Selection of gamma analysis acceptance criteria in IMRT QA using Gafchromic EBT3 film dosimetry

AbstractBackground and purposeThis study reported the justification and selection of acceptable γ criteria with respect to low (6 MV) and high (15 MV) photon beams for intensity-modulated radiation therapy quality assurance (IMRT QA) using the Gafchromic external beam therapy 3 (EBT3) film.Materials and methodsFive-field step-and-shoot IMRT was used to treat 16 brain IMRT patients using the dual-energy DHX-S linear accelerator (Varian Medical System, Palo Alto, CA, USA). Dose comparisons between computed values of the treatment planning system (TPS) and Gafchromic EBT3 film were evaluated based on γ analysis using the Film QA Pro software. The dose distribution was analysed with gamma area histograms (GAHs) generated using different γ criteria (3%/2 mm, 3%/3 mm and 5%/3 mm) for the 6 and 15 MV photon beams, to optimise the best distance-to-agreement (DTA) criteria with respect to the beam energy.ResultsFrom the comparison between the dose distributions acquired from the TPS and EBT3 film, a DTA criterion of 3%/2 mm showed less dose differences (DDs) with passing rates up to 93% for the 6 MV photon beams, while for the 15 MV a relaxed DTA criterion of 5%/3 mm was consistent with the DD acceptability criteria with a 95% passing rate.ConclusionsOur results suggested that high-energy photon beams required relaxed DTA criteria for the brain IMRT QA, while low-energy photon beams showed better results even with tight DTA criteria.

Download Full-text

SU-E-T-381: Evaluation of Calculated Dose Accuracy for Organs-At-Risk Located at Out-Of-Field in a Commercial Treatment Planning System for High Energy Photon Beams Produced From TrueBeam Accelerators

Medical Physics ◽

10.1118/1.4924742 ◽

2015 ◽

Vol 42 (6Part18) ◽

pp. 3421-3421

Author(s):

L Wang ◽

G Ding

Keyword(s):

Treatment Planning ◽

Organs At Risk ◽

High Energy ◽

Planning System ◽

Treatment Planning System ◽

High Energy Photon ◽

Photon Beams ◽

Energy Photon ◽

Calculated Dose ◽

Dose Accuracy

Download Full-text

Dosimetric Studies of Mixed Energy Intensity Modulated Radiation Therapy for Prostate Cancer Treatments

Journal of Radiotherapy ◽

10.1155/2014/760206 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

K. Abdul Haneefa ◽

K. K. Shakir ◽

A. Siddhartha ◽

T. Siji Cyriac ◽

M. M. Musthafa ◽

...

Keyword(s):

Prostate Cancer ◽

Radiation Therapy ◽

Intensity Modulated Radiation Therapy ◽

High Energy ◽

Photon Beam ◽

Planning System ◽

Treatment Planning System ◽

Intensity Modulated ◽

Mixed Beam ◽

Mixed Field

Dosimetric studies of mixed field photon beam intensity modulated radiation therapy (IMRT) for prostate cancer using pencil beam (PB) and collapsed cone convolution (CCC) algorithms using Oncentra MasterPlan treatment planning system (v. 4.3) are investigated in this study. Three different plans were generated using 6 MV, 15 MV, and mixed beam (both 6 and 15 MV). Fifteen patients with two sets of plans were generated: one by using PB and the other by using CCC for the same planning parameters and constraints except the beam energy. For each patient’s plan of high energy photons, one set of photoneutron measurements using solid state neutron track detector (SSNTD) was taken for this study. Mean percentage of V66 Gy in the rectum is 18.55±2.8, 14.58±2.1, and 16.77±4.7 for 6 MV, 15 MV, and mixed-energy plans, respectively. Mean percentage of V66 Gy in bladder is 16.54±2.1, 17.42±2.1, and 16.94±41.9 for 6 MV, 15 MV, and mixed-energy plans, respectively. Mixed fields neutron contribution at the beam entrance surface is 45.62% less than at 15 MV photon beam. Our result shows that, with negligible neutron contributions, mixed field IMRT has considerable dosimetric advantage.

Download Full-text

The effect of the carbon fibre insert for the Varian Exact™ couch on the attenuation and build-up of high energy photon beams

Journal of Radiotherapy in Practice ◽

10.1017/s1460396910000373 ◽

2010 ◽

Vol 10 (2) ◽

pp. 77-83 ◽

Cited By ~ 3

Author(s):

ML Wilson ◽

WP Colley ◽

AW Beavis

Keyword(s):

