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Evaluation and risk factors of volume and dose differences of selected structures in patients with head and neck cancer treated on Helical TomoTherapy by using Deformable Image Registration tool

Bąk Bartosz, Skrobała Agnieszka, Adamska Anna, Józefacka Natalia, Styś Sara, Malicki Julian

Polish Journal of Medical Physics and Engineering

2022

Vol. 28, Iss. 2

60--68

Introduction: The aim of this study was the evaluation of volume and dose differences in selected structures in patients with head and neck cancer during treatment on Helical TomoTherapy (HT) using a commercially available deformable image registration (DIR) tool. We attempted to identify anatomical and clinical predictive factors for significant volume changes probability. Material and methods: According to our institutional protocol, we retrospectively evaluated the group of 20 H&N cancer patients treated with HT who received Adaptive Radiotherapy (ART) due to soft tissue alterations spotted on daily MVCT. We compared volumes on initial computed tomography (iCT) and replanning computed tomography (rCT) for clinical target volumes (CTV) – CTV1 (the primary tumor) and CTV2 (metastatic lymph nodes), parotid glands (PG) and body contour (B-body). To estimate the planned and delivered dose discrepancy, the dose from the original plan was registered and deformed to create a simulation of dose distribution on rCT (DIR-rCT). Results: The decision to replan was made at the 4th week of RT (N = 6; 30%). The average volume reduction in parotid right PG[R] and left PG[L] was 4.37 cc (18.9%) (p < 0.001) and 3.77 cc (16.8%) (p = 0.004), respectively. In N = 13/20 cases, the delivered dose was greater than the planned dose for PG[R] of mean 3 Gy (p < 0.001), and in N = 6/20 patients for PG[L] the mean of 3.6 Gy (p = 0.031). Multivariate regression analysis showed a very strong predictor explaining 88% (R2 = 0.88) and 83% (R2 = 0.83) of the variance based on the mean dose of iPG[R] and iPG[L] (p < 0.001), respectively. No statistically significant correlation between volume changes and risk factors was found. Conclusions: Dosimetric changes to the target demonstrated the validity of replanning. A DIR tool can be successfully used for dose deformation and ART qualification, significantly reducing the workload of radiotherapy centers. In addition, the mean dose for PG was a significant predictor that may indicate the need for a replan.

The Issues of Catchment Boundaries Delimitation in a Suburban Area – the Case Study of Poznań Metropolitan Area, Poland

Mrozik Karol, Napierała Michał, Adamska Anna

Journal of Ecological Engineering

2020

Vol. 21, nr 3

202--208

The urbanisation and suburbanisation processes are considered to have a detrimental impact on the environment. Increasing the share of the impervious surfaces is one of their main negative effects, particularly in and near the cities, affecting the water relations of basins. It also results in new catchment boundaries formation and, in many cases, changes in the physiographic parameters affecting the accuracy of hydrological and hydraulic calculations of small suburban catchments. This study is an attempt to delimit the catchment boundaries located in the suburban area of Poznań city, Poland, in three variants: according to the Raster Hydrographical Map of Poland and Raster Topographical Map of Poland, digital elevation model, and rainwater sewage system. The analyses were conducted with ArcGIS software, and the results were additionally verified with geodesic measurements on site. This work focuses mainly on the impact of anthropogenic pressure on the catchment shape and the course of its boundaries. The analyses were conducted on the Rów WB stream catchment located in the Skórzewo village, Dopiewo municipality, which stands out within the Poznań Metropolitan Area as the area where the suburbanisation process is the most intensified. This study proved that the agrotechnical and drainage works performed in undeveloped, agricultural areas affected catchment shape and size as much as suburbanisation itself. According to the authors, the suburban catchment boundaries should be regularly updated due to the intensity of the new investments development and additionally verified on site.