scholarly journals Portal Dosimetry as a patient specific Quality Assurance tool for Volumetric Arc Radiotherapy

2021 ◽  
Vol 9 (1) ◽  
pp. 29-33
Author(s):  
Vikram Rathore ◽  
◽  
Mr. V.K Mishra ◽  
Dr. V Choudhary ◽  
Mr. G.S. Gautam ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Patient Specific ◽  
Advanced Technique ◽  
Mean Values ◽  
Treatment Patient ◽  
Portal Dosimetry ◽  
Gamma Index ◽  
Patient Specific Qa ◽  
The Mean ◽  
Pre Treatment

Introduction: Volumetric Arc Radiotherapy (VMAT) is an advanced technique. Calculations of VMATplans are not so accurate even with State-of-Art dose calculation algorithms due to their complexity.Hence pre-treatment patient specific Quality Assurance (QA) of each VMAT plan is required. In thepresent study Electronic Portal Imaging Device (EPID) based portal dosimetry system was used forpre-treatment patient specific QA. Material and Methods: A total of 50 patients were chosen inthis study. Verification plans of each patient were calculated for portal dosimetry then executed onthe EPID system to measure the spatial distribution of radiation dose. Calculated and measured dosedistribution were compared to evaluate Gamma Index (GI) passing criteria of Dose Difference (DD)of 3% and Distance–to-Agreement (DTA) of 3mm, Area Gamma (γ% ≤1) >95%, Average Gamma(gAve) <0.5% and Maximum Gamma (gMax) <3.5%. Results: The mean values of Area Gamma (γ%≤1) were observed to be varied from 99.14±0.23% to 99.87±0.18%. The Mean Values of AverageGamma (gAve) are found to vary from 0.19±0.05% to 0.15±0.04% and the mean values ofMaximum Gamma (gMax) found to be varied from 1.94±0.37% to 1.59±0.41%. All the plans werepassed the gamma index criteria with very good agreement. Thus the use of Portal Dosimetry forpre-treatment patient QA is found to be a very useful, quick, precise, efficient and effective pre-treatment patient specific QA tool for VMAT treatment. Conclusion: Portal Dosimetry can be utilizedfor routine use for patient specific quality assurance for Volumetric Arc Radiotherapy treatment.

Retrospective analysis of portal dosimetry pre-treatment quality assurance of intracranial SRS/SRT VMAT treatment plans

2021 ◽  
pp. 1-13
Author(s):  
Ernest Osei ◽  
Sarah Graves ◽  
Johnson Darko
Keyword(s):  
Quality Assurance ◽  
Retrospective Analysis ◽  
Low Dose ◽  
Treatment Quality ◽  
Patient Specific ◽  
Portal Dosimetry ◽  
Treatment Plans ◽  
The Mean ◽  
Pre Treatment ◽  
Action Levels

Abstract Background: The complexity associated with the treatment planning and delivery of stereotactic radiosurgery (SRS) or stereotactic radiotherapy (SRT) volumetric modulated arc therapy (VMAT) plans which employs continuous dynamic modulation of dose rate, field aperture and gantry speed necessitates diligent pre-treatment patient-specific quality assurance (QA). Numerous techniques for pre-treatment VMAT treatment plans QA are currently available with the aid of several different devices including the electronic portal imager (EPID). Although several studies have provided recommendations for gamma criteria for VMAT pre-treatment QA, there are no specifics for SRS/SRT VMAT QA. Thus, we conducted a study to evaluate intracranial SRS/SRT VMAT QA to determine clinical action levels for gamma criteria based on the institutional estimated means and standard deviations. Materials and methods: We conducted a retrospective analysis of 118 EPID patient-specific pre-treatment QA dosimetric measurements of 47 brain SRS/SRT VMAT treatment plans using the integrated Varian solution (RapidArcTM planning, EPID and Portal dosimetry system) for planning, delivery and EPID QA analysis. We evaluated the maximum gamma (γmax), average gamma (γave) and percentage gamma passing rate (%GP) for different distance-to-agreement/dose difference (DTA/DD) criteria and low-dose thresholds. Results: The gamma index analysis shows that for patient-specific SRS/SRT VMAT QA with the portal dosimetry, the mean %GP is ≥98% for 2–3 mm/1–3% and Field+0%, +5% and +10% low-dose thresholds. When applying stricter spatial criteria of 1 mm, the mean %GP is >90% for DD of 2–3% and ≥88% for DD of 1%. The mean γmax ranges: 1·32 ± 1·33–2·63 ± 2·35 for 3 mm/1–3%, 1·57 ± 1·36–2·87 ± 2·29 for 2 mm/1–3% and 2·36 ± 1·83–3·58 ± 2·23 for 1 mm/1–3%. Similarly the mean γave ranges: 0·16 ± 0·06–0·19 ± 0·07 for 3 mm/1–3%, 0·21 ± 0·08–0·27 ± 0·10 for 2 mm/1–3% and 0·34 ± 0·14–0·49 ± 0·17 for 1 mm/1–3%. The mean γmax and mean γave increase with increased DTA and increased DD for all low-dose thresholds. Conclusions: The establishment of gamma criteria local action levels for SRS/SRT VMAT pre-treatment QA based on institutional resources is imperative as a useful tool for standardising the evaluation of EPID-based patient-specific SRS/SRT VMAT QA. Our data suggest that for intracranial SRS/SRT VMAT QA measured with the EPID, a stricter gamma criterion of 1 mm/2% or 1 mm/3% with ≥90% %GP could be used while still maintaining an in-control QA process with no extra burden on resources and time constraints.

