open access

Vol 25, No 3 (2020)
Original research articles
Published online: 2020-05-01
Submitted: 2019-01-16
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Assessment of skin dose in breast cancer radiotherapy: on-phantom measurement and Monte Carlo simulation

Mohammad Taghi Bahreyni Toossi, Nastaran Mohamadian, Mohammad Mohammadi, Mahdi Ghorbani, Mohsen Hassani, Benyamin Khajetash, Farideh Khorshidi, Courtney Knaup
DOI: 10.1016/j.rpor.2020.03.008
·
Rep Pract Oncol Radiother 2020;25(3):456-461.

open access

Vol 25, No 3 (2020)
Original research articles
Published online: 2020-05-01
Submitted: 2019-01-16

Abstract

Aim

The main purpose of the present study is assessment of skin dose in breast cancer radiotherapy.

Background

Accurate assessment of skin dose in radiotherapy can provide useful information for clinical considerations.

Materials and methods

A RANDO phantom was irradiated using a 6 MV Siemens Primus linac with medial and tangential radiotherapy fields for simulating breast cancer treatment. Dosimetry was also performed on various positions across the fields using an EBT3 radiochromic film. Similar conditions of measurement on the RANDO phantom including field size, irradiation angle, number of fields, etc. were subsequently simulated via the Monte Carlo N-Particle Transport code (MCNP). Ultimately, dose values for corresponding points from both methods were compared.

Results

Considering dosimetry using radiochromic films on the RANDO phantom, there were points having underdose and overdose based on the prescribed dose and skin tolerance levels. In this respect, 81.25% and 18.75% of the points had underdose and overdose, respectively. In some cases, several differences were observed between the measurement and the MCNP simulation results associated with skin dose.

Conclusion

Based on the results of the points which had underdose, it was suggested that a bolus should be used for the given points. With regard to overdose points, it was advocated to consider skin tolerance dose in treatment planning. Differences between the measurement and the MCNP simulation results might be due to voxel size of tally cells in simulations, effect of beam’s angle of incidence, validation time of linac’s head, lack of electronic equilibrium in the build-up region, as well as MCNP tally type.

Abstract

Aim

The main purpose of the present study is assessment of skin dose in breast cancer radiotherapy.

Background

Accurate assessment of skin dose in radiotherapy can provide useful information for clinical considerations.

Materials and methods

A RANDO phantom was irradiated using a 6 MV Siemens Primus linac with medial and tangential radiotherapy fields for simulating breast cancer treatment. Dosimetry was also performed on various positions across the fields using an EBT3 radiochromic film. Similar conditions of measurement on the RANDO phantom including field size, irradiation angle, number of fields, etc. were subsequently simulated via the Monte Carlo N-Particle Transport code (MCNP). Ultimately, dose values for corresponding points from both methods were compared.

Results

Considering dosimetry using radiochromic films on the RANDO phantom, there were points having underdose and overdose based on the prescribed dose and skin tolerance levels. In this respect, 81.25% and 18.75% of the points had underdose and overdose, respectively. In some cases, several differences were observed between the measurement and the MCNP simulation results associated with skin dose.

Conclusion

Based on the results of the points which had underdose, it was suggested that a bolus should be used for the given points. With regard to overdose points, it was advocated to consider skin tolerance dose in treatment planning. Differences between the measurement and the MCNP simulation results might be due to voxel size of tally cells in simulations, effect of beam’s angle of incidence, validation time of linac’s head, lack of electronic equilibrium in the build-up region, as well as MCNP tally type.

Get Citation

Keywords

Skin dosimetry; Breast cancer; EBT3 radiochromic film; Monte Carlo simulation

About this article
Title

Assessment of skin dose in breast cancer radiotherapy: on-phantom measurement and Monte Carlo simulation

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 25, No 3 (2020)

Pages

456-461

Published online

2020-05-01

DOI

10.1016/j.rpor.2020.03.008

Bibliographic record

Rep Pract Oncol Radiother 2020;25(3):456-461.

Keywords

Skin dosimetry
Breast cancer
EBT3 radiochromic film
Monte Carlo simulation

Authors

Mohammad Taghi Bahreyni Toossi
Nastaran Mohamadian
Mohammad Mohammadi
Mahdi Ghorbani
Mohsen Hassani
Benyamin Khajetash
Farideh Khorshidi
Courtney Knaup

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