Dosimetric Comparison of CyberKnife with Other Radiosurgical Modalities for an Ellipsoidal Target

Neurosurgery ◽  
2003 ◽  
Vol 53 (5) ◽  
pp. 1155-1163 ◽  
Author(s):  
Cheng Yu ◽  
Gabor Jozsef ◽  
Michael L.J. Apuzzo ◽  
Zbigniew Petrovich
Keyword(s):  
Radiation Dose ◽  
Linear Accelerator ◽  
Normal Tissue ◽  
Intensity Modulated Radiotherapy ◽  
Treatment Modalities ◽  
Conformity Index ◽  
Target Coverage ◽  
Homogeneity Index ◽  
Three Dimensional Model ◽  
Treatment Plans

Abstract OBJECTIVE To compare treatment plans obtained with the CyberKnife (CK) (Accuray, Inc., Sunnyvale, CA) with those of other commonly used radiosurgical modalities, such as the gamma knife (GK), linear accelerator multiple arcs, conformally shaped static fields, and intensity-modulated radiotherapy (IMRT). METHODS An ellipsoidal simulated target was chosen centrally located in a three-dimensional model of a patient's head acquired with magnetic resonance or computed tomographic imaging. It was 25 mm in diameter and 35 mm long. The aims of treatment plans were 100% target volume coverage with an appropriate isodose line, minimum radiation dose to normal tissue, and clinically acceptable delivery. These plans were evaluated by use of a dose-volume histogram and other commonly used radiosurgical parameters such as target coverage, homogeneity index, and conformity index. RESULTS All selected treatment modalities were equivalent in providing full target coverage. For dose homogeneity, all modalities except for multiple isocenter plans for GK (homogeneity index, 2.0) were similar (homogeneity index, ≅1.25). Dose conformity was essentially equivalent for all treatment plans except for IMRT, which had a slightly higher value (conformity index, ≅1.27). There was a substantial variation in the radiation dose to normal tissue between the studied modalities, particularly at the lower dose levels. CONCLUSION CK plans seemed to be more flexible for a given target size and shape. For a target of limited volume and essentially of any shape, one could obtain similarly good conformal dosimetry with CK and GK. For a regular-shaped but other than spherical target, homogeneous dose distribution could be obtained with all selected modalities except for multiple isocenters, linear accelerator multiple arcs, or GK. Both IMRT and conformally shaped static fields offered good alternative treatment modalities to CK, GK, or linear accelerator multiple arc radiosurgery, with slightly inferior dosimetry in conformity (IMRT).

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.

A simple dose gradient measurement tool to complement the conformity index

2006 ◽  
Vol 105 (Supplement) ◽  
pp. 194-201 ◽  
Author(s):  
Ian Paddick ◽  
Bodo Lippitz
Keyword(s):  
Low Dose ◽  
Target Volume ◽  
Mean Value ◽  
Treatment Modalities ◽  
Measurement Tool ◽  
Conformity Index ◽  
Treatment Plans ◽  
Prescription Isodose ◽  
Gradient Measurement

✓A dose gradient index (GI) is proposed that can be used to compare treatment plans of equal conformity. The steep dose gradient outside the radiosurgical target is one of the factors that makes radiosurgery possible. It therefore makes sense to measure this variable and to use it to compare rival plans, explore optimal prescription isodoses, or compare treatment modalities.The GI is defined as the ratio of the volume of half the prescription isodose to the volume of the prescription isodose. For a plan normalized to the 50% isodose line, it is the ratio of the 25% isodose volume to that of the 50% isodose volume.The GI will differentiate between plans of similar conformity, but with different dose gradients, for example, where isocenters have been inappropriately centered on the edge of the target volume.In a retrospective series of 50 dose plans for the treatment of vestibular schwannoma, the optimal prescription isodose was assessed. A mean value of 40% (median 38%, range 30–61%) was calculated, not 50% as might be anticipated. The GI can show which of these prescription isodoses will give the steepest dose falloff outside the target.When planning a multiisocenter treatment, there may be a temptation to place some isocenters on the edge of the target. This has the apparent advantage of producing a plan of good conformity and a predictable prescription isodose; however, it risks creating a plan that has a low dose gradient outside the target. The quality of this dose gradient is quantified by the GI.

scholarly journals Dosimetric and biological comparison of treatment plans between EDGE and CyberKnife systems in stereotactic body radiation therapy for localized prostate cancer

