UK audit of target volume and organ at risk delineation and dose optimisation for cervix radiotherapy treatments

2020 ◽  
Vol 93 (1110) ◽  
pp. 20190897
Author(s):  
Jennifer Cannon ◽  
Peter Bownes ◽  
Joshua Mason ◽  
Rachel Cooper
Keyword(s):  
Cervical Cancer ◽  
At Risk ◽  
Planning Target Volume ◽  
Treatment Plan ◽  
Target Volume ◽  
Dose Fractionation ◽  
Treatment Technique ◽  
Dose Optimisation ◽  
Treatment Plans ◽  
Organ At Risk

Objective: Assessment of the extent of variation in delineations and dose optimisation performed at multiple UK centres as a result of interobserver variation and protocol differences. Methods: CT/MR images of 2 cervical cancer patients previously treated with external beam radiotherapy (EBRT) and Brachytherapy were distributed to 11 UK centres. Centres delineated structures and produced treatment plans following their local protocol. Organ at risk delineations were assessed dosimetrically through application of the original treatment plan and target volume delineations were assessed in terms of variation in absolute volume and length, width and height. Treatment plan variation was assessed across all centres and across centres that followed EMBRACE II. Treatment plans were assessed using total EQD2 delivered and were compared to EMBRACE II dose aims. Variation in combined intracavitary/interstitial brachytherapy treatments was also assessed. Results: Brachytherapy target volume delineations contained variation due to differences in protocol used, window/level technique and differences in interpretations of grey zones. Planning target volume delineations were varied due to protocol differences and extended parametrial tissue inclusion. All centres met EMBRACE II plan aims for PTV V95 and high-riskclinical target volume D90 EQD2, despite variation in prescription dose, fractionation and treatment technique. Conclusion: Brachytherapy target volume delineations are varied due to differences in contouring guidelines and protocols used. Planning target volume delineations are varied due to the uncertainties surrounding the extent of parametrial involvement. Dosimetric optimisation is sufficient across all centres to satisfy EMBRACE II planning aims despite significant variation in protocols used. Advances in knowledge: Previous multi-institutional audits of cervical cancer radiotherapy practices have been performed in Europe and the USA. This study is the first of its kind to be performed in the UK.

scholarly journals Clinical Validation and Treatment Plan Evaluation Based on Auto-Delineation of the Clinical Target Volume for Prostate Cancer Radiotherapy

2022 ◽  
Author(s):  
Jing Shen ◽  
Yinjie TAO ◽  
Hui GUAN ◽  
Hongnan ZHEN ◽  
Lei HE ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
At Risk ◽  
Organs At Risk ◽  
Treatment Plan ◽  
Statistical Significance ◽  
Locally Advanced ◽  
Target Volume ◽  
Ct Scans ◽  
Dice Similarity Coefficient ◽  
Treatment Plans

Abstract Purpose Clinical target volumes (CTV) and organs at risk (OAR) could be auto-contoured to save workload. The goal of this study was to assess a convolutional neural network (CNN) for totally automatic and accurate CTV and OAR in prostate cancer, while also comparing anticipated treatment plans based on auto-contouring CTV to clinical plans. Methods From January 2013 to January 2019, 217 computed tomography (CT) scans of patients with locally advanced prostate cancer treated at our hospital were collected and analyzed. CTV and OAR were delineated with a deep learning based method, which named CUNet. The performance of this strategy was evaluated using the mean Dice similarity coefficient (DSC), 95th percentile Hausdorff distance (95HD), and subjective evaluation. Treatment plans were graded using predetermined evaluation criteria, and % errors for clinical doses to the planned target volume (PTV) and organs at risk(OARs) were calculated. Results The defined CTVs had mean DSC and 95HD values of 0.84 and 5.04 mm, respectively. For one patient's CT scans, the average delineation time was less than 15 seconds. When CTV outlines from CUNetwere blindly chosen and compared to GT, the overall positive rate in clinicians A and B was 53.15% vs 46.85%, and 54.05% vs 45.95%, respectively (P>0.05), demonstrating that our deep machine learning model performed as good as or better than human demarcation Furthermore, 8 testing patients were chosen at random to design the predicted plan based on the auto-courtoring CTV and OAR, demonstrating acceptable agreement with the clinical plan: average absolute dose differences of D2, D50, D98, Dmean for PTV are within 0.74%, and average absolute volume differences of V45, V50 for OARs are within 3.4%. Without statistical significance (p>0.05), the projected findings are comparable to clinical truth. Conclusion The experimental results show that the CTV and OARs defined by CUNet for prostate cancer were quite close to the ground reality.CUNet has the potential to cut radiation oncologists' contouring time in half. When compared to clinical plans, the differences between estimated doses to CTV and OAR based on auto-courtoring were small, with no statistical significance, indicating that treatment planning for prostate cancer based on auto-courtoring has potential.

