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Chen XM, Xu CD, Zeng LP, Huang XT, Chen AQ, Liu L, Lin LW, Jia LC, Li H, Jiang XB. Analysis of Individualized Silicone Rubber Bolus Using Fan Beam Computed Tomography in Postmastectomy Radiotherapy: A Dosimetric Evaluation and Skin Acute Radiation Dermatitis Survey. Technol Cancer Res Treat 2024; 23:15330338241229367. [PMID: 38297814 PMCID: PMC10832424 DOI: 10.1177/15330338241229367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 11/28/2023] [Accepted: 01/03/2024] [Indexed: 02/02/2024] Open
Abstract
Objective: To investigate the dosimetric effects of using individualized silicone rubber (SR) bolus on the target area and organs at risk (OARs) during postmastectomy radiotherapy (PMRT), as well as evaluate skin acute radiation dermatitis (ARD). Methods: A retrospective study was performed on 30 patients with breast cancer. Each patient was prepared with an individualized SR bolus of 3 mm thickness. Fan-beam computed tomography (FBCT) was performed at the first and second fractions, and then once a week for a total of 5 times. Dosimetric metrics such as homogeneity index (HI), conformity index (CI), skin dose (SD), and OARs including the heart, lungs, and spinal cord were compared between the original plan and the FBCTs. The acute side effects were recorded. Results: In targets' dosimetric metrics, there were no significant differences in Dmean and V105% between planning computed tomography (CT) and actual treatments (P > .05), while the differences in D95%, V95%, HI, and CI were statistically significant (P < .05). In OARs, there were no significant differences between the Dmean, V5, and V20 of the affected lung, V5 of the heart and Dmax of the spinal cord (P > .05) except the V30 of affected lung, which was slightly lower than the planning CT (P < .05). In SD, both Dmax and Dmean in actual treatments were increased than plan A, and the difference was statistically significant (P < .05), while the skin-V20 and skin-V30 has no difference. Among the 30 patients, only one patient had no skin ARD, and 5 patients developed ARD of grade 2, while the remaining 24 patients were grade 1. Conclusion: The OR bolus showed good anastomoses and high interfraction reproducibility with the chest wall, and did not cause deformation during irradiation. It ensured accurate dose delivery of the target and OARs during the treatment, which may increase SD by over 101%. In this study, no cases of grade 3 skin ARD were observed. However, the potential of using OR bolus to reduce grade 1 and 2 skin ARD warrants further investigation with a larger sample size.
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Affiliation(s)
- Xue-mei Chen
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Chen-di Xu
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Li-ping Zeng
- Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong Province, P.R. China
| | - Xiao-tong Huang
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Ao-qiang Chen
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Lu Liu
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Liu-wen Lin
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
| | - Le-cheng Jia
- Shenzhen United Imaging Research Institute of Innovative Medical Equipment, Shenzhen, Guangdong Province, P.R. China
| | - Hua Li
- Shenzhen United Imaging Research Institute of Innovative Medical Equipment, Shenzhen, Guangdong Province, P.R. China
| | - Xiao-bo Jiang
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, P.R. China
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Keiper TD, Kisling K, Hua P, Manger RP. Comparing brass mesh to tissue equivalent bolus materials for volumetric modulated arc therapy chest wall irradiation. J Appl Clin Med Phys 2023; 24:e14054. [PMID: 37287131 PMCID: PMC10476985 DOI: 10.1002/acm2.14054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 03/08/2023] [Accepted: 04/01/2023] [Indexed: 06/09/2023] Open
Abstract
PURPOSE To compare the superficial dose when using brass mesh bolus (BMB), no bolus, or 3 mm tissue-equivalent bolus with a pseudo-flash volumetric modulated arc therapy (VMAT) breast treatment planning technique. METHODS Two different beam arrangements for right-sided irradiation and one beam arrangement for bilateral irradiation were planned on an inhomogeneous thorax phantom in accordance with our clinical practice for VMAT postmastectomy radiotherapy (PMRT). Plans were optimized using pseudo-flash and representative critical organ optimization structures were used to shape the dose. Plans were delivered without bolus, with 3 mm tissue-equivalent bolus (TEB), or with one-layer BMB. Optically stimulated luminescence dosimeter (OSLD) and radiochromic film measurements were taken and analyzed to determine the superficial dose in each case and the relative enhancement from the no bolus delivery. RESULTS Superficial dose measured with OSLDs was found to be 76.4 ± 4.5%, 103.0 ± 6.1%, and 98.1 ± 5.8% of prescription for no physical bolus (NB), TEB, and BMB, respectively. Superficial dose was observed to increase from lateral to medial points when measured with film. However, the relative increase in superficial dose from NB was consistent across the profile with an increase of 43 ± 2.1% and 34 ± 3.3% of prescription for TEB and BMB, respectively. The results are in good agreement with expectations from the literature and the experience with tangential radiotherapy. CONCLUSION Three millimeter TEB and one-layer BMB were shown to provide similar enhancement to the superficial dose compared to delivery without bolus. BMB, which does not significantly affect dose at depth and is more conformal to the patient surface, is an acceptable alternative to 3 mm TEB for chest wall PMRT patients treated with pseudo-flash PMRT.
