conformity index
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2021 ◽  
Vol 11 (12) ◽  
pp. 1311
Author(s):  
Dorota Maria Borowicz ◽  
Konstantin N. Shipulin ◽  
Gennady V. Mytsin ◽  
Agnieszka Skrobała ◽  
Piotr Milecki ◽  
...  

Few studies have directly compared passive scattering (PS) to intensity-modulated proton therapy (IMPT) in the delivery of ultra-hypofractionated proton beams to the localized prostate cancer (PCa). In this preliminary study involving five patients previously treated with CyberKnife, treatment plans were created for PS and IMPT (36.25 CGE in five fractions with two opposing fields) to compare the dosimetric parameters to the planning target volume (PTV) and organs-at-risk (OAR: rectum, bladder, femoral heads). Both plans met the acceptance criteria. Significant differences were observed in the minimum and maximum doses to the PTV. The mean dose to the PTV was lower for PS (35.62 ± 0.26 vs. 37.18 ± 0.14; p = 0.002). Target coverage (D98%) was better for IMPT (96.79% vs. 99.10%; p = 0.004). IMPT resulted in significantly lower mean doses to the rectum (16.75 CGE vs. 6.88 CGE; p = 0.004) and bladder (17.69 CGE vs. 5.98 CGE p = 0.002). High dose to the rectum (V36.25 CGE) were lower with PS, but not significantly opposite to high dose to the bladder. No significant differences were observed in mean conformity index values, with a non-significant trend towards higher mean homogeneity index values for PS. Non-significant differences in the gamma index for both fields were observed. These findings suggest that both PS and IMPT ultra-hypofractionated proton therapy for PCa are highly precise, offering good target coverage and sparing of normal tissues and OARs.


Author(s):  
Yassine Beltaifa ◽  
Hussein Hamdi ◽  
Giorgio Spatola ◽  
Anne Balossier ◽  
Louise Merly ◽  
...  

<b><i>Background:</i></b> Radiosurgery has demonstrated good safety and efficacy in the treatment of multiple brain metastases (BMs). However, multi-target dose planning can be challenging and time-consuming. A recently developed real-time inverse treatment planning (IP) by convex optimization has been demonstrated to produce high-quality treatment plans with good conformity and selectivity in single-target plans. We intended to test the capacity of this IP to rapidly generate efficient plans while optimizing the preservation of normal tissue in multiple BM. <b><i>Methods:</i></b> Seventy-nine patients (mean age 62.4, age range 22–85) with a total of 272 BMs were treated by Gamma Knife Radiosurgery. All subjects were treated using a forward planning (FP) technique by an expert neurosurgeon. The new Intuitive Plan was applied and able to automatically generate an alternative plan for each patient. All planning variables were collected from the IP to be compared with the corresponding measurements obtained from the FP. A paired sample <i>t</i> test was applied to compare the 2 plans for the following variables: brain volumes receiving 10 Gy (V10) (primary endpoint), and 12 Gy (V12), planning indices (selectivity, coverage, gradient, and Paddick Conformity Index [PCI]), beam-on time (BOT), and integral doses. Additionally, the noninferiority margin for each item was calculated, and the 2 plans were compared for noninferiority using a paired <i>t</i> test. <b><i>Results:</i></b> The mean age of patients was 62.4 years old (age range 22–85), with a sex ratio of 1.02. The average number of lesions per patient was 3.4 (range 1–12). The mean prescription dose was 21.46 Gy (range 14–24 Gy). Noninferiority of the IP was concluded for V10, V12, prescription isodose volume, BOT, PCI, and selectivity. The V10 (and V12) was significantly lower with the IP (<i>p</i> &#x3c; 0.001). These volumes were 8.69 cm<sup>3</sup> ± 11.39 and 5.47 cm<sup>3</sup> ± 7.03, respectively, for the FP and 7.57 cm<sup>3</sup> ± 9.44 and 4.78 cm<sup>3</sup> ± 5.86 for the IP. Only the coverage was significantly lower with the IP (−2.3%, <i>p</i> &#x3c; 0.001), but both selectivity (+17%) and PCI (+15%) were significantly higher with the IP than FP (<i>p</i> &#x3c; 0.001). <b><i>Conclusion:</i></b> This IP demonstrated its capacity to generate multi-target plans rapidly, with a dose to the brain (V10) and BOT noninferior to the one of a human expert planner. These results would benefit from confirmation in a larger prospective series.


2021 ◽  
Vol 55 (4) ◽  
pp. 499-507
Author(s):  
Yuan Xu ◽  
Pan Ma ◽  
Zhihui Hu ◽  
Yuan Tian ◽  
Kuo Men ◽  
...  

