Optimisation of user-selectable volumetric modulated arc therapy (VMAT) planning parameters: A study of VMAT arcs for prostate and head-and-neck cancers

2021 ◽  
pp. 1-15
Author(s):  
Ghulam Murtaza ◽  
Zaheer Abbas Gillani ◽  
Shahid Mehmood ◽  
Jalil Ur Rehman ◽  
Ehsan Ullah Khan ◽  
...  
Keyword(s):  
At Risk ◽  
Head And Neck Cancer ◽  
Head And Neck ◽  
Treatment Planning ◽  
Neck Cancer ◽  
Organs At Risk ◽  
Planning System ◽  
Treatment Planning System ◽  
Target Coverage ◽  
Single Arc

Abstract Objective: To evaluate different VMAT planning techniques for a multi-leaf collimator (MLC)providing maximum aperture of 21 × 16 cm². Methods: A VMAT planning study of nine prostate and nine head-and-neck cancer patients was carried out. The patients were previously treated with Intensity Modulated Radiotherapy (IMRT) technique during 2014-15, at radiation oncology SanBortolo Hospital, Vicenza, Italy. Three VMAT plans for each of prostate and head-and-neck cancer patient were optimized using Pinnacle treatment planning system for 6MV photon beam from ElektaSynergyS®Linac system. Single arc, dual arc and combined two independent-single-arcs were optimized for collimator angle 45°. VMAT treatment planning comparison was made among single-arc dual-arc and combined two independent-single-arcs. The student’s t-test (two-sided) with p ? 0.05 was applied for significant difference between dose volume indices of plans. Results: All VMAT techniques produced clinically acceptable plans for prostate, while for head-and-neck, DA and ISAs significantly improved target coverage compared to SA. Single arc is sufficient for prostate, while inefficient in case of head-and-neck dose-planning. In spite of having different VMAT optimization approach dual arc and two combined independent-single-arcs provided very similar target coverage, while dual arc improved sparing of organs-at-risk. Similar treatment delivery times were observed for DA and ISAs VMAT techniques. Conclusion: Single arc is sufficient for prostate, while inefficient in case of head-and-neck dose-planning.Dual arc and two combined independent-single-arcs provided similar PTV coverage, while DA provided better sparing of organs at risk. Continuous...

A hybrid approach for head and neck cancer using online image guidance and offline adaptive radiotherapy planning

2019 ◽  
Vol 18 (03) ◽  
pp. 271-275 ◽  
Author(s):  
Roopam Srivastava ◽  
P.K. Sharma ◽  
K.J. Maria Das ◽  
Jayanand Manjhi
Keyword(s):  
Computed Tomography ◽  
Head And Neck Cancer ◽  
Head And Neck ◽  
Neck Cancer ◽  
Dose Distribution ◽  
Treatment Plan ◽  
Planning System ◽  
Radiotherapy Planning ◽  
Treatment Planning System ◽  
Medical Systems

AbstractBackgroundThis is a prospective study to evaluate the dosimetric benefits of treatment plan adaptation for patients who had undergone repeat computed tomography (ReCT)and re-planning due to treatment-induced anatomical changes during radiotherapy.Materials and MethodsThis study involved five head and neck cancer patients who had their treatment plan modified, based on weekly thrice imaging protocol. Impact of mid-course imaging was assessed in patients using ReCT and cone beam computed tomography (CBCT)-based dose verification. Patients were imaged, apart from their initial CT, during the course of their radiation therapy with a ReCT and on board imager CBCT (Varian Medical Systems Inc., Palo Alto, CA, USA). Each CBCT/CT series was rigidly registered to the initial CT in the treatment planning system Eclipse (Varian Medical Systems Inc.) using bony landmarks. The structures were copied to the current CBCT/CT series and, where needed, manually edited slicewise. The dose distribution from the treatment plan was viewed as of the current anatomy by applying the treatment plan the CBCT/CT series, and studying the corresponding dose–volume histograms for organs at risk doses.ResultsThe reduction of parotid volumes due to weight loss was observed in all patients, which means an increase in predicted mean doses of parotid when initial CT plan was re-calculated on ReCT and CBCT (Table 1). This explains the necessity of adaptive planning. The predicted mean dose of parotid glands was increased and constraints to spinal cord and skin were exceeded, so re-planning was performed.ConclusionsThe CBCT is a useful tool to view anatomic changes in patients and get an estimate of their impact on dose distribution. Re-planning based on imaging in head and neck patients during the course of radiotherapy is mandatory to reduce side effects.

scholarly journals Benefits of deep learning for delineation of organs at risk in head and neck cancer

2019 ◽  
Vol 138 ◽  
pp. 68-74 ◽  
Author(s):  
J. van der Veen ◽  
S. Willems ◽  
S. Deschuymer ◽  
D. Robben ◽  
W. Crijns ◽  
...  
Keyword(s):  
At Risk ◽  
Head And Neck Cancer ◽  
Deep Learning ◽  
Head And Neck ◽  
Neck Cancer ◽  
Organs At Risk

Impact of setup error on integral dose in head and neck cancer treated with intensity modulated radiation therapy