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Affiliation(s)
- Timothy D. Keiper
- Department of Radiation Medicine and Applied SciencesMoores Cancer CenterUniversity of California San DiegoLa JollaCaliforniaUSA
- California Protons Cancer Therapy CenterSan DiegoCaliforniaUSA
| | - Kelly Kisling
- Department of Radiation Medicine and Applied SciencesMoores Cancer CenterUniversity of California San DiegoLa JollaCaliforniaUSA
| | - Patricia Hua
- Department of Radiation Medicine and Applied SciencesMoores Cancer CenterUniversity of California San DiegoLa JollaCaliforniaUSA
| | - Ryan P. Manger
- Department of Radiation Medicine and Applied SciencesMoores Cancer CenterUniversity of California San DiegoLa JollaCaliforniaUSA
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Miéville FA, Pitteloud N, Achard V, Lamanna G, Pisaturo O, Tercier PA, Allal AS. Post-mastectomy radiotherapy: Impact of bolus thickness and irradiation technique on skin dose. Z Med Phys 2023:S0939-3889(23)00041-7. [PMID: 37150728 DOI: 10.1016/j.zemedi.2023.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 02/27/2023] [Accepted: 03/08/2023] [Indexed: 05/09/2023]
Abstract
PURPOSE To determine 10 MV IMRT and VMAT based protocols with a daily bolus targeting a skin dose of 45 Gy in order to replace the 6 MV tangential fields with a 5 mm thick bolus on alternate days method for post-mastectomy radiotherapy. METHOD We measured the mean surface dose along the chest wall PTV as a function of different bolus thicknesses for sliding window IMRT and VMAT plans. We analyzed surface dose profiles and dose homogeneities and compared them to our standard 6 MV strategy. All measurements were performed on a thorax phantom with Gafchromic films while dosimetric plans were computed using the Acuros XB algorithm (Varian). RESULTS We obtained the best compromise between measured surface dose (mean dose and homogeneity) and skin toxicity threshold obtained from the literature using a daily 3 mm thick bolus. Mean surface doses were 91.4 ± 2.8% [85.7% - 95.4%] and 92.2 ± 2.3% [85.6% - 95.2%] of the prescribed dose with IMRT and VMAT techniques, respectively. Our standard 6 MV alternate days 5 mm thick bolus leads to 89.0 ± 3.7% [83.6% - 95.5%]. Mean dose differences between measured and TPS results were < 3.2% for depths as low as 2 mm depth. CONCLUSION 10 MV IMRT-based protocols with a daily 3 mm thick bolus produce a surface dose comparable to the standard 6 MV 5 mm thick bolus on alternate days method but with an improved surface dose homogeneity. This allows for a better control of skin toxicity and target volume coverage.
