scholarly journals Dosimetric comparison of jaw tracking in intensity modulated and volumetric modulated arc radiotherapy for carcinoma of cervix

2019 ◽  
Vol 25 (3) ◽  
pp. 155-164
Author(s):  
Karthick Raj Mani ◽  
Muhtasim Aziz Muneem ◽  
Nazneen Sultana ◽  
Tanjina Hossain ◽  
Tabinda Basharat ◽  
...  
Keyword(s):  
Femoral Head ◽  
Dose Reduction ◽  
Low Dose ◽  
Intensity Modulated Radiotherapy ◽  
Conformity Index ◽  
P Value ◽  
Intensity Modulated ◽  
Carcinoma Of Cervix ◽  
Target Volumes ◽  
Volumetric Modulated Arc Radiotherapy

Abstract Aim: To study the dosimetric advantages of the jaw tracking technique in intensity-modulated radiotherapy (IMRT) and volumetric modulated arc radiotherapy (VMAT) for carcinoma of cervix patients. Materials and Methods: We retrospectively selected ten previously treated cervix patients in this study. All the ten patients underwent CT simulation along with immobilization and positional devices. Targets and organ at risks (OARs) were delineated slice by slice for all the patients. All the patients were planned for IMRT and VMAT with intend to deliver 50 Gy in 25 fractions. All the plans were planned with 6 MV photon beam using millennium-120 multi leaf collimator (MLC) using the TrueBeam linear accelerator. IMRT and VMAT plans were performed with jaw tracking (JT) and with static jaw (SJ) techniques by keeping the same constraints and priorities for the target volumes and critical structures for a particular patient. For standardization, all the plans were normalized to the target mean of the planning target volume. All the plans were accepted with the criteria of bladder mean dose < 40 Gy and rectum mean dose < 40 Gy without compromising the target volumes. Target conformity, dose to the critical structures and low dose volumes were recorded and analyzed for IMRT and VMAT plans with and without jaw tracking for all the patients. Results: The conformity index average of all patients followed by standard deviation (̄x± σ̄x) for JT-IMRT, SJ-IMRT, JT-VMAT and SJ-VMAT were 1.176 ± 0.139, 1.175 ± 0.139, 1.193 ± 0.220 and 1.228 ± 0.192 and homogeneity index were 0.089 ± 0.022, 0.085 ± 0.024, 0.102 ± 0.016 and 0.101 ± 0.016. In low dose volume J,T-IMRT shows a 5.4% (p-value < 0.001) overall reduction in volume receiving at least 5 Gy (V5) compared to SJ-IMRT, whereas 1.2% reduction was observed in V5 volume in JT-VMAT compared to SJ-VMAT. JT-IMRT showed mean reduction in rectum and bladder of 1.34% (p-value < 0.001) and 1.46% (p-value < 0.001) compared to SJ-IMRT, while only 0.30% and 0.03% reduction were observed between JT-VMAT and SJ-VMAT. JT-IMRT plans also showed considerable dose reduction to inthe testine, right femoral head, left femoral head and cauda compared to the SJ-IMRT plans. Conclusion: Jaw tracking resulted in decreased dose to critical structures in IMRT and VMAT plans. But significant dose reductions were observed for critical structures in the JT-IMRT compared to SJ-IMRT technique. In JT-VMAT plans dose reduction to the critical structures were not significant compared to the JT-IMRT due to relatively lesser monitor units in the VMAT plans.

scholarly journals Volumetric Modulated Arc Therapy for Head and Neck Cancer: A Dosimetric and Treatment Planning Comparison with Intensity Modulated Radiotherapy Techniques

2021 ◽  
Author(s):  
Brijesh Goswami ◽  
Suresh Yadav ◽  
Rakesh Kumar Jain ◽  
Pradeep Goswami
Keyword(s):  
Head And Neck Cancer ◽  
Head And Neck ◽  
Neck Cancer ◽  
Intensity Modulated Radiotherapy ◽  
Patient Comfort ◽  
Conformity Index ◽  
P Value ◽  
Target Coverage ◽  
Treatment Technique ◽  
Intensity Modulated