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. e17056-e17056
Author(s):  
R. V. Prabhakar ◽  
K. P. Haresh ◽  
M. A. Laviraj ◽  
G. K. Rath ◽  
P. K. Julka
Keyword(s):  
Head And Neck Cancer ◽  
Head And Neck ◽  
Neck Cancer ◽  
Intensity Modulated Radiation Therapy ◽  
Planning System ◽  
Treatment Planning System ◽  
Target Tissue ◽  
Setup Error ◽  
Integral Dose ◽  
Posterior Direction

e17056 Background: Intensity modulated radiation therapy (IMRT) has been widely used in the treatment of head and neck cancer and has the potential of escalating the dose with less morbidity. Integral dose is a concern in radiotherapy especially with IMRT as it may lead to an increase in second malignancies. Setup error is another important issue in radiotherapy which affects the final treatment outcome. In this study, the effect of setup error on non-target integral dose (NTID) for head and neck cancer treated with IMRT has been studied. Methods: Twelve patients of carcinoma of nasopharynx treated by IMRT with simultaneous integrated boost technique were included. The dose to the gross tumor volume (PTV70), CTV1 (PTV59.4) and CTV2 (PTV54) were planned for 70 Gy, 59.4 Gy and 54 Gy respectively in 33 fractions. All the patients were planned with nine equally spaced beams. The IMRT plan was generated in Eclipse treatment planning system using sliding window technique. Keeping it as the base plan, the patient setup error was simulated in the treatment planning system for 3 mm, 5 mm and 10 mm by shifting the isocenter in all three dimensions viz. anterior, posterior, superior, inferior, right lateral and left lateral. NTID was calculated from the following relation NTID = (non-target tissue volume X mean non-target tissue dose)/1000. Paired sample t-test was performed to compare NTID for different shifts with no shift (statistical significance: p < 0.05). Results: The mean NTID for no shift was 120.75 ± 22.85 (median: 116.59). The mean NTID with isocenter shift along the anterior direction were 119.87 ± 22.80, 119.24 ± 22.80, 117.97 ± 22.52 for 3 mm, 5 mm and 10 mm respectively. Similarly, the NTID for the posterior shifts were 121.59 ± 22.96, 122.08 ± 23.07 and 123.26 ± 23.34 for 3 mm, 5 mm and 10 mm respectively. The anterior and posterior setup error showed statistically significant difference (p < 0.0001) for NTID compared to no shift whereas lateral, superior and inferior setup errors were found to be statistically insignificant. Conclusions: Setup error is an important issue in radiotherapy. Our study shows that setup error along the posterior direction significantly increases NTID. Hence, the setup error along the posterior direction may increase the risk of second malignances in IMRT. No significant financial relationships to disclose.

scholarly journals Application of dose-volume histogram prediction in biologically related models for nasopharyngeal carcinomas treatment planning

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Wufei Cao ◽  
Yongdong Zhuang ◽  
Lixin Chen ◽  
Xiaowei Liu
Keyword(s):  
Spinal Cord ◽  
At Risk ◽  
Treatment Planning ◽  
Organs At Risk ◽  
Planning System ◽  
Treatment Planning System ◽  
Dose Volume Histogram ◽  
Parotid Glands ◽  
Dose Volume ◽  
Dose Sparing

Abstract Purpose In this study, we employed a gated recurrent unit (GRU)-based recurrent neural network (RNN) using dosimetric information induced by individual beam to predict the dose-volume histogram (DVH) and investigated the feasibility and usefulness of this method in biologically related models for nasopharyngeal carcinomas (NPC) treatment planning. Methods and materials One hundred patients with NPC undergoing volumetric modulated arc therapy (VMAT) between 2018 and 2019 were randomly selected for this study. All the VMAT plans were created using the Monaco treatment planning system (Elekta, Sweden) and clinically approved: > 98% of PGTVnx received the prescribed doses of 70 Gy, > 98% of PGTVnd received the prescribed doses of 66 Gy and > 98% of PCTV received 60 Gy. Of these, the data from 80 patients were used to train the GRU-RNN, and the data from the other 20 patients were used for testing. For each NPC patient, the DVHs of different organs at risk were predicted by a trained GRU-based RNN using the information given by individual conformal beams. Based on the predicted DVHs, the equivalent uniform doses (EUD) were calculated and applied as dose constraints during treatment planning optimization. The regenerated VMAT experimental plans (EPs) were evaluated by comparing them with the clinical plans (CPs). Results For the 20 test patients, the regenerated EPs guided by the GRU-RNN predictive model achieved good consistency relative to the CPs. The EPs showed better consistency in PTV dose distribution and better dose sparing for many organs at risk, and significant differences were found in the maximum/mean doses to the brainstem, brainstem PRV, spinal cord, lenses, temporal lobes, parotid glands and larynx with P-values < 0.05. On average, compared with the CPs, the maximum/mean doses to these OARs were altered by − 3.44 Gy, − 1.94 Gy, − 1.88 Gy, 0.44 Gy, 1.98 Gy, − 1.82 Gy and 2.27 Gy, respectively. In addition, significant differences were also found in brainstem and spinal cord for the dose received by 1 cc volume with 4.11 and 1.67 Gy dose reduction in EPs on average. Conclusion The GRU-RNN-based DVH prediction method was capable of accurate DVH prediction. The regenerated plans guided by the predicted EUDs were not inferior to the manual plans, had better consistency in PTVs and better dose sparing in critical OARs, indicating the usefulness and effectiveness of biologically related model in knowledge-based planning.

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