Comparison of electron IMRT to helical photon IMRT and conventional photon irradiation for treatment of breast and chest wall tumours.
OBJECTIVE
Conventional irradiation of breast and chest wall tumours may cause high doses in underlying organs. Intensity-modulated radiation therapy (IMRT) with photons achieves high conformity between treated and tumour volume but is associated with considerable low-dose effects which may induce secondary malignancies. We compare treatment plans of electron IMRT to helical photon IMRT and conventional irradiation.


METHODS
Treatment planning for three patients (breast, chest wall plus lymph nodes, sarcoma of medial chest wall/sternum) was performed using XiO 4.3.3 (CMS) for conventional photon irradiation, Hi-Art 2.2.2.05 (TomoTherapy) for helical photon IMRT, and a self-designed programme for electron IMRT.


RESULTS
The techniques resulted in similar mean and maximum target doses. Target coverage by the 95%-isodose was best with tomotherapy. Mean ipsilateral lung doses were similar with all techniques. Electron IMRT achieved best sparing of heart, and contralateral breast. Compared with photon IMRT, electron IMRT allowed better sparing of contralateral lung and total healthy tissue.


CONCLUSIONS
Electron IMRT is superior to conventional irradiation, as it allows satisfying target coverage and avoids high doses in underlying organs. Its advantage over photon IMRT is better sparing of most organs at risk (low-dose effects) which reduces the risk of radiation-induced malignancies.
Gauer
Tobias
T
Department of Radiotherapy and Radio-Oncology, University Medical Center Hamburg-Eppendorf, Germany. t.gauer@uke.uni-hamburg.de
Engel
Konrad
K
Kiesel
Antje
A
Albers
Dirk
D
Rades
Dirk
D
D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D004583:Electrons; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D017785:Photons; D011878:Radiotherapy / Q000145:classification / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D013899:Thoracic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D035441:Thoracic Wall / Q000473:pathology