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Flejmer, A. M., Chehrazi, B., Josefsson, D., Toma-Dasu, I. & Dasu, A. (2017). Impact of physiological breathing motion for breast cancer radiotherapy with proton beam scanning: An in silico study. Physica medica (Testo stampato), 39, 88-94
Open this publication in new window or tab >>Impact of physiological breathing motion for breast cancer radiotherapy with proton beam scanning: An in silico study
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2017 (English)In: Physica medica (Testo stampato), ISSN 1120-1797, E-ISSN 1724-191X, Vol. 39, p. 88-94Article in journal (Refereed) Published
Abstract [en]

This study investigates the impact of breathing motion on proton breast treatment plans. Twelve patients with CT datasets acquired during breath-hold-at-inhalation (BHI), breath-hold-at-exhalation (BHE) and in free-breathing (FB) were included in the study. Proton plans were designed for the left breast for BHI and subsequently recalculated for BHE or designed for FB and recalculated for the extreme breath-hold phases. The plans were compared from the point of view of their target coverage and doses to organs-at-risk. The median amplitude of breathing motion determined from the positions of the sternum was 4.7 mm (range 0.5-14.6 mm). Breathing motion led to a degradation of the dose coverage of the target (heterogeneity index increased from 4-7% to 8-11%), but the degraded values of the dosimetric parameters of interest fulfilled the clinical criteria for plan acceptance. Exhalation decreased the lung burden [average dose 3.1-4.5 Gy (RBE)], while inhalation increased it [average dose 5.8-6.8 Gy (RBE)]. The individual values depended on the field arrangement. Smaller differences were seen for the heart [average dose 0.1-0.2 Gy (RBE)] and the LAD [1.9-4.6 Gy (RBE)]. Weak correlations were generally found between changes in dosimetric parameters and respiratory motion. The differences between dosimetric parameters for various breathing phases were small and their expected clinical impact is consequently quite small. The results indicated that the dosimetric parameters of the plans corresponding to the extreme breathing phases are little affected by breathing motion, thus suggesting that this motion might have little impact for the chosen beam orientations with scanned proton beams.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Cancer and Oncology
Identifiers
urn:nbn:se:liu:diva-127369 (URN)10.1016/j.ejmp.2017.06.001 (DOI)000405493200012 ()28606833 (PubMedID)
Note

Funding agencies: LiU Cancer research network at Linkoping University and Region Ostergotland (Sweden)

Available from: 2016-04-23 Created: 2016-04-23 Last updated: 2018-05-02Bibliographically approved
Flejmer, A. M., Edvardsson, A., Dohlmar, F., Josefsson, D., Nilsson, M., Witt Nyström, P. & Dasu, A. (2016). Respiratory gating for proton beam scanning versus photon 3D-CRT for breast cancer radiotherapy. Acta Oncologica, 55(5), 577-583
Open this publication in new window or tab >>Respiratory gating for proton beam scanning versus photon 3D-CRT for breast cancer radiotherapy
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2016 (English)In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 55, no 5, p. 577-583Article in journal (Refereed) Published
Abstract [en]

Background Respiratory gating and proton therapy have both been proposed to reduce the cardiopulmonary burden in breast cancer radiotherapy. This study aims to investigate the additional benefit of proton radiotherapy for breast cancer with and without respiratory gating.

Material and methods Twenty left-sided patients were planned on computed tomography (CT)-datasets acquired during enhanced inspiration gating (EIG) and free-breathing (FB), using photon three-dimensional conformal radiation therapy (3D-CRT) and scanned proton beams. Ten patients received treatment to the whole breast only (WBO) and 10 were treated to the breast and the regional lymph nodes (BRN). Dosimetric parameters characterizing the coverage of target volumes and the cardiopulmonary burden were compared using a paired, two-tailed Student’s t-test.

