scholarly journals A Large Area Pixelated Silicon Array Detector for Independent Transit In Vivo Dosimetry

2022 ◽  
Vol 12 (2) ◽  
pp. 537
Author(s):  
Owen J. Brace ◽  
Iolanda Fuduli ◽  
Saree Alnaghy ◽  
Albert T. Le ◽  
Jeremy A. Davis ◽  
...  
Keyword(s):  
Imaging System ◽  
Planning System ◽  
Treatment Planning System ◽  
In Vivo Dosimetry ◽  
Array Detector ◽  
Large Area ◽  
Imaging Device ◽  
Percentage Difference ◽  
Transit Dosimetry

A large area pixelated silicon array detector named “MP987” has been developed for in vivo dosimetry. The detector was developed to overcome the non-water equivalent response of EPID (Electronic Portal Imaging Device) dosimetry systems, due to the shortfalls of the extensive corrections required. The detector, readout system and software have all been custom designed to be operated independently from the linac with the array secured directly above the EPID, to be used in combination with the 6 MV imaging system. Dosimetry characterisation measurements of percentage depth dose (PDD), dose rate dependence, radiation damage, output factors (OF), profile measurements, linearity and uniformity were performed. Additionally, the first pre-clinical tests with this novel detector of a transit dosimetry characterization and a collapsed IMRT (intensity-modulated radiation therapy) study are presented. Both PDD and OF measurements had a percentage difference of less than 2.5% to the reference detector. A maximum change in sensitivity of 4.3 ± 0.3% was observed after 30 kGy of gamma accumulated dose. Transit dosimetry measurements through a homogeneous Solid Water phantom had a measured dose within error of the TPS calculations, for field sizes between 3 × 3 cm2 and 10 × 10 cm2. A four-fraction collapsed IMRT plan on a lung phantom had absolute dose pass fractions between the MP987 and TPS (treatment planning system) from 94.2% to 97.4%, with a 5%/5 mm criteria. The ability to accurately measure dose at a transit level, without the need for correction factors derived from extensive commissioning data collection procedures, makes the MP987 a viable alternative to the EPID for in vivo dosimetry. This MP987 is this first of its kind to be successfully developed specifically for a dual detector application.

Quality assurance of linear accelerator: a comprehensive system using electronic portal imaging device

2018 ◽  
Vol 18 (02) ◽  
pp. 138-149
Author(s):  
P. Niyas ◽  
K. K. Abdullah ◽  
M. P. Noufal ◽  
R. Vysakh
Keyword(s):  
Quality Assurance ◽  
Linear Accelerator ◽  
Planning System ◽  
Treatment Planning System ◽  
Patient Specific ◽  
Array Detector ◽  
Electronic Portal Imaging Device ◽  
Imaging Device ◽  
Portal Imaging ◽  
Electronic Portal Imaging

AbstractAimThe Electronic Portal Imaging Device (EPID), primarily used for patient setup during radiotherapy sessions is also used for dosimetric measurements. In the present study, the feasibility of EPID in both machine and patient-specific quality assurance (QA) are investigated. We have developed a comprehensive software tool for effective utilisation of EPID in our institutional QA protocol.Materials and methodsPortal Vision aS1000, amorphous silicon portal detector attached to Clinac iX—Linear Accelerator (LINAC) was used to measure daily profile and output constancy, various Multi-Leaf Collimator (MLC) checks and patient plan verification. Different QA plans were generated with the help of Eclipse Treatment Planning System (TPS) and MLC shaper software. The indigenously developed MATLAB programs were used for image analysis. Flatness, symmetry, output constancy, Field Width at Half Maximum (FWHM) and fluence comparison were studied from images obtained from TPS and EPID dosimetry.ResultsThe 3 years institutional data of profile constancy and patient-specific QA measured using EPID were found within the acceptable limits. The daily output of photon beam correlated with the output obtained through solid phantom measurements. The Pearson correlation coefficients are 0.941 (p = 0.0001), 0.888 (p = 0.0188) and 0.917 (p = 0.0007) for the years of 2014, 2015 and 2016, respectively. The accuracy of MLC for shaping complex treatment fields was studied in terms of FWHM at different portions of various fields, showed good agreement between TPS-generated and EPID-measured MLC positions. The comparison of selected patient plans in EPID with an independent 2D array detector system showed statistically significant correlation between these two systems. Percentage difference between TPS computed and EPID measured fluence maps calculated for number of patients using MATLAB code also exhibited the validity of those plans for treatment.

scholarly journals Commissioning of total body irradiation using plastic bead bags

2020 ◽  
Vol 61 (6) ◽  
pp. 959-968
Author(s):  
Yuichi Akino ◽  
Shintaro Maruoka ◽  
Katsuyuki Yano ◽  
Hiroshi Abe ◽  
Fumiaki Isohashi ◽  
...  
Keyword(s):  
Total Body Irradiation ◽  
Scatter Correction ◽  
Effective Density ◽  
Planning System ◽  
Whole Body ◽  
Treatment Planning System ◽  
In Vivo Dosimetry ◽  
Total Body ◽  
Plastic Bead