Introduction: Traditional Intensity Modulated Radiotherapy (IMRT) techniques used many beam angles; the result of this is significant increase in beam on time as well as Monitor Units (MU) also. Due to all of these there is a need of faster treatment modality to increase the patient comfort and lesser organ movement. Aim: To compare the triple arc RapidArc technique with nine field IMRT techniques for different head and neck cancer, focusing on target coverage and dose received by the Organs At Risk (OARs). Materials and Methods: Retrospectively, Computed Tomography (CT) datasets of 20 patients of Squamous Cell Carcinoma (SCC) of the Oro-pharynx and Hypo-pharynx treated during January 2019 to December 2019 were chosen for this study. For every patient, two different treatment plans were created, one by using the triple arc RapidArc technique and others by using nine fixed fields IMRT technique. For Planning Target Volume (PTV), the dose volume parameters D98% and D2% (dose received by the 98%, and 2% of the volume), homogeneity index, and Conformity Index (CI) were evaluated for dosimetric comparison. For OARs, the analysis included the mean dose, the maximum dose expressed as D2%. Additionally, the Beam On Time (BOT) and the number of MUs were analysed. A paired two-tailed t-test was performed to compare the RapidArc technique with the IMRT technique for radiotherapy treatment of different head and neck cancers. The p-value <0.05 was considered for the significance of statistical inferences. Results: Comparable target coverage and better sparing of OARs were achieved with the RapidArc technique in comparison to IMRT. Homogeneity and conformity were also in favour of the RapidArc plan. The dosimetric results with I’MatriXX measurements of RapidArc plans were similar to IMRT plans. All detector points passed 3 mm and 3% gamma criteria for IMRT plans and also for RapidArc plans. Conclusion: RapidArc is a faster and precise treatment technique. RapidArc provides better target coverage with good OARs sparing. Most significant change occurs in the number of MUs and treatment time, which is much lesser in RapidArc.

scholarly journals Effect of Photon Energy on Conventional Intensity-Modulated Radiotherapy and Rapid Arc Radiotherapy Planning for Deep-Seated Targets in Carcinoma Cervix

2019 ◽  
Vol 05 (01) ◽  
pp. 24-33
Author(s):  
Manindra Bhushan ◽  
Girigesh Yadav ◽  
Deepak Tripathi ◽  
Lalit Kumar ◽  
Abhinav Dewan ◽  
...  
Keyword(s):  
Photon Energy ◽  
Intensity Modulated Radiotherapy ◽  
Target Volume ◽  
Radiotherapy Planning ◽  
Treatment Modalities ◽  
Conformity Index ◽  
P Value ◽  
Carcinoma Cervix ◽  
Intensity Modulated ◽  
Significant Difference

Abstract Introduction To evaluate the dosimetric effect of photon energies on fixed field intensity-modulated radiotherapy (IMRT) and dual arc (DA) planning and to compare the dosimetric differences between conventional IMRT and DA radiotherapy planning. Materials and Methods IMRT and DA plans were generated for 15 patients having cervical cancer using different photon energies. IMRT and DA plans were generated using seven fields and double arcs, respectively. Dosimetric comparison was done in terms of planning target volume (PTV) coverage, sparing of organ at risk (OAR), homogeneity index (HI), conformity index (CI), and monitor units (MUs). Photo-neutron (energy ≤10MV) contribution was not considered for this study. Near region (NR) and far region (FR) were contoured to evaluate the dose deposited in nontarget area. Results No significant difference was observed (p > 0.05) in PTV coverage for conventional IMRT and DA; however, 6 MV yielded significantly better coverage over 15 MV (p < 0.05) for both the treatment modalities. Mean bladder dose was significantly more for conventional IMRT compared with DA. For rectal mean dose, p-value was nonsignificant for IMRT in comparison to DA, while significant difference was observed for change in photon energies for both treatment modalities respectively, except for 10 MV versus 15 MV DA plans. Significant improvements in HI (except 6 MV vs. 10 MV DA), CI (except 6 MV vs. 10 MV IMRT and DA), MUs, NR, and FR were noted. Conclusion DA generates more conformal, homogenous plans, requires less numbers of MUs, and deposits fewer doses to NR and FR regions of nontarget tissues in comparison to conventional IMRT. Although increase in photon energy for IMRT and DA plans reduces numbers of MUs and dose deposited to NR and FR regions, yet the choice for treatment of carcinoma cervix remains 6 MV due to production of photo-neutrons at higher energies.

scholarly journals Comparison of intensity modulated radiotherapy treatment plans between 1.5 T MR-Linac and conventional linac

2020 ◽  
Author(s):  
Shouliang Ding ◽  
Yongbao Li ◽  
Hongdong Liu ◽  
Rui Li ◽  
Bin Wang ◽  
...  
Keyword(s):  
Low Dose ◽  
Intensity Modulated Radiotherapy ◽  
Planning System ◽  
Treatment Planning System ◽  
Conformity Index ◽  
Skin Dose ◽  
Multiple Tumor ◽  
Intensity Modulated ◽  
Delivery Technique ◽  
Step And Shoot

