scholarly journals Dose Prediction Models Based on Geometric and Plan Optimization Parameter for Adjuvant Radiotherapy Planning Design in Cervical Cancer Radiotherapy

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hui Tang ◽  
Yazheng Chen ◽  
Jialiang Jiang ◽  
Kemin Li ◽  
Jing Zeng ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Prediction Models ◽  
Organs At Risk ◽  
Target Volume ◽  
Radiotherapy Planning ◽  
Factors Affecting ◽  
Dose Prediction ◽  
Plan Optimization ◽  
Dose Volume ◽  
Optimization Parameters

The prediction of an additional space for the dose sparing of organs at risk (OAR) in radiotherapy is still difficult. In this pursuit, the present study was envisaged to find out the factors affecting the bladder and rectum dosimetry of cervical cancer. Additionally, the relationship between the dose-volume histogram (DVH) parameters and the geometry and plan dose-volume optimization parameters of the bladder/rectum was established to develop the dose prediction models and guide the planning design for lower OARs dose coverage directly. Thirty volume modulated radiation therapy (VMAT) plans from cervical cancer patients were randomly chosen to build the dose prediction models. The target dose coverage was evaluated. Dose prediction models were established by univariate and multiple linear regression among the dosimetric parameters of the bladder/rectum, the geometry parameters (planning target volume (PTV), volume of bladder/rectum, overlap volume of bladder/rectum (OV), and overlapped volume as a percentage of bladder/rectum volume (OP)), and corresponding plan dose-volume optimization parameters of the nonoverlapping structures (the structure of bladder/rectum outside the PTV (NOS)). Finally, the accuracy of the prediction models was evaluated by tracking d = (predicted dose-actual dose)/actual in additional ten VMAT plans. V30, V35, and V40 of the bladder and rectum were found to be multiple linearly correlated with the relevant OP and corresponding dose-volume optimization parameters of NOS (regression R2 > 0.99, P < 0.001 ). The variations of these models were less than 0.5% for bladder and rectum. Percentage of bladder and rectum within the PTV and the dose-volume optimization parameters of NOS could be used to predict the dose quantitatively. The parameters of NOS as a limited condition could be used in the plan optimization instead of limiting the dose and volume of the entire OAR traditionally, which made the plan optimization more unified and convenient and strengthened the plan quality and consistency.

scholarly journals The Relationship Between Late Morbidity and Dose–Volume Parameter of Rectum in Combined Intracavitary/Interstitial Cervix Cancer Brachytherapy: A Mono-Institutional Experience

2021 ◽  
Vol 11 ◽  
Author(s):  
Ning Zhang ◽  
Ying Liu ◽  
Dongmei Han ◽  
Xin Guo ◽  
Zhuang Mao ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
At Risk ◽  
Clinical Target Volume ◽  
Organs At Risk ◽  
Locally Advanced ◽  
Probit Model ◽  
Target Volume ◽  
Advanced Cervical Cancer ◽  
Locally Advanced Cervical Cancer ◽  
Dose Volume