2020 ◽  
Author(s):  
Zhitao Dai ◽  
Lian Zhu ◽  
Tingting Cao ◽  
Aihua Wang ◽  
Xueling Guo ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radiation Therapy ◽  
Normal Tissue ◽  
Stereotactic Body Radiation Therapy ◽  
Localized Prostate Cancer ◽  
Conformity Index ◽  
Delivery Time ◽  
Plan Quality ◽  
Dose Volume ◽  
Treatment Plans

Abstract Aims: The aim of this study was to make a quantitative comparison of plan quality between MLC-based EDGE system and the cone-based CyberKnife system in stereotactic body radiation therapy (SBRT) for patients with localized prostate cancer.Materials and methods: Ten patients with prostate volumes ranging from 34.65 to 82.16 cc were used for prostate SBRT. Treatment plans were created for both EDGE and CyberKnife G4 systems using the same dose-volume constraints. Dosimetric indices including Planning Tumor Volume (PTV) coverage, conformity index (CI), new conformity index (nCI), homogeneity index (HI), gradient index (GI) were applied for target, while the sparing of critical organs, including bladder, rectum, femoral heads, urethra, penile bulk and normal tissue outside PTV), were evaluated interms of various dose-volume metrics and integral dose (ID). Meanwhile, the required delivery time and number of monitor units (MUs) during irradiation were measured to estimate the treatment efficiency. The radiobiological indices such as equivalent uniform dose (EUD), tumor control probability (TCP) and the normal tissue complication probability (NTCP) were also analyzed. Results: All dose constraints were achieved by both systems. It showed that the DEGE plans results were closest to the CK plans results in terms of PTV coverage, HI and GI. For EDGE, more conformal dose distribution in the target as well as reduced exposure of critical organs were obtained together with reduction of 91% delivery time and 72% monitor units. EDGE plans also got lower EUD for bladder, rectum, urethra and penile bulk, which associated with reduction of NTCPs. However, higher values of EUD and TCP for tumor were obtained with CK plans. Conclusions: Our study indicated that both systems were capable of producing almost equivalent plan quality and can meet clinical requirements. CyberKnife G4 system has higher target dose while EDGE system has more advantages based on the considerations of normal tissue sparing and delivery efficiency. With abundant clinical experience, CK provides accurate SBRT treatment with high quality. EDGE system also can be considered to be an option for SBRT treatment for localized prostate cancer treatment.

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.

Dosimetric and radiobiological comparison of external beam radiotherapy using simultaneous integrated boost technique for esophageal cancer in different location.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e15505-e15505
Author(s):  
Lu Wang ◽  
Jinming Yu
Keyword(s):  
Esophageal Cancer ◽  
External Beam Radiotherapy ◽  
Intensity Modulated Radiotherapy ◽  
Target Volume ◽  
Simultaneous Integrated Boost ◽  
Conformity Index ◽  
Tumor Control ◽  
Tumor Control Probability ◽  
Integrated Boost ◽  
Treatment Plans

e15505 Background: Based on dosimetry and radiobiology to compare treatment plans for esophageal cancer (EC) in different location using intensity modulated radiotherapy (IMRT), volumetric modulated arc radiotherapy (VMAT) and helical tomotherapy(HT) with simultaneous integrated boost (SIB) technique. Methods: A total of 20 patients including 5 cases respectively located in the cervix, upper, middle and lower thorax were generated for IMRT, VMAT and HT plans. The dose volume histogram statistics, conformity index (CI), homogeneity index (HI), tumor control probability (TCP) and normal tissues control probability (NTCP) were analyzed to evaluate treatment plans. Results: HT showed significantly improvement over IMRT and VMAT in terms of CI(0.93±0.03), HI(0.07±0.03) and TCP(88.08±0.82%) in cervical EC(p<0.05). IMRT greatly developed TCP(88.29±1.79%;85.11±0.79%), and offered superior CIs (0.87±0.04;0.90±0.01) and HIs(0.10±0.01; 0.06±0.01) compared with VMAT and HT in upper and middle thoracic EC(p<0.05). Meanwhile, the V30(33.30±6.49%), mean dose (2559.00±219.64cGy) and NTCP(0.50±0.61%) of heart for IMRT were significantly reduced than other two techniques in middle thoracic EC. Patients with lower thoracic EC yielded the similar CIs and HIs(all p>0.05) for the 3 techniques, but VMAT showed the lowest NTCP of lungs (0.01±0.01%) with improved TCP (84.84±1.13%). Conclusions: HT was a good option with little lung and heart involvement as it achieved superior dose conformality and uniformity. IMRT was a perfect strategy with large thoracic involvement. It significantly improved tumor local control and reduced heart dose and complications with acceptable dose to lungs. VMAT was preferred with a smaller target volume but surrounded by more heart and less lungs. Individually choosing optimal technique for EC in different location will be warranted.

