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Impact of Changes in Body Shapes On Radiation Therapy Dose Distribution After Uterine Cervical Cancer Surgery

M Sasaki1*, H Ikushima2, K Kitagawa3, Y Kano4, M Tominaga5, H Honda6, W Sugimoto7, M Oita8, (1) Institute of Biomedical Sciences, Tokushima University Graduate School,Tokushima, JP, (2) Institute of Biomedical Sciences, Tokushima University Graduate School,Tokushima, JP, (3)Graduate School of Health Sciences, Tokushima University,Tokushima,JP(4)Graduate School of Health Sciences, Tokushima University,Tokushima,JP(5) Institute of Biomedical Sciences, Tokushima University Graduate School,Tokushima, JP, (6) Ehime University Hospital, Ehime, JP, (7) Tokushima Prefectural Central Hospital, Tokushima, JP, (8) Okayama University Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama, 33, JP

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose:
Patients receiving uterine cervical cancer might not be able to eat during radiation therapy, because of the effects of concurrent chemo-radiotherapy; this may lead to changes in the patient's body shape the treatment period. When performing image-guided radiotherapy, it is necessary to immediately determine whether the treatment can be performed on the day or re-planning is required. The purpose of this study was to determine indicators of re-planning by examining the effects of changing body contours on the radiation therapy dose.

Methods:
The original body contour was reduced by 1 cm in the front portion (Structure-set 1) and by 1 cm in all directions except the back (Structure-set 2). Based on the original dose distribution, the recalculated dose distribution was performed using a structure set created using the body contours of Structure-set 1 and Structure-set 2. The difference between the original and recalculated dose distributions of the two structure-sets was evaluated through gamma analysis (GA).

Results:
When the body contour was reduced by 1 cm only in the front, a pass rate of 90% or more was obtained through GA, with a criterion of 2 mm/2% in all cases. In contrast, when the body contour was reduced by 1 cm in all directions except the back, significant differences in the dose distribution that varied from each other were observed in each case.

Conclusion:
Our results suggest that dose re-planning is rarely required when the body shape is reduced by only 1 cm in the front.

Keywords

Dosimetry

Taxonomy

IM/TH- Image Analysis (Single Modality or Multi-Modality): Image registration

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