PurposeTo establish a dose volume–effect relationship for predicting late rectal complication (LRC) in locally advanced cervical cancer patients treated with external beam radiotherapy (EBRT) followed by combined intracavitary/interstitial brachytherapy (IC/IS-BT).Materials and MethodsA retrospective analysis was performed in 110 patients with locally advanced cervical cancer who underwent definitive radiotherapy combined with IC/IS-BT from July 2010 to September 2018. We report the 90% of the target volume receiving the minimum dose for high risk clinical target volume (HR-CTV D90) and intermediate risk clinical target volume (IR-CTV D90), and the minimum doses to the most exposed 0.1, 1, and 2 cm³ D0.1cm3,D1cm3,D2cm3 doses at the International Commission on Radiation Units and Measurements (DICRU) for organs at risk (OARs). The total dose of EBRT plus brachytherapy was transformed to the biologically equivalent dose in 2 Gy fractions (EQD2) with α/β value of 10 Gy for target, 3 Gy for organs at risk using the linear quadratic model. The morbidity was scored according to the Radiation Therapy Oncology Group (RTOG) criteria. The Probit model was used to establish a prediction model on rectum between the organs at risk for dose and LRC. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of dose volume parameters for LRC.ResultsThe median follow-up time was 72.3 months. The mean ( ± standard deviation) D2cm3,D1cm3,D0.1cm3, and DICRU values of rectum were 64.72 ± 7.47 GyEQD2, 70.18 ± 5.92 GyEQD2, 79.32 ± 7.86 GyEQD2, and 67.22 ± 7.87 GyEQD2, respectively. The Probit model showed significant relationships between D1cm3 or D0.1cm3, and the probability of grade1–4, grade 2–4 rectal events at 1 year, and between D1cm3and the probability of grade2–4 rectal events at 3 and 5 years. The dose values for 10% complication rates (ED10) of D1cm3were 74.18 (70.42–76.71) GyEQD2, 67.80 (59.91, 71.08) GyEQD2, 66.37 (52.00, 70.27) GyEQD2 for grade 2–4 with rectal morbidity at 1, 3, and 5 years, respectively.ConclusionOur study proved that D1cm3 andD0.1cm3were considered as useful dosimetric parameters for predicting the risk of grade1–4 and grade2–4 LRC at 1-year, and D1cm3might be an indicator for predicting grade2-4 LRC at 3/5years. The patients with rectal D1cm3&gt;66.37–74.18 GyEQD2 should be closely observed for grade2–4 LRC.

scholarly journals Effect of the dwell time deviation constraint on brachytherapy treatment planning for cervical cancer

2021 ◽  
Vol 49 (8) ◽  
pp. 030006052110374
Author(s):  
Gaoshu Yan ◽  
Shengwei Kang ◽  
Bin Tang ◽  
Jie Li ◽  
Pei Wang ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Dwell Time ◽  
Organs At Risk ◽  
Organ Dose ◽  
Target Volume ◽  
Time Data ◽  
Step Size ◽  
Dose Volume ◽  
Prescription Dose ◽  
The Mean

Objective This study aimed to quantify the effect of the dwell time deviation constraint (DTDC) on brachytherapy treatment for cervical cancer. Methods A retrospective study was carried out on 20 patients with radical cervical cancer. The DTDC values changed from 0.0 to 1.0 by a step size of 0.2. We adjusted the optimization objectives to ensure that all plans were optimized to a high-risk clinical target volume (HRCTV) D90 (the dose to 90% of the HRCTV) = 6 Gy, while keeping the dose to the organs at risk as low as possible. The dose–volume histogram parameters and the dwell time data were compared between plans with different DTDC values. Results The HRCTV volume covered by 150% of the prescription dose gradually increased with increasing DTDC values. As the DTDC value increased from 0.0 to 1.0, the effective dwell point proportion increased from 61.78% to 90.30%. The mean dwell time initially decreased with an increase in the DTDC value, reached the minimum value at DTDC = 0.8, then slightly increased at DTDC = 1.0. Conclusions When using inverse planning simulated annealing optimization for radical cervical cancer cases, the recommended DTDC value is approximately 0.6 if the organ dose needs to be limited.

A study to assess the feasibility of using CT (±diagnostic MRI) instead of MRI at brachytherapy in image guided brachytherapy in cervical cancer

2014 ◽  
Vol 13 (4) ◽  
pp. 438-446 ◽  
Author(s):  
Bhavana Rai ◽  
Firuza D. Patel ◽  
Parsee Tomar ◽  
Oinam A. Singh ◽  
Vijai Simha ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Organs At Risk ◽  
Target Volume ◽  
Clinical Findings ◽  
Maximum Width ◽  
Dose Volume Histograms ◽  
Dose Volume ◽  
Disease Extension ◽  
Magnetic Resonance Imaging Mri ◽  
Ct And Mri

