Tangent field technique of TomoDirect improves dose distribution for whole‐breast irradiation

Abstract

TomoDirect (TD) is an intensity‐modulated radiotherapy system that uses a fixed gantry angle instead of rotational beam delivery. Here, we investigated the effect of the multiple beam technique of TomoDirect on dose distribution compared with commonly‐used tangential beams. We included 45 consecutive patients with right breast cancer who underwent postoperative radiotherapy in our institute in the present study. Clinical target volume (CTV) was the whole right breast. The planning target volume (PTV) was created by expanding the CTV by a 0.5 cm margin. Paired TD plans were generated for each patient; a two‐beam plan using paired tangential beams and a six‐beam plan with four additional beams with modified gantry angles of ± 5° from the original tangential beam set. A prescribed dose of 50 Gy was defined for 50% isodoses of the PTV. The six‐beam plan delivered significantly more homogeneous doses to the PTV than the two‐beam plan; and the mean dose to the PTV in the six‐beam plan more closely reflected the prescribed dose. V20Gy and mean dose to the right lung and mean dose to the whole body were also significantly decreased in the six‐beam plan. However, duration of radiation exposure was 1 min longer in the six‐beam plan than in the two‐beam plan. The dose distribution to the target and organs at risk were improved with the six‐beam plan relative to the two‐beam plan without increasing the whole‐body radiation dose. The six‐beam plan using TD is a simple technique that can be routinely applied to whole‐breast irradiation in clinical practice.PACS number: 87.55

A treatment planning comparison of contemporary photon-based radiation techniques for breast cancer

“…Overall, TD was significantly superior to all other techniques in terms of IL sparing. Compared to previous studies, IL mean values obtained from our study in G1 were 14.9 ± 5. similar for FiF [10,15,16,32], s-IMRT 2f [14][15][16]31], s-IMRT 4f [14,31,32], VMAT [10,[14][15][16] and HT [10,18,32] while for TD it was lower than those previously published [23,32]. Rotational techniques significantly increased the low dose spillage to the contra-lateral lung as highlighted in particular by the V5Gy values that still remained well below the dose constraints as well as the endpoint for radio-induced pneumonitis.…”

Dosimetric and Radiobiological Comparison of Five Techniques for Postmastectomy Radiotherapy with Simultaneous Integrated Boost

“…Advanced RT techniques, such as fixed-field IMRT (ff-IMRT), or further developments, such as TomoTherapy, now allow treating multiple target volumes with different prescribed doses in a single plan. Previous studies have demonstrated that IMRT and TomoTherapy outperformed conventional three-dimensional conformal radiotherapy (3DCRT) for the whole breast irradiation [6][7][8]. Several studies have already been published comparing various treatment modalities for PMRT treatment without the boost scheme [9][10][11] and the whole breast irradiation [8,12,13].…”

Dosimetric study of the plan quality and dose to organs at risk on tangential breast treatments using the Halcyon linac

“…For breast cancer patients, reducing the dose to OARs from radiotherapy treatments is important as the 10‐year survival probability for diagnosed stage I and II patients treated with radiation after breast‐conserving therapy is higher than 60% . Several studies have reported dose to the OARs from the different modalities available for radiation delivery including three dimensional conformal therapy (3D‐CRT), tomotherapy, static‐field intensity‐modulated radiation therapy (IMRT) and volumetric arc therapy (VMAT) …”