open access

Vol 15, No 1 (2010)
Published online: 2010-01-01
Submitted:
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EPID in vivo dosimetry in RapidArc technique

Krzysztof Slosarek, Marta Szlag, Barbara Bekman, Aleksandra Grzadziel
DOI: 10.1016/j.rpor.2010.01.003
·
Rep Pract Oncol Radiother 2010;15(1):8-14.

open access

Vol 15, No 1 (2010)
Published online: 2010-01-01
Submitted:

Abstract

Aim

The aim of the study was to estimate the dose at the reference point applying an aSi-EPID device in the course of patient treatment.

Materials and methods

The method assumes direct proportionality between EPID signal and dose delivered to the patient reference point during the treatment session. The procedure consists of treatment plan calculation for the actual patient in the arc technique. The plan was realized with an elliptic water-equivalent phantom. An ionization chamber inside the phantom measured the dose delivered to the reference point. Simultaneously, the EPID matrix measured the CU distribution. EPID signal was also registered during patient irradiation with the same treatment plan. The formula for in vivo dose calculation was based on the CU(g) function, EPID signal registered during therapy and the relation between the dose and EPID signal level measured for the phantom. In vivo dose was compared with dose planned with the treatment planning system.

Irradiation was performed with a Clinac accelerator by Varian Medical Systems in the RapidArc technique. The Clinac was equipped with an EPID matrix (electronic portal image device) of aSi-1000. Treatment plans were calculated with the Eclipse/Helios system. The phantom was a Scanditronix/Wellhöfer Slab phantom, and the ionization chamber was a 0.6[[ce:hsp sp="0.25"/]]ccm PTW chamber.

Results

In vivo dose calculations were performed for five patients. Planned dose at the reference point was 2[[ce:hsp sp="0.25"/]]Gy for each treatment plan. Mean in vivo dose was in the range of 1.96–2.09.

Conclusions

Our method was shown to be appropriate for in vivo dose evaluation in the RapidArc technique.

Abstract

Aim

The aim of the study was to estimate the dose at the reference point applying an aSi-EPID device in the course of patient treatment.

Materials and methods

The method assumes direct proportionality between EPID signal and dose delivered to the patient reference point during the treatment session. The procedure consists of treatment plan calculation for the actual patient in the arc technique. The plan was realized with an elliptic water-equivalent phantom. An ionization chamber inside the phantom measured the dose delivered to the reference point. Simultaneously, the EPID matrix measured the CU distribution. EPID signal was also registered during patient irradiation with the same treatment plan. The formula for in vivo dose calculation was based on the CU(g) function, EPID signal registered during therapy and the relation between the dose and EPID signal level measured for the phantom. In vivo dose was compared with dose planned with the treatment planning system.

Irradiation was performed with a Clinac accelerator by Varian Medical Systems in the RapidArc technique. The Clinac was equipped with an EPID matrix (electronic portal image device) of aSi-1000. Treatment plans were calculated with the Eclipse/Helios system. The phantom was a Scanditronix/Wellhöfer Slab phantom, and the ionization chamber was a 0.6[[ce:hsp sp="0.25"/]]ccm PTW chamber.

Results

In vivo dose calculations were performed for five patients. Planned dose at the reference point was 2[[ce:hsp sp="0.25"/]]Gy for each treatment plan. Mean in vivo dose was in the range of 1.96–2.09.

Conclusions

Our method was shown to be appropriate for in vivo dose evaluation in the RapidArc technique.

Get Citation

Keywords

Arc technique; Portal dosimetry; IMRT; Verification; Electronic portal imaging device

About this article
Title

EPID in vivo dosimetry in RapidArc technique

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 15, No 1 (2010)

Pages

8-14

Published online

2010-01-01

DOI

10.1016/j.rpor.2010.01.003

Bibliographic record

Rep Pract Oncol Radiother 2010;15(1):8-14.

Keywords

Arc technique
Portal dosimetry
IMRT
Verification
Electronic portal imaging device

Authors

Krzysztof Slosarek
Marta Szlag
Barbara Bekman
Aleksandra Grzadziel

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