scholarly journals Clinical Experience Using the SRS MapCHECK for Patient Specific Plan Verification of Flattening Filter Free, Non-Coplanar Stereotactic Brain Plans Using HyperARC.

2021 ◽  
Author(s):  
Mark Ashburner ◽  
Koki Mugabe
Keyword(s):  
Treatment Planning ◽  
Treatment Plan ◽  
Patient Specific ◽  
High Dose ◽  
Pass Rates ◽  
Ion Chamber ◽  
Ionisation Chamber ◽  
Regional Cancer Centre ◽  
Single Isocenter ◽  
Chamber Measurements

Abstract HyperArc (HA) treatment planning from Varian is a stereotactic specific planning tool enabling quick and efficient optimisation of treatment planning, and delivery. HA was commissioned and implemented at Waikato Regional Cancer Centre (WRCC) in 2019 to fulfil the demands of dose delivery for stereotactic radiosurgery (SRS), allowing for treatment of multiple targets with a single isocenter at non-coplanar angles. The extra levels of plan complexity involved in creating and verifying HA SRS plans required extensive checks and verifications using film and an ion chamber, along with a significant allocation of time and resources. The Sun Nuclear SRS MapCHECK (SRSMC) offered an alternative to the cumbersome film measurements. It is an all-encompassing tool meeting the requirements of TG 218 and ICRU 91 for complex treatment plan verification, claiming to save time and effort, without sacrificing accuracy, enabling for a smoother planning and verification process. SRSMC was initially commissioned on 6MV single target treatments using standard planning, then updated and commissioned for 6FFF multi-target non-coplanar treatments using HA. The SRSMC gamma pass rates were compared to film measurements in the same plane, and the central diode CAX reading compared to ionisation chamber measurements at the same position for a range of plans covering a range of PTV sizes and plan complexities. Pass rates on the SRSMC were comparable to measurements using film (Gamma 3%/1mm, 99.41%, 96.39% SRSMC and film respectively). The central diode is an adequate surrogate for a chamber measurement if the SRSMC is positioned in a similar position as that of the ionisation chamber would be – high dose homogenous region, avoiding steep gradients (mean dose difference Diode vs Chamber: -0.73%). Differences between exposing non-coplanar plans at couch 0 and at planned couch angles were negligible (Gamma 3%/1mm 99.28 coplanar, 99.41% non-coplanar on SRSMC). At WRCC the SRSMC has replaced film and chamber measurements for plan verifications of 6FFF HA multiple metastatic brain treatments at a single isocenter and we are currently investigating its use in other treatment sites.

scholarly journals Evaluation of Delta4DVH Anatomy in 3D Patient-Specific IMRT Quality Assurance

2020 ◽  
Vol 19 ◽  
pp. 153303382094581
Author(s):  
Du Tang ◽  
Zhen Yang ◽  
Xunzhang Dai ◽  
Ying Cao
Keyword(s):  
Quality Assurance ◽  
Treatment Planning ◽  
Treatment Plan ◽  
Planning System ◽  
Treatment Planning System ◽  
Patient Specific ◽  
Pencil Beam ◽  
Ion Chamber ◽  
Passing Rate ◽  
Gamma Passing Rate

