open access

Vol 21, No 3 (2016)
Original research articles
Published online: 2016-05-01
Submitted: 2015-08-05
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Evaluating deviations in prostatectomy patients treated with IMRT

Ana Cravo Sá, Ana Peres, Mónica Pereira, Carina Marques Coelho, Fátima Monsanto, Ana Macedo, Adrian Lamas
DOI: 10.1016/j.rpor.2015.11.004
·
Rep Pract Oncol Radiother 2016;21(3):266-270.

open access

Vol 21, No 3 (2016)
Original research articles
Published online: 2016-05-01
Submitted: 2015-08-05

Abstract

Aim

To evaluate the deviations in prostatectomy patients treated with IMRT in order to calculate appropriate margins to create the PTV.

Background

Defining inappropriate margins can lead to underdosing in target volumes and also overdosing in healthy tissues, increasing morbidity.

Material and methods

223 CBCT images used for alignment with the CT planning scan based on bony anatomy were analyzed in 12 patients treated with IMRT following prostatectomy. Shifts of CBCT images were recorded in three directions to calculate the required margin to create PTV.

Results and discussion

The mean and standard deviation (SD) values in millimetres were −0.05[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]1.35 in the LR direction, −0.03[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]0.65 in the SI direction and −0.02[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]2.05 the AP direction. The systematic error measured in the LR, SI and AP direction were 1.35[[ce:hsp sp="0.25"/]]mm, 0.65[[ce:hsp sp="0.25"/]]mm, and 2.05[[ce:hsp sp="0.25"/]]mm with a random error of 2.07[[ce:hsp sp="0.25"/]]mm; 1.45[[ce:hsp sp="0.25"/]]mm and 3.16[[ce:hsp sp="0.25"/]]mm, resulting in a PTV margin of 4.82[[ce:hsp sp="0.25"/]]mm; 2.64[[ce:hsp sp="0.25"/]]mm, and 7.33[[ce:hsp sp="0.25"/]]mm, respectively.

Conclusion

With IGRT we suggest a margin of 5[[ce:hsp sp="0.25"/]]mm, 3[[ce:hsp sp="0.25"/]]mm and 8[[ce:hsp sp="0.25"/]]mm in the LR, SI and AP direction, respectively, to PTV1 and PTV2. Therefore, this study supports an anisotropic margin expansion to the PTV being the largest expansion in the AP direction and lower in SI.

Abstract

Aim

To evaluate the deviations in prostatectomy patients treated with IMRT in order to calculate appropriate margins to create the PTV.

Background

Defining inappropriate margins can lead to underdosing in target volumes and also overdosing in healthy tissues, increasing morbidity.

Material and methods

223 CBCT images used for alignment with the CT planning scan based on bony anatomy were analyzed in 12 patients treated with IMRT following prostatectomy. Shifts of CBCT images were recorded in three directions to calculate the required margin to create PTV.

Results and discussion

The mean and standard deviation (SD) values in millimetres were −0.05[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]1.35 in the LR direction, −0.03[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]0.65 in the SI direction and −0.02[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]2.05 the AP direction. The systematic error measured in the LR, SI and AP direction were 1.35[[ce:hsp sp="0.25"/]]mm, 0.65[[ce:hsp sp="0.25"/]]mm, and 2.05[[ce:hsp sp="0.25"/]]mm with a random error of 2.07[[ce:hsp sp="0.25"/]]mm; 1.45[[ce:hsp sp="0.25"/]]mm and 3.16[[ce:hsp sp="0.25"/]]mm, resulting in a PTV margin of 4.82[[ce:hsp sp="0.25"/]]mm; 2.64[[ce:hsp sp="0.25"/]]mm, and 7.33[[ce:hsp sp="0.25"/]]mm, respectively.

Conclusion

With IGRT we suggest a margin of 5[[ce:hsp sp="0.25"/]]mm, 3[[ce:hsp sp="0.25"/]]mm and 8[[ce:hsp sp="0.25"/]]mm in the LR, SI and AP direction, respectively, to PTV1 and PTV2. Therefore, this study supports an anisotropic margin expansion to the PTV being the largest expansion in the AP direction and lower in SI.

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Keywords

Prostate tumour; Intensity modulated radiotherapy; Planning target volume margin; Cone beam computed tomography; Geometric uncertainty

About this article
Title

Evaluating deviations in prostatectomy patients treated with IMRT

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 21, No 3 (2016)

Pages

266-270

Published online

2016-05-01

DOI

10.1016/j.rpor.2015.11.004

Bibliographic record

Rep Pract Oncol Radiother 2016;21(3):266-270.

Keywords

Prostate tumour
Intensity modulated radiotherapy
Planning target volume margin
Cone beam computed tomography
Geometric uncertainty

Authors

Ana Cravo Sá
Ana Peres
Mónica Pereira
Carina Marques Coelho
Fátima Monsanto
Ana Macedo
Adrian Lamas

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