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 Comparison of the Dosimetric Influence of Applicator Displacement on 2D and 3D Brachytherapy for Cervical Cancer Treatment

2021 ◽  
Vol 20 ◽  
pp. 153303382110412
Author(s):  
Ailin Wu ◽  
Du Tang ◽  
Aidong Wu ◽  
Yunqin Liu ◽  
Liting Qian ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Organs At Risk ◽  
Three Dimensional ◽  
Target Volume ◽  
Posterior Direction ◽  
3D Volume ◽  
The Right ◽  
2D And 3D ◽  
Dose Change ◽  
Anterior Posterior

To compare the dosimetric influence of applicator displacement on two-dimensional brachytherapy (2D-BT) and three-dimensional brachytherapy (3D-BT) for cervical cancer. Nineteen patients who received computed tomography-guided tandem-and-ovoid (T&O) brachytherapy were retrospectively selected. Both 2D (point-based) and 3D (volume-based) plans with and without virtual applicator displacement in the 3 axes were created for each patient. Dose changes at point A, D90 of the high-risk clinical target volume (HR-CTV) and intermediate-risk CTV (IR-CTV), and the D0.1cc, D1cc, D2cc, and D5cc of organs-at-risk (OARs) caused by applicator displacement were evaluated. Both 2D-BT and 3D-BT plans were sensitive to T&O applicator displacement. The D90 of the CTV and the dose at point A were very sensitive to applicator displacement in the right–left direction ( X-axis). An applicator shift of >2 mm in the X-axis resulted in a change of >5% in the dose at point A and D90 of HR-CTV and IR-CTV. In addition, the doses to the OARs were mostly affected by applicator displacement in the anterior–posterior direction ( Z-axis). A displacement of <1.5 mm in the Z-axis was required to avoid a dose change of >10% for OARs. For both 2D-BT and 3D-BT plans, T&O displacement greater than  ± 2 mm in the X-axis or T&O applicator displacement  ± 1.5 mm in the Z-axis resulted in significant dose changes to the tumor and OARs. In comparison with 3D-BT plans, 2D-BT plans delivered a higher dose to the tumor, and the OARs received more undesirable doses when applicator displacement occurred. The influence of applicator displacement on the doses to the tumor and OARs differed between 2D-BT and 3D-BT. Physicians should take individual patient differences into account when selecting a brachytherapy plan to mitigate the influence of applicator displacement.

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.

Clinical dosimetry optimization in spinal metastases

2009 ◽  
Vol 8 (1) ◽  
pp. 35-40
Author(s):  
P. Pedrosa ◽  
C. Lucena ◽  
I.J. Sainz
Keyword(s):  
Organs At Risk ◽  
Three Dimensional ◽  
Spinal Metastases ◽  
Target Volume ◽  
The Body ◽  
High Dose ◽  
Prescription Dose ◽  
The Mean ◽  
Posterior Anterior ◽  
Anterior Posterior

AbstractIntroduction: Radiotherapy is commonly used to treat spinal metastases. The aim of this study was to compare conventional dosimetry (posterior–anterior fields) with an optimized three-dimensional conformal plan (using oblique fields).Material and Methods: Fifteen patients were selected, and split into three groups of five based on tumour localization: cervical, dorsal and lumbar. Reference planning comprised of two fields: anterior–posterior. The planning target volume (PTV) was covered with 90% of the prescribed doses, minimizing anterior field weight and not exceeding 120%. The alternative consisted of three fields: two oblique posterior fields with wedge and anterior field. The PTV was covered with 95% of the prescription dose, minimizing the anterior field weight with 107% of overdose as a limit. The patient received 8 Gy in one fraction; retreatment with an additional fraction was feasible, safe and effective if persistent or recurrent bone pain was present. Five fractions of 4 Gy were used for cervical cases. To consider the future patients toxicity we evaluated the mean dose, V90 and V70 parameters in each plan.Results: Dosimetric parameters of organs at risk were not significantly different from one trial to another. The optimized plan followed ICRU criteria, reaching PTV coverage of 95–107% range of the prescription dose. In the conventional plan, high dose had to be accepted to obtain 90% of coverage in the target.Conclusions: In contrast with the anterior–posterior configuration, oblique fields improve dose conformity and limit high dose all of the body except the spinal cord.

Comparison of image-based three-dimensional treatment planning using AcurosTM BV and AAPM TG-43 algorithm for intracavitary brachytherapy of carcinoma cervix

2016 ◽  
Vol 15 (3) ◽  
pp. 254-262 ◽  
Author(s):  
Mourougan Sinnatamby ◽  
Vivekanandan Nagarajan ◽  
K S. Reddy ◽  
Gunaseelan Karunanidhi ◽  
Vivekanandam Singhavajala
Keyword(s):  
Treatment Planning ◽  
Organs At Risk ◽  
Three Dimensional ◽  
Tumour Volume ◽  
Target Volume ◽  
Mean Value ◽  
Intracavitary Brachytherapy ◽  
Carcinoma Cervix ◽  
Significant Difference ◽  
The Mean

AbstractAimTo compare the image-based three-dimensional treatment planning using AcurosTM BV and AAPM TG-43 algorithm for intracavitary brachytherapy of carcinoma cervix.Materials and methodsTwenty-seven patients with cancer cervix, stage IIB or IIIB with vaginal involvement limited to the upper third of the vagina was included into the study. Intracavitary treatments with the patient in this study done with computed tomography and magnetic resonance imaging compatible ring applicator. Groupe European de Curietherapie and European Society for Therapeutic Radiology and Oncology recommended doses to target volumes and organs at risk compared using dose volume histogram.ResultsThe mean value of Point ‘A’ dose was compared between AcurosTM BV and TG-43, which indicates 0·13% difference. The differences in the mean dose to gross tumour volume for various volumes are V100% 0·28%, V150% 1·22% and V200% 1·03%; all volumes showed small difference but statistical significant (p<0·05). The mean dose of high-risk clinical target volume (HRCTV) D90 using AcurosTM BV was 8·47 Gy, which was 1·63% less compared with TG-43. The mean point A dose using AcurosTM BV is 1·04 times the dose to D90 of mean HRCTV. The same difference was observed in comparison with TG43. D2cc and D0·1cc of the bladder, rectum and sigmoid showed a statistically significant difference (p<0·05) in comparison with TG-43.ConclusionThe differences in dosimetric parameters between the AcurosTM BV and TG-43 proved to be statistically significant. The difference is very small, and they are clinically insignificant.

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.

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