Results Protons ensured comparable or better target coverage than photons in all patients during both EIG and FB. The heterogeneity index decreased from 12% with photons to about 5% with protons. The mean dose to the ipsilateral lung was reduced in BRN patients from 12 Gy to 7 Gy (RBE) in EIG and from 14 Gy to 6-7 Gy (RBE) in FB, while for WBO patients all values were about 5-6 Gy (RBE). The mean dose to heart decreased by a factor of four in WBO patients [from 1.1 Gy to 0.3 Gy (RBE) in EIG and from 2.1 Gy to 0.5 Gy (RBE) in FB] and 10 in BRN patients [from 2.1 Gy to 0.2 Gy (RBE) in EIG and from 3.4 Gy to 0.3 Gy (RBE) in FB]. Similarly, the mean and the near maximum dose to left anterior descending artery (LAD) were significantly lower (p<0.05) with protons in comparison with photons.

Conclusion Proton spot scanning has a high potential to reduce the irradiation of organs at risk and other normal tissues for most patients, beyond what could be achieved with EIG and photon therapy. The largest dose sparing has been seen for BRN patients, both in terms of cardiopulmonary burden and integral dose.

National Category
Cancer and Oncology
Identifiers
urn:nbn:se:liu:diva-123274 (URN)10.3109/0284186X.2015.1120883 (DOI)000375566700008 ()
Note

Funding agencies:  LiU Cancer research network at Linkoping University; Region Ostergotland; ALF Grants from Region Ostergotland (Sweden)

Available from: 2015-12-09 Created: 2015-12-09 Last updated: 2017-04-24
Flejmer, A. M., Witt Nyström, P., Dohlmar, F., Josefsson, D. & Dasu, A. (2015). Potential benefit of scanned proton beam versus photons as adjuvant radiation therapy in breast cancer. International Journal of Particle Therapy, 1(4), 845-855
Open this publication in new window or tab >>Potential benefit of scanned proton beam versus photons as adjuvant radiation therapy in breast cancer
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2015 (English)In: International Journal of Particle Therapy, ISSN 2331-5180, Vol. 1, no 4, p. 845-855Article in journal (Refereed) Published
Abstract [en]

Purpose: To investigate the feasibility of using scanned proton beams as adjuvant radiation therapy for breast cancer. Long-term cardiopulmonary complications may worsen the quality of life and reduce the positive contribution of radiation therapy, which has been known to improve long-term control of locoregional disease as well as the long-term survival for these patients.

Materials and Methods: Ten patients with stage I-III cancer (either after mastectomy or lumpectomy, left- or right-sided) were included in the study. The patients were identified from a larger group where dose heterogeneity in the target and/or hotspots in the normal tissues qualified them for irregular surface compensator planning with photons. The patients underwent planning with 2 scanned proton beam planning techniques, single-field uniform dose and intensity-modulated proton therapy, and the results were compared with those from irregular surface compensator. All volumes of interest were delineated and reviewed by experienced radio-oncologists. The patients were prescribed 50 GyRBE in 25 fractions. Dosimetric parameters of interest were compared with a paired, 2-tailed Student t test.

Results: The proton plans showed comparable or better target coverage than the original photon plans. There were also large reductions with protons in mean doses to the heart (0.2 versus 1.3 GyRBE), left anterior descending artery (1.4 versus 6.4 GyRBE), and the ipsilateral lung (6.3 versus 7.7 GyRBE). This reduction is important from the point of view of the quality of life of the patients after radiation therapy. No significant differences were found between single-field uniform dose and intensity-modulated proton therapy plans.

Conclusion: Spot scanning technique with protons may improve target dose homogeneity and further reduce doses to the organs at risk compared with advanced photon techniques. The results from this study indicate a potential for protons as adjuvant radiation therapy in breast cancer and a further step toward the individualization of treatment based on anatomic and comorbidity characteristics.