AbstractPurposeTo compare the contours and dose volume histograms (DVH) parameters of the high-risk clinical target volume (HRCTV) contoured on computed tomography (CT) using clinical findings at brachytherapy, clinical findings at brachytherapy with magnetic resonance imaging (MRI) at diagnosis and HRCTV defined on MRI at brachytherapy in cervical cancer patients.Materials and methodsFifteen patients undergoing MRI-guided image-based brachytherapy underwent both CT and MRI after applicator insertion. Two sets of contours were defined on CT. In the first set, the HRCTV was defined with the help of clinical findings at brachytherapy (CT-HRCTV). In the second set, HRCTV was defined with MRI at diagnosis and clinical findings at brachytherapy (CT-HRCTVdmri). This was compared with the HRCTV defined on MRI at brachytherapy (MR-HRCTV). The doses to the organs at risk (OARs) were compared for CT and MRI.ResultsA significant overestimation of the maximum width and width at point A was observed for CT-HRCTV (p −0·00; 0·00) and CT-HRCTVdmri (p −0·03; 0·01), respectively. The height was underestimated with CT-HRCTV in patients with intrauterine disease extension. For a single fraction, the mean difference in the D90 for the CT contours was <1 Gy. The doses to the OARs were comparable.ConclusionsCT may be an alternative when facilities for MRI image-based brachytherapy are lacking, provided at least one MRI is available before brachytherapy.

Technical illustration of Volumetric arc conformal radiotherapy planning in a case of paratesticular sarcoma

2021 ◽  
pp. 1-6
Author(s):  
Anil Gupta ◽  
Rambha Pandey ◽  
Seema Sharma ◽  
Vivek Ghosh ◽  
Ekta Dhamija ◽  
...  
Keyword(s):  
Organs At Risk ◽  
Target Volume ◽  
Radiotherapy Planning ◽  
Current Evidence ◽  
Lower Grade ◽  
Malignant Tumours ◽  
Target Volume Delineation ◽  
Volume Delineation ◽  
Delivery Technique ◽  
Technical Illustration

Abstract Introduction: Paratesticular sarcoma are extremely rare malignant tumours. Unlike other sites, they tend to be lower grade and have higher propensity of lymphatic spread. They tend to fail locally and occasionally in the regional lymph nodes. In the absence of target volume delineation guidelines and technical illustration of conformal planning, we have made an attempt to illustrate conformal planning methodology and define target volume based on current evidence in a case of paratesticular sarcoma. Methods: We are presenting a case of 62-year-old male who presented with 15-cm scrotal swelling and underwent high inguinal orchidectomy with ligation of spermatic cord. Histopathology presented a well-differentiated leiomyosarcoma of epididymis. Post-operative radiotherapy target volume included the tumour bed, ipsilateral inguinal nodes and lower pelvic nodes as the clinical target volume. Conclusion: Adjuvant radiotherapy using advanced delivery technique such as volumetric arc technique can provide good dose distribution with good sparing of organs at risk. The downside of conformal radiation delivery is that it is a resource-intensive and has no established target volume delineation guidelines.

scholarly journals A novel index for assessing treatment plan quality in stereotactic radiosurgery

2018 ◽  
Vol 129 (Suppl1) ◽  
pp. 118-124 ◽  
Author(s):  
Alexis Dimitriadis ◽  
Ian Paddick
Keyword(s):  
Stereotactic Radiosurgery ◽  
Treatment Plan ◽  
Efficiency Index ◽  
Target Volume ◽  
Surrounding Tissue ◽  
Plan Quality ◽  
Multiple Target ◽  
Integral Dose ◽  
Plan Optimization ◽  
Dose Volume

OBJECTIVEStereotactic radiosurgery (SRS) is characterized by high levels of conformity and steep dose gradients from the periphery of the target to surrounding tissue. Clinical studies have backed up the importance of these factors through evidence of symptomatic complications. Available data suggest that there are threshold doses above which the risk of symptomatic radionecrosis increases with the volume irradiated. Therefore, radiosurgical treatment plans should be optimized by minimizing dose to the surrounding tissue while maximizing dose to the target volume. Several metrics have been proposed to quantify radiosurgical plan quality, but all present certain weaknesses. To overcome limitations of the currently used metrics, a novel metric is proposed, the efficiency index (η50%), which is based on the principle of calculating integral doses: η50% = integral doseTV/integral dosePIV50%.METHODSThe value of η50% can be easily calculated by dividing the integral dose (mean dose × volume) to the target volume (TV) by the integral dose to the volume of 50% of the prescription isodose (PIV50%). Alternatively, differential dose-volume histograms (DVHs) of the TV and PIV50% can be used. The resulting η50% value is effectively the proportion of energy within the PIV50% that falls into the target. This value has theoretical limits of 0 and 1, with 1 being perfect. The index combines conformity, gradient, and mean dose to the target into a single value. The value of η50% was retrospectively calculated for 100 clinical SRS plans.RESULTSThe value of η50% for the 100 clinical SRS plans ranged from 37.7% to 58.0% with a mean value of 49.0%. This study also showed that the same principles used for the calculation of η50% can be adapted to produce an index suitable for multiple-target plans (Gη12Gy). Furthermore, the authors present another adaptation of the index that may play a role in plan optimization by calculating and minimizing the proportion of energy delivered to surrounding organs at risk (OARη50%).CONCLUSIONSThe proposed efficiency index is a novel approach in quantifying plan quality by combining conformity, gradient, and mean dose into a single value. It quantifies the ratio of the dose “doing good” versus the dose “doing harm,” and its adaptations can be used for multiple-target plan optimization and OAR sparing.