Abstract The goal of total body irradiation (TBI) is to deliver a dose to the whole body with uniformity within ±10%. The purpose of this study was to establish the technique of TBI using plastic bead bags. A lifting TBI bed, Model ORP-TBI-MN, was used. The space between the patient’s body and the acrylic walls of the bed was filled with polyacetal bead bags. Patients were irradiated by a 10 MV photon beam with a source to mid-plane distance of 400 cm. The monitor unit (MU) was calculated by dose-per-MU, tissue-phantom-ratio and a spoiler factor measured in solid water using an ionization chamber. The phantom-scatter correction factor, off-center ratio and the effective density of the beads were also measured. Diode detectors were used for in vivo dosimetry (IVD). The effective density of the beads was 0.90 ± 0.09. The point doses calculated in an I’mRT phantom with and without heterogeneity material showed good agreement, with measurements within 3%. An end-to-end test was performed using a RANDO phantom. The mean ± SD (range) of the differences between the calculated and IVD-measured mid-plane doses was 1.1 ± 4.8% (−5.9 to 5.0%). The differences between the IVD-measured doses and the doses calculated with Acuros XB of the Eclipse treatment planning system (TPS) were within 5%. For two patients treated with this method, the differences between the calculated and IVD-measured doses were within ±6% when excluding the chest region. We have established the technique of TBI using plastic bead bags. The TPS may be useful to roughly estimate patient dose.

Effect of correction/calibration factors on accuracy of in vivo dose delivery with cylindrical n-type Isorad diode in conventional radiotherapy

2013 ◽  
Vol 13 (2) ◽  
pp. 180-188
Author(s):  
Kashif Islam ◽  
Asdar ul Haque ◽  
Muzaffar Hussain ◽  
Sohail Murad ◽  
Khan Muhammad ◽  
...  
Keyword(s):  
Radiation Treatment ◽  
Planning System ◽  
Treatment Planning System ◽  
In Vivo Dosimetry ◽  
Correction Factors ◽  
Dose Delivery ◽  
Calculated Correction ◽  
Treatment Plans ◽  
Palliative Patient

AbstractPurposeThe main aim was to use pre-calculated correction factors and calibration factors for measurement of accuracy of dose delivery before implementation of such in vivo dosimetry on real patients visiting for first radiation treatment. These factors were verified by generating the most common treatment plans on human phantom except for breast and colon using cobalt-60 unit.Materials and methodsSix treatment plans were generated, i.e. nasopharynx, bladder, prostate, brain, larynx and lung of human phantom, total 18 fields were planned keeping in view the correction factors which are to be verified. MULTIDATA Decision Support System 2.5, Shimadzu simulator, Isorad diode-n type, electrometer patient dose monitor and ATOM Adult male human phantom were used.Results and conclusionFor 18 fields, the dose delivery was accurate in the range 0·29–6·74%. The deviation between measured and expected doses to nasopharynx, lung, bladder, prostate, brain and larynx cases of human phantom ranged from 1·44–3·89%, 0·29–0·54%, 0·44–6·18%, 0·54–5·16%, 0·33–4·90%, 5·58–6·74%, respectively. In 30 palliative patient cases, the first radiation treatment was also monitored. The accuracy of dosimety ranged from 1·05% to 5·35%. This study is helpful to identify areas of improvement in treatment of patients like quality control/quality assurance (QA) of treatment planning system, beam data modifications, machine repair maintenance, QA audit in radiotherapy.

Characterisation and use of OSLD for in vivo dosimetry in head and neck intensity-modulated radiation therapy

2020 ◽  
pp. 1-7
Author(s):  
L. Jose Solomon Raj ◽  
Benedicta Pearlin ◽  
B. S. Timothy Peace ◽  
Rajesh Isiah ◽  
I. Rabi Raja Singh
Keyword(s):  
Radiation Therapy ◽  
Head And Neck ◽  
Dose Rate ◽  
Intensity Modulated Radiation Therapy ◽  
Rate Dependence ◽  
Planning System ◽  
Treatment Planning System ◽  
In Vivo Dosimetry ◽  
Intensity Modulated

Abstract Aim: This study reveals the characteristic nature and the use of optically stimulated luminescence dosimeters (OSLD) as an in vivo dosimetry tool for head and neck intensity-modulated radiation therapy (IMRT). Materials and methods: Calibration and characterisation of OSLD such as sensitivity, reproducibility, dose-rate dependence, beam quality dependence, output factor measurement and comparison of two bleaching techniques using halogen and compact fluorescent lamp (CFL) were initially performed. Later, eye dose measurements were performed for head and neck IMRT patients using OSLD and were compared with the corresponding dose calculated by the treatment planning system (TPS). Results: While the sensitivity was found to be within ±5%, the dose-rate dependence and reproducibility were found to be within ±3%. The OSLD showed an under-response of 3% for 15 MV and an increase in response by 5% for Co60 (1·25 MeV) when compared with the 6 MV X-ray beam. Therefore, a separate calibration for different beam energies is required. The percentage deviation of OSLD to that of TPS was found to be within ±2·77%. The OSLD has been successfully used for the in vivo dosimetry of patients who received IMRT. Hence, it is concluded that OSLDs can serve as effective dosimeters for in vivo dosimetry.

