open access

Vol 20, No 3 (2015)
Original research articles
Published online: 2015-05-01
Submitted: 2014-01-25
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Set-up uncertainty during postmastectomy radiotherapy with Segmented Photon Beams Technique

Anna Semaniak, Paweł Kukołowicz
DOI: 10.1016/j.rpor.2015.01.009
·
Rep Pract Oncol Radiother 2015;20(3):181-187.

open access

Vol 20, No 3 (2015)
Original research articles
Published online: 2015-05-01
Submitted: 2014-01-25

Abstract

Aim

To verify the reproducibility of patients irradiated after mastectomy on the immobilization system designed and manufactured for our hospital and to compare the Internal Protocol (IP) with the modified-No Action Level Protocol.

Background

Application of forward IMRT techniques requires a good reproducibility of patient positioning. To minimize the set-up error, an effective immobilization system is important.

Materials and methods

The study was performed for two groups of 65 each. In the first group, portal images for anterior field were taken in 1–3 fractions and, subsequently, three times a week. In this group, the mNAL protocol was used. In the second group, the IP was used. The portal images from the anterior field and from the gantry 0 were taken during the 1–3 and 10 fractions. In both groups, image registration was performed off-line. For each group the systematic and random errors and PTV margin were calculated.

Results

In the first group the value of the population systematic errors and random errors were 1.6[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]1.6[[ce:hsp sp="0.25"/]]mm for the left–right, and 1.5[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]1.7[[ce:hsp sp="0.25"/]]mm for the cranial–caudal directions, respectively, 1.7[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]1.3[[ce:hsp sp="0.25"/]]mm, and 1.9[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]1.3[[ce:hsp sp="0.25"/]]mm for the second group. The PTV margins for the left–right and cranial–caudal directions were 5.1 and 4.9[[ce:hsp sp="0.25"/]]mm for the first group and 5.4 and 6.4[[ce:hsp sp="0.25"/]]mm for the second group.

Conclusions

For patients immobilized with our support device treated according to the mNAL protocol or IP, a good set-up reproducibility was obtained. Implementation of IP limits the number of required images.

Abstract

Aim

To verify the reproducibility of patients irradiated after mastectomy on the immobilization system designed and manufactured for our hospital and to compare the Internal Protocol (IP) with the modified-No Action Level Protocol.

Background

Application of forward IMRT techniques requires a good reproducibility of patient positioning. To minimize the set-up error, an effective immobilization system is important.

Materials and methods

The study was performed for two groups of 65 each. In the first group, portal images for anterior field were taken in 1–3 fractions and, subsequently, three times a week. In this group, the mNAL protocol was used. In the second group, the IP was used. The portal images from the anterior field and from the gantry 0 were taken during the 1–3 and 10 fractions. In both groups, image registration was performed off-line. For each group the systematic and random errors and PTV margin were calculated.

Results

In the first group the value of the population systematic errors and random errors were 1.6[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]1.6[[ce:hsp sp="0.25"/]]mm for the left–right, and 1.5[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]1.7[[ce:hsp sp="0.25"/]]mm for the cranial–caudal directions, respectively, 1.7[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]1.3[[ce:hsp sp="0.25"/]]mm, and 1.9[[ce:hsp sp="0.25"/]]±[[ce:hsp sp="0.25"/]]1.3[[ce:hsp sp="0.25"/]]mm for the second group. The PTV margins for the left–right and cranial–caudal directions were 5.1 and 4.9[[ce:hsp sp="0.25"/]]mm for the first group and 5.4 and 6.4[[ce:hsp sp="0.25"/]]mm for the second group.

Conclusions

For patients immobilized with our support device treated according to the mNAL protocol or IP, a good set-up reproducibility was obtained. Implementation of IP limits the number of required images.

Get Citation

Keywords

Patient positioning; Systematic error; Random error

About this article
Title

Set-up uncertainty during postmastectomy radiotherapy with Segmented Photon Beams Technique

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 20, No 3 (2015)

Pages

181-187

Published online

2015-05-01

DOI

10.1016/j.rpor.2015.01.009

Bibliographic record

Rep Pract Oncol Radiother 2015;20(3):181-187.

Keywords

Patient positioning
Systematic error
Random error

Authors

Anna Semaniak
Paweł Kukołowicz

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