Abstract Background Non-coplanar volumetric modulated arc therapy (ncVMAT) is proposed to reduce toxicity in heart and lungs for locoregional radiotherapy of left-sided breast cancer, including internal mammary nodes (IMN). Patients and methods This retrospective study included 10 patients with left-sided breast cancer who underwent locoregional radiotherapy after breast-conserving surgery. For each patient, the ncVMAT plan was designed with four partial arcs comprising two coplanar arcs and two non-coplanar arcs, with a couch rotating to 90°. The prescribed dose was normalized to cover 95% of planning target volume (PTV), with 50 Gy delivered in 25 fractions. For each ncVMAT plan, dosimetric parameters were compared with the coplanar volumetric modulated arc therapy (coV-MAT) plan. Results T here were improvements in conformity index, homogeneity index and V55 of total target volume (PTVall) comparing ncVMAT to coVMAT (p < 0.001). Among the organs at risk, the average V30, V20, V10, V5, and mean dose (Dmean) of the heart decreased significantly (p < 0.001). Furthermore, ncVMAT significantly reduced the mean V20, V10, V5, and Dmean of left lung and the mean V10 and V5 and Dmean of contralateral lung (p < 0.001). An improved sparing of the left anterior descending coronary artery and right breast were also observed with ncVMAT (p < 0.001). Conclusions Compared to coVMAT, ncVMAT provides improved conformity and homogeneity of whole P TV, better dose sparing of the heart, bilateral lungs, left anterior descending coronary artery (LAD), and right breast for locoregional radiotherapy of left-sided breast cancer with IMN, potentially reducing the risk of normal tissue damage.


2021 ◽  
Author(s):  
Bongkot Jia-Mahasap ◽  
Chakri Madla ◽  
Patumrat Sri ◽  
Imjai Chitapanarux ◽  
Ekkasit Tharavichitkul ◽  
...  

Abstract Background: Specific radiation delivered to the tumor by stereotactic radiosurgery (SRS) has become widely used in the treatment of brain metastasis. This study aimed to compare radiation dosimetry and its parameters from SRS using three different modalities: Helical Tomotherapy (HT), Volumetric Modulated Arc Therapy (VMAT), and Cone-based Linac Radiosurgery (Cone-based). Methods: Patients who had experienced oligo-brain metastasis received SRS in our treatment center. Each contouring dataset was re-planned to create radiation dosimetry in all three treatment systems (HT, VMAT, and Cone-based). The parameters of conformity index (CI), homogeneity index (HI), CI50, and gradient index (CGI) were analyzed to compare the effects of the three techniques. Results: A total of 21 patients with 39 lesions were included in this study. For single lesion, Cone-based and VMAT revealed statistically identical CI, CI50, and CGI values, while exhibiting the poorest HI value. For multiple lesions, Cone-based provided the best CI50 and CGI values. VMAT displayed better CI50 and CGI values than HT. Moreover, VMAT exhibited the lowest BrainV5Gy value and displayed the shortest beam on time (BoT) calculation. Lastly, Decision Score analysis demonstrated better performance in VMAT when compared to the Cone-based approach. Conclusions: Our data indicated the dosimetric comparison between three radiation techniques for single and multiple lesions. The Cone-based technique revealed the poorest HI value. On the other hand, VMAT provided the best estimated BoT value. Moreover, we have reported on the feasibility of SRS using HT, which has been associated with well-tolerability and an acceptable level of radiation output.Trial registration: Thai Clinical Trials Registry (TCTR) ID No. TCTR20200803006Date of registration: 24 July 2020 (Retrospectively registered)URL: http://www.thaiclinicaltrials.org/show/TCTR20200803006