Carbon Fibre ◽

External Beam Radiotherapy ◽

High Energy ◽

Planning System ◽

Treatment Planning System ◽

Skin Dose ◽

Angle Of Incidence ◽

Photon Beams ◽

Radiation Beam ◽

Tolerance Dose

AbstractCarbon fibre couch inserts are widely used in external beam radiotherapy to provide rigid and lightweight patient support. Carbon fibre is often perceived to be essentially radiotranslucent implying that it does not interfere with the radiation beam. However, there is evidence in the literature which suggests that this perception may not be appropriate, particularly at oblique angles of incidence. Furthermore, there is evidence indicating that the use of carbon fibre significantly reduces the skin sparing effect. In this study, the radiation attenuation and surface dose enhancement characteristics of the carbon fibre insert for the Varian ExactTM couch have been investigated. It was found that attenuation increased significantly with increasing angle of incidence, resulting in in-phantom dose reductions of up to 6% at 6 MV and 4% at 15 MV. It has been shown that it is possible to model couch attenuation on a commercial treatment planning system (Elekta CMS XiO) by including the carbon fibre insert in the planning computed tomography (CT) dataset. Finally, the carbon fibre insert was found to significantly increase skin dose to the patient. The skin dose was approximately three times as large when the couch insert was added to 6 and 15 MV photon beams. However, even with this substantial increase it is highly unlikely that the skin tolerance dose will be exceeded.

Download Full-text

Validation of Monaco Treatment Planning System for Intensity-Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT®) on ELEKTA Infinity™ Linear Accelerator

E3S Web of Conferences ◽

10.1051/e3sconf/202129701014 ◽

2021 ◽

Vol 297 ◽

pp. 01014

Author(s):

Saad Zouiri ◽

Meriem Tantaoui ◽

Mounir El Hassani ◽

Abdenbi El Moutaoukkil ◽

Abdellatif Ennakri ◽

...

Keyword(s):

Treatment Planning ◽

Linear Accelerator ◽

Volumetric Modulated Arc Therapy ◽

Intensity Modulated Radiation Therapy ◽

Dose Calculation ◽

Planning System ◽

Treatment Planning System ◽

Dosimetric Data ◽

Gamma Analysis ◽

Matrix Detector

The objective of this study is to evaluate the dosimetric precision of the Monte Carlo (MC) algorithm to validate the Monaco® (Elekta) treatment planning system for the two radiotherapy techniques IMRT and VMAT® on the Infinity™ Elekta linear accelerator. Several irradiation plans were created on the Monaco® treatment planning system (TPS) and calculated by the integrated MC algorithm for its validation. The same plans were applied experimentally using the Matrixx Evolution 2D array with its appropriate phantom. All measurements were performed by superimposition with those calculated on the Infinity™ linear accelerator (ELEKTA). The calculated and measured dosimetric data were overlaid to make the comparison of what is realistic and what was simulated using the MyQA (IBA) software associated with the Matrixx. Good agreement was observed between calculated and measured data using 3%, 3mm distance to agreement (DTA) and low dose threshold 5% criteria. Global gamma analysis passing rates for all tests are greater than 95%. An agreement less than 2 mm is shown for open fields and homogenous dose test. However, there was increase in the agreement criteria above 3 mm for chair and pyramid test as a result of high gradient dose regions especially at the edge of target volumes. Results obtained from this study allowed, in one hand to confirm the accuracy of our MC model dose calculation with Monaco® TPS, and in the other hand, the use of the matrix detector as a standard tool for IMRT/VMAT® patient quality control.

Download Full-text

Evaluation of Breast Cancer Radiation Therapy Techniques in Outfield Organs of Rando Phantom with Thermoluminescence Dosimeter

Journal of Biomedical Physics and Engineering ◽

10.31661/jbpe.v0i0.1067 ◽

2019 ◽

Cited By ~ 1

Author(s):

M Behmadi ◽

H Gholamhosseinian ◽

M Mohammadi ◽

Sh Naseri ◽

M Momennezad ◽

...

Keyword(s):

Breast Cancer ◽

Radiation Treatment ◽

High Energy ◽

Planning System ◽

Treatment Planning System ◽

Secondary Cancer ◽

High Energy Photon ◽

Energy Photon ◽

Cancer Radiotherapy ◽

Breast Cancer Radiotherapy

Background: Given the importance of scattered and low doses in secondary cancer caused by radiation treatment, the point dose of critical organs, which were not subjected to radiation treatment in breast cancer radiotherapy, was measured.Objective: The purpose of this study is to evaluate the peripheral dose in two techniques of breast cancer radiotherapy with two energies. Methods: Eight different plans in two techniques (conventional and conformal) and two photon energies (6 and 15 MeV) were applied to Rando Alderson Phantom’s DICOM images. Nine organs were contoured in the treatment planning system and specified on the phantom. To measure the photon dose, forty-eight thermoluminescence dosimeters (MTS700) were positioned in special places on the above nine organs and plans were applied to Rando phantom with Elekta presice linac. To obtain approximately the same dose distribution in the clinical organ volume, a wedge was used on planes with an energy of 6 MeV photon. Results: Point doses in critical organs with 8 different plans demonstrated that scattering in low-energy photon is greater than high-energy photon. In contrast, neutron contamination in high-energy photon is not negligible. Using the wedge and shield impose greater scattering and neutron contamination on patients with low-and high-energy photon, respectively. Conclusion: Deciding on techniques and energies required for preparing an acceptable treatment plan in terms of scattering and neutron contamination is a key issue that may affect the probability of secondary cancer in a patient.

Download Full-text