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Andersson, P., Pettersson, N., Lindberg, A., Swanpalmer, J. & Chakarova, R. (2021). Effects of lung tissue characterization in radiotherapy of breast cancer under deep inspiration breath hold when using Monte Carlo dosimetry. Physica medica (Testo stampato), 90, 83-90
Open this publication in new window or tab >>Effects of lung tissue characterization in radiotherapy of breast cancer under deep inspiration breath hold when using Monte Carlo dosimetry
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2021 (English)In: Physica medica (Testo stampato), ISSN 1120-1797, E-ISSN 1724-191X, Vol. 90, p. 83-90Article in journal (Refereed) Published
Abstract [en]

Purpose: To investigate the sensitivity of Monte Carlo (MC) calculated lung dose distributions to lung tissue characterization in external beam radiotherapy of breast cancer under Deep Inspiration Breath Hold (DIBH). Methods: EGSnrc based MC software was employed. Mean lung densities for one hundred patients were analysed. CT number frequency and clinical dose distributions were calculated for 15 patients with mean lung density below 0.14 g/cm3. Lung volume with a pre-defined CT numbers was also considered. Lung tissue was characterized by applying different CT calibrations in the low-density region and air-lung tissue thresholds. Dose impact was estimated by Dose Volume Histogram (DVH) parameters. Results: Mean lung densities below 0.14 g/cm3 were found in 10% of the patients. CT numbers below −960 HU dominated the CT frequency distributions with a high rate of CT numbers at −990 HU. Mass density conversion approach influenced the DVH shape. V4Gy and V8Gy varied by 7% and 5% for the selected patients and by 9% and 3.5% for the pre-defined lung volume. V16Gy and V20Gy, were within 2.5%. Regions above 20 Gy were affected. Variations in air- lung tissue differentiation resulted in DVH parameters within 1%. Threshold at −990 HU was confirmed by the CT number frequency distributions. Conclusions: Lung dose distributions were more sensitive to variations in the CT calibration curve below lung (inhale) density than to air-lung tissue differentiation. Low dose regions were mostly affected. The dosimetry effects were found to be potentially important to 10% of the patients treated under DIBH.

Place, publisher, year, edition, pages
Associazione Italiana di Fisica Medica, 2021
Keywords
Absorbed dose, Breast cancer radiotherapy, DIBH, Lung tissue characterization, Monte Carlo simulations, Article, breast cancer, breath holding, cancer radiotherapy, computer assisted tomography, deep inspiration breath hold, dose volume histogram, dosimetry, external beam radiotherapy, human, inspiratory capacity, lung parenchyma, lung volume, major clinical study, patient selection, radiation dose distribution, respiratory airflow, tissue characterization
National Category
Cancer and Oncology
Identifiers
urn:nbn:se:ri:diva-56926 (URN)10.1016/j.ejmp.2021.09.009 (DOI)2-s2.0-85115614148 (Scopus ID)
Note

Funding details: Västra Götalandsregionen; Funding details: Strålsäkerhetsmyndigheten, SSM; Funding text 1: Financial support of King Gustav the V Jubilee Clinic Foundation, The Swedish Radiation Safety Authority and The Healthcare Committee, Region Västra Götaland are greatly acknowledged.

Available from: 2021-11-22 Created: 2021-11-22 Last updated: 2022-01-20Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-7250-1443

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