Three-dimensional quality assurance of IMRT prostate plans using gel dosimetry

This study aims to confirm the usefulness of patient-specific quality assurance (PSQA) using three-dimensional (3D)-printed phantoms in ensuring the stability of IORT and the precision of the treatment administered. In this study, five patient-specific chest phantoms were fabricated using a 3D printer such that they were dosimetrically equivalent to the chests of actual patients in terms of organ density and shape around the given target, where a spherical applicator was inserted for breast IORT treatment via the INTRABEAM™ system. Models of lungs and soft tissue were fabricated by applying infill ratios corresponding to the mean Hounsfield unit (HU) values calculated from CT scans of the patients. The two models were then assembled into one. A 3D-printed water-equivalent phantom was also fabricated to verify the vendor-provided depth dose curve. Pieces of an EBT3 film were inserted into the 3D-printed customized phantoms to measure the doses. A 10 Gy prescription dose based on the surface of the spherical applicator was delivered and measured through EBT3 films parallel and perpendicular to the axis of the beam. The shapes of the phantoms, CT values, and absorbed doses were compared between the expected and printed ones. The morphological agreement among the five patient-specific 3D chest phantoms was assessed. The mean differences in terms of HU between the patients and the phantoms was 2.2 HU for soft tissue and −26.2 HU for the lungs. The dose irradiated on the surface of the spherical applicator yielded a percent error of −2.16% ± 3.91% between the measured and prescribed doses. In a depth dose comparison using a 3D-printed water phantom, the uncertainty in the measurements based on the EBT3 film decreased as the depth increased beyond 5 mm, and a good agreement in terms of the absolute dose was noted between the EBT3 film and the vendor data. These results demonstrate the applicability of the 3D-printed chest phantom for PSQA in breast IORT. This enhanced precision offers new opportunities for advancements in IORT.

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Gel Dosimetry with Radio-Fluorogenic Coumarin

10.20944/preprints201805.0176.v1 ◽

2018 ◽

Author(s):

Peter A. Sandwall ◽

Brandt P. Bastow ◽

Henry B. Spitz ◽

Howard R. Elson ◽

Michael Lamba ◽

...

Keyword(s):

Free Radicals ◽

Carboxylic Acid ◽

Three Dimensional ◽

High Energy ◽

Water Radiolysis ◽

Gel Dosimetry ◽

Rate Dependency ◽

High Energy Radiation ◽

Energy Radiation ◽

Hydroxyl Free Radicals

In radiotherapy, accurate deposition of energy to the targeted volume is vital to ensure effective treatment. Gel dosimeters are attractive detection systems, as tissue substitutes with potential to yield three-dimensional dose distributions. Radio-fluorogenesis is creation fluorescent chemical products in response to energy deposition from high-energy radiation. This report shares studies of a radio-fluorogenic gel dosimetry system, gelatin with coumarin-3-carboxlyic acid (C3CA), for the quantification of imparted energy. Aqueous solutions exposed to ionizing radiation result in the production of hydroxyl free radicals through water radiolysis. Interactions between hydroxyl free radicals and coumarin-3-carboxylic acid produce a fluorescent product. 7-hydroxy-coumarin-3-carboxylic acid has a blue (445 nm) emission, following UV to near UV (365–405 nm) excitation. Effects of C3CA concentration and pH buffers were investigated for this system. The response of the system was explored with respect to strength, type, and exposure rate of high-energy radiation. Results show a linear dose response relationship with a dose-rate dependency and no energy or type dependencies. This report supports the utility of gelatin-C3CA for phantom studies of radio-fluorogenic processes.

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Quality Assurance of Three Dimensional Treatment Planning System For External Photon Beam Radiotherapy

IOSR Journal of Applied Physics ◽

10.9790/4861-090301125133 ◽

2017 ◽

Vol 09 (3) ◽

pp. 125-133

Author(s):

Moamen M.O.M. Aly ◽

Hani Negm ◽

Shimaa. A. Fouad

Keyword(s):

Quality Assurance ◽

Treatment Planning ◽

Three Dimensional ◽

Photon Beam ◽

Planning System ◽

Treatment Planning System

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Incremental Inspection for Microrobotic Quality Assurance

Volume 1: 15th International Conference on Advanced Vehicle Technologies; 10th International Conference on Design Education; 7th International Conference on Micro- and Nanosystems ◽

10.1115/detc2013-12790 ◽

2013 ◽

Cited By ~ 2

Author(s):

David L. Christensen ◽

Elliot W. Hawkes ◽

Annjoe Wong-Foy ◽

Ronald E. Pelrine ◽

Mark R. Cutkosky

Keyword(s):

Quality Assurance ◽

Standard Deviation ◽

Carbon Fiber ◽

Bond Strength ◽

Rapid Prototyping ◽

Three Dimensional ◽

Good Resolution ◽

Measurement Standard ◽

Directional Microphone ◽

Inspection Techniques

This paper addresses inspection techniques that can be performed by microrobots used for fabricating three dimensional structures. In contrast to most commercial rapid prototyping processes, the parallelism afforded by microrobot teams allows incremental inspection of structures during assembly. In the present case, this approach is applied to parts fabricated from carbon fiber struts bonded with UV-cured epoxy. Preliminary tests involving thermal and vibrational inspection methods are described and compared with the results of FEA models of the joints. Vibrational inspection performed by microrobots and recorded using a directional microphone, characterizes bond joint natural frequency with good resolution (an average measurement standard deviation of 5Hz over a range of 650–1215 Hz). These effective stiffness measurements are correlated with ultimate bond strength as well. The measurements are sufficient to distinguish between joints that do or do not have desired amounts of adhesive.

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