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Affiliation(s)
- Frédéric A Miéville
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland.
| | - Nicolas Pitteloud
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
| | - Vérane Achard
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
| | - Giorgio Lamanna
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
| | - Olivier Pisaturo
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
| | - Pierre-Alain Tercier
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
| | - Abdelkarim S Allal
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
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Sakai Y, Monzen H, Tamura M, Nakamura K, Nishimura Y. Double enhancement effect of a surface dose with tungsten rubber bolus in photon radiotherapy for keloids and superficial tumors. Phys Eng Sci Med 2023; 46:179-184. [PMID: 36484890 DOI: 10.1007/s13246-022-01208-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022]
Abstract
To clarify the dosimetric characteristics of a real-time variable shape rubber-containing tungsten (STR) bolus in a clinical plan and investigate the efficacy of the STR bolus in photon radiotherapy for keloids and other superficial tumors. A 5 mm gel bolus or 1 mm STR bolus was placed on a solid water phantom. Tangential irradiation was performed using a TomoTherapy Radixact-X9 and 6 MV X-ray flattening-filter-free beam, and the surface dose was measured with radiochromic film. Clinical-like plans (TomoDirect; TD and TomoHelical; TH) were applied with the same geometry and the dose distributions were measured. The increase in surface dose by the build-up effect and backscatter was 37.7% and 8.0% for the gel bolus, and 40.5% and 26.4% for the STR bolus, respectively. In the TD and TH plans, the increase in surface dose was 27.4% and 48.3% for the gel bolus, and 39.0% and 63.2% for the STR bolus. Similary, changes in the sagittal plane dose were - 3.9% and 6.1% for the gel bolus, and - 6.3% and 6.9% for the STR bolus. The STR bolus effectively increased the surface dose by the build-up effect and backscatter in photon radiotherapy for keloids and other superficial tumors.
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Affiliation(s)
- Yusuke Sakai
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Onohigashi, Osakasayama, Osaka, 589-8511, Japan
- Department of Radiotherapy, Takarazuka City Hospital, 4-5-1 Kohama, Takarazuka, Hyogo, 665-0827, Japan
| | - Hajime Monzen
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Onohigashi, Osakasayama, Osaka, 589-8511, Japan.
| | - Mikoto Tamura
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Onohigashi, Osakasayama, Osaka, 589-8511, Japan
| | - Kenji Nakamura
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Onohigashi, Osakasayama, Osaka, 589-8511, Japan
- Department of Radiotherapy, Takarazuka City Hospital, 4-5-1 Kohama, Takarazuka, Hyogo, 665-0827, Japan
| | - Yasumasa Nishimura
- Department of Radiation Oncology, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osakasayama, Osaka, 589-8511, Japan
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Lobo D, Banerjee S, Srinivas C, Athiyamaan MS, Reddy S, Sunny J, Ravichandran R, Kotian H, Prakash Saxena PU. Surface Dose Measurements in Chest Wall Postmastectomy Radiotherapy to Achieve Optimal Dose Delivery with 6 MV Photon Beam. J Med Phys 2021; 46:324-333. [PMID: 35261503 PMCID: PMC8853458 DOI: 10.4103/jmp.jmp_59_21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/23/2021] [Accepted: 07/08/2021] [Indexed: 11/04/2022] Open
Abstract
Aim A tissue-equivalent bolus of sufficient thickness is used to overcome build up effect to the chest wall region of postmastectomy radiotherapy (PMRT) patients with tangential technique till Radiation Therapy Oncology Group (RTOG) Grade 2 (dry desquamation) skin reaction is observed. The aim of this study is to optimize surface dose delivered to chest wall in three-dimensional radiotherapy using EBT3 film. Materials and Methods Measurements were conducted with calibrated EBT3 films with thorax phantom under "open beam, Superflab gel (0.5 cm) and brass bolus conditions to check correlation against TPS planned doses. Eighty-two patients who received 50 Gy in 25# were randomly assigned to Group A (Superflab 0.5 cm gel bolus for first 15 fractions followed by no bolus in remaining 10 fractions), Group B or Group C (Superflab 0.5 cm gel or single layer brass bolus, respectively, till reaching RTOG Grade 2 skin toxicity). Results Phantom measured and TPS calculated surface doses were within - 5.5%, 4.7%, and 8.6% under open beam, 0.5 cm gel, and single layer of brass bolus applications, respectively. The overall surface doses (OSD) were 80.1% ±2.9% (n = 28), 92.6% ±4.6% (n = 28), and 87.4% ±4.7% (n = 26) in Group A, B, and C, respectively. At the end of treatment, 7 out of 28; 13 out of 28; and 9 out of 26 patients developed Grade 2 skin toxicity having the OSD value of 83.0% ±1.6% (n = 7); 93.7% ±3.2% (n = 13); and 89.9% ±5.6% (n = 9) in Groups A, B, and C, respectively. At the 20th-23rd fraction, 2 out of 7; 6 out of 13; and 4 out of 9 patients in Groups A, B, and C developed a Grade 2 skin toxicity, while the remaining patients in each group developed at the end of treatment. Conclusions Our objective to estimate the occurrence of optimal dose limit for bolus applications in PMRT could be achieved using clinical EBT3 film dosimetry. This study ensured correct dose to scar area to protect cosmetic effects. This may also serve as quality assurance on optimal dose delivery for expected local control in these patients.
