Intensity modulated radiotherapy and 3D conformal radiotherapy for whole breast irradiation: a comparative dosimetric study and introduction of a novel qualitative index for plan evaluation, the normal tissue index

Journal Article · Tue Sep 15 04:00:00 EDT 2015 · Journal of Medical Radiation Sciences (Print)

DOI:https://doi.org/10.1002/JMRS.126· OSTI ID:22420147

Yim, Jackie; Suttie, Clare; Bromley, Regina; Morgia, Marita; Lamoury, Gillian ^[1]

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1. Department of Radiation Oncology, Royal North Shore Hospital, St Leonards, New South Wales (Australia)

We report on a retrospective dosimetric study, comparing 3D conformal radiotherapy (3DCRT) and hybrid intensity modulated radiotherapy (hIMRT). We evaluated plans based on their planning target volume coverage, dose homogeneity, dose to organs at risk (OARs) and exposure of normal tissue to radiation. The Homogeneity Index (HI) was used to assess the dose homogeneity in the target region, and we describe a new index, the normal tissue index (NTI), to assess the dose in the normal tissue inside the tangent treatment portal. Plans were generated for 25 early-stage breast cancer patients, using a hIMRT technique. These were compared with the 3DCRT plans of the treatment previously received by the patients. Plan quality was evaluated using the HI, NTI and dose to OARs. The hIMRT technique was significantly more homogenous than the 3DCRT technique, while maintaining target coverage. The hIMRT technique was also superior at minimising the amount of tissue receiving D{sub 105%} and above (P < 0.0001). The ipsilateral lung and contralateral breast maximum were significantly lower in the hIMRT plans (P < 0.05 and P < 0.005), but the 3DCRT technique achieved a lower mean heart dose in left-sided breast cancer patients (P < 0.05). Hybrid intensity modulated radiotherapy plans achieved improved dose homogeneity compared to the 3DCRT plans and superior outcome with regard to dose to normal tissues. We propose that the addition of both HI and NTI in evaluating the quality of intensity modulated radiotherapy (IMRT) breast plans provides clinically relevant comparators which more accurately reflect the new paradigm of treatment goals and outcomes in the era of breast IMRT.

• OSTI ID: 22420147
• Journal Information: Journal of Medical Radiation Sciences (Print), Journal Name: Journal of Medical Radiation Sciences (Print) Journal Issue: 3 Vol. 62; ISSN 2051-3895
• Country of Publication: Australia
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
DOSES
HAZARDS
HYBRIDIZATION
INDEXES
IRRADIATION
MAMMARY GLANDS
NEOPLASMS
PATIENTS
RADIOTHERAPY