Estimation of daily interfractional larynx residual setup error after isocentric alignment for head and neck radiotherapy: quality assurance implications for target volume and organs-at-risk margination using daily CT on-rails imaging

Purpose: The aim of this study is to comparatively examine the possibility of reducing the exposure dose to organs at risk, such as the hippocampus and lens, and improving the dose distribution of the planned target volume with and without the use of a head-tilting base plate in hippocampal-sparing whole-brain radiotherapy using tomotherapy. Methods: Five paired images of planned head computed tomography without and with tilt were analyzed. The hippocampus and planning target volume were contoured according to the RTOG 0933 contouring atlas protocol. The hippocampal zone to be avoided was delineated using a 5-mm margin. The prescribed radiation dose was 30 Gy in 10 fractions. The absorbed dose to planning target volume dose, absorbed dose to the organ at risk, and irradiation time were evaluated. The paired t-test was used to analyze the differences between hippocampal-sparing whole-brain radiotherapy with head tilts and without head tilts. Results: Hippocampal-sparing whole-brain radiotherapy with tilt was not superior in planning target volume doses using the homogeneity index than that without tilt; however, it showed better values, and for Dmean and D2%, the values were closer to 30 Gy. Regarding the hippocampus, dose reduction with tilt was significantly greater at Dmax, Dmean, and Dmin, whereas regarding the lens, it was significantly greater at Dmax and Dmin. The irradiation time was also predominantly shorter. Conclusion: In our study, a tilted hippocampal-sparing whole-brain radiotherapy reduced the irradiation time by >10%. Therefore, our study indicated that hippocampal-sparing whole-brain radiotherapy with tomotherapy should be performed with a tilt. The head-tilting technique might be useful during hippocampal-sparing whole-brain radiotherapy. This method could decrease the radiation exposure time, while sparing healthy organs, including the hippocampus and lens.

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Deep Learning-Based Delineation of Head and Neck Organs at Risk: Geometric and Dosimetric Evaluation

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/j.ijrobp.2019.02.040 ◽

2019 ◽

Vol 104 (3) ◽

pp. 677-684 ◽

Cited By ~ 15

Author(s):

Ward van Rooij ◽

Max Dahele ◽

Hugo Ribeiro Brandao ◽

Alexander R. Delaney ◽

Berend J. Slotman ◽

...

Keyword(s):

At Risk ◽

Deep Learning ◽

Head And Neck ◽

Organs At Risk

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Effect of Surgical Mask on Setup Error in Head and Neck Radiotherapy

Technology in Cancer Research & Treatment ◽

10.1177/1533033820974021 ◽

2020 ◽

Vol 19 ◽

pp. 153303382097402

Author(s):

Yi Ding ◽

Pingping Ma ◽

Wei Li ◽

Xueyan Wei ◽

Xiaoping Qiu ◽

...

Keyword(s):

Head And Neck ◽

Radiation Treatment ◽

Virus Disease ◽

T Test ◽

Setup Error ◽

Setup Errors ◽

Significant Difference ◽

The Mean ◽

Head And Neck Radiotherapy ◽

Head Neck

Purpose: With the widespread prevalence of Corona Virus Disease 2019 (COVID-19), cancer patients are suggested to wear a surgical mask during radiation treatment. In this study, cone beam CT (CBCT) was used to investigate the effect of surgical mask on setup errors in head and neck radiotherapy. Methods: A total of 91 patients with head and neck tumors were selected. CBCT was performed to localize target volume after patient set up. The images obtained by CBCT before treatment were automatically registered with CT images and manually fine-tuned. The setup errors of patients in 6 directions of Vrt, Lng, Lat, Pitch, Roll and Rotation were recorded. The patients were divided into groups according to whether they wore the surgical mask, the type of immobilization mask used and the location of the isocenter. The setup errors of patients were calculated. A t-test was performed to detect whether it was statistically significant. Results: In the 4 groups, the standard deviation in the directions of Lng and Pitch of the with surgical mask group were all higher than that in the without surgical mask group. In the head-neck-shoulder mask group, the mean in the Lng direction of the with surgical mask group was larger than that of the without surgical mask group. In the lateral isocenter group, the mean in the Lng and Pitch directions of the with surgical mask group were larger than that of the without surgical mask group. The t-test results showed that there was significant difference in the setup error between the 2 groups ( p = 0.043 and p = 0.013, respectively) only in the Lng and Pitch directions of the head-neck-shoulder mask group. In addition, the setup error of 6 patients with immobilization open masks exhibited no distinguished difference from that of the patients with regular immobilization masks. Conclusion: In the head and neck radiotherapy patients, the setup error was affected by wearing surgical mask. It is recommended that the immobilization open mask should be used when the patient cannot finish the whole treatment with a surgical mask.

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