3D dosimetry on Ru-106 plaque for ocular melanoma treatments

Gueli, Anna Maria; Mannino, Giovanni; Troja, S. O.; Asero, G.; Burrafato, G.; Vincolis, R. De; Greco, C.; Longhitano, N.; Occhipinti, Annalisa; Pansini, F.; Stella, Giuseppe

doi:10.1016/j.radmeas.2011.07.032

Cited by 20 publications

(5 citation statements)

References 14 publications

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“…While image guidance and 3D dose distributions have been used for ocular proton therapy for decades (Goitein & Miller 1983), only few treatment planning systems exist for ocular brachytherapy, with the most widely used being Plaque Simulator. The accuracy of Plaque Simulator has been investigated using radio chromatic film and diode detectors for both Ru‐106 and Iodine‐125 brachytherapy (Knutsen et al 2001; Gueli et al 2011; Poder & Corde 2013), all demonstrating good agreement between calculated and measured dose. In extension, the benefit of 3D image‐guided dose calculation for accurately estimating delivered dose from I‐125 brachytherapy has been shown in a reanalysis of dose distributions from the collaborative ocular melanoma study (COMS) using Plaque Simulator (Krintz et al 2003).…”

Section: Discussionmentioning

confidence: 99%

3D image‐guided treatment planning for Ruthenium‐106 brachytherapy of choroidal melanomas

Espensen

Kiilgaard

Klemp

et al. 2020

Acta Ophthalmologica

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Background Current standard treatment procedures for Ruthenium‐106 (Ru‐106) brachytherapy for choroidal melanomas do not use 3D image‐guided treatment planning. We evaluated the potential impact of introducing 3D treatment planning and quantified the theoretical clinical benefits in terms of tumour control probability (TCP) and normal tissue complication probability (NTCP). Materials and methods Treatment plans for thirty‐two patients were optimized using 3D image‐guided treatment planning and compared to the original 2D clinical plans. Optimization of plans was done in an image‐based treatment planning system by optimizing the plaque position and treatment time such that the entire tumour received the prescribed dose of 100 Gy. TCP and NTCP for 2D clinical plans and optimized 3D image‐guided plans were estimated from published outcome prediction models and compared within patients using Wilcoxon signed‐rank test. Results The median minimum tumour dose (D99%) for 2D clinical plans was 93 Gy (range: 23–158 Gy), corresponding to 5‐year TCP of 75% (IQR 61–86%), while median tumour D99% for optimized 3D image‐guided plans was 115 Gy (range 103–141 Gy), corresponding to TCP of 82% (IQR 80–84%). This was a statistically significant increase in estimated TCP (median increase in TCP 8% (IQR: −5–23, p = 0.006). While the dose to normal tissue increased somewhat, there was no significant change in NTCP. Conclusion 3D treatment planning theoretically allows for improved tumour dose delivery for Ru‐106 brachytherapy of choroidal melanomas, resulting in a significant increase in expected tumour control compared to traditional approaches using 2D calculations. The deliverability of optimized plans, and potential increased risk of late complications, will have to be confirmed in future clinical studies.

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Section: Discussionmentioning

confidence: 99%

3D image‐guided treatment planning for Ruthenium‐106 brachytherapy of choroidal melanomas

Espensen

Kiilgaard

Klemp

et al. 2020

Acta Ophthalmologica

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“…27 Additional dosimetry studies have included the use of scintillation detectors, thermoluminescent dosimeters, semiconductor detectors, radiochromic films, diamond detectors, diode detectors, alanine pellets, alanine-polymer film, and ionization chambers. [28][29][30][31][32][33][34][35][36][37][38] For 106 Ru/ 106 Rh plaques, all current measurement techniques rely on the use of a calibrated device to perform relative dosimetry, as opposed to an extrapolation chamber where dose is determined directly as a primary measurement device.…”

Section: Introductionmentioning

confidence: 99%

A convex windowless extrapolation chamber to measure surface dose rate from ¹⁰⁶Ru/¹⁰⁶Rh episcleral plaques