Keywords
breast radiation therapy, proton radiation therapy, pencil beam scanning, irregular surface compensator, fractionated radiation therapy
National Category
Cancer and Oncology
Identifiers
urn:nbn:se:liu:diva-112949 (URN)10.14338/IJPT-14-00013.1 (DOI)
Available from: 2014-12-31 Created: 2014-12-31 Last updated: 2016-04-27
Ardenfors, O., Josefsson, D. & Dasu, A. (2014). Are IMRT treatments in the head and neck region increasing the risk of secondary cancers?. Acta Oncologica, 53(8), 1041-1047
Open this publication in new window or tab >>Are IMRT treatments in the head and neck region increasing the risk of secondary cancers?
2014 (English)In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 53, no 8, p. 1041-1047Article in journal (Refereed) Published
Abstract [en]

Background: Intensity modulated radiation therapy (IMRT) has been increasingly employed for treating head and neck (H&N) tumours due to its ability to produce isodoses suitable for the complex anatomy of the region. The aim of this study was to assess possible differences between IMRT and conformal radiation therapy (CRT) with regard to risk of radiation-induced secondary malignancies for H&N tumours.

Material and Methods: IMRT and CRT plans were made for 10 H&N adult patients and the resulting treatment planning data were used to calculate the risk of radiation-induced malignancies in four different tissues. Three risk models with biologically relevant parameters were used for calculations. The influence of scatter radiation and repeated imaging sessions has also been investigated.

Results: The results showed that the total lifetime risks of developing radiation-induced secondary malignancies from the two treatment techniques, CRT and IMRT, were comparable and in the interval 0.9-2.5%. The risk contributions from the primary beam and scatter radiation were comparable, whereas the contribution from repeated diagnostic imaging was considerably smaller.

Conclusion: The results indicated that the redistribution of the dose characteristic to IMRT leads to a redistribution of the risks in individual tissues. However, the total levels of risk were similar between the two irradiation techniques considered.

Place, publisher, year, edition, pages
Informa Healthcare, 2014
National Category
Cancer and Oncology Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-106634 (URN)10.3109/0284186X.2014.925581 (DOI)000340892900008 ()24983652 (PubMedID)
Available from: 2014-05-16 Created: 2014-05-16 Last updated: 2017-12-05
Flejmer, A. M., Josefsson, D., Nilsson, M., Stenmarker, M. & Dasu, A. (2014). Clinical implications of the ISC technique for breast cancer radiotherapy and comparison with clinical recommendations. Anticancer Research, 34(7), 3563-3568
Open this publication in new window or tab >>Clinical implications of the ISC technique for breast cancer radiotherapy and comparison with clinical recommendations
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2014 (English)In: Anticancer Research, ISSN 0250-7005, E-ISSN 1791-7530, Vol. 34, no 7, p. 3563-3568Article in journal (Refereed) Published
Abstract [en]

Purpose: The project studied the implications of using the irregular surface compensator (ISC) technique in comparison to three-dimensional conformal radiation therapy (3D-CRT) for breast cancer treatment. ISC is an electronic compensation algorithm that modulates the fluence across the radiation fields to compensate for irregularly shaped surfaces and deliver a homogeneous dose to a compensation plane. Methods: Ten breast cancer patients (five left- and five right-sided) were planned with both techniques. The planning was done for 50 Gy in 25 fractions with 2 Gy per fraction in all patients. Physical parameters such as doses to the clinical target volume (CTV-T) and the planned target volume (PTV), heterogeneity index and doses to lung and heart were determined and compared for the treatment plans. Results: The ISC technique led to significantly better coverage of the CTV-T and PTV in almost all patients with statistically significant better homogeneity of the dose distribution. The contralateral lung and the heart receive the same doses with both ISC and 3D-CRT plans. However, ISC showed a trend towards decreasing the volumes of the ipsilateral lung irradiated with high doses. Consequently this led to better compliance with the national recommendations for breast radiotherapy. Conclusion: The ISC technique leads to an improvement of the target coverage and the radiation burden of the ipsilateral lung thus allowing better compliance with the national recommendations and increasing the potential for improved quality of life for breast cancer patients. It should therefore be preferred over 3D-CRT for breast cases with difficult dose homogeneity to the PTV or CTV-T.

Place, publisher, year, edition, pages
International Institute of Anticancer Research, 2014
Keywords
breast radiotherapy, irregular surface compensator, fractionated radiotherapy, irradiation technique
National Category
Cancer and Oncology
Identifiers
urn:nbn:se:liu:diva-106944 (URN)000338780300044 ()24982370 (PubMedID)
Available from: 2014-05-28 Created: 2014-05-28 Last updated: 2017-12-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7193-4458

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