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Affiliation(s)
- Dilson Lobo
- Department of Radiation Oncology, Kasturba Medical College (A Constituent Institution of Manipal Academy of Higher Education), Mangalore, Karnataka, India
| | - Sourjya Banerjee
- Department of Radiation Oncology, Kasturba Medical College (A Constituent Institution of Manipal Academy of Higher Education), Mangalore, Karnataka, India
| | - Challapalli Srinivas
- Department of Radiation Oncology, Kasturba Medical College (A Constituent Institution of Manipal Academy of Higher Education), Mangalore, Karnataka, India
| | - M S Athiyamaan
- Department of Radiation Oncology, Kasturba Medical College (A Constituent Institution of Manipal Academy of Higher Education), Mangalore, Karnataka, India
| | - Shreyas Reddy
- Department of Radiation Oncology, Kasturba Medical College (A Constituent Institution of Manipal Academy of Higher Education), Mangalore, Karnataka, India
| | - Johan Sunny
- Department of Radiation Oncology, Kasturba Medical College (A Constituent Institution of Manipal Academy of Higher Education), Mangalore, Karnataka, India
| | - Ramamoorthy Ravichandran
- Department of Radiation Oncology, Kasturba Medical College (A Constituent Institution of Manipal Academy of Higher Education), Mangalore, Karnataka, India
| | - Himani Kotian
- Department of Community Medicine, Kasturba Medical College (A Constituent Institution of Manipal Academy of Higher Education), Mangalore, Karnataka, India
| | - P U Prakash Saxena
- Department of Radiation Oncology, Kasturba Medical College (A Constituent Institution of Manipal Academy of Higher Education), Mangalore, Karnataka, India
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Okuhata K, Tamura M, Monzen H, Nishimura Y. Dosimetric characteristics of a thin bolus made of variable shape tungsten rubber for photon radiotherapy. Phys Eng Sci Med 2021; 44:1249-1255. [PMID: 34542835 DOI: 10.1007/s13246-021-01059-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022]
Abstract
In this study, we aim to clarify the dosimetric characteristics of a real time variable shape rubber containing tungsten (STR) as a thin bolus in 6-MV photon radiotherapy. The percentage depth doses (PDDs) and lateral dose profiles (irradiation field = 10 × 10 cm2) in the water-equivalent phantom were measured and compared between no bolus, a commercial 5-mm gel bolus, and 0.5-, 1-, 2-, and 3-mm STR boluses. The characteristics of the PDDs were evaluated according to relative doses at 1 mm depth (D1mm) and depth of maximum dose (dmax). To determine the distance of the shift caused by the STR bolus, the PDD value at a depth of 100 mm without a bolus was obtained. For each STR thickness, the difference between the depth corresponding to this PDD value and 100 mm was calculated. The penumbra size and width of the 50% dose were evaluated using lateral dose profiles. The D1mm with no bolus, 5-mm gel bolus, and 0.5-, 1-, 2-, and 3-mm STR boluses were 47.6%, 91.5%, 78.2%, 86.6%, 89.3%, and 89.4%, respectively, and the respective dmax values were 15, 10, 13, 12, 11, and 10 mm. The shifting distance of the 0.5-, 1-, 2-, and 3-mm STR boluses were 2.7, 4.4, 4.8, and 4.9 mm, respectively. There were no differences for those in lateral dose profiles. The 1-mm-thick STR thin bolus shifted the depth dose profile by 4.4 mm and could be used as a customized bolus for photon radiotherapy.
