scholarly journals Interobserver variation in clinical target volume and organs at risk segmentation in post-parotidectomy radiotherapy: can segmentation protocols help?

2012 ◽  
Vol 85 (1016) ◽  
pp. e530-e536 ◽  
Author(s):  
M Mukesh ◽  
R Benson ◽  
R Jena ◽  
A Hoole ◽  
T Roques ◽  
...  
Keyword(s):  
At Risk ◽  
Clinical Target Volume ◽  
Organs At Risk ◽  
Target Volume ◽  
Interobserver Variation

Comparative dosimetry of brachytherapy treatment planning between a volume-based plan by CT and a point-based plan by TAUS in CT datasets for brachytherapy

2021 ◽  
pp. 1-8
Author(s):  
Chaiyaporn Pintakham ◽  
Ekkasit Tharavichitkul ◽  
Somsak Wanwilairat ◽  
Wannapha Nobnop
Keyword(s):  
At Risk ◽  
Treatment Planning ◽  
Sigmoid Colon ◽  
Clinical Target Volume ◽  
Organs At Risk ◽  
Target Volume ◽  
Reference Points ◽  
Uterine Perforation ◽  
Target Dose ◽  
The Mean

Abstract Aim: To evaluate comparative dosimetry of brachytherapy treatment planning between a volume-based plan by computed tomography (CT) and a point-based plan by transabdominal ultrasound (TAUS) in CT datasets for brachytherapy. Materials and methods: From 2019 to 2021, 59 different datasets of CT images were collected from 38 patients treated by intracavitary brachytherapy with tandem ovoid or tandem ring applicators. At that time, TAUS was performed to prevent uterine perforation and to evaluate topography of the cervix during application. In volume-based planning by CT, the target dose was used to keep the dose at 90% of high-risk clinical target volume (HR-CTV), to give a dose of at least 7Gy, while in the point-based plan by TAUS, the target dose was used to keep the minimum dose to eight cervix reference points (measured by TAUS), to give a dose of at least 7Gy. The doses to targets and organs at risk were evaluated and compared between volume-based planning by CT and the point-based plan by TAUS. Results: Of 59 fractions, a tandem ovoid applicator was used in 48 fractions (81·3%). In the volume-based plan by CT, the mean doses to HR-CTV(D90), intermediate-risk clinical target volume (IR-CTV)(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 7·0, 3·9, 4·9, 2·9 and 3·3 Gy, respectively, while in the point-based plan by TAUS, the mean doses to HR-CTV(D90), IR-CTV(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 8·2, 4·6, 5·9, 3·4 and 3·9 Gy, respectively. The percentages of mean dose differences between TAUS and CT of HR-CTV(D90), IR-CTV(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 17·7, 19·5, 20·5, 19·5, 21·3 and 19·8%, respectively. With the target dose to the point-based plan by TAUS (7 Gy to the cervix reference points), this was close to D98 of HR-CTV with a mean percentage of difference of 0·6%. Findings: The point-based plan by TAUS showed higher values to targets and organs at risk than the volume-based plan by CT. With the point-based plan by TAUS, it was close to D98 of HR-CTV.

scholarly journals Atlas Sampling for Prone Breast Automatic Segmentation of Organs at Risk: The Importance of Patients’ Body Mass Index and Breast Cup Size for an Optimized Contouring of the Heart and the Coronary Vessels

2020 ◽  
Vol 19 ◽  
pp. 153303382092062
Author(s):  
Xinzhuo Wang ◽  
Raymond Miralbell ◽  
Odile Fargier-Bochaton ◽  
Shelley Bulling ◽  
Jean Paul Vallée ◽  
...  
Keyword(s):  
Body Mass Index ◽  
At Risk ◽  
Body Mass ◽  
Clinical Target Volume ◽  
Organs At Risk ◽  
Automatic Segmentation ◽  
Coronary Vessels ◽  
Target Volume ◽  
Breast Volume ◽  
Mean Similarity

Objective: Delineation of organs at risk is a time-consuming task. This study evaluates the benefits of using single-subject atlas-based automatic segmentation of organs at risk in patients with breast cancer treated in prone position, with 2 different criteria for choosing the atlas subject. Together with laterality (left/right), the criteria used were either (1) breast volume or (2) body mass index and breast cup size. Methods: An atlas supporting different selection criteria for automatic segmentation was generated from contours drawn by a senior radiation oncologist (RO_A). Atlas organs at risk included heart, left anterior descending artery, and right coronary artery. Manual contours drawn by RO_A and automatic segmentation contours of organs at risk and breast clinical target volume were created for 27 nonatlas patients. A second radiation oncologist (RO_B) manually contoured (M_B) the breast clinical target volume and the heart. Contouring times were recorded and the reliability of the automatic segmentation was assessed in the context of 3-D planning. Results: Accounting for body mass index and breast cup size improved automatic segmentation results compared to breast volume-based sampling, especially for the heart (mean similarity indexes >0.9 for automatic segmentation organs at risk and clinical target volume after RO_A editing). Mean similarity indexes for the left anterior descending artery and the right coronary artery edited by RO_A expanded by 1 cm were ≥0.8. Using automatic segmentation reduced contouring time by 40%. For each parameter analyzed (eg, D2%), the difference in dose, averaged over all patients, between automatic segmentation structures edited by RO_A and the same structure manually drawn by RO_A was <1.5% of the prescribed dose. The mean heart dose was reliable for the unedited heart segmentation, and for right-sided treatments, automatic segmentation was adequate for treatment planning with 3-D conformal tangential fields. Conclusions: Automatic segmentation for prone breast radiotherapy stratified by body mass index and breast cup size improved segmentation accuracy for the heart and coronary vessels compared to breast volume sampling. A significant reduction in contouring time can be achieved by using automatic segmentation.

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