open access

Vol 23, No 1 (2018)
Original research articles
Published online: 2018-01-01
Submitted: 2017-07-05
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Energy spectrum and dose enhancement due to the depth of the Lipiodol position using flattened and unflattened beams

Daisuke Kawahara, Shuichi Ozawa, Akito Saito, Tomoki Kimura, Tatsuhiko Suzuki, Masato Tsuneda, Sodai Tanaka, Kazunari Hioki, Takeo Nakashima, Yoshimi Ohno, Yuji Murakami, Yasushi Nagata
DOI: 10.1016/j.rpor.2017.12.004
·
Rep Pract Oncol Radiother 2018;23(1):50-56.

open access

Vol 23, No 1 (2018)
Original research articles
Published online: 2018-01-01
Submitted: 2017-07-05

Abstract

Aim

Lipiodol was used for stereotactic body radiotherapy combining trans arterial chemoembolization. Lipiodol used for tumour seeking in trans arterial chemoembolization remains in stereotactic body radiation therapy. In our previous study, we reported the dose enhancement effect in Lipiodol with 10× flattening-filter-free (FFF). The objective of our study was to evaluate the dose enhancement and energy spectrum of photons and electrons due to the Lipiodol depth with flattened (FF) and FFF beams.

Methods

FF and FFF for 6[[ce:hsp sp="0.25"/]]MV beams from TrueBeam were used in this study. The Lipiodol (3[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]3[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]3[[ce:hsp sp="0.25"/]]cm3) was located at depths of 1, 3, 5, 10, 20, and 30[[ce:hsp sp="0.25"/]]cm in water. The dose enhancement factor (DEF) and the energy fluence were obtained by Monte Carlo calculations of the particle and heavy ion transport code system (PHITS).

Results

The DEFs at the centre of Lipiodol with the FF beam were 6.8, 7.3, 7.6, 7.2, 6.1, and 5.7% and those with the FFF beam were 20.6, 22.0, 21.9, 20.0, 12.3, and 12.1% at depths of 1, 3, 5, 10, 20, and 30[[ce:hsp sp="0.25"/]]cm, respectively, where Lipiodol was located in water. Moreover, spectrum results showed that more low-energy photons and electrons were present at shallow depth where Lipiodol was located in water. The variation in the low-energy spectrum due to the depth of the Lipiodol position was more explicit with the FFF beam than that with the FF beam.

Conclusions

The current study revealed variations in the DEF and energy spectrum due to the depth of the Lipiodol position with the FF and FFF beams. Although the FF beam could reduce the effect of energy dependence due to the depth of the Lipiodol position, the dose enhancement was overall small. To cause a large dose enhancement, the FFF beam with the distance of the patient surface to Lipiodol within 10[[ce:hsp sp="0.25"/]]cm should be used.

Abstract

Aim

Lipiodol was used for stereotactic body radiotherapy combining trans arterial chemoembolization. Lipiodol used for tumour seeking in trans arterial chemoembolization remains in stereotactic body radiation therapy. In our previous study, we reported the dose enhancement effect in Lipiodol with 10× flattening-filter-free (FFF). The objective of our study was to evaluate the dose enhancement and energy spectrum of photons and electrons due to the Lipiodol depth with flattened (FF) and FFF beams.

Methods

FF and FFF for 6[[ce:hsp sp="0.25"/]]MV beams from TrueBeam were used in this study. The Lipiodol (3[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]3[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]3[[ce:hsp sp="0.25"/]]cm3) was located at depths of 1, 3, 5, 10, 20, and 30[[ce:hsp sp="0.25"/]]cm in water. The dose enhancement factor (DEF) and the energy fluence were obtained by Monte Carlo calculations of the particle and heavy ion transport code system (PHITS).

Results

The DEFs at the centre of Lipiodol with the FF beam were 6.8, 7.3, 7.6, 7.2, 6.1, and 5.7% and those with the FFF beam were 20.6, 22.0, 21.9, 20.0, 12.3, and 12.1% at depths of 1, 3, 5, 10, 20, and 30[[ce:hsp sp="0.25"/]]cm, respectively, where Lipiodol was located in water. Moreover, spectrum results showed that more low-energy photons and electrons were present at shallow depth where Lipiodol was located in water. The variation in the low-energy spectrum due to the depth of the Lipiodol position was more explicit with the FFF beam than that with the FF beam.

Conclusions

The current study revealed variations in the DEF and energy spectrum due to the depth of the Lipiodol position with the FF and FFF beams. Although the FF beam could reduce the effect of energy dependence due to the depth of the Lipiodol position, the dose enhancement was overall small. To cause a large dose enhancement, the FFF beam with the distance of the patient surface to Lipiodol within 10[[ce:hsp sp="0.25"/]]cm should be used.

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Keywords

Energy spectrum; Lipiodol; Monte Carlo calculation

About this article
Title

Energy spectrum and dose enhancement due to the depth of the Lipiodol position using flattened and unflattened beams

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 23, No 1 (2018)

Pages

50-56

Published online

2018-01-01

DOI

10.1016/j.rpor.2017.12.004

Bibliographic record

Rep Pract Oncol Radiother 2018;23(1):50-56.

Keywords

Energy spectrum
Lipiodol
Monte Carlo calculation

Authors

Daisuke Kawahara
Shuichi Ozawa
Akito Saito
Tomoki Kimura
Tatsuhiko Suzuki
Masato Tsuneda
Sodai Tanaka
Kazunari Hioki
Takeo Nakashima
Yoshimi Ohno
Yuji Murakami
Yasushi Nagata

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