Is it necessary to eliminate the posterior dose margin in prostate brachytherapy to achieve an acceptably low risk of late rectal morbidity?
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| Title: | Is it necessary to eliminate the posterior dose margin in prostate brachytherapy to achieve an acceptably low risk of late rectal morbidity? |
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| Authors: | Waterman, Frank M.1 frank.waterman@mail.tju.edu, Dicker, Adam P.1 |
| Source: | International Journal of Radiation Oncology, Biology, Physics. Sep2003, Vol. 57 Issue 1, p293-299. 7p. |
| Subjects: | Prostate cancer, Rectal cancer, Radiotherapy |
| Abstract: | : PurposeThe use of a posterior dose margin in 125I prostate brachytherapy is controversial. The posterior margin is often eliminated to lower the risk of late rectal morbidity (Radiation Therapy Oncology Group protocols 9805 and P-0019), but this may compromise the posterior prostate dose coverage. The purpose of this work is to determine whether it is necessary to eliminate the posterior margin to achieve an acceptably low risk of Grade 2 (bleeding/ulceration) late rectal morbidity.: Methods and materialsThe present work is an extension of a previous study in which we reported the probability of Grade 2 late rectal morbidity (bleeding/ulceration) as a function of the maximum rectal dose. Here, we define the relationship between the maximum rectal dose and the width of the posterior dose margin. From this relationship, and the probability of late morbidity determined earlier, we assessed the probability of late rectal morbidity as a function of the width of the posterior dose margin. The present work was based on the preplans of 15 permanent 125I prostate seed implants having volumes ranging from 19 to 78 cm3. All used peripheral loading with 125I sources in the range 0.35–0.45 mCi. The maximum rectal dose was taken to be the isodose line coincident with the posterior edge of the prostate. The maximum rectal dose and the corresponding margin width were determined from the isodose distribution. The sensitivity of the relationship between the maximum rectal dose and the margin width to the prostate volume, the seed density, and the distance of the most posterior seeds from the posterior edge of the prostate was investigated.: ResultsThe maximum rectal dose is directly proportional to the margin width. This relationship is relatively insensitive to the prostate volume and the seed density, but is sensitive to the location of the posterior seeds relative to the posterior edge of the gland. Moving the seeds from 5 mm to 3 mm from the edge typically increased the maximum rectal dose by 17%. With the posterior seeds 3 mm from the edge, the maximum rectal doses that corresponded to 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm margins were 187 ± 6 Gy, 222 ± 8 Gy, 257 ± 11 Gy, 292 ± 14 Gy, and 327 ± 17 Gy, respectively. The corresponding probabilities that a patient will experience late rectal morbidity are ≤1%, ≤2%, ≤3%, ≤5%, and ≤7%, respectively.: ConclusionsOur results indicate that a 2–3-mm posterior dose margin can be used in prostate brachytherapy with a relatively low (2–3%) risk of Grade 2 (bleeding/ulceration) late rectal morbidity, provided the sources in the posterior row are implanted at least 3 mm from the edge of the prostate. A practical guideline is to keep the maximum rectal dose below 150% of the target dose. [Copyright &y& Elsevier] |
| Copyright of International Journal of Radiation Oncology, Biology, Physics is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Header | DbId: egs DbLabel: Engineering Source An: 10427912 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Is it necessary to eliminate the posterior dose margin in prostate brachytherapy to achieve an acceptably low risk of late rectal morbidity? – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Waterman%2C+Frank+M%2E%22">Waterman, Frank M.</searchLink><relatesTo>1</relatesTo><i> frank.waterman@mail.tju.edu</i><br /><searchLink fieldCode="AR" term="%22Dicker%2C+Adam+P%2E%22">Dicker, Adam P.</searchLink><relatesTo>1</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22International+Journal+of+Radiation+Oncology%2C+Biology%2C+Physics%22">International Journal of Radiation Oncology, Biology, Physics</searchLink>. Sep2003, Vol. 57 Issue 1, p293-299. 7p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Prostate+cancer%22">Prostate cancer</searchLink><br /><searchLink fieldCode="DE" term="%22Rectal+cancer%22">Rectal cancer</searchLink><br /><searchLink fieldCode="DE" term="%22Radiotherapy%22">Radiotherapy</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: : PurposeThe use of a posterior dose margin in 125I prostate brachytherapy is controversial. The posterior margin is often eliminated to lower the risk of late rectal morbidity (Radiation Therapy Oncology Group protocols 9805 and P-0019), but this may compromise the posterior prostate dose coverage. The purpose of this work is to determine whether it is necessary to eliminate the posterior margin to achieve an acceptably low risk of Grade 2 (bleeding/ulceration) late rectal morbidity.: Methods and materialsThe present work is an extension of a previous study in which we reported the probability of Grade 2 late rectal morbidity (bleeding/ulceration) as a function of the maximum rectal dose. Here, we define the relationship between the maximum rectal dose and the width of the posterior dose margin. From this relationship, and the probability of late morbidity determined earlier, we assessed the probability of late rectal morbidity as a function of the width of the posterior dose margin. The present work was based on the preplans of 15 permanent 125I prostate seed implants having volumes ranging from 19 to 78 cm3. All used peripheral loading with 125I sources in the range 0.35–0.45 mCi. The maximum rectal dose was taken to be the isodose line coincident with the posterior edge of the prostate. The maximum rectal dose and the corresponding margin width were determined from the isodose distribution. The sensitivity of the relationship between the maximum rectal dose and the margin width to the prostate volume, the seed density, and the distance of the most posterior seeds from the posterior edge of the prostate was investigated.: ResultsThe maximum rectal dose is directly proportional to the margin width. This relationship is relatively insensitive to the prostate volume and the seed density, but is sensitive to the location of the posterior seeds relative to the posterior edge of the gland. Moving the seeds from 5 mm to 3 mm from the edge typically increased the maximum rectal dose by 17%. With the posterior seeds 3 mm from the edge, the maximum rectal doses that corresponded to 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm margins were 187 ± 6 Gy, 222 ± 8 Gy, 257 ± 11 Gy, 292 ± 14 Gy, and 327 ± 17 Gy, respectively. The corresponding probabilities that a patient will experience late rectal morbidity are ≤1%, ≤2%, ≤3%, ≤5%, and ≤7%, respectively.: ConclusionsOur results indicate that a 2–3-mm posterior dose margin can be used in prostate brachytherapy with a relatively low (2–3%) risk of Grade 2 (bleeding/ulceration) late rectal morbidity, provided the sources in the posterior row are implanted at least 3 mm from the edge of the prostate. A practical guideline is to keep the maximum rectal dose below 150% of the target dose. [Copyright &y& Elsevier] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of International Journal of Radiation Oncology, Biology, Physics is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/S0360-3016(03)00571-6 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 7 StartPage: 293 Subjects: – SubjectFull: Prostate cancer Type: general – SubjectFull: Rectal cancer Type: general – SubjectFull: Radiotherapy Type: general Titles: – TitleFull: Is it necessary to eliminate the posterior dose margin in prostate brachytherapy to achieve an acceptably low risk of late rectal morbidity? Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Waterman, Frank M. – PersonEntity: Name: NameFull: Dicker, Adam P. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 09 Text: Sep2003 Type: published Y: 2003 Identifiers: – Type: issn-print Value: 03603016 Numbering: – Type: volume Value: 57 – Type: issue Value: 1 Titles: – TitleFull: International Journal of Radiation Oncology, Biology, Physics Type: main |
| ResultId | 1 |
