Clinical evaluation of a transmission detector system and comparison with a homogeneous 3D phantom dosimeter

Abstract

To evaluate the performances of the Dolphin system for pre-treatment verification (IBA Dosimetry, Schwarzenbruck, Germany) based on transmission measurements, employing a clinical perspective. Methods and materials: Fifty treatment plans were verified by Dolphin and Delta 4 detectors (Scandidos, Uppsala, Sweden) during the same session and subsequently by the Delta 4 itself. The attenuation factor of the transmission detector (required for on-line dosimetry) was evaluated by comparing Delta 4 measurements with and without Dolphin. Gamma evaluation was performed to compare the plan dose with the one delivered in case of Delta 4 and Dolphin (gamma analysis within the structures). Dose-volume based parameters for PTV and OARs doses were considered for Compass calculation and Dolphin reconstruction and clinical decisions were made by two expert physicians in order to assess the "pass", "fail" or "evaluate" grade of the treatment plans. A statistical analysis was performed to investigate the eventual correlation between Delta 4 gamma analysis and Dolphin clinical evaluation. Results: A value of 10.7% ± 0.7% was found for detector attenuation. No patients were classified as "fail" by the two instruments as well as by physicians. No correlation was found between the Delta 4 gamma metric and physician classification; conversely, a significant correlation was observed for Dolphin between the numbers of points with gamma ≥1 (gamma failure rate, as evaluated by the Dolphin) in the PTV area and clinical decision. Conclusion: The Dolphin system demonstrated to be an accurate detector for pre-treatment purposes and could be used as a clinical decision making tool for plan acceptance.

Evaluation of the effects of implementing a diode transmission device into the clinical workflow

“…Attenuation of 6 MV beams along the central axis for the various detectors they compared ranged from 1.0% to 7.2%, with ion-chamberbased devices typically having higher attenuation (ranging from 3.3% to 7.2%) and diode transmission devices typically having lower attenuation (~1%). Another available transmission detector not included in the comparison by Li et al [13] is the Dolphin detector (IBA Dosimetry, Schwarzenbuck, Germany) [18,20,21]. The Dolphin is a 2D array of 1513 plane-parallel ion chambers.…”

Efficient dose–volume histogram–based pretreatment patient‐specific quality assurance methodology with combined deep learning and machine learning models for volumetric modulated arc radiotherapy

“…Another one is the ArcCHECK‐3DVH system (Sun Nuclear Corporation, Melbourne, FL, USA). A strict commissioning of Dolphin‐Compass and ArcCHECK‐3DVH, including the validation of accuracy for array measurement, beam modeling, and dose reconstruction, was performed in advance according to the manufacturer's standards 36,37 …”

“…A strict commissioning of Dolphin-Compass and ArcCHECK-3DVH, including the validation of accuracy for array measurement, beam modeling, and dose reconstruction, was performed in advance according to the manufacturer's standards. 36,37 In addition to the general accepted GPRs and individual volume-based GIs, the DEs% and volumetric errors (VEs%) between the TPS and measurement reconstructed dose distribution were recorded and analyzed by the Compass and 3DVH programs, respectively. 17,38 For target coverage, D mean and D max (mean and maximum dose), D 2 and D 98 (D x : dose received by x% of the volume), and V 95 and V 100 (V x : volume irradiated by x% of the prescription dose) of the PTV were calculated and compared.…”

Validation of Monte Carlo multithreading TOpas 3.6 software in order to simulate the 6 MV Elekta Synergy MLCi2 platform linac

“…Also, our dosimetry calculation was carried out according to AAPM’s TG-51 protocol [ 9 ]. The experiment data were obtained utilizing a cylindrical ionization chamber, type Scanditronix Wellhofer CC13 having an active volume of 0.13 cm 3 installed over a motorized guide in a resistance temperature detector of IBA Blue Phantom [ 10 ].…”