Comprehensive evaluation of electron radiation dose using beryllium oxide dosimeters at breast radiotherapy

2019 ◽  
Vol 19 (1) ◽  
pp. 38-44
Author(s):  
Serdar Şahin ◽  
Eren Şahiner ◽  
Fatih Göksel ◽  
Niyazi Meriç
Keyword(s):  
Comprehensive Evaluation ◽  
Absorbed Dose ◽  
Beryllium Oxide ◽  
Left Breast ◽  
Planning System ◽  
Treatment Planning System ◽  
Breast Radiotherapy ◽  
The Mean ◽  
Beam Dose

AbstractIntroduction:In this study, the differences between calculated and measured dose values were then analysed to assess the performance, in terms of accuracy, of the tested treatment planning system (TPS) algorithms applied to calculate electron beam dose targeted and non-targeted the breast region.Materials and methods:The beryllium oxide (BeO) dosimeters placed on the female RANDO phantom were irradiated 12 MeV electron energy with medical linear accelerator and repeatedly read in the Risø thermoluminescence (TL)/optically stimulated luminescence (OSL) system via OSL method at least three times.Results:For electron treatment, one made quantitative comparisons of the dose distributions calculated by TPSs with those from the measurements by OSL at various points in the RANDO phantom.The mean dose measured from the dosimeters placed on the female RANDO phantom target left breast region was 160 cGy and non-target right breast region was 1·2 cGy. Analysis of Generalised Gaussian Pencil Beam (GGPB) and Electron Monte Carlo (eMC) algorithms for determined region mean point dose values, respectively, 174 and 164 cGy. Two algorithms for non-targeted region calculated same point dose values of 0·2 cGy.Conclusions:The results of this study showed that BeO dosimeters can be used with OSL method in radiotherapy applications and it is a very important tool for the determination of targeted/non-targeted absorbed dose.

Dosimetric comparison of fractionated radiosurgery plans using frameless Gamma Knife ICON and CyberKnife systems with linear accelerator–based radiosurgery plans for multiple large brain metastases

2020 ◽  
Vol 132 (5) ◽  
pp. 1473-1479 ◽  
Author(s):  
Eun Young Han ◽  
He Wang ◽  
Dershan Luo ◽  
Jing Li ◽  
Xin Wang
Keyword(s):  
Brain Metastases ◽  
Gamma Knife ◽  
Linear Accelerator ◽  
Treatment Time ◽  
Target Volume ◽  
Planning System ◽  
Treatment Planning System ◽  
Normal Brain ◽  
Large Brain ◽  
The Mean

OBJECTIVEFor patients with multiple large brain metastases with at least 1 target volume larger than 10 cm3, multifractionated stereotactic radiosurgery (MF-SRS) has commonly been delivered with a linear accelerator (LINAC). Recent advances of Gamma Knife (GK) units with kilovolt cone-beam CT and CyberKnife (CK) units with multileaf collimators also make them attractive choices. The purpose of this study was to compare the dosimetry of MF-SRS plans deliverable on GK, CK, and LINAC and to discuss related clinical issues.METHODSTen patients with 2 or more large brain metastases who had been treated with MF-SRS on LINAC were identified. The median planning target volume was 18.31 cm3 (mean 21.31 cm3, range 3.42–49.97 cm3), and the median prescribed dose was 27.0 Gy (mean 26.7 Gy, range 21–30 Gy), administered in 3 to 5 fractions. Clinical LINAC treatment plans were generated using inverse planning with intensity modulation on a Pinnacle treatment planning system (version 9.10) for the Varian TrueBeam STx system. GK and CK planning were retrospectively performed using Leksell GammaPlan version 10.1 and Accuray Precision version 1.1.0.0 for the CK M6 system. Tumor coverage, Paddick conformity index (CI), gradient index (GI), and normal brain tissue receiving 4, 12, and 20 Gy were used to compare plan quality. Net beam-on time and approximate planning time were also collected for all cases.RESULTSPlans from all 3 modalities satisfied clinical requirements in target coverage and normal tissue sparing. The mean CI was comparable (0.79, 0.78, and 0.76) for the GK, CK, and LINAC plans. The mean GI was 3.1 for both the GK and the CK plans, whereas the mean GI of the LINAC plans was 4.1. The lower GI of the GK and CK plans would have resulted in significantly lower normal brain volumes receiving a medium or high dose. On average, GK and CK plans spared the normal brain volume receiving at least 12 Gy and 20 Gy by approximately 20% in comparison with the LINAC plans. However, the mean beam-on time of GK (∼ 64 minutes assuming a dose rate of 2.5 Gy/minute) plans was significantly longer than that of CK (∼ 31 minutes) or LINAC (∼ 4 minutes) plans.CONCLUSIONSAll 3 modalities are capable of treating multiple large brain lesions with MF-SRS. GK has the most flexible workflow and excellent dosimetry, but could be limited by the treatment time. CK has dosimetry comparable to that of GK with a consistent treatment time of approximately 30 minutes. LINAC has a much shorter treatment time, but residual rotational error could be a concern.