Purpose: To evaluate the performance of Delta4DVH Anatomy in patient-specific intensity-modulated radiotherapy quality assurance. Materials and Methods: Dose comparisons were performed between Anatomy doses calculated with treatment plan dose measured modification and pencil beam algorithms, treatment planning system doses, film doses, and ion chamber measured doses in homogeneous and inhomogeneous geometries. The sensitivity of Anatomy doses to machine errors and output calibration errors was also investigated. Results: For a Volumetric Modulated Arc Therapy (VMAT) plan evaluated on the Delta4 geometry, the conventional gamma passing rate was 99.6%. For a water-equivalent slab geometry, good agreements were found between dose profiles in film, treatment planning system, and Anatomy treatment plan dose measured modification and pencil beam calculations. Gamma passing rate for Anatomy treatment plan dose measured modification and pencil beam doses versus treatment planning system doses was 100%. However, gamma passing rate dropped to 97.2% and 96% for treatment plan dose measured modification and pencil beam calculations in inhomogeneous head & neck phantom, respectively. For the 10 patients’ quality assurance plans, good agreements were found between ion chamber measured doses and the planned ones (deviation: 0.09% ± 1.17%). The averaged gamma passing rate for conventional and Anatomy treatment plan dose measured modification and pencil beam gamma analyses in Delta4 geometry was 99.6% ± 0.89%, 98.54% ± 1.60%, and 98.95% ± 1.27%, respectively, higher than averaged gamma passing rate of 97.75% ± 1.23% and 93.04% ± 2.69% for treatment plan dose measured modification and pencil beam in patients’ geometries, respectively. Anatomy treatment plan dose measured modification dose profiles agreed well with those in treatment planning system for both Delta4 and patients’ geometries, while pencil beam doses demonstrated substantial disagreement in patients’ geometries when compared to treatment planning system doses. Both treatment planning system doses are sensitive to multileaf collimator and monitor unit (MU) errors for high and medium dose metrics but not sensitive to the gantry and collimator rotation error smaller than 3°. Conclusions: The new Delta4DVH Anatomy with treatment plan dose measured modification algorithm is a useful tool for the anatomy-based patient-specific quality assurance. Cautions should be taken when using pencil beam algorithm due to its limitations in handling heterogeneity and in high-dose gradient regions.

Dose-escalated adaptive image-guided radiotherapy versus high-dose-rate brachytherapy monotherapy for low-risk prostate cancer.

2013 ◽  
Vol 31 (6_suppl) ◽  
pp. 145-145
Author(s):  
Ovidiu Marina ◽  
Daniel J. Krauss ◽  
Donald Brabbins ◽  
Michelle Wallace ◽  
Alvaro A Martinez ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Treatment Plan ◽  
Target Volume ◽  
Low Risk ◽  
Definitive Treatment ◽  
Patient Specific ◽  
High Dose ◽  
Treatment Type ◽  
Risk Prostate Cancer ◽  
Low Risk Prostate Cancer

145 Background: Both IGRT and HDR are used for definitive treatment of low-risk prostate. No comparative study of these contemporary modalities exists. Methods: Charts for patients with low-risk prostate cancer by NCCN criteria treated 1999-2012 were reviewed. For IGRT, the clinical target volume (CTV) included the prostate and proximal seminal vesicles. A CT-based, off-line adaptive treatment plan was made with a patient-specific confidence-limited planning target volume (cl-PTV) based on the planning plus four additional daily CT scans. Overall survival (OS) was calculated by the Kaplan-Meier method (log-rank test), with Cox regression for uni- and multi-variate analysis. Cumulative incidence (Gray’s test), with competing risks analysis (Fine and Gray) were used for biochemical control (BC) and freedom from local recurrence (FFLR). Results: There were 598 IGRT and 399 HDR patients (see Table), with a median follow-up of 6.1 and 3.6 years, respectively (p<0.001). The median prescribed IGRT dose was 75.6 Gy (range 73.8-79.2). HDR doses were 24 Gy (n=126) or 27 Gy (n=151) in 2 fractions, or 36 Gy (n=3) or 38 Gy (n=335) in 4 fractions. Five- and 10-year BC was 99% and 94% for IGRT and 98% and 95% for HDR (p=0.77); FFLR was 100% and 99% for both (p=0.89); and OS was 95% and 75% for IGRT and 97% and 85% for HDR (p=0.04). On multivariate analysis, predictors (p<0.10) for OS were age (p<0.001) and PNI (p=0.04); for LR, PPC (p=0.01); and for BC, a trend for PSA (p=0.08). Treatment type was not a predictor of OS, BC or FFLR (p>0.5). Conclusions: Both dose- escalated IGRT and HDR monotherapy yield similarly excellent outcomes for low-risk prostate cancer. Our experience supports the continued use of brachytherapy as monotherapy in low-risk prostate cancer. [Table: see text]

scholarly journals High-dose-rate brachytherapy for breast cancer: a patient-specific approach – first results

