

dose-rate measurement except in particular, highly contrived circumstances.

2) Energy compensated geiger tubes. These have been surrounded with a

coating which reduces the sensitivity to betas and increases the

sensitivity

to high-energy gammas, thus producing a general-purpose dose-rate detector.

All pocket bleeper / personal electronic dose rate monitors use this type

of

device.

A range of these instruments are illustrated on:

http://www.tsgxray.com/radiation_monitoring.htm

The two types of instrument have very different uses. If you need wheels,

you

can choose a bicycle or a truck, but they are not interchangeable.

I have 5 different types of energy compensated detectors in use, and 3

types

of end/side window types.

[...and ...]

A Geiger-Muller tube is a radiation detector that comes in dozens of

different types, from tiny, energy-compensated tubes used in 'pocket

bleepers' through to large area, thin window 'pancake' detectors.

Examples of the range at:

http://www.bicron.com/tgmdetectors/catalog.htm

They are by far the most commonly used electronic radiation detectors.

They are usually used in 'single purpose' instruments, so we have

instruments

for contamination checking, and different ones for dose-rate measurement.

Some, like Alisa's one, have a window that can be opened. With the window

shut you have an energy compensated unit for dose rate measurements, with

the

window open you have a contamination monitor. In practice, such instruments

are an uneasy compromise and do neither job as well as the proper

instrument.

Proportional counters are usually used for very special purposes and are

not

common as either dose-rate meters or as general contamination monitors.

Ionization chambers are the most common proper dose-rate meters, the

industry

workhorse being the Victoreen Cutie-Pie (physicists joke).

A range of pictures can be seen on:

http://www.qaltek.com/PORTABLES/portables.htm

Ian

Ian Adam

Radiation Safety Officer

The Institute of Cancer Research

Cotswold Road

Sutton

Surrey

SM2 5NG

Tel: 020 8722 4250

Fax: 020 8722 4300

EMail: iana@...

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[... and this, from a member .... ]

What I have found is that the geiger counter has kept me much

more cautious than I would have been if I hadn't had it. It also made my

husband understand the problem. (He tended to dismiss it faster than I

did.)

The counter has shown me giving off radioactivity a lot longer than the

" guidelines " given to me by any hospital. If I had followed the

" guidelines "

I would have been kissing my husband before it was actually safe.

Also, the last time I took an RAI dose, I asked them to measure me at the

hospital, and then measured myself when I got outside with my own geiger

counter. They both read the same. I don't pretend to think that they are

perfect in their measurements, but I think they are better than guessing.

What I have found is.... that which we can't see, smell, taste, hear or

touch, we tend to dismiss much faster. The geiger counter gave me a way to

see and hear the radioactivity and therefore made it more " real " to me.

I wouldn't expose anyone before the recommended time, but with the geiger

counter it helped me to reinforce the fact to the rest of my family that I

needed to stay isolated.

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[Guest guest]

Was that me who you read about covering things with plastic wrap? I

probably should have made it clearer what I meant by " everything " -

don't take that too literally. I meant everything that I had

PLANNED to cover, NOT everything in my house :-). I covered only

things that I was touching a lot, like the doorknobs of " my " bedroom

and bathroom, mouse and keyboard, tv remotes, stuff like that. A large

part of the idea was to remind my husband NOT to touch things that I

was using all the time - I used pink plastic wrap. And I tend to err

far on the side of caution :-).

A friend loaned us a geiger counter, but it was one of those that

wasn't really designed to measure anything other than really really

big stuff, so we didn't have any success with it. Thought it'd be

fun, though - sorry it didn't work out.

I'm off in the morning for another week away - see y'all when I get

back. I may be able to tap into the group while I'm gone, but am not

sure about it.

Cheers,

Alisa

2/15/2002: Nodule found during bad sore throat

2/27/2002: FNA - suspicious for pap

3/4/2002: Hysterectomy/oopherectomy-possible ovarian cancer - BENIGN!!

4/9/2002: TT - Stage 2 pap encapsuled in 2.5 x 2 x 1.6 cm nodule,

Hashimotos discovered

5/28/2002: TBS (2 mCi dose on 5/24) and 100 mCi RAI

6/6/2002: TBS - No sign of mets

Currently - 140mcg Levoxyl

Age: 48 Location: near Seattle WA

Please feel free to email me privately anytime

Check out my posts:

Radioactive Girl - http://groups.yahoo.com/group/Thyca/message/19472

My LID - http://groups.yahoo.com/group/Thyca/message/15872

My RAI - http://groups.yahoo.com/group/Thyca/message/15873

>

> > Even after spending 1-2 days in the hospital for an RAI, I gather

> > that one must be careful at home for the next 1-2 weeks. One post

> > said that she covered everything in plastic wrap. I'm not up for

> > that but I do want to be careful. Since the iodine can be easily

> > cleaned up, it strikes me that it would be really useful to go

over

> > your room with a geiger counter after you " cooled off " . It would

> > have to have adequate sensitivity. Has anybody ever done this?

> > Where would you get such a thing? How expensive is it?

>

> Steve -

>

> A few members that I know of have bought Geiger counters for home

use and

> entertainment (see the comments of one, at the end).

>

> Ian has written several letters about them, copied below.

>

> -

> NYC

>

> BTW - I assume you've read the collection of post ablation

precautions (msg

> #18077)? There are almost as many versions and variations of

precautions

> as there are low iodine diets. But covering everything in plastic

is

> generally not necessary.

>