Dose assessment to the Bladder during Intracavitary Brachytherapy of the Cervix using Gafchromic films

2017 ◽  
pp. 97-105
Author(s):  
J. Avevor ◽  
S. N. A. Tagoe ◽  
J. H. Amuasi ◽  
J. J. Fletcher ◽  
I. Shirazu
Keyword(s):  
Treatment Planning ◽  
Maximum Dose ◽  
Mean Difference ◽  
Planning System ◽  
Treatment Planning System ◽  
In Vivo Dosimetry ◽  
Intracavitary Brachytherapy ◽  
Gafchromic Films ◽  
System Verification ◽  
The Mean

Intracavitary brachytherapy procedures are used for cervical cancer treatment, by the insertion of radioactive implants directly into the diseased tissues. During the treatment process, the bladder together with surrounding tissues are exposed to radiations. Clinical complications do results from high doses received by parts of the bladder during intracavitary brachytherapy of the cervix. The aim of this study is to assess the dose delivered to the bladder using Gafchromic films and compare it with the optimized dose calculated by the Brachy Prowess 4.60 Treatment Planning System (TPS) reports for empirical validation and system verification. Fletcher suite applicators were used to perform thirty (30) different clinical insertions on the constructed cervix phantom and results evaluated. The mean difference between the doses calculated by the TPS and the doses measured by the Gafchromic film for the bladder at the distance of 0.5cm from the edge of the film was 16.3 % (range -35.33 to +39.37). At a distance of 1.5cm for the bladder, the mean difference was 19.4% (range -49.48 to +30.39). The TPS calculated maximum dose was typically higher than the measured maximum dose. However, in some cases, the measured doses were found to be higher than the doses calculated by the TPS. This is due to positional inaccuracies of the sources during treatment planning. It is recommended that in vivo dosimetry be performed in addition to computation.

scholarly journals A Special Report on 2019 International Planning Competition and a Comprehensive Analysis of Its Results

2020 ◽  
Vol 10 ◽  
Author(s):  
Jiayun Chen ◽  
Jianrong Dai ◽  
Ahmad Nobah ◽  
Sen Bai ◽  
Nan Bi ◽  
...  
Keyword(s):  
Work Experience ◽  
Medical Physics ◽  
Large Population ◽  
Locally Advanced ◽  
Planning System ◽  
Treatment Planning System ◽  
Plan Quality ◽  
Wide Range ◽  
The Mean ◽  
International Planning

PurposeThe aim of this work is to introduce the 2019 International Planning Competition and to analyze its results.Methods and materialsA locally advanced non-small cell lung cancer (LA-NSCLC) case using the simultaneous integrated boost approach was selected. The plan quality was evaluated by using a ranking system in accordance with practice guidelines. Planners used their clinical Treatment Planning System (TPS) to generate the best possible plan along with a survey, designed to obtain medical physics aspects information. We investigated the quality of the large population of plans designed by worldwide planners using different planning and delivery systems. The correlations of plan quality with relevant planner characteristics (work experience, department scale, and competition experience) and with technological parameters (TPS and modality) were examined.ResultsThe number of the qualified plans was 287 with a wide range of scores (38.61–97.99). The scores showed statistically significant differences by the following factors: 1) department scale: the mean score (89.76 ± 8.36) for planners from the departments treating >2,000 patients annually was the highest of all; 2) competition experience: the mean score for the 107 planners with previous competition experience was 88.92 ± 9.59, statistically significantly from first-time participants (p = .001); 3) techniques: the mean scores for planners using VMAT (89.18 ± 6.43) and TOMO (90.62 ± 7.60) were higher than those using IMRT (82.28 ± 12.47), with statistical differences (p <.001). The plan scores were negligibly correlated with the planner’s years of work experience or the type of TPS used. Regression analysis demonstrated that plan score was associated with dosimetric objectives that were difficult to achieve, which is generally consistent with a clinical practice evaluation. However, 51.2% of the planners abandoned the difficult component of total lung receiving a dose of 5 Gy in their plan design to achieve the optimal plan.ConclusionThe 2019 international planning competition was carried out successfully, and its results were analyzed. Plan quality was not correlated with work experiences or the TPS used, but it was correlated with department scale, modality, and competition experience. These findings differed from those reported in previous studies.

