• Int. J. Radiat. Oncol. Biol. Phys. · Oct 1999

    Effect of post-implant edema on the rectal dose in prostate brachytherapy.

    • F M Waterman and A P Dicker.
    • Department of Radiation Oncology, Kimmel Cancer Center, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA, USA. frank.waterman@mail.tju.edu
    • Int. J. Radiat. Oncol. Biol. Phys. 1999 Oct 1; 45 (3): 571-6.

    PurposeTo characterize the effect of prostate edema on the determination of the dose delivered to the rectum following the implantation of 125I or 103Pd seeds into the prostate.Methods And MaterialsFrom 3 to 5 post-implant computed tomography (CT) scans were obtained on 9 patients who received either 125I or 103Pd seed implants. None of the patients received hormone therapy. The outer surface of the rectum was outlined on each axial CT image from the base to the apex of the prostate. The D10 rectal surface dose, defined as the dose which encompasses only 10% of the surface area of the rectum, was determined from each CT scan by compiling a dose-surface histogram (DSH) of the rectal surface. The magnitude and half-life of the post-implant edema in each of these implants is known from the results of a previously published study based on the analysis of the serial CT scans.ResultsAs the prostate edema resolved, the distance between the most posterior implanted seeds and the anterior surface of the rectum decreased. As a result, the D10 rectal surface dose increased with each successive post-implant CT scan until the edema resolved. The dose increased exponentially at approximately the same rate the prostate volume decreased. The D10 rectal surface dose at 30 days post-implant ranged from 16% to 190% (mean 68 +/- 50%) greater than on day 0. The dose on day 30 was at least 50% greater in 6 of 9 cases.ConclusionThe rectal surface dose determined by analysis of a post-implant CT scan of an 125I or 103Pd prostate seed implant depends upon the timing of the CT scan. The dose indicated by the CT scan on day 30 is typically at least 50% greater than that indicated by the CT scan on day 0. Because of this difference, it is important to keep the timing of the post-implant CT in mind when specifying dose thresholds for rectal morbidity.

      Pubmed     Full text   Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…