scholarly journals Positional Accuracy of Treating Multiple Versus Single Vertebral Metastases With Stereotactic Body Radiotherapy

2016 ◽  
Vol 16 (2) ◽  
pp. 231-237 ◽  
Author(s):  
Joe H. Chang ◽  
Arnjeet Sangha ◽  
Derek Hyde ◽  
Hany Soliman ◽  
Sten Myrehaug ◽  
...  
Keyword(s):  
At Risk ◽  
Planning Target Volume ◽  
Stereotactic Body Radiotherapy ◽  
Target Volume ◽  
Vertebral Metastases ◽  
Positional Accuracy ◽  
Computed Tomography Images ◽  
Organ At Risk ◽  
The Mean ◽  
Residual Errors

The aim of this study is to determine whether stereotactic body radiotherapy for multiple vertebral metastases treated with a single isocenter results in greater intrafraction errors than stereotactic body radiotherapy for single vertebral metastases and to determine whether the currently used spinal cord planning organ at risk volume and planning target volume margins are appropriate. Intrafraction errors were assessed for 65 stereotactic body radiotherapy treatments for vertebral metastases. Cone beam computed tomography images were acquired before, during, and after treatment for each fraction. Residual translational and rotational errors in patient positioning were recorded and planning organ at risk volume and planning target volume margins were calculated in each direction using this information. The mean translational residual errors were smaller for single (0.4 (0.4) mm) than for multiple vertebral metastases (0.5 (0.7) mm; P = .0019). The mean rotational residual errors were similar for single (0.3° (0.3°) and multiple vertebral metastases (0.3° (0.3°); P = .862). The maximum calculated planning organ at risk volume margin in any direction was 0.83 mm for single and 1.22 for multiple vertebral metastases. The maximum calculated planning target volume margin in any direction was 1.4 mm for single and 1.9 mm for multiple vertebral metastases. Intrafraction errors were small for both single and multiple vertebral metastases, indicating that our strategy for patient immobilization and repositioning is robust. Calculated planning organ at risk volume and planning target volume margins were smaller than our clinically employed margins, indicating that our clinical margins are appropriate.

scholarly journals The Treatment Planining of Rectum Tumors and The Use of The Wedge Filter for Ensuring The Correct Isodoses

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Idajet Selmani ◽  
Partizan Malkaj
Keyword(s):  
Planning Target Volume ◽  
Treatment Plan ◽  
Target Volume ◽  
The Body ◽  
Planning System ◽  
Treatment Planning System ◽  
Volume Of Interest ◽  
Dose Volume ◽  
Treatment Plans ◽  
Wedge Filter

One of the most important issues in the field of radiotherapy is the correct distribution of the dose around the volume of interest or planning target volume (PTV). For making this possible the exact isodose in a treatment plan has to cover the PTV, so it is used the wedge which is a part of the linear accelerator head. Wedge plays the role of a filter and usually it is called wedge filter. The wedge filter is in use almost in all treatment plans, for all the parts of the body. In this paper it is consider the use of the wedge filter for treatment of rectum tumors. The process starts with the scanning of the patient and the deliantion of the interest’s volums in the Monaco system. In the following the imagins have been sent in the treatment planning system for making the nesessary plans for treatment of the rectum. Two plans were done, one with the use of the wedge and the other without using it. The dose volume histogram helps for compering the results of the plans. The best conformity of the isodoses it was for the plan with the use of wedge through volume of interest, which is planning target volume (PTV).

scholarly journals Implementation of 3D-CT based brachytherapy in the postoperative radiotherapy of cervical cancer: Treatment technique and dose-volume parameters

