Dosimetric Comparison of Whole Breast Radiotherapy Using Field-in-Field and Volumetric Modulated Arc Therapy Techniques in Left-Sided Breast Cancer Patients

Abstract

The radiotherapy of left-sided breast cancers is challenging because of neighboring critical organs, posing an increased risk of complications. Various radiation delivery techniques have been used to deliver the desired dose of radiation to the target area while keeping the doses to nearby structures within constraints.The main aim of this study is to quantify doses delivered to the organs at risk (OARs) including heart, left lung, spinal cord, and contralateral breast, and to the planning target volume (PTV) using Field-in-Field (FIF) and Volumetric Modulated Arc Therapy (VMAT). Patients and methodsA retrospective review of 15 left-sided breast cancer patients was done. All the patients underwent breastconserving surgery and adjuvant radiation. For every patient, two different radiation treatment plans were formulated and compared for the PTV coverage and doses to OARs, including heart, ipsilateral lung, spinal cord, and contralateral breast.The radiation treatment techniques utilized for this purpose were FIF and VMAT. The homogeneity index (HI), and conformity index (CI) required for the treatment planning were also calculated. Data was analyzed using Statistical Package for the Social Sciences (IBM Corp., Armonk, USA). An Independent T-test was used for statistical analysis. ResultsThe mean age was 41 years and the majority of them were stage II. Total nine patients were given 4005centi Gray (cGy) in 15 fractions (fr) followed by 10Gy boost, hence receiving a total dose of 5005cGy in 20fr. While remaining six patients were given a total dose 4005cGy in 15fr without any boost.All patients were hypofractionated and the dose was delivered at a rate of 267cGy per fr. The FIF technique utilized in breast cancer radiation significantly reduced the mean doses to OARs: mean heart dose (3.81cGy), ipsilateral lung dose (V16-15cGy), mean contralateral breast dose (0.03cGy), and maximum spinal cord dose (0.18cGy); as compared to VMAT technique which delivered comparatively higher doses: mean heart dose (8.85cGy), ipsilateral lung dose (V16-19.82cGy), mean contralateral breast dose (4.59cGy), and maximum spinal cord dose (7.14cGy).There was a significant mean difference between doses of OARs and all p-values were statistically significant (p<0.005). Moreover, the FIF technique also improves the dose distribution of PTV in terms of dose homogeneity. However, the conformity index is more enhanced with VMAT as opposed to FIF. ConclusionThe FIF technique is more advantageous than the VMAT planning technique because it provides better dose distribution in terms of PTV coverage and significantly lower doses to OARs in radiotherapy to left-sided breast cancer.

Assessment of Field-in-Field, 3-Field, and 4-Field Treatment Planning Methods for Radiotherapy of Gastro-Esophageal Junction Cancer

“…Wedge-based beams are frequently employed in conformal treatment planning in radiation therapy to account for the tissue heterogeneity and abnormalities by malignant tumors [14,29]; however, the use of wedges has some shortages, such as inapplicability for large target areas and scattering of emissions towards normal tissues [30,31]. Compared with 3D CRT, the FIF technique uses simple (i.e., non-wedged) beams and can be performed at each center equipped with MLCs.…”

External-Beam-Accelerated Partial-Breast Irradiation Reduces Organ-at-Risk Doses Compared to Whole-Breast Irradiation after Breast-Conserving Surgery

“…Among the WBI patients, the maximum dose to the spinal cord was smaller compared to the APBI patients without irradiation of the periclavicular region (0.5 ± 0.3 Gy vs. 1.5 ± 1.1 Gy, p < 0.001) and clearly higher with this treatment (9.0 ± 5.5 Gy vs. 1.5 ± 1.1 Gy, p = 0.000). The maximum doses in the literature range between 0.18 Gy and 28.0 Gy depending on the particular technique used [ 45 , 46 ].…”

Off‐isocentric VMAT technique for breast cancer: Effective dose reduction to organs at risk and its applicability based on patient anatomy

“…Currently, there exists a spectrum of opinions regarding the superiority of one planning technique over another, even in breast‐ only treatment 11,21–27 . Multiple factors, ranging from the specific equipment in use and the experience of the physicist to the field arrangements, optimization process, and individual patient anatomies, influence the outcomes.…”

“…Currently, there exists a spectrum of opinions regarding the superiority of one planning technique over another, even in breast‐ only treatment. 11 , 21 , 22 , 23 , 24 , 25 , 26 , 27 Multiple factors, ranging from the specific equipment in use and the experience of the physicist to the field arrangements, optimization process, and individual patient anatomies, influence the outcomes. However, by introducing parameters that delve into the nuanced differences between patients, we can mitigate the variance introduced by patient anatomy in treatment results.…”