Abstract Background To assess the dosimetric qualities and usability of planning for 1.5 T MR-Linac based intensity modulated radiotherapy (MRL-IMRT) for various clinical sites in comparison with IMRT plans using a conventional linac.Methods In total of 17 patients with disease sites in the brain, esophagus, lung, rectum and vertebra were re-planned retrospectively for simulated MRL-IMRT using the Elekta Unity dedicated treatment planning system (TPS) Monaco (v5.40.01). Currently, the step-and-shoot (ss) is the only delivery technique for IMRT available on Unity. All patients were treated on an Elekta Versa HD™ with IMRT using the dynamic multileaf collimator (dMLC) technique, and the plans were designed using Monaco v5.11. For comparison, the same dMLC-IMRT plan was recalculated with the same machine and TPS but only changing the technique to step-and-shoot. The dosimetric qualities of the MRL-IMRT plans, to be evaluated by the Dose Volume Histograms (DVH) metrics, Homogeneity Index and Conformity Index, were compared with the clinical plans. The planning usability was measured by the optimization time and the number of Monitor Units (MUs).Results Comparing MRL-IMRT with conventional linac based plans, there were no clinically significant differences between any of the DVH parameters studied for multiple tumor sites. However, MRL-IMRT plans had significantly increased dose to skin and low dose region of normal tissue. Furthermore, MRL-IMRT plans had significantly reduced optimization time by comparing conventional linac based plans. The number of MUs of MRL-IMRT was increased by 23% compared with ss-IMRT, and no difference from dMLC-IMRT.Conclusions Clinically acceptable plans can be achieved with 1.5 T MR-Linac system for multiple tumor sites. The planning efficiency of MRL-IMRT was improved due to the reduced optimization time. However the increase in skin dose and low dose region was also observed in MRL-IMRT plans.

Helical tomotherapy for advanced esophageal cancer improves target conformity and homogeneity: A comparison with fixed-field intensity-modulated radiotherapy

2015 ◽  
Vol 11 (3) ◽  
pp. 3146-3155
Author(s):  
Luhua Wang
Keyword(s):  
Esophageal Cancer ◽  
Field Intensity ◽  
Helical Tomotherapy ◽  
Intensity Modulated Radiotherapy ◽  
Matched Pair ◽  
Conformity Index ◽  
Target Coverage ◽  
Advanced Esophageal Cancer ◽  
Fixed Field ◽  
Intensity Modulated

Purpose: To evaluate the usefulness of helical tomotherapy (HT) in the treatment of advanced esophageal cancer (EC) and compare target homogeneity, conformity and normal tissue doses between HT and fixed-field intensity-modulated radiotherapy (ff-IMRT).Methods: In all, 23 patients with cT3-4N0-1M0-1a thoracic EC (upper esophagus, 9 patients; middle esophagus, 6; distal esophagus, 6 and esophagogastric junction, 2) who were treated with ff-IMRT (60 Gy in 30 fractions) were re-planned for HT and ff-IMRT with the same clinical require­ments. Comparisons were performed using the Wilcoxon matched-pair signed-rank test.Results: Compared with ff-IMRT, HT significantly reduced the homogeneity index for thoracic, upper, middle and distal ECs by 38%, 31%, 36% and 33%, respectively (P < 0.05). The conformity index was increased by HT for thoracic, upper and middle ECs by 9%, 9% and 18%, respectively (P < 0.05). Target coverage was improved by 1% with HT (P < 0.05). The mean lung dose was significantly reduced by HT for thoracic and upper ECs (P < 0.05). The V20 (volume receiving at least 20 Gy) and higher dose volumes of the lungs were decreased by HT in all cases, but the differences were significant for thoracic, upper and distal ECs (P < 0.05), with reductions of 2.1%, 3.1% and 2.2%, respectively. HT resulted in a larger lung V5 for thoracic, upper, middle and distal ECs, with increases of 3.5%, 1.5%, 7.2% and 3.2%, respectively. Heart sparing was significantly better with HT than with ff-IMRT in terms of the V30 and V40 for thoracic, upper, middle and distal ECs (P < 0.05).Conclusions: Compared to ff-IMRT, HT provides superior target coverage, conformity and homogeneity, with reduced the volume of high doses to the lungs and heart for advanced EC. HT may be a treatment option for advanced EC, especially upper EC.

scholarly journals Quality of Automated Stereotactic Radiosurgery Plans in Patients with 4 to 10 Brain Metastases