2020 ◽  
Vol 29 (4) ◽  
pp. 146-157
Author(s):  
A.V. Demianovich ◽  
◽  
D.B. Sanin ◽  
V.V. Martynova ◽  
N.B. Borysheva ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Radiation Exposure ◽  
Dose Rate ◽  
Treatment Plan ◽  
High Dose Rate ◽  
Accelerated Partial Breast Irradiation ◽  
Patient Specific ◽  
Partial Breast Irradiation ◽  
High Dose ◽  
High Dose Rate Brachytherapy

The study purpose was to demonstrate developed treatment scheme for breast cancer high-dose-rate brachytherapy with 192Ir and evaluate received radiation exposure. The results of re-search are discussed in the paper. Thirty patients of median age of 63 years with diagnosed T1N0M0 breast cancer received treatment between August, 2017 and June, 2019 in A. Tsyb MRRC. All patients underwent lumpectomy followed by accelerated partial breast irradiation (APBI) with single radiation dose of 3.4 Gy and total dose of 34 Gy. A patient received two frac-tions of irradiation daily, the interval between them was no less than 6 hours. The treatment dura-tion was 5 days. The treatment outcomes were assessed in terms of the treatment planning in-cluding radiation exposure to the target, healthy tissues and organs-at-risk. The study highlighted that determined dosimetric parameters correspond to those given in the approved treatment pro-tocol and meet the international recommendations. As the result of this research it is shown that treatment plan for each patient should be developed individually. Since the follow-up period is small, further studies will be conducted. This will allow early detection of toxic effects of brachy-therapy and the analysis of living status.

Knowledge-based radiotherapy treatment planning

2015 ◽  
Author(s):  
◽  
Lindsey Appenzoller Olsen
Keyword(s):  
Quality Control ◽  
Treatment Planning ◽  
Treatment Plan ◽  
Radiotherapy Planning ◽  
Patient Specific ◽  
Plan Quality ◽  
Radiotherapy Treatment Planning ◽  
Knowledge Based ◽  
Knowledge Based Planning ◽  
Radiotherapy Treatment

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Knowledge-based planning (KBP) has become a prominent area of research in radiation oncology in the last five years. The development of KBP aims to address the lack of systematic quality control and plan quality variability in radiotherapy treatment planning by providing achievable, patient-specific optimization objectives derived from a model trained with a cohort of previously treated, site-specific plans. This dissertation intended to develop, evaluate, and implement a knowledge-based planning system to reduce variability and improve radiotherapy treatment plan quality. The project aimed to 1) develop and validate an algorithm to train mathematical models that predict dose-volume histograms for organs at risk in radiotherapy planning, 2) implement the algorithm into a software application in order to transfer the technology into clinical practice, and 3) evaluate the impact of the software system (algorithm + application) on reducing variability and improving radiotherapy treatment plan quality through knowledge transfer. The presented work demonstrates that a KBP model is beneficial to radiotherapy planning. The developed models adequately describe what is dosimetrically achievable for patient specific anatomy and have proven useful in outlier detection for quality control of radiotherapy planning. The KBP paradigm has also demonstrated ability to improve treatment plan quality through benchmarking and transfer of knowledge between institutions.

Automated construction of an intraoperative high-dose-rate treatment plan library for the Varian brachytherapy treatment planning system

Brachytherapy ◽  
2016 ◽  
Vol 15 (4) ◽  
pp. 531-536 ◽  
Author(s):  
Christopher L. Deufel ◽  
Keith M. Furutani ◽  
Robert A. Dahl ◽  
Michael G. Haddock
Keyword(s):  
Dose Rate ◽  
Treatment Planning ◽  
Treatment Plan ◽  
High Dose Rate ◽  
Planning System ◽  
Treatment Planning System ◽  
High Dose

Does inadequate Point-A dose warrant treatment plan modifications in CT-image-based cervix high dose-rate brachytherapy planning? A dosimetric perspective

