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Comparison of Dose Distribution and Dose Indexes in Whole Breast Irradiation Plans With/without Breath-Hold Technique Using Dynamic Movable Head of Tilt/pan Angles

N Hayashi1*, Y Takada2 , T Mizuno2 , T Murai3 , (1) Fujita Health University, Tayoake, (2) Ogaki Tokushukai Hospital, Ogaki, 21, (3) Nagoya City University, Nagoya,


(Wednesday, 7/17/2019) 10:00 AM - 10:30 AM

Room: Exhibit Hall | Forum 1

Purpose: The VERO-4DRT system is available dynamic head tilt/pan angled irradiation with the field size of 15 cm x 15 cm. With this system, it is possible to improve dose distribution using the field-in-field technique with breath-hold irradiation for breast cancer. The purpose of this study is to compare dose plans retrospectively in whole breast irradiation with- and without breath-hold technique.

Methods: A total of 57 cases with breast cancer underwent whole breast irradiation using VERO-4DRT system with- and without breath-hold technique was analyzed retrospectively. The rate of with- and without breath-hold was 32 and 25 cases, respectively. All radiotherapy treatment plans were created by i-Plan workstation (BrainLAB) with tangential field-in-field technique. In order to avoid inter-planner variation, all structures were delineated by a radiation oncologist, then beam arrangements were designed by a medical physicist. The dose distribution and dose indexes such as Dmax, D98, D95, D50, D5, D2 at PTV and V20, V10 at lung were analyzed and compared statistically between with- and without breath-hold.

Results: The volumes of PTV in the group of with- and without breath-hold were 589.9 ± 254.5 cc and 689.5 ± 261.7 cc, respectively. The volumes of lung in the group of with- and without breath-hold were 3167.6 ± 668.1 cc and 2367.5 ± 503.2 cc, respectively. The V20 of with-and without breath-hold were 5.86 ± 1.98% and 7.16 ± 2.76%, respectively. The comparison of D95 was not statistically significant difference, but V20 and V10 were indicated as statistically significant difference.

Conclusion: The dynamic tilt/pan angled breath-hold tangential field-in-field technique is useful for patient with breast cancer to improve dose distribution using VERO-4DRT system. With breath-hold, the dose in lung was reduced with statistically significant difference compared to whole breast irradiation without breath-hold.


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