Author(s):  
Yashaswini B. R. ◽  
Kumara Swamy

Background: This study was conducted to compare dosimetric parameters and dose to specific organs at risk (spinal cord and parotids) between intensity modulated radiation therapy (IMRT) and helical tomotherapy (HT) in head and neck squamous cell carcinomas (HNSCC).Methods: Thirty patients with histologically proven HNSCC were treated with chemo radiotherapy, to a dose of 60-70 Gray in 30-35 fractions. This study consists of two arms; IMRT arm and tomotherapy arm. Fifteen consecutive patients treated under IMRT and 15 patients were treated under helical tomotherapy, along with concurrent chemotherapy. PTV1 encompasses low risk planning target volume (PTV) which receives 50 Gy; PTV2 encompasses intermediate risk PTV which receives 54-60 Gy and PTV3 encompasses high risk PTV which receives 66-70 Gy. After completion of planning, dose to the organs at risk (OARs) and targets, homogeneity index and conformity index were evaluated, and tabulated.Results: On evaluation of plans we found that V95% in PTV1, PTV2 and PTV3 were 91.82%, 96.85% and 90.67% respectively for IMRT and 99.25%, 99.68% and 99.73% respectively for tomotherapy. For PTV3, V110% was 0.11% for IMRT and 0.01% for tomotherapy. Homogeneity index in IMRT arm was 0.285 and it was 0.206 in tomotherapy arm. Conformity index was found to be 1.04 for IMRT plans and 1.06 for tomotherapy plans. When mean dose to contra lateral parotids was evaluated, it was 26.91 Gy in IMRT arm and 25.97 Gy in tomotherapy arm. Max dose to spinal cord was better in tomotherapy (43.07 Gy in IMRT and 34.41 Gy in tomotherapy).Conclusions: There was statistically significant reduction in spinal cord maximum dose and point doses in tomotherapy plans compared to IMRT plans. The decrease in spinal cord dose can increase the tolerance reserve which can be useful in dose escalation or re-irradiation if required. There was also decrease in contra lateral parotid doses (not statistically significant). There was significant improvement in V95% in tomotherapy arm compared to IMRT arm, indicating the significantly superior coverage of target volumes in helical tomotherapy plans compared to IMRT plans. V110% (hot spots) inside the target was very minimal in tomotherapy arm compared to IMRT arm. Conformity index, homogeneity index between two arms were comparable.


2021 ◽  
Vol 009 (01) ◽  
pp. 86-100
Author(s):  
Vian Dedi Pratama ◽  
◽  
Sukandar Sukandar ◽  
Marjono Marjono ◽  
Andi Kurniawan ◽  
...  

Taman Kili-Kili Beach is designated as an Essential Ecosystem Area (KEE). 188/39/KPTS/013/2020. According to the Supervisory Community Group (Pokmaswas), in 2011-2020, there was an increase in broodstock as many as 52 turtles, and the eggs saved as many as 3323 eggs. However, since 2013 Pokmaswas data shows a decrease in the population of hawksbill and green turtles in turtle conservation areas, which is thought to be caused by climate change, global warming, and animals. This study aims to analyze environmental baselines, turtle populations, and the value of turtle ecotourism (ecological, economic values) and develop strategies to support turtle conservation at Taman Kili-Kili Beach Trenggalek Regency. The results of the adjustment of nesting habitats and turtle ecotourism, calculation of the Habitat Conformity Index (IKH) of turtle nesting, IKH = 77.77%, which belongs to the category (S1) is very suitable to be used as a conservation area and turtle nesting habitat. While the results of the calculation of the Turtle Ecotourism Conformity Index (IKW), IKW = 84.93%, which is included in the (S1) category, which is very suitable for use a turtle tourism area. The strategy for developing turtle ecotourism is in quadrant II, meaning that it utilizes the strengths possessed in the turtle conservation area by minimizing the threats that it will experience.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hsiu-Wen Ho ◽  
Ching-Chieh Yang ◽  
Hsiu-Man Lin ◽  
Hsiao-Yun Chen ◽  
Chun-Chiao Huang ◽  
...  

AbstractTo evaluate the potential benefit of HyperArc (HA) fractionated stereotactic radiotherapy (FSRT) for the benign brain lesion. Sixteen patients with a single deep-seated, centrally located benign brain lesion treated by CyberKnife (CK, G4 cone-based model) were enrolled. Treatment plans for HA with two different optimization algorithms (SRS NTO and ALDO) and coplanar RapidArc (RA) were generated for each patient to meet the corresponding treatment plan criteria. These four FSRT treatment plans were divided into two groups—the homogeneous delivery group (HA-SRS NTO and coplanar RA) and the inhomogeneous delivery group (HA-ALDO and cone-based CK)—to compare for dosimetric outcomes. For homogeneous delivery, the brain V5, V12, and V24 and the mean brainstem dose were significantly lower with the HA-SRS NTO plans than with the coplanar RA plans. The conformity index, high and intermediate dose spillage, and gradient radius were significantly better with the HA-SRS NTO plans than with the coplanar RA plans. For inhomogeneous delivery, the HA-ALDO exhibited superior PTV coverage levels to the cone-based CK plans. Almost all the doses delivered to organs at risk and dose distribution metrics were significantly better with the HA-ALDO plans than with the cone-based CK plans. Good dosimetric distribution makes HA an attractive FSRT technique for the treatment of benign brain lesions.


