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 Automatic Segmentation of Clinical Target Volume and Organs-At-Risk for Breast Conservative Radiotherapy Using a Convolutional Neural Network

2021 ◽  
Author(s):  
Zhikai Liu ◽  
Fangjie Liu ◽  
Wanqi Chen ◽  
Yinjie Tao ◽  
Xia Liu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Spinal Cord ◽  
At Risk ◽  
Clinical Target Volume ◽  
Organs At Risk ◽  
Target Volume ◽  
Contralateral Breast ◽  
Dice Similarity Coefficient ◽  
Proposed Model ◽  
The Mean

Abstract Background and Objective: Delineation of the clinical target volume (CTV) and organs at risk (OARs) is very important for radiotherapy but is time-consuming and prone to inter- and intra-observer variation. We trained and evaluated a U-Net-based model to provide fast and consistent auto-segmentation for breast cancer radiotherapy. Methods: We collected 160 patients’ computed tomography (CT) scans with early-stage breast cancer who underwent breast-conserving surgery (BCS) and were treated with radiotherapy in our center. CTV and OARs (contralateral breast, heart, lungs and spinal cord) were delineated manually by two experienced radiation oncologists. The data were used for model training and testing. The dice similarity coefficient (DSC) and 95th Hausdorff distance (95HD) were used to assess the performance of our model. CTV and OARs were randomly selected as ground truth (GT) masks, and artificial intelligence (AI) masks were generated by the proposed model. The contours were randomly distributed to two clinicians to compare CTV score differences. The consistency between two clinicians was tested. We also evaluated time cost for auto-delineation. Results: The mean DSC values of the proposed method were 0.94, 0.95, 0.94, 0.96, 0.96 and 0.93 for breast CTV, contralateral breast, heart, right lung, left lung and spinal cord, respectively. The mean 95HD values were 4.31 mm, 3.59 mm, 4.86 mm, 3.18 mm, 2.79 mm and 4.37 mm for the above structures respectively. The average CTV scores for AI and GT were 2.92 versus 2.89 when evaluated by oncologist A (P=.612), and 2.75 versus 2.83 by oncologist B (P=.213), with no statistically significant differences. The consistency between two clinicians was poor (Kappa=0.282). The times for auto-segmentation of CTV and OARs were 3.88 s and 6.15 s. Conclusions: Our proposed model can improve the speed and accuracy of delineation compared with U-Net, while it performed equally well with the segmentation generated by oncologists.

Impact of CT-based planning and bladder volume changes on the dosimetry of vaginal vault brachytherapy

2021 ◽  
pp. 1-7
Author(s):  
Jeyaanth Venkatasai ◽  
Jebakarunya Ramireddy ◽  
Arvind Sathyamurthy ◽  
Henry Finlay Godson ◽  
Reka Karuppusami ◽  
...  
Keyword(s):  
Clinical Target Volume ◽  
Organs At Risk ◽  
Three Dimensional ◽  
Target Volume ◽  
Bladder Distension ◽  
Full Bladder ◽  
The Mean ◽  
2D And 3D ◽  
Planning Ct ◽  
Empty Bladder

Abstract Aim: To compare dose to target and organs at risk (OARs) in conventional plan (2D) versus computed tomography (CT)-based three-dimensional (3D) plan in vaginal cuff brachytherapy (VBT) and to compare the effect of bladder distension on target and OARs dosimetry. Materials and methods: Post-hysterectomy patients with an indication for VBT were included in the study. All patients underwent planning CT scans with a full bladder and an empty bladder protocol. For each CT, two plans were generated—one library-based 2D plan and another CT-based 3D plan. Dosimetric parameters were recorded for clinical target volume (CTV) and OARs. Results: A total of 92 observations were made from data collected from 46 patients. Difference between CTV dose in terms of 2D and 3D plans were not statistically significant for CTV (p = 0·11). Significant reduction in D0·1cc, D1cc and D2cc dose parameters were observed in bladder, rectum, sigmoid and bowel doses with the 3D plan (p < 0·001). Bladder distension showed a 20% reduction in dose for bowel (p < 0·001). Bladder distension also showed a 6·12% (p = 0·047) increase in D2cc, but there was a significant reduction in the mean dose to the bladder. Conclusion: Our study demonstrates the dosimetric benefits with 3D CT-based planning for VBT over 2D-based conventional planning and benefit of bladder distension in the reduction of bowel dose without compromising dose to the target volume.

scholarly journals Comparative dosimetric study between point and volume based brachytherapy in definitive treatment of de novo carcinoma cervix

2016 ◽  
Author(s):  
Rahat Hadi ◽  
Mohammad Azam ◽  
Pooja Gupta ◽  
Satyajeet Rath ◽  
Mohammad Ali ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Treatment Planning ◽  
Clinical Target Volume ◽  
De Novo ◽  
Target Volume ◽  
Definitive Treatment ◽  
High Dose ◽  
Carcinoma Cervix ◽  
Cross Sectional ◽  
The Mean

Introduction: Cervical cancer has a high incidence in developing countries including India. Brachytherapy (BT) is an important component in the curative management of carcinoma of the cervix, and significantly improves survival. In gynaecologic BT, correlation between the radiation dose and the normal tissue effects have been assessed using point doses. Since 1985, these points have been defined in the international commission of radiation units and measurements (ICRU-38) report. However GEC-ESTRO recommended volume based treatment planning in their respective series (I-IV). For cervical cancer BT, the correlation of ICRU point doses and volume based treatment planning is investigational till date. Analysis becomes feasible when cross sectional image-based treatment planning for BT using computerized tomography (CT) or magnetic resonance imaging (MRI) is utilised as per GEC-ESTRO recommendation. Methods: It is a retrospective pilot study includes patients (pts.) of carcinoma cervix treated with high dose rate (HDR) BT 9 Gy in 2 fractions 1 week apart. All volume based dosimeteric parameters regarding high risk clinical target volume (HRCTV), intermediate risk clinical target volume (IRCTV) like D90, D100 and for organ at risk (OAR) D 0.1 cc, D 1.0 cc and D 2.0 cc were delineated and dose coverage was analysed in point dose based planning. Results: We have analysed twenty pts. of squamous cell carcinoma (SCC) cervix. The median age was 52 yrs. (41-65 yrs), stage II B 10 pts. & III B 10 pts. The mean value of D90 & D100 in HRCTV during I and II session were 8.64, 6.75 and 5.76, 4.36 Gy respectively. Same values for IRCTV were 6.31, 4.91 and 3.68, 3.15 Gy respectively. Analysis of OARs demonstrated that mean dose received by 0.1, volume of bladder during I and II session received 10.68, 9.47, by 1 cc volume 8.39, 7.57 and by 2 cc volume 6.84, 6.21 Gy respectively. The mean dose received by 0.1 cc of rectum were 11.59, 10.12, by 1 cc volume 9.53, 8.19 and by 2 cc volume 7.76, 6.81 Gy respectively. In point based analysis mean dose delivered to bladder point during I and II session were 5.63, 6.02 and to rectum point were 5.98, 5.46 Gy respectively. Doses to 0.1 cc volume of bladder and rectum were higher in volume based BT as compared to point based BT in respective fractions. Conclusion: Both HRCTV and IRCTV had better dose coverage in 1st fraction as compared to 2nd fraction. Point doses to bladder and rectum is underestimated in point based (ICRU-38) BT. We need more number of pts in prospective randomized trial for more consistent result.

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