Industrial Radiography Accidents

["Richard, Mack L" <mrichar@iupui.edu>]

Radsafers:



First, please understand that I have limited knowledge/experience with

industrial radiography.  I've seen the sources/shields (as I recall the

radiographers referred to these as "cameras") and have a basic understanding

of how they function.  With that disclaimer out of the way, I wonder if some

modifications to these cameras might help prevent some of these overexposure

problems.



It seems that in a number of overexposure cases I've read about, the

radiographer fails to perform a radiation survey after the source has

supposedly but unsuccessfully been retracted into the shield.  Whether the

failure is forgetfulness, negligence, pending tee time, etc., the result is

the same.  Someone stated that these devices have some type of indicator to

advise the radiographer of the source position.  While not explicitly

stated, I assume that to mean either a mechanical or electro-mechanical

device (i.e., it doesn't actually measure radiation).



Here's a thought on a solution to this problem.  Would it not be possible to

place some type of detector on the side of the shield where the source exits

the shield that would be connected to a flashing light to indicate the

presence of elevated levels of radiation?  One could even configure the

"on-off" switch so that when the source guide tube is connected, it

automatically turns the detector on (that prevents the radiographer from

forgetting to turn on the detector).  Of course, a "threshold" level would

have to be set to prevent the detector from activating the flashing light

due to radiation shining through the shield.  Since this would have to be a

battery powered detector, one would also like to see some type of audible or

visual warning if the batteries are low.



Granted, as the source is extended away from the shield through the guide

tube, the detector may quit flashing due to a reduction in radiation

intensity.  Thus, if the source became detached in the guide tube at some

distance from the shield, there would be no indication of a problem.

However, the radiographer would know something was amiss if the light didn't

begin flashing as he retracted the source back into the shield.  Given this

drawback, such a device shouldn't replace the post irradiation survey.



This idea is similar to what we utilize when we perform "high dose rate

(HDR)" brachytherapy.  HDR brachytherapy involves remotely threading a 10 Ci

Ir-192 source through a catheter (thin plastic "guide" tube for you

non-medical types) into a specific area of a patient's body (e.g., tumor).

This is necessarily performed in a shielded room.  Although the HDR console

indicates the status of the source position, we are required to have a

separate monitoring system that monitors the radiation in the room to

independently indicate the presence/absence of radiation in the room.  At

the end of the treatment, we perform a survey with a portable survey

instrument before we take the patient out of the treatment room.



It seems that such a system might help to prevent these overexposures

(unfortunately, nothing is 100%).  Perhaps such a system would be cost

prohibitive or not compatible for the various camera configurations.  As I

said, my knowledge of industrial radiography is limited and sometimes

ignorance is bliss.  I won't be offended if someone comes up with a laundry

list of reasons why this won't work.



Just my 2 cents worth (see, you may have gotten what you paid for).



Regards,

Mack R.



Mack L. Richard, M.S., C.H.P.

Radiation Safety Officer - IUPUI/Indiana Univ. Med. Cntr.

Phone #: (317) 274-0330   Fax #: (317) 274-2332

E-Mail Address:  mrichar@iupui.edu



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