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Re: Off-focus radiation from Diagnostic X-ray tubes



>References: <35747852.E26E1E5B@frontiernet.net>
>Date:         Thu, 4 Jun 1998 08:55:32 -0400
>Reply-To: Medical Physics Mailing List <MEDPHYS@LISTS.WAYNE.EDU>
>Sender: Medical Physics Listserver <medphys@lists.wayne.edu>
>From: "Dr. Robert Dixon" <rdixon@RAD.BGSM.EDU>
>Subject:      Re: Off-focus radiation from Diagnostic X-ray tubes
>X-To:         upmedphy@frontiernet.net
>To: MEDPHYS@LISTS.WAYNE.EDU
>
>Bob,
>Some of the old Machlett collimators produced significant off- focal
>radiation since their primary diaphram had a wide angle of acceptance
>and could "see" a larger area of the tube/anode. These were often fitted
>as add on collimators to tube housings of various manufacturers. Find
>some of these and you will have a rich experimental playground.
>
>Bob Dixon
>
>Bob Pizzutiello wrote:
>>
>> On rare occasion we have observed this probem on radiographs, seen as a
>> subtle low-contrast image of anatomy beyond the collimated x-ray field.
>> We recently took some images with a pseudo pinhole camera and observed
>> what may be off-focus radiation from a newly installed, refurbished
>> x-ray system. Unfortunately, we are not aware of anything that has been
>> written on this subject, and we would like to say something scientific
>> and more definitive about this effect.
>>
>> If anyone has played with (detected or studied) off-focus radiation
>> before, or can suggest a reference, we would be most grateful for any
>> pointers. We are in the process of repeating these measurements on some
>> other x-ray tubes, to get a sense of the response of "normals". Perhaps
>> we may have something to report afterwards.
>>
>> Please call or e-mail us directly, if you would like to chat and
>> conserve BW. Of course, general interest comments are the reason we all
>> subscribe to the listserver.
>>
>> Many thanks.
>> -Bob Pizzutiello and Roland Wong
>> (716) 924-0350
>>
>>                     *****
>> Frequently Asked Questions (FAQ) for Medphys at:
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>
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