scholarly journals A Simple and Effective Method to Improve Pinnacle Auto-planning Based on Rectal Cancer

2021 ◽  
Author(s):  
Lei Hua ◽  
Gang Chen ◽  
Han Xiao ◽  
Xiangou Pan ◽  
JianYing Zhang
Keyword(s):  
Rectal Cancer ◽  
Preoperative Radiotherapy ◽  
Reference Group ◽  
Organs At Risk ◽  
Target Volume ◽  
The Other ◽  
Control Group ◽  
Initial Experience ◽  
Acceptable Range ◽  
Optimization Parameters

Abstract Background: Try to re-optimize the results of pinnacle Auto-planning (AP) and explore the feasibility of obtaining more dosiologically advantageous AP plans by reducing "experience-based optimization parameters". Methods: 35 rectal cancer cases with preoperative radiotherapy were selected and all plans are designed retrospectively with Pinnacle9.1 AP. Firstly we take the doctor's clinical prescription as a universal optimization parameters, get the first reference group CP; secondly we set the results of manual plans (MP) which were already used for clinical treatments as the optimization parameters, replacing the physicist's initial experience, get the second reference group IE; at last we reduce the results of MP by 15% as the optimization parameters , get the control group T. By keeping the other optimization conditions unchanged, we designed AP plans for all three groups. Wilcoxon rank sum tests were performed for CP-T and IE-T based on the dosiological parameters of the planning target volume(PTV) and organs at risk(OARs). Results: Dose distribution of all three groups was in a clinically acceptable range. The dose of OARs in T group was significantly lower than CP and IE,the differences were statistically significant. Conclusion: Experience-based AP plan has a space for re-optimization, and appropriately reducing the results of MP as optimization parameters is a simple and feasible way.

Dose volume histogram analysis for organs at risk when using 6 external beam techniques for radical prostatic irradiation

2000 ◽  
Vol 2 (1) ◽  
pp. 17-25 ◽  
Author(s):  
T. Haycocks ◽  
J. Mui ◽  
H. Alasti ◽  
C. Catton
Keyword(s):  
At Risk ◽  
Organs At Risk ◽  
Area Under The Curve ◽  
Target Volume ◽  
Dose Volume Histograms ◽  
Treatment Techniques ◽  
Dose Volume ◽  
Femoral Heads ◽  
Curve Method ◽  
Set Up

Ten patients with prostate cancer were each planned with 3 conventional and 3 conformal isocentric treatment techniques to compare the relative radiation doses to the bladder and rectal walls, and femoral head using dose volume histograms (DVH). The DVH were calculated for each organ and each technique, and the plans were ranked using the area under the curve method and also by the relative radiation dose given to specific normal tissue volumes.The results show that for the planning target volume chosen, the 4 field non-coplanar technique delivers the least dose to the bladder, the 6 field coplanar technique delivers the least dose to the rectum and the 3 field oblique technique delivers the least dose to the femoral heads. The 4-field technique with no shielding contributes the most dose to the bladder and rectum and the 6 field coplanar technique contributes the most dose to the femoral heads.No technique was shown to be optimal for all the organs at risk, but both the 6 field and 4 field non-coplanar field arrangements were shown to be superior techniques for minimising both the bladder and rectal dosage. The choice of technique will therefore depend on other factors such as the total prescribed dose, the ease of set-up and the ease of verification of isocentre reproducibility.

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