Dosimetric and biological comparison of treatment plans between LINAC and robot  systems in stereotactic body radiation therapy for localized prostate cancer

2021 ◽  
Author(s):  
Zhitao Dai ◽  
Lian Zhu ◽  
Tingting Cao ◽  
Aihua Wang ◽  
Xueling Guo ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radiation Therapy ◽  
Normal Tissue ◽  
Stereotactic Body Radiation Therapy ◽  
Localized Prostate Cancer ◽  
Conformity Index ◽  
Delivery Time ◽  
Plan Quality ◽  
Dose Volume ◽  
Treatment Plans

Abstract Aims The aim of this study was to make a quantitative comparison of plan quality between MLC-based EDGE system and the cone-based CyberKnife system in stereotactic body radiation therapy (SBRT) for patients with localized prostate cancer. Materials and methods Ten patients with prostate volumes ranging from 34.65 to 82.16 cc were used for prostate SBRT. Treatment plans were created for both EDGE and CyberKnife G4 systems using the same dose-volume constraints. Dosimetric indices including Planning Tumor Volume (PTV) coverage, conformity index (CI), new conformity index (nCI), homogeneity index (HI), gradient index (GI) were applied for target, while the sparing of critical organs, including bladder, rectum, femoral heads, urethra, penile bulk and normal tissue outside PTV), were evaluated interms of various dose-volume metrics and integral dose (ID). Meanwhile, the required delivery time and number of monitor units (MUs) during irradiation were measured to estimate the treatment efficiency. The radiobiological indices such as equivalent uniform dose (EUD), tumor control probability (TCP) and the normal tissue complication probability (NTCP) were also analyzed. Results All dose constraints were achieved by both systems. It showed that the DEGE plans results were closest to the CK plans results in terms of PTV coverage, HI and GI. For EDGE, more conformal dose distribution in the target as well as reduced exposure of critical organs were obtained together with reduction of 91% delivery time and 72% monitor units. EDGE plans also got lower EUD for bladder, rectum, urethra and penile bulk, which associated with reduction of NTCPs. However, higher values of EUD and TCP for tumor were obtained with CK plans. Conclusions Our study indicated that both systems were capable of producing almost equivalent plan quality and can meet clinical requirements. CyberKnife G4 system has higher target dose while EDGE system has more advantages based on the considerations of normal tissue sparing and delivery efficiency. With abundant clinical experience, CK provides accurate SBRT treatment with high quality. EDGE system also can be considered to be an option for SBRT treatment for localized prostate cancer treatment.

Two-arc volumetric modulated arc therapy to provide dosimetric advantages for pancreas stereotactic body radiotherapy.

2016 ◽  
Vol 34 (4_suppl) ◽  
pp. 445-445
Author(s):  
Jason K Molitoris ◽  
Christopher Brown ◽  
Shifeng Chen ◽  
Kimberly Marter ◽  
Kristin Spaeth ◽  
...  
Keyword(s):  
Normal Tissue ◽  
Locally Advanced ◽  
Volumetric Modulated Arc Therapy ◽  
Advanced Pancreatic Cancer ◽  
Intensity Modulated Radiotherapy ◽  
Target Volume ◽  
Breath Hold ◽  
Target Coverage ◽  
Delivery Time ◽  
Arc Therapy