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3458
Author(s):  
Anna Petoukhova ◽  
Roland Snijder ◽  
Rudolf Wiggenraad ◽  
Linda de Boer-de Wit ◽  
Ivonne Mudde-van der Wouden ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Stereotactic Radiosurgery ◽  
Irradiation Time ◽  
Intensity Modulated Radiotherapy ◽  
Pass Rate ◽  
Conformity Index ◽  
Index Gradient ◽  
Single Isocenter ◽  
Volumetric Modulated Arc Radiotherapy

The purpose was to compare linac-based stereotactic radiosurgery and hypofractionated radiotherapy plan quality of automated planning, intensity modulated radiotherapy (IMRT) and manual dynamic conformal arc (DCA) plans as well as single- and multiple-isocenter techniques for multiple brain metastases (BM). For twelve patients with four to ten BM, seven non-coplanar linac-based plans were created: a manually planned DCA plan with a separate isocenter for each metastasis, a single-isocenter dynamic IMRT plan, an automatically generated single-isocenter volumetric modulated arc radiotherapy (VMAT) plan, four automatically generated single-isocenter DCA plans with three or five couch angles, with high or low sparing of normal tissue. Paddick conformity index, gradient index (GI), mean dose, total V12Gy and V5Gy of uninvolved brain, number of monitor units (MUs), irradiation time and pass rate were compared. The GI was significantly higher for VMAT than for separate-isocenter, IMRT, and all automatically generated plans. The number of MUs was lowest for VMAT, followed by automatically generated DCA and IMRT plans and highest for manual DCA plans. Irradiation time was the shortest for automatically planned DCA plans. Automatically generated linac-based single-isocenter plans for multiple BM reduce the number of MUs and irradiation time with at least comparable GI and V5Gy relative to the reference separate-isocenter DCA plans.

Overestimation of Low-Dose Radiation in Intensity-Modulated Radiotherapy with Sliding-Window Technique

2009 ◽  
Vol 185 (12) ◽  
pp. 821-829 ◽  
Author(s):  
Hilke Vorwerk ◽  
Daniela Wagner ◽  
Björn Seitz ◽  
Hans Christiansen ◽  
Hendrik A. Wolff ◽  
...  
Keyword(s):  
Low Dose ◽  
Intensity Modulated Radiotherapy ◽  
Sliding Window ◽  
Low Dose Radiation ◽  
Intensity Modulated ◽  
Window Technique ◽  
Dose Radiation

scholarly journals Treatment planning for MLC based robotic radiosurgery for brain metastases: plan comparison with circular fields and suggestions for planning strategies

2017 ◽  
Vol 3 (2) ◽  
pp. 151-154
Author(s):  
Daniela Schmitt ◽  
Rami El Shafie ◽  
Sebastian Klüter ◽  
Nathalie Arians ◽  
Kai Schubert ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Low Dose ◽  
Treatment Time ◽  
Conformity Index ◽  
High Dose ◽  
Gradient Index ◽  
Plan Comparison ◽  
Robotic Radiosurgery ◽  
Target Volumes ◽  
Beam Transmission

AbstractTo evaluate the possible range of application of the new InCise2 MLC for the CyberKnife M6 system in brain radiosurgery, a plan comparison was made for 10 brain metastases sized between 1.5 and 9cm3 in 10 patients treated in a single fraction each. The target volumes consist of a PTV derived by expanding the GTV by 1mm and were chosen to have diversity in the cohort regarding regularity of shape, location and the structures needed to be blocked for beam transmission in the vicinity. For each case, two treatment plans were optimized: one using the MLC and one using the IRIS-collimator providing variable circular fields. Plan re-quirements were: dose prescription to the 70% isodose line (18 or 20Gy), 100% GTV coverage, ≥98% PTV coverage, undisturbed central high dose region (95% of maximum dose) and a conformity index as low as possible. Plan com-parison parameters were: conformity index (CI), high-dose gradient index (GIH), low-dose gradient index (GIL), total number of monitor units (MU) and expected treatment time (TT). For all cases, clinically acceptable plans could be gen-erated with the following results (mean±SD) for CI, GIH, GIL, MU and TT, respectively for the MLC plans: 1.09±0.03, 2.77±0.26, 2.61±0.08, 4514±830MU and 27±5min and for the IRIS plans: 1.05±0.01, 3.00±0.35, 2.46±0.08, 8557±1335MU and 42±7min. In summary, the MLC plans were on average less conformal and had a shallower dose gradient in the low dose region, but a steeper dose gradient in the high dose region. This is accompanied by a smaller vol-ume receiving 10Gy. A plan by plan comparison shows that usage of the MLC can spare about one half of the MUs and one third of treatment time. From these experiences and results suggestions for MLC planning strategy can be de-duced.

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