2009 ◽  
Vol 56 (4) ◽  
pp. 201-207
Author(s):  
V. Plesinac-Karapandzic ◽  
N. Borojevic ◽  
B. Markovic ◽  
V. Stankovic ◽  
S. Vuckovic ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
At Risk ◽  
Cancer Treatment ◽  
Postoperative Radiotherapy ◽  
Reference Points ◽  
Intracavitary Brachytherapy ◽  
Treatment Technique ◽  
3D Ct ◽  
Dose Volume ◽  
Organ At Risk

Intracavitary brachytherapy has an important roll in developing complications in postoperative radiotherapy of cervical cancer. 3D-CT based brachytherapy gives precisely estimating doses to organ at risk. In this study, we show our preliminary results in implementation of 3D-imaging based postoperative brachytherapy of cervical cancer: treatment technique and dose-volume parameters. During 2009 year, in 6 patients with early stage I-II of cervical cancer, brachytherapy treatment planning was based on the radiographs and CT imaging brachytherapy technique. Mean values of ICRU reference points of rectum was R max 4,2Gy and bladder B max. 4,5Gy, while estimated volume-dose parameters D0.1 cm 3 D1.0 cm 3 D2.0 cm 3 were presented with higher dose. Volume of organ at risk reflected the need for better bladder preparation. Our initial experience in performing CT-based brachytherapy, enabled us to introduce the characteristics of the parameters, assessment of their significance from the aspect of mutual relations applicators and organs at risk. Further analysis are needed, for monitoring the effects of 3D planning on complications.

scholarly journals Impact of Geometric Uncertainties on Dose Distribution During Intensity Modulated Radiotherapy of Head-and-neck Cancer: The Need for a Planning Target Volume and A Planning Organ-at-Risk Volume

2006 ◽  
Vol 13 (3) ◽  
pp. 108-115 ◽  
Author(s):  
O. Ballivy ◽  
W. Parker ◽  
T. Vuong ◽  
G. Shenouda ◽  
H. Patrocinio
Keyword(s):  
Spinal Cord ◽  
At Risk ◽  
Neck Cancer ◽  
Intensity Modulated Radiotherapy ◽  
Target Volume ◽  
Ct Scans ◽  
Target Coverage ◽  
Geometric Uncertainties ◽  
Intensity Modulated ◽  
Organ At Risk

We assessed the effect of geometric uncertainties on target coverage and on dose to the organs at risk (OARS) during intensity-modulated radiotherapy (IMRT) for head-and-neck cancer, and we estimated the required margins for the planning target volume (PTV) and the planning organ-at-risk volume (PRV). For eight headand- neck cancer patients, we generated IMRT plans with localization uncertainty margins of 0 mm, 2.5 mm, and 5.0 mm. The beam intensities were then applied on repeat computed tomography (CT) scans obtained weekly during treatment, and dose distributions were recalculated. The dose–volume histogram analysis for the repeat CT scans showed that target coverage was adequate (V100 ≥ 95%) for only 12.5% of the gross tumour volumes, 54.3% of the upper-neck clinical target volumes (CTVS), and 27.4% of the lower-neck CTVS when no margins were added for PTV. The use of 2.5-mm and 5.0-mm margins significantly improved target coverage, but the mean dose to the contralateral parotid increased from 25.9 Gy to 29.2 Gy. Maximum dose to the spinal cord was above limit in 57.7%, 34.6%, and 15.4% of cases when 0-mm, 2.5-mm, and 5.0-mm margins (respectively) were used for PRV. Significant deviations from the prescribed dose can occur during IMRT treatment delivery for headand- neck cancer. The use of 2.5-mm to 5.0-mm margins for PTV and PRV greatly reduces the risk of underdosing targets and of overdosing the spinal cord.

scholarly journals Use of a Head-Tilting Baseplate During Tomotherapy to Shorten the Irradiation Time and Protect the Hippocampus and Lens in Hippocampal Sparing-Whole Brain Radiotherapy

2021 ◽  
Vol 20 ◽  
pp. 153303382098682
Author(s):  
Kosei Miura ◽  
Hiromasa Kurosaki ◽  
Nobuko Utsumi ◽  
Hideyuki Sakurai
Keyword(s):  
At Risk ◽  
Planning Target Volume ◽  
Irradiation Time ◽  
Organs At Risk ◽  
Absorbed Dose ◽  
Whole Brain Radiotherapy ◽  
Target Volume ◽  
Whole Brain ◽  
Brain Radiotherapy ◽  
Hippocampal Sparing

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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