2013 ◽  
Vol 12 (4) ◽  
pp. 318-325
Author(s):  
R. Yaparpalvi ◽  
K. J. Mehta ◽  
S. Mutyala ◽  
H. C. Kuo ◽  
L. Hong ◽  
...  
Keyword(s):  
Treatment Planning ◽  
Treatment Plan ◽  
Tumour Size ◽  
High Dose Rate ◽  
High Dose ◽  
Ct Image ◽  
Organ Doses ◽  
Prescription Dose ◽  
Critical Organ ◽  
Median Cumulative Dose

AbstractBackground and purposeTo investigate whether inadequate dose to Point-A necessitates treatment plan changes in a time of computed tomography (CT)-image-guided brachytherapy treatment planning for cervix cancer.Materials and methodsA total of 125 tandem and ovoid insertions from 25 cervix patients treated were reviewed. CT-image-based treatment planning was carried out for each insertion. Point-A is identified and the dose documented; however, dose optimisation in each plan was based on covering target while limiting critical organ doses (PlanTarget). No attempts were made to equate prescription and Point-A dose. For each insertion, a second hypothetical treatment plan was generated by prescribing dose to Point-A (PlanPoint-A). Plans were inter-compared using dose–volume histogram analyses.ResultsA total of 250 treatment plans were analysed. For the study population, the median cumulative dose at Point-A was 80 Gy (range 70–95) for PlanTarget compared with 84·25 Gy for PlanPoint-A. Bladder and rectal doses were higher for PlanPoint-A compared with PlanTarget (p < 0·0001). Target D90 did not correlate with Point-A dose (p = 0·60).ConclusionsDepending on applicator geometry, tumour size and patient anatomy, Point-A dose may vary in magnitude compared with prescription dose. Treatment plan modifications purely based on inadequate Point-A dose are unnecessary, as these may result in higher organ-at-risk doses and not necessarily improve target coverage.

scholarly journals Feasibility of a Reusable Radiochromic Dosimeter

2021 ◽  
Vol 11 (21) ◽  
pp. 9906
Author(s):  
Joseph R. Newton ◽  
Maxwell Recht ◽  
Joseph A. Hauger ◽  
Gabriel Segarra ◽  
Chase Inglett ◽  
...  
Keyword(s):  
Treatment Planning ◽  
Optical Density ◽  
Dose Distribution ◽  
Ease Of Use ◽  
Planning System ◽  
Treatment Planning System ◽  
Patient Specific ◽  
High Dose ◽  
Wide Range ◽  
Radiochromic Dosimeter

The current practice for patient-specific quality assurance (QA) uses ion chambers or diode arrays primarily because of their ease of use and reliability. A standard routine compares the dose distribution measured in a phantom with the dose distribution calculated by the treatment planning system for the same experimental conditions. For the particular problems encountered in the treatment planning of complex radiotherapy techniques, such as small fields/segments and dynamic delivery systems, additional tests are required to verify the accuracy of dose calculations. The dose distribution verification should be throughout the total 3D dose distribution for a high dose gradient in a small, irradiated volume, instead of the standard practice of one to several planes with 2D radiochromic (GAFChromic) film. To address this issue, we have developed a 3D radiochromic dosimeter that improves the rigor of current QA techniques by providing high-resolution, complete 3D verification for a wide range of clinical applications. The dosimeter is composed of polyurethane, a radical initiator, and a leuco dye, which is radiolytically oxidized to a dye absorbing at 633 nm. Since this chemical dosimeter is single-use, it represents a significant expense. The purpose of this research is to develop a cost-effective reusable dosimeter formulation. Based on prior reusability studies, three promising dosimeter formulations were studied using small volume optical cuvettes and irradiated to known clinically relevant doses of 0.5–10 Gy. After irradiation, the change in optical density was measured in a spectrophotometer. All three formulations retained linearity of optical density response to radiation upon re-irradiations. However, only one formulation retained dose sensitivity upon at least five re-irradiations, making it ideal for further evaluation as a 3D dosimeter.

Sign in / Sign up

Export Citation Format

Share Document