Normal tissue sparing potential of scanned proton beams with and without respiratory gating for the treatment of internal mammary nodes in breast cancer radiotherapy

Proton therapy has shown potential for reducing doses to normal tissues in breast cancer radiotherapy. However data on the impact of protons when including internal mammary nodes (IMN) in the target for breast radiotherapy is comparatively scarce. This study aimed to evaluate normal tissue doses when including the IMN in regional RT with scanned proton beams, with and without respiratory gating. The study cohort was composed of ten left-sided breast patients CT-scanned during enhanced inspiration gating (EIG) and free-breathing (FB). Proton plans were designed for the target including or excluding the IMN. Targets and organs-at-risk were delineated according to RTOG guidelines. Comparison was performed between dosimetric parameters characterizing target coverage and OAR radiation burden. Statistical significance of differences was tested using a paired, two-tailed Student's t-test. Inclusion of the IMN in the target volume led to a small increase of the cardiopulmonary burden. The largest differences were seen for the ipsilateral lung where the mean dose increased from 6.1 to 6.6 Gy (RBE) (P < 0.0001) in FB plans and from 6.9 to 7.4 Gy (RBE) (P = 0.003) in EIG plans. Target coverage parameters were very little affected by the inclusion of IMN into the treatment target. Radiotherapy with scanned proton beams has the potential of maintaining low cardiovascular burden when including the IMN into the target, irrespective of whether respiratory gating is used or not.

Flejmer, Anna M.,1971-Linköping University,Linköpings universitet,Avdelningen för Kirurgi, Ortopedi och Onkologi,Medicinska fakulteten,Region Östergötland, Onkologiska kliniken US,The Skandion Clinic, Uppsala, Sweden(Swepub:liu)annfl57 (författare)
Edvardsson, AnneliLund University,Lunds universitet,Medicinsk strålningsfysik, Lund,Sektion V,Institutionen för kliniska vetenskaper, Lund,Medicinska fakulteten,Medical Radiation Physics, Lund,Section V,Department of Clinical Sciences, Lund,Faculty of Medicine(Swepub:lu)med-ae5 (författare)
Witt Nyström, PetraThe Skandion Clinic, Uppsala, Sweden,Aarhus University Hospital(Swepub:uu)petwi362 (författare)
The Skandion Clinic, Uppsala, SwedenAvdelningen för Kirurgi, Ortopedi och Onkologi (creator_code:org_t)

Ingår i:Physica medica (Testo stampato): Elsevier BV52, s. 81-851120-17971724-191X

Av författaren/redakt...: Dasu, Alexandru; Flejmer, Anna M. ...; Edvardsson, Anne ...; Witt Nyström, Pe ...

Om ämnet

MEDICIN OCH HÄLSOVETENSKAP: MEDICIN OCH HÄLS ...; och Klinisk medicin; och Cancer och onkol ...

MEDICIN OCH HÄLSOVETENSKAP: MEDICIN OCH HÄLS ...; och Klinisk medicin; och Radiologi och bi ...

Av lärosätet: Uppsala universitet; Linköpings universitet; Lunds universitet

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