2019

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Purpose A convex windowless extrapolation chamber was developed as a primary measurement device to determine surface dose rate from curved 106Ru/106Rh episcleral plaques. Methods A convex extrapolation chamber without an entrance window was constructed for this work, and surface dose rate measurements were performed with two curved CCB‐type 106Ru/106Rh plaques (S/N 2545 and 2596) manufactured by Eckert & Ziegler BEBIG. FARO® Gage measurements were performed to verify the radius of curvature for the convex electrode and the concave plaque surface. Furthermore, the collecting electrode area was verified through capacitance measurements. Chamber correction factors for divergence and backscatter were generated using the EGSnrc cavity user code. For each source, surface dose rate was measured with the convex extrapolation chamber and compared with on‐contact measurements made with curved un‐laminated EBT3 film strips. A Monte Carlo correction was generated for radiochromic film measurements to account for volume averaging within the active layer and effects of phantom scatter. Additionally, extrapolation chamber results for each plaque were compared with scintillation detector measurements performed by the manufacturer. For the second source (S/N 2596), a comparison was also made with the Monte Carlo‐corrected surface dose rate measured at the National Physical Laboratory (NPL) using cylindrical alanine pellets. Finally, source measurements were performed using conventional ionization chambers (Exradin A26, A1SL, and A20) within a custom fixture to investigate the transfer of extrapolation chamber surface dose rate to clinics. Results For the first 106Ru/106Rh plaque (S/N 2545), average surface dose rate from the convex windowless extrapolation chamber was found to be 1.5% higher than the corresponding value from curved un‐laminated EBT3 film measurements and 5.6% lower than the manufacturer value. For the second source (S/N 2596), the extrapolation chamber surface dose rate was 2.5% higher than the un‐laminated EBT3 film result, 4.5% lower than the manufacturer value, and 3.9% higher compared to corrected alanine measurements made at NPL. Total uncertainty in the extrapolation chamber measurement was estimated to be approximately ± 7.0% (k = 2). For the plaque measurements made using conventional ionization chambers with a custom fixture, surface dose rate from the transfer technique was found to agree within 3.8% with the expected convex extrapolation chamber result for S/N 2596. Conclusions A convex windowless extrapolation chamber was developed as a primary measurement device for 106Ru/106Rh plaques. Through comparison with the extrapolation chamber, the accuracy of surface dose rate measurements from current dosimetry techniques was assessed and agreement was seen within 5.6%. Finally, it was found that conventional ionization chambers could be calibrated with a reference 106Ru/106Rh plaque in order to transfer the extrapolation chamber result for surface dose rate to clinics.

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“…Gafchromic TM XR-QA2 films have also been used for dose measurements in other areas of diagnostic radiology, such as Contrast Enhanced Digital Mammography (CEDM) [14], Computed Tomography Fluoroscopy (CTF) [15], dental Cone Beam CT [16] and in Micturating Cysto Urethro Gram (MCUG) procedures [17], showing satisfactory results. Radiochromic films can be extended from 2-D to 3-D reference dosimetry systems by embedding the sheets of the films between water equivalent plastics designed to either simulate ideal geometrical conditions (square slabs) [18] or even inhomogeneous human-like phantoms, e.g. Rando [7].…”

Section: Introductionmentioning

confidence: 99%

3-D dose distribution for organ dose measurement in CT thoracic exams using Gafchromic™ XR-QA2 films

et al. 2019

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A: The patient dose in radiodiagnostic is currently monitored through an ionizing radiation exposure index named Volume Computed Tomography Dose Index (CTDI vol ) and the Dose-Length Product (DLP), displayed by CT scanner and measurable through a 100 mm long pencil ionization chamber, inserted in a homogeneous cylindrical PMMA phantom. The phantom is 14 cm long and has a diameter of 16 (32) cm that represents the adult head (body). One of the main flaws of such a method is that it does not return any information on the dose distribution to organs, and the average absorbed dose value, due to the material and dimensions of both the phantom and the ionization chamber, might be either underestimated or overestimated depending upon the patient size. With the aim to obtain complementary information, this work presents a method to estimate organ dose in the thoracic area of an anthropomorphic woman phantom in CT, by employing Gafchromic TM XR-QA2 and computational 3-D reconstruction methods. Lungs, heart, and spinal cord have been chosen as a dosimetry case study. XR-QA2 films have been placed between the phantom slabs in the thoracic area and scanned with a multi-slice CT scanner. 2-D and 3-D absorbed dose distributions for each organ have been analyzed, by means of a custom code in Matlab ® . Critical aspects in the dose distributions have been found for the spinal-cord case (serial organ) where the dose distribution is non normal and the maximum dose value is ∼ 30 mGy while a maximum dose value between 26 and 28 mGy has been measured elsewhere. K: Dosimetry concepts and apparatus; Computerized Tomography (CT) and Computed Radiography (CR); Medical-image reconstruction methods and algorithms, computer-aided diagnosis 1Corresponding author.

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3D dosimetry on Ru-106 plaque for ocular melanoma treatments

Cited by 20 publications

References 14 publications

3D image‐guided treatment planning for Ruthenium‐106 brachytherapy of choroidal melanomas

3D image‐guided treatment planning for Ruthenium‐106 brachytherapy of choroidal melanomas

A convex windowless extrapolation chamber to measure surface dose rate from ¹⁰⁶Ru/¹⁰⁶Rh episcleral plaques

3-D dose distribution for organ dose measurement in CT thoracic exams using Gafchromic™ XR-QA2 films

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3D dosimetry on Ru-106 plaque for ocular melanoma treatments

Cited by 20 publications

References 14 publications

3D image‐guided treatment planning for Ruthenium‐106 brachytherapy of choroidal melanomas

3D image‐guided treatment planning for Ruthenium‐106 brachytherapy of choroidal melanomas

A convex windowless extrapolation chamber to measure surface dose rate from 106Ru/106Rh episcleral plaques

3-D dose distribution for organ dose measurement in CT thoracic exams using Gafchromic™ XR-QA2 films

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A convex windowless extrapolation chamber to measure surface dose rate from ¹⁰⁶Ru/¹⁰⁶Rh episcleral plaques