open access

Vol 23, No 5 (2018)
Original research articles
Published online: 2018-09-01
Submitted: 2016-10-13
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Cardiac risk and MCNP/SISCODES doses in RT of the left internal mammary chain with photon and electron portals

Tarcisio Passos Campos, Bruno M. Mendes, Bruno Trindade, Wagner L. Araujo
DOI: 10.1016/j.rpor.2018.07.004
·
Rep Pract Oncol Radiother 2018;23(5):384-391.

open access

Vol 23, No 5 (2018)
Original research articles
Published online: 2018-09-01
Submitted: 2016-10-13

Abstract

Aim

The present study evaluated the increment of cardiac risk (CR) and absorbed dose in radiotherapy of the internal mammary chain (IMC), in particular with photon portals of 4 6 MV, and cobalt therapy (Co60); and, electron portals of 8, 12 and 16 MeV applied in the left breast, considering the adoption of a combined photon (16 Gy) and electron (30 Gy) protocols.

Materials and methods

The modified ICRP-reference female model of 60 kg, 163 cm and 43 years of age, coil RCP-AF, was modelled. The MCNP6/SICODES codes were employed, where the spatial dose distributions and dose-volume histograms were generated. Toxicity limits and a CR model were considered.

Results

CR associated with the 6 MV, 4 MV and Co60 portals increased 41.1; 40.6 and 34.5%, respectively; while, in 8, 12 and 16 MeV portals, they were 5.0, 32.5 and 49.2%, respectively. High anomalous scatter radiation from electron portals was found in the left lung providing an average dose of 3.3–5.0 Gy.

Conclusions

To RCP-AF, the Co60 portal for IMC-RT presented more attractive dose distribution, whose 16 Gy for photon-component produced less CR increase, 5% lower than the other photon portals. Considering electron portals, the smallest CR increase was produced by 8 MeV portal while 12–16 MeV made the risk higher. There is a call for a less hardened energetic spectrum in order to reduce CR; however, holding suitable IMC penetration. A combined Co60/8–12 MeV may bring benefits, reducing CR. The lowest risk was found to 46 Gy electron portals exclusively.

Abstract

Aim

The present study evaluated the increment of cardiac risk (CR) and absorbed dose in radiotherapy of the internal mammary chain (IMC), in particular with photon portals of 4 6 MV, and cobalt therapy (Co60); and, electron portals of 8, 12 and 16 MeV applied in the left breast, considering the adoption of a combined photon (16 Gy) and electron (30 Gy) protocols.

Materials and methods

The modified ICRP-reference female model of 60 kg, 163 cm and 43 years of age, coil RCP-AF, was modelled. The MCNP6/SICODES codes were employed, where the spatial dose distributions and dose-volume histograms were generated. Toxicity limits and a CR model were considered.

Results

CR associated with the 6 MV, 4 MV and Co60 portals increased 41.1; 40.6 and 34.5%, respectively; while, in 8, 12 and 16 MeV portals, they were 5.0, 32.5 and 49.2%, respectively. High anomalous scatter radiation from electron portals was found in the left lung providing an average dose of 3.3–5.0 Gy.

Conclusions

To RCP-AF, the Co60 portal for IMC-RT presented more attractive dose distribution, whose 16 Gy for photon-component produced less CR increase, 5% lower than the other photon portals. Considering electron portals, the smallest CR increase was produced by 8 MeV portal while 12–16 MeV made the risk higher. There is a call for a less hardened energetic spectrum in order to reduce CR; however, holding suitable IMC penetration. A combined Co60/8–12 MeV may bring benefits, reducing CR. The lowest risk was found to 46 Gy electron portals exclusively.

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Keywords

Internal mammary chain; Breast radiation therapy; Lymph nodes; Electron; Photon

About this article
Title

Cardiac risk and MCNP/SISCODES doses in RT of the left internal mammary chain with photon and electron portals

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 23, No 5 (2018)

Pages

384-391

Published online

2018-09-01

DOI

10.1016/j.rpor.2018.07.004

Bibliographic record

Rep Pract Oncol Radiother 2018;23(5):384-391.

Keywords

Internal mammary chain
Breast radiation therapy
Lymph nodes
Electron
Photon

Authors

Tarcisio Passos Campos
Bruno M. Mendes
Bruno Trindade
Wagner L. Araujo

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