Cardiac dose evaluation in patients undergoing breast radiotherapy in the modern era.

2014 ◽  
Vol 32 (26_suppl) ◽  
pp. 78-78
Author(s):  
Christopher A. Peters ◽  
Andrew Kaleda ◽  
Anthony Manfredo ◽  
Elizabeth Tapen ◽  
Lawrence Koutcher
Keyword(s):  
Breast Cancer ◽  
Multivariate Analysis ◽  
Critical Role ◽  
Univariate Analysis ◽  
Metastatic Breast ◽  
Planning System ◽  
Treatment Planning System ◽  
Breast Radiotherapy ◽  
Heart Dose ◽  
Mean Heart Dose

78 Background: Breast radiotherapy (RT) after conservative surgery improves overall survival and minimizes locoregional recurrence. The therapeutic ratio of adjuvant RT continues to improve with time. Cardiac toxicity from breast cancer treatment remains a concern, and can result from chemotherapy, biologic therapy, or RT in a dose-dependent fashion. Dose to avoidance structures can be minimized as technological improvements in radiotherapy evolve. We sought to investigate heart and coronary artery dose using modern RT techniques. Methods: We reviewed 164 consecutive non-metastatic breast cancer patients treated with adjuvant breast RT, from 3/2011 to 12/2013. 8 patients were excluded because they did not complete the prescribed dose. Patients were treated on 3 different machines, at 2 centers. Data was extracted using both the treatment planning system and electronic medical records. Univariate analysis was done using t-test and one way ANOVA for variables predicting higher mean heart dose (MHD). Multivariate analysis was performed using multiple linear regression. p values ≤0.05 were considered significant. Results: The median age of our cohort was 63 (range 33-85), and 90% had ≤ stage 2 disease. 53% had left sided RT, 45% right, and 2% had bilateral RT. 18% had breast/chest wall and nodal RT, with 2% dedicated IMN targeting. 22% of patients were treated prone. The median dose, including boost, was 60.4 Gy (range 42.4-66.4). 35% received cytotoxic chemotherapy and 10% received trastuzumab. Mean heart dose was 1.4Gy (SD 2.2), and mean LAD dose was 4.9Gy (SD 4.4). MHD were lower in the prone position compared to supine, but did not reach statistical significance p=0.3. Advanced AJCC stage grouping, left sided or bilateral treatment, breast/nodal target volume, and helical treatment were associated with significantly higher MHD on univariate analysis. On multivariate analysis, only breast/nodal volume and helical technique remained significant, both p<0.001. Conclusions: Modern techniques result in low heart and LAD doses in our series. Because adjuvant breast RT plays a critical role in the definitive management of breast cancer, these data are reassuring to patients, physicians, and payers.

scholarly journals The accuracy and safety of CT-guided iodine-125 seeds implantation assisted by 3D non-coplanar template for retroperitoneal recurrent carcinoma.

2020 ◽  
Author(s):  
Weijuan Jiang ◽  
Ping Jiang ◽  
Shuhua Wei ◽  
Yuliang Jiang ◽  
Zhe Ji ◽  
...  
Keyword(s):  
Real Time ◽  
Planning System ◽  
Treatment Planning System ◽  
Angular Deviation ◽  
Ct Guided ◽  
The Mean ◽  
Iodine 125 ◽  
Preoperative Plan ◽  
Time Plan

