open access

Vol 19, No 3 (2014)
Published online: 2014-05-01
Submitted: 2013-06-24
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Comparative analysis of image guidance in two institutions for prostate cancer patients

Tomasz Piotrowski, Slav Yartsev, George Rodrigues, Tomasz Bajon
DOI: 10.1016/j.rpor.2013.12.001
·
Rep Pract Oncol Radiother 2014;19(3):206-213.

open access

Vol 19, No 3 (2014)
Published online: 2014-05-01
Submitted: 2013-06-24

Abstract

Aim/Background

The analysis of systematic and random errors obtained from the pooled data on inter-fraction prostate motion during radiation therapy in two institutions.

Materials and methods

Data of 6085 observations for 216 prostate cancer patients treated on tomotherapy units in two institutions of position correction shifts obtained by co-registration of planning and daily CT studies were investigated. Three independent variables: patient position (supine or prone), target (prostate or prostate bed), and imaging mode (normal or coarse) were analyzed. Systematic and random errors were evaluated and used to calculate the margins for different options of referencing based on the position corrections observed with one, three, or five imaging sessions.

Results

Statistical analysis showed that only the difference between normal and coarse modes of imaging was significant, which allowed to merge the supine and prone position sub-groups as well as the prostate and prostate bed patients. In the normal and coarse imaging groups, the margins calculated using systematic and random errors in the medio-lateral and cranio-caudal directions (5.5[[ce:hsp sp="0.25"/]]mm and 4.5[[ce:hsp sp="0.25"/]]mm, respectively) were similar, but significantly different (5.3[[ce:hsp sp="0.25"/]]mm for the normal mode and 7.1[[ce:hsp sp="0.25"/]]mm for the coarse mode) in the anterio-posterior direction. The reference scheme based on the first three fractions (R3) was found to be the optimal one.

Conclusions

The R3 reference scheme effectively reduced systematic and random errors. Larger margins in the anterio-posterior direction should be used during prostate treatment on the tomotherapy unit, as coarse imaging mode is chosen in order to reduce imaging time and dose.

Abstract

Aim/Background

The analysis of systematic and random errors obtained from the pooled data on inter-fraction prostate motion during radiation therapy in two institutions.

Materials and methods

Data of 6085 observations for 216 prostate cancer patients treated on tomotherapy units in two institutions of position correction shifts obtained by co-registration of planning and daily CT studies were investigated. Three independent variables: patient position (supine or prone), target (prostate or prostate bed), and imaging mode (normal or coarse) were analyzed. Systematic and random errors were evaluated and used to calculate the margins for different options of referencing based on the position corrections observed with one, three, or five imaging sessions.

Results

Statistical analysis showed that only the difference between normal and coarse modes of imaging was significant, which allowed to merge the supine and prone position sub-groups as well as the prostate and prostate bed patients. In the normal and coarse imaging groups, the margins calculated using systematic and random errors in the medio-lateral and cranio-caudal directions (5.5[[ce:hsp sp="0.25"/]]mm and 4.5[[ce:hsp sp="0.25"/]]mm, respectively) were similar, but significantly different (5.3[[ce:hsp sp="0.25"/]]mm for the normal mode and 7.1[[ce:hsp sp="0.25"/]]mm for the coarse mode) in the anterio-posterior direction. The reference scheme based on the first three fractions (R3) was found to be the optimal one.

Conclusions

The R3 reference scheme effectively reduced systematic and random errors. Larger margins in the anterio-posterior direction should be used during prostate treatment on the tomotherapy unit, as coarse imaging mode is chosen in order to reduce imaging time and dose.

Get Citation

Keywords

Pooled database; Helical tomotherapy; Prostate cancer; Image guidance; MVCT; Margins

About this article
Title

Comparative analysis of image guidance in two institutions for prostate cancer patients

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 19, No 3 (2014)

Pages

206-213

Published online

2014-05-01

DOI

10.1016/j.rpor.2013.12.001

Bibliographic record

Rep Pract Oncol Radiother 2014;19(3):206-213.

Keywords

Pooled database
Helical tomotherapy
Prostate cancer
Image guidance
MVCT
Margins

Authors

Tomasz Piotrowski
Slav Yartsev
George Rodrigues
Tomasz Bajon

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