445 Background: Stereotactic body radiation therapy(SBRT) is increasingly used in locally advanced pancreatic cancer (LAPC). SBRT can be delivered using 3D conformal, static intensity modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT) techniques. Prior data suggest advantages of using VMAT over IMRT for single-fraction pancreas SBRT. We performed the first dosimetric comparison of IMRT with one and two arc VMAT for 5-fraction pancreas SBRT, a more commonly used regimen. Methods: We generated 5-fraction SBRT plans for 12 LAPC patients who were previously treated at our institution with standard fractionation. The prescription dose was 33 Gy delivered in 6.6 Gy fractions. Assuming breath hold, 3 plans were generated for each patient: 9-beam static IMRT, 1-arc VMAT (VMAT1), and 2-arc VMAT (VMAT2) targeting the primary tumor. Target coverage and normal tissue doses were compared between the delivery techniques. Results: Each plan met target coverage planning goals. More VMAT2 plans (100%) were able to meet all normal tissue constraints than VMAT1 (83.3%) or IMRT (75%). Duodenal dose was most lowest for VMAT2 compared to VMAT1 and IMRT for mean dose (8.66 vs. 9.00 vs. 8.99 Gy); D4% (25.9 vs. 26.6 vs. 26.3 Gy); V10Gy (38.02 vs. 39.33 vs. 40.11%), V15Gy (23.98 vs. 25.88 vs. 25.97%), V20Gy (12.73 vs. 13.84 vs. 14.95%), and V25Gy (5.96 vs. 6.85 vs. 6.78%)(all p < 0.05). The tumors closest to the duodenum had statistically significantly improved V30Gy for VMAT2 compared to VMAT1 and IMRT (both p < 0.001). VMAT1 and VMAT2 reduced dose to the stomach, spinal cord, and liver compared to IMRT; kidney dose, however, was lowest using IMRT. VMAT2 plans had the highest conformity, but required the most monitor units to deliver. Delivery time was significantly longer with IMRT, compared to VMAT1 and VMAT2 (8.25 vs. 2.16 vs. 3.33 mins). Conclusions: These data suggest that VMAT2 should be strongly considered for 5-fraction pancreas SBRT because of superior normal tissue sparing, more conformal target volume coverage, and faster treatment delivery time (compared to IMRT). Further evaluation is needed to clarify whether the dosimetric advantages of VMAT2 are clinically significant.

scholarly journals Effect of smoothing on treatment plan efficiency in IMRT: eclipse Helios™ dose optimisation

2012 ◽  
Vol 11 (4) ◽  
pp. 229-238 ◽  
Author(s):  
KS Armoogum
Keyword(s):  
Organs At Risk ◽  
Treatment Plan ◽  
Intensity Modulated Radiotherapy ◽  
Planning System ◽  
Treatment Planning System ◽  
Conformity Index ◽  
Homogeneity Index ◽  
Medical Systems ◽  
Dose Optimisation ◽  
Smoothing Parameters

AbstractBackground and purpose: This study examined the effect of varying the X–Y smoothing values on the average Leaf Pair Opening (LPO), MUFactor and total number of monitor units (MU) in a cohort of 20 prostate and head and neck (H&N) patients treated with dynamic intensity-modulated radiotherapy (IMRT).Material and methods: Plans were created using Varian Eclipse™ Treatment Planning System (TPS) version 8.9.09 (Varian Medical Systems, Palo Alto, CA). Clinically approved and dosimetrically verified plans were used as a reference plans. These were re-optimised varying the X and Y smoothing parameters from 0 to 100 in various combinations.Results: For the prostate patients, at X = 0 and Y = 0, the average LPO was 2.4 cm (σ = 0.20 cm) and 3.5 cm (σ = 0.35 cm) for X = 100 and Y = 100. For H&N, the LPO averaged over all fields increased from 1.7 cm (σ = 0.17 cm) at X = 0 and Y = 0 to 2.3 cm (σ = 0.27 cm) at X = 100 and Y = 90. The MUFactor decreased from 1.81 (σ = 0.19) at X = 0 and Y = 0 to 1.38 (σ = 0.11) at X = 100 and Y = 100 for prostates and from 1.50 (σ = 0.14) at X = 0 and Y = 0 to 1.24 (σ = 0.09) for X = 100 and Y = 90 for H&N. Total MU for prostates decreased from 1028.0 (σ = 244.6) at X = 0 and Y = 0 to 688.4 (σ = 159.3) at X = 100 and Y = 100 and from 913 (σ = 267.2) at X = 0 and Y = 0 to 696 (σ = 214.03) at X = 100 and Y = 90 for H&N.Conclusions: Increasing smoothing decreases MUFactor, decreases total MU and increases average LPO but does not greatly enhance organs at risk (OAR) sparing. The Homogeneity Index (HI) and Paddick Conformity Index (CIPAD) appear to vary little after increasing smoothing up to approximately X = 80 and Y = 70.

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