Implementation of an in vivo radiochromic film QA procedure

2016 ◽  
Author(s):  
◽  
Jason Stanford
Keyword(s):  
Quality Assurance ◽  
Radiation Treatment ◽  
Radiochromic Film ◽  
In Vivo Dosimetry ◽  
Patient Specific ◽  
Attractive Alternative ◽  
Quality Assurance Procedure ◽  
Imaging Device ◽  
Treatment Techniques

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Advance treatment techniques, such as IMRT and dynamic conformal arc delivery, are novel radiation treatment procedures at the forefront of accurate and precise radiotherapy. However, the risk of suboptimal treatment resulting in injury is far greater with these techniques due to their complexity. An in vivo quality assurance system is the most appropriate validation of the delivered dose to the patient from these techniques. The intent of this research is to propose an in vivo dosimetry quality assurance procedure using radiochromic film. This research proved that radiochromic in vivo dosimetry is a viable method of detecting spatial patient specific errors in radiotherapy; however, the process is time consuming and not sensitive enough for dosimetric errors associated with weight change. Although time consuming, in vivo radiochromic dosimetry is an attractive alternative for small cancer centers and developing countries without the large startup capital to acquire the electronic portal imaging device necessary for EPID in vivo dosimetry.

scholarly journals [OA051] Toward a new treatment planning system accounting for in-vivo proton range verification in proton therapy

2018 ◽  
Vol 52 ◽  
pp. 21
Author(s):  
Liheng Tian ◽  
Georgios Dedes ◽  
Guillaume Landry ◽  
Florian Kamp ◽  
Katharina Niepel ◽  
...  
Keyword(s):  
Treatment Planning ◽  
Proton Therapy ◽  
Planning System ◽  
Treatment Planning System ◽  
New Treatment ◽  
Range Verification

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 Use of artificial neural network for pretreatment verification of intensity modulation radiation therapy fields

2019 ◽  
Vol 92 (1102) ◽  
pp. 20190355 ◽  
Author(s):  
Seied Rabie Mahdavi ◽  
Asieh Tavakol ◽  
Mastaneh Sanei ◽  
Seyed Hadi Molana ◽  
Farshid Arbabi ◽  
...  
Keyword(s):  
Neural Network ◽  
High Speed ◽  
Pass Rate ◽  
Planning System ◽  
Treatment Planning System ◽  
Two Dimensional ◽  
Dose Verification ◽  
Quality Assurance Procedure ◽  
Imaging Device ◽  
Artificial Neural

Objective: The accuracy of dose delivery for intensity modulated radiotherapy (IMRT) treatments should be determined by an accurate quality assurance procedure. In this work, we used artificial neural networks (ANNs) as an application for the pre-treatment dose verification of IMRT fields based two-dimensional-fluence maps acquired by an electronic portal imaging device (EPID). Methods: The ANN must be trained and validated before use for the pretreatment dose verification. Hence, 60 EPID fluence maps of the anteroposterior prostate and nasopharynx IMRT fields were used as an input for the ANN (feed forward type), and a dose map of those fluence maps that were acquired by two-dimensional Array Seven29TM as an output for the ANN. Results: After the training and validation of the neural network, the analysis of 20 IMRT anteroposterior fields showed excellent agreement between the ANN output and the dose map predicted by the treatment planning system. The average overall global and local γ field pass rate was greater than 90% for the prostate and nasopharynx fields, with the 2 mm/3% criteria. Conclusion: The results indicated that the ANN can be used as a fast and powerful tool for pretreatment dose verification, based on an EPID fluence map. Advances in knowledge: In this study, ANN is proposed for EPID based dose validation of IMRT fields. The proposed method has good accuracy and high speed in response to problems. Neural network show to be low price and precise method for IMRT fields verification

In Vivo Diode Dosimetry for Imrt Treatments Generated by Pinnacle Treatment Planning System

2009 ◽  
Vol 34 (1) ◽  
pp. 26-29 ◽  
Author(s):  
Parham Alaei ◽  
Patrick D. Higgins ◽  
Bruce J. Gerbi
Keyword(s):  
Treatment Planning ◽  
Planning System ◽  
Treatment Planning System
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