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Re: seed implant
>References: <342a7bc4.3568a13d@aol.com>
>Date: Tue, 26 May 1998 19:57:37 -0400
>Reply-To: oncology@hgo.net
>Sender: Medical Physics Listserver <medphys@lists.wayne.edu>
>From: Wayne Butler <oncology@HGO.NET>
>Organization: Wheeling Hospital
>Subject: Re: seed implant
>To: MEDPHYS@LISTS.WAYNE.EDU
>
>Iyer77 wrote:
>>
>> Are we all prescribing to 160Gy or 144gy--TG-43.The Rad.Oncs still write
>> 160Gy.Our MMS computer calculates according to TG-43.
>> Charlaes Narayanan, Reid Hospital.
>
>At a recent conference in Seattle on advanced prostate brachytherapy for
>well established programs, 20% of the participants admitted in an
>electronic query that they did not know whether their physicists were
>using TG-43 or some other system. Most of the long term cinical data
>has been published by groups in New York and Seattle using 160Gy end
>points. However, 160Gy was not the same in those two cities and is
>considerably different from TG-43 (Bice et al.; IJROBP 40:1237-1241,
>1998). Those calculating to 160Gy using TG-43 are dose escalating by
>about 10%, depending on whom you are trying to emulate.
>
>I had hoped that the physics community switching to TG-43 would
>eliminate the appalling errors reported in another recent red journal
>article (Prete et al.; IJROBP 40:1001-1005, 1998). 35 of the busiest
>implant programs were asked to use their computers to calculate the dose
>at 1cm and 2cm from a single 1mCi I-125 and Pd-103 seed. For each
>isotope, the range of results varied by a factor of 3 with a standard
>deviation of 20%. Only 1/4 of respondents were using TG-43 at the time
>of the survey and some of their answers were also wildly divergent.
>Today, based on the recent Seattle meeting, 3/4 of centers are using
>TG-43 in calculations, but if there is inadequate communication and
>understanding between docs and physicists, a new error mode appears, and
>a new dosimetry survey may result in another black eye for physics.
>
>Ready for the quiz? E-mail me your answers to the following and I will
>post a summary to the list:
>
>1. Calculate the total dose at 1cm and 2cm from a 1mCi Amersham 6711
>I-125 seed.
>
>2. Calculate the total dose at 1cm and 2cm from a 1mCi Theragenics 200
>Pd-103 seed.
>
>3. Which calculation formalism do you use? (point source TG-43,
>Seattle NWTI, Memorial, etc.)
>
>4. Could your docs writing prostate brachytherapy prescriptions answer
>#3 satisfactorily?
>
>5. Would it be clear to an outsider reading the prescription which
>calculation protocol was intended?
>
>Thanks,
>
>Wayne
>--
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Wayne Butler, Ph.D.
>Schiffler Oncology Center
>Wheeling Hospital Phone: 304-243-3983
>One Medical Park Fax: 304-243-5047
>Wheeling, WV 26003 E-mail: oncology@hgo.net
>
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
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