A comparative dosimetric study for treating left-sided breast cancer for small breast size using five different radiotherapy techniques: conventional tangential field, filed-in-filed, Tangential-IMRT, Multi-beam IMRT and VMAT

Abstract

Background and purposesTo compare the dosimetry for the left-sided breast cancer treatment using five different radiotherapy techniques.Materials and methodsTwenty patients with left sided breast cancer were treated with conservative surgery followed by radiotherapy. They were planned using five different radiotherapy techniques, including: 1) conventional tangential wedge-based fields (TW); 2) field-in-field (FIF) technique; 3) tangential inverse planning intensity-modulated radiation therapy (T-IMRT); 4) multi-field IMRT (M-IMRT); and 5) volumetric modulated arc therapy (VMAT). The CTV, PTV and OARs including the heart, the regions of coronary artery (CA), the contralateral breast, the left and right lung were delineated. The PTV dose was prescribed 50Gy and V47.5≥95%. Same dose constraint was used for all five plans. The planned volumetric dose of PTV and PRV-OARs were compared and analyzed.ResultsExcept VMAT (Average V47.5 was 94.72%±1.2%), all the other four plans were able to meet the V95% (V47.5) requirement. T-IMRT plan improved the PTV dose homogeneity index (HI) by 0.02 and 0.03 when compared to TW plan and VMAT plan, and decreased the V5, V10 and V20 of all PRV-OARs. However, the high dose volume (≥ 30Gy) of the PRV-OARs in T-IMRT plan had no statistically significant difference compared with the other two inverse plans. In all five plans, the dose volume of coronary artery area showed a strong correlation to the dose volume of the heart (the correlation coefficients were 0.993, 0.996, 1.000, 0.995 and 0.986 respectively).ConclusionCompared to other techniques, the T-IMRT technology reduced radiation dose exposure to normal tissues and maintained reasonable target homogeneity, VMAT is not recommended for left-sided breast cancer treatment. In five techniques, the dose-volume histogram (DVH) of the heart can be used to predict the dose-volume histogram (DVH) of the coronary artery.

Heart dose reduction in breast cancer treatment with simultaneous integrated boost

“…The following values were determined for group b: 3D-CRT, 1.5 ± 0.9 Gy; hybrid, 1.1 ± 0.6 Gy (p < 0.01). There is on average 1 Gy less load on the heart for left-sided tumors 3D-CRT three-dimensional conformal radiotherapy, PTV planning target volume, SIB simultaneous integrated boost, HI homogeneity index, CI conformity index Jin et al argued against the use of only VMAT for radiation of left-sided mammary carcinoma because of the high volume that is exposed to low dose and the comparably high dose of the contralateral breast and lung [6]. Moreover, Badakhshi et al could not find an advantage of the sole use of VMAT for the treatment of breast cancer when compared with 3D-CRT and IMRT [7].…”

Cardiac Side-effects From Breast Cancer Radiotherapy

“…For example, in the context of whole breast radiotherapy alone, Jin et al [21] reported values for the volume of heart receiving 20 Gy or more (V 20Gy ) of 5.6% for standard tangential wedged fields, 4.3% for forward-planned IMRT, 2.1% for seven-field IMRT and 2.0% for tangential inverseplanned IMRT, suggesting a benefit from the inverseplanned approaches. However, the more complex the field arrangement, the larger the low-dose bath of radiation, such that the mean heart dose may actually be increased by multifield IMRT approaches.…”

A Dosimetric Study of Conformal Radiotherapy Plan With Wedge and Field-in-Field-Forward-Planned Radiotherapy in Left Sided Breast Cancer.

“…Also, VMAT plan had advantages in reducing the volume of high dose with increased volume of lower dose (22)., G. Yavas et al, reported that the monitor units required for the FIF 1950 technique were lower when compared to CRT technique (7). In field in field strategy, the monitor units were adjusted among the sub-fields and even an increase in the number of sub-fields wouldn't have much change in the MUs.…”