scholarly journals Analysis of Clinical Patient-Specific Pre-Treatment Quality Assurance with the New Helical TomoTherapy® Platform, following the AAPM TG-218 Report

2021 ◽  
Author(s):  
Marco Fusella ◽  
Samuele Cavinato ◽  
Alessandra Germani ◽  
Marta Paiusco ◽  
Nicola Pivato ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Helical Tomotherapy ◽  
Treatment Quality ◽  
Patient Specific ◽  
Mean Values ◽  
Clinical Patient ◽  
Passing Rate ◽  
Pre Treatment ◽  
Delivery Accuracy ◽  
Global And Local

Abstract Purpose: This study presents patient-specific quality assurance (QA) results from the first 395 clinical cases for the new helical TomoTherapy® platform (Radixact) coupled with dedicated Precision TPS.Methods: The passing rate of the Gamma Index (GP%) of 395 helical QA of patient-specific Tomotherapy, acquired with ArcCHECK, is presented, analysed and correlated to various parameters of the plan. Following TG-218 recommendations, the clinic specific action limit (ALcs) and tolerance limit (TLcs) were calculated for our clinic and monitored during the analysed period.Results: the mean values ​​(± 1 standard deviation) of GP% (3% / 2mm) (both global and local normalization) are: 97.6% and 90.9%, respectively. The proposed ALcs and TLcs, after a period of two years’ process monitoring are 89.4% and 91.1% respectively.Conclusions: The phantom measurements closely match the planned dose distributions, demonstrating that the calculation accuracy of the new Precision TPS and the delivery accuracy of the Radixact unit are adequate, with respect to international guidelines and reports. Furthermore, a first correlation with the planning parameters was made. Action and tolerance limits have been set for the new Radixact Linac.

MO-FG-CAMPUS-TeP1-01: An Efficient Method of 3D Patient Dose Reconstruction Based On EPID Measurements for Pre-Treatment Patient Specific QA

2016 ◽  
Vol 43 (6Part31) ◽  
pp. 3718-3718
Author(s):  
R David ◽  
B Zwan ◽  
J Hindmarsh ◽  
E Seymour ◽  
K Kandasamy ◽  
...  
Keyword(s):  
Efficient Method ◽  
Patient Dose ◽  
Patient Specific ◽  
Dose Reconstruction ◽  
Treatment Patient ◽  
Patient Specific Qa ◽  
Pre Treatment

scholarly journals Analysis of clinical patient-specific pre-treatment quality assurance with the new helical tomotherapy platform, following the AAPM TG-218 report

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Marco Fusella ◽  
Samuele Cavinato ◽  
Alessandra Germani ◽  
Marta Paiusco ◽  
Nicola Pivato ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Helical Tomotherapy ◽  
Treatment Quality ◽  
Patient Specific ◽  
Mean Values ◽  
Clinical Patient ◽  
Passing Rate ◽  
Pre Treatment ◽  
Delivery Accuracy ◽  
Global And Local

Abstract Purpose This study presents patient-specific quality assurance (QA) results from the first 395 clinical cases for the new helical TomoTherapy® platform (Radixact) coupled with dedicated Precision TPS. Methods The passing rate of the Gamma Index (GP%) of 395 helical QA of patient-specific tomotherapy, acquired with ArcCHECK, is presented, analysed and correlated to various parameters of the plan. Following TG-218 recommendations, the clinic specific action limit (ALcs) and tolerance limit (TLcs) were calculated for our clinic and monitored during the analysed period. Results The mean values ​​(± 1 standard deviation) of GP% (3%/2 mm) (both global and local normalization) are: 97.6% and 90.9%, respectively. The proposed ALcs and TLcs, after a period of two years’ process monitoring are 89.4% and 91.1% respectively. Conclusions The phantom measurements closely match the planned dose distributions, demonstrating that the calculation accuracy of the new Precision TPS and the delivery accuracy of the Radixact unit are adequate, with respect to international guidelines and reports. Furthermore, a first correlation with the planning parameters was made. Action and tolerance limits have been set for the new Radixact Linac.

Urinary Steroids in Depressive Illness

1971 ◽  
Vol 16 (4) ◽  
pp. 224-227 ◽  
Author(s):  
A. Balfour Sclare ◽  
J. K. Grant
Keyword(s):  
Depressive Illness ◽  
Post Treatment ◽  
Normal Range ◽  
Mean Values ◽  
Female Patients ◽  
Significant Difference ◽  
The Mean ◽  
Pre Treatment ◽  
Depressive Patients ◽  
Source Of Information

A longitudinal study of urinary 17-OHCS in 16 depressive patients showed mean values within the accepted normal range. There were no significant differences between pre-treatment and post-treatment values; only the female patients showed a tendency to have somewhat lower post-treatment levels. 17-KS output was measured in 18 depressive patients. The mean values were within the normal range. There was no significant difference between pre-treatment and post-treatment values although the female patients displayed a tendency towards somewhat lower levels following treatment. DHA and EA excretion were measured in 9 depressive patients. There was a very wide variance in the findings. There was no significant difference between pre-treatment and post-treatment levels. The significance of the above findings is discussed. It is considered that measurements of urinary excretion of corticosteroids in affective disorders constitute a limited source of information.

SU-E-T-401: On the Use of Onboard Portal Dosimetry for Patient-Specific QA of RapidArc Plans

2013 ◽  
Vol 40 (6Part17) ◽  
pp. 297-297
Author(s):  
H Abbas ◽  
D Carlson ◽  
J Deng ◽  
R Nath ◽  
Z Chen
Keyword(s):  
Patient Specific ◽  
Portal Dosimetry ◽  
Patient Specific Qa
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