Abstract Purpose To investigate the accuracy, dosimetric parameters and safety of 3D-printing non co-planar template (3D-PNCT) assisted CT-guidance for radioactive iodine-125 (125I) seed implantation brachytherapy (RSI-BT) for retroperitoneal recurrent carcinomas. Methods and materials: We enrolled 15 patients with 17 retroperitoneal recurrent carcinomas after external beam radiotherapy (EBRT). All patients received CT-guided 125I RSI-BT assisted by 3D-PNCT successfully. We compared the original needles insertion position, angular and the needle tips distance deviations of preoperative plan with that of intra-operative in brachytherapy treatment-planning system (B-TPS). The dosimetric parameters of RSI-BT were evaluated on preoperative plan, intra-operative real-time plan and postoperative plan, including D90, D100, V100, V150 and V200. The quality assurance of RSI-BT evaluated on conformal index (CI), external index (EI), homogeneity index (HI) of the targets were compared among preoperative plan, intra-operative real-time plan and postoperative plan. The peri-operation complications and re-radiation related toxicity were assessed. Results The median follow-up was 8.2 months (range 1-18.5months). One patient lost follow-up after RSI-BT. 14 patients were assessed for response rate and toxicity. The mean entrance point distance deviation for all 165 needles was 4.50 ± 4.10 mm (range, 0–30). The mean angular deviation was 2.70 ± 3.00 degrees (range, 0–20). The needles tip distances deviation was 6.90 ± 6.00 mm (range, -30-28). D90 for preoperative plan, intra-operative plan and postoperative plan were 140.55 ± 23.93, 124.25 ± 28.04,128.98 ± 22.75. There was significant difference between D90 of preoperative plan with that of intraoperative plan (p = 0.036). Four patients reached CR, three patients reached PR, three patients were SD and three patients was PD. Four patients with middle pain became moderate, two with moderate pain relived completely after RSI-BT. The others parameters showed no differences among preoperative plan, intraoperative plan and postoperative plan. The perioperative complications were observed in four patients, including three patients of grade 1 and one patient of grade 2. No ≥ grade 3 side-effects were observed. Conclusion CT-guided 125I RSI-BT assisted by 3D-PNCT was a safe, accurate and feasible strategy for recurrent carcinomas located in retroperitoneal regions.

scholarly journals A Plan Robustness Qualification Method of Volumetric Arc Radiotherapy (VMAT) of Set Up Uncertainty in Nasopharyngeal Carcinoma (NPC) Radiotherapy

2021 ◽  
Author(s):  
Zhen Ding ◽  
Xiaoyong Xiang ◽  
Qi Zeng ◽  
Jun Ma ◽  
Zhitao Dai ◽  
...  
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Parotid Gland ◽  
Evaluation Method ◽  
Biological Evaluation ◽  
Planning System ◽  
Treatment Planning System ◽  
Tumor Control ◽  
The Mean ◽  
Set Up ◽  
Dose Variation

Abstract Purpose: To evaluate the set-up sensitivity of VMAT plans for Nasopharyngeal carcinoma (NPC) treatment by proposing a plan robustness evaluation method. Methods: 10 patients were selected for this study. A 2-arc volumetric-modulated arc therapy (VMAT) plan was generated for each patient using Varian Eclipse (13.6 Version) treatment planning system (TPS). 5 uncertainty plans (U-plans) were calculated based on the first 5 times set-up errors acquired from cone beam comuter tomography (CBCT). The dose differences and plan robustness of all the PTVs, CTVs, GTVs, and organs at risk (OARs) were analyzed. Tumor control probability (TCP) and normal tissues complication probability (NTCP) were calculated for biological evaluation. Results: The mean dose differences of D98 and D95 (△D98 and△D95) of PTVnx were respectively 3.30 Gy and 2.02 Gy. The △D98 and△D95 of CTVnx were 1.12 Gy and 0.58 Gy. The △D98 and△D95 of GTVnx were 0.56 Gy and 0.33 Gy. The dose coverage of GTVnx and CTVnx was guaranteed with minor dose variation. GTVnd exhibited strong robustness with little variation of D98 (0.5%) and D95 (0.9%). The △D98 and△D95 of CTVnd were 1.39 Gy and 1.03 Gy, distinctively lower than those in PTVnd (2.8 Gy and 2.0 Gy). No marked mean dose variations of Dmean were seen. The mean reduction of TCP (△TCP) in GTVnx and CTVnx were respectively 0.4% and 0.3%. The mean △TCP of GTVnd and CTVnd were 0.92 % and 1.3 % respectively. The CTV exhibited the largest △TCP (2.2 %). In OARs, the optical nerve chiasma was the one with the highest change, with a mean dose variation of 8.81 Gy. The Dmean of bilateral parotids varied in a large range. The mean reduction of NTCP (△NTCP) in the left parotid gland was 13.30%, which sharply increased the risk of parotid gland dysfunction. Conclusion: VMAT plans had a strong sensitivity to set-up uncertainty in NPC radiotherapy, due to the high degree of modulation. We proposed an effective method to evaluate the plan robustness of VMAT plans. Plan robustness and complexity should be taken into account in photon radiotherapy.

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