2021 ◽  
Vol 11 (20) ◽  
pp. 9686
Author(s):  
Hsiao-Wen Chiu ◽  
Lu-Han Lai ◽  
Chien-Yi Ting

Adjuvant radiotherapy is an important treatment modality after breast-conserving surgery. Due to its proximity, radiation therapy for the left breast can often lead to an escalated heart dose that can result in heart diseases. The purpose of this study was to evaluate the heart dose reduction by using lead shields surrounding the left breast. The doses of a 3D conformal radiotherapy (3D-CRT) plan, an intensity-modulated radiotherapy (IMRT) plan, and volumetric-modulated arc therapy (VMAT) to the left breast tumor in a CIRS ATOM anthropomorphic female adult phantom were measured by optically stimulated luminescence dosimeters (OSLDs). To protect critical organs, the skin around the target area was covered by lead shields of two different thicknesses (0.125 mm and 0.25 mm). The results showed that compared to IMRT and 3D-CRT, VMAT provided better planning target volume (PTV) coverage, a better conformity index (CI), and homogeneity index (HI). With the use of lead shields, the thyroid dose was reduced by 5.12–27.5% and 20.51–30%, respectively; the heart dose was reduced by 49.41–50.12% and 56.38–57.42%, respectively; and the lung dose was reduced by 1.23–45.22% and 0.98–57.83%, respectively. Although the clinical application of lead shields was rare, this study verified that it could effectively decrease the heart dose from 4.31 ± 0.09 Gy to 1.88–2.18 Gy, thereby potentially reducing the risk of associated heart diseases by 14.8%. Further works to implement this method into clinical practice are needed.


Author(s):  
Reshma Bhaskaran ◽  
Sajeev George Pulickal ◽  
Harikrishnan Reghu ◽  
Aparna Perumangat ◽  
Girish Babu Moolath

Abstract Aim: There are only limited studies available in literature that discuss methods to reduce the oesophageal dose and acute oesophagitis during breast cancer radiotherapy. The aim of this study is to compare dose volumetric parameters of oesophagus in radiation treatment of breast with and without oesophagus delineation. Methods: Treatment plans of 44 patients, who underwent chest wall and supraclavicular fossa irradiation, were selected for the study. Oesophagus was later delineated and treatment replanned using three-dimensional conformal radiotherapy (3DCRT) considering oesophagus as an organ at risk (OAR). The dose prescribed was 40 Gy/15 fractions to the planning target volume (PTV). Dose volumetric parameters of oesophagus such as maximum dose (Dmax), mean dose (Dmean), the percentage of oesophagus volume receiving ≥15Gy (V15), ≥25Gy(V25), ≥33Gy(V33) and ipsilateral lung volume parameters V4, V8 and V16 were compared with already executed plans in which oesophagus was not delineated. Results: Contouring the oesophagus as an OAR as a part of the radiotherapy treatment for Carcinoma Breast resulted in statistically significant reduction in dose to the oesophagus. No statistically significant change was found in the ipsilateral lung volume parameters. No compromise in plan quality was required as evident from the statistically non-significant differences in Homogeneity index and Conformity index. Findings: 3DCRT planning with oesophagus delineation can be considered as a method to reduce oesophageal dose and the acute oesophageal toxicity during radiotherapy for carcinoma breast.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wuji Sun ◽  
Kunzhi Chen ◽  
Yu Li ◽  
Wenming Xia ◽  
Lihua Dong ◽  
...  

AbstractTo optimize the collimator angles in dual-arc volumetric modulated arc therapy (VMAT) plans for whole-brain radiotherapy with hippocampus and inner ear sparing (HIS-WBRT). Two sets of dual-arc VMAT plans were generated for 13 small-cell lung cancer patients: (1) The collimator angles of arcs 1 and 2 (θ1/θ2) were 350°/10°, 350°/30°, 350°/45°, 350°/60°, and 350°/80°, i.e., the intersection angle of θ1 and θ2 (Δθ) increased. (2) θ1/θ2 were 280°/10°, 300°/30°, 315°/45°, 330°/60°, and 350°/80°, i.e., Δθ = 90°. The conformity index (CI), homogeneity index (HI), monitor units (MUs), and dosimetric parameters of organs-at-risk were analyzed. Quality assurance for Δθ = 90° plans was performed. With Δθ increasing towards 90°, a significant improvement was observed for most parameters. In 350°/80° plans compared with 350°/10° ones, CI and HI were improved by 1.1% and 25.2%, respectively; MUs were reduced by 16.2%; minimum, maximum, and mean doses (D100%, Dmax, and Dmean, respectively) to the hippocampus were reduced by 5.5%, 6.3%, and 5.4%, respectively; Dmean to the inner ear and eye were reduced by 0.7% and 5.1%, respectively. With Δθ kept at 90°, the plan quality was not significantly affected by θ1/θ2 combinations. The gamma-index passing rates in 280°/10° and 350°/80° plans were relatively lower compared with the other Δθ = 90° plans. Δθ showed a significant effect on dual-arc VMAT plans for HIS-WBRT. With Δθ approaching 90°, the plan quality exhibited a nearly continuous improvement, whereas with Δθ = 90°, the effect of θ1/θ2 combination was insignificant.


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