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Affiliation(s)
- Katsuya Okuhata
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Onohigashi, Osakasayama, Osaka, 5898511, Japan.,Department of Radiology, Kansai Electric Power Hospital, 2-1-7 Fukushima, Fukushima-ku, Osaka-shi, Osaka, 5530003, Japan
| | - Mikoto Tamura
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Onohigashi, Osakasayama, Osaka, 5898511, Japan
| | - Hajime Monzen
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Onohigashi, Osakasayama, Osaka, 5898511, Japan.
| | - Yasumasa Nishimura
- Department of Radiation Oncology, Faculty of Medicine, Kindai University, 377-2 Onohigashi, Osakasayama, Osaka, 5898511, Japan
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Fiedler DA, Hoffman S, Roeske JC, Hentz CL, Small W, Kang H. Dosimetric assessment of brass mesh bolus and transparent polymer-gel type bolus for commonly used breast treatment delivery techniques. Med Dosim 2021; 46:e10-e14. [PMID: 33536152 DOI: 10.1016/j.meddos.2021.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/08/2020] [Accepted: 01/05/2021] [Indexed: 11/29/2022]
Abstract
We investigated skin dose enhancements of brass mesh bolus (BMB) and a recently developed transparent polymer-gel bolus (PGB) for clinically relevant breast treatment delivery techniques. The dose enhancement of the breast surface with BMB and PGB were compared to that of tissue-equivalent bolus. Three breast treatment plans were generated on CT scans of an anthropomorphic chest phantom: tangential step-and-shoot 3D conformal (3DCRT) planned using Field-in-Field (FiF), tangential sliding-window 3DCRT using Electronic Compensator (EC), and volumetric modulated arc therapy (VMAT). All plans were created using 6 MV photons and a prescription dose (Rx) of 180 cGy per fraction. Skin doses of all 3 plans were measured with radiochromic films, separately delivered in triplicate. Each plan was delivered to the phantom without bolus, and then with BMB (1 or 2 layers; 3 or 10 mm tissue-equivalent), PGB, and Superflab (3, 5, and 10 mm tissue-equivalent). Doses were determined by reading the radiochromic films with a flatbed scanner, and analyzing the images using a calibration curve for each specific batch. For all bolus types and plans, surface doses averaged over the 3 measurements were between 88.4% and 107.4% of Rx. Without bolus, average measured skin doses were between 51.2% and 64.2% of Rx. Skin doses with BMB and PGB were comparable to that with tissue-equivalent bolus. Over all 3 treatment delivery techniques, using BMB resulted in average skin doses of 92.8% and 102.1% for 1- and 2 layers, respectively, and using PGB results in average skin doses of 94.8%, 98.2%, and 99.7% for 3, 5, and 10-mm tissue-equivalent, respectively. The average measured skin doses with BMB and PGB agreed within ± 3% compared to the tissue-equivalent thickness bolus. We concluded that BMB and PGB are clinically equivalent in skin dose enhancement for breast treatment as the 3, 5, and 10 mm tissue-equivalent bolus.
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Affiliation(s)
- Derek A Fiedler
- Department of Radiation Oncology, Loyola University Medical Center, Maywood, IL, 60637 USA
| | - Sabrina Hoffman
- Department of Radiation Oncology, Loyola University Medical Center, Maywood, IL, 60637 USA
| | - John C Roeske
- Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardine Cancer Center, Loyola University Chicago, Maywood, IL, 60637 USA
| | - Courtney L Hentz
- Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardine Cancer Center, Loyola University Chicago, Maywood, IL, 60637 USA
| | - William Small
- Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardine Cancer Center, Loyola University Chicago, Maywood, IL, 60637 USA
| | - Hyejoo Kang
- Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardine Cancer Center, Loyola University Chicago, Maywood, IL, 60637 USA.
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eXaSkin: A novel high-density bolus for 6MV X-rays radiotherapy. Phys Med 2020; 80:42-46. [PMID: 33096418 DOI: 10.1016/j.ejmp.2020.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 08/04/2020] [Accepted: 09/01/2020] [Indexed: 11/21/2022] Open
Abstract
PURPOSE To evaluate eXaSkin, a novel high-density bolus alternative to commercial tissue-equivalent Superflab, for 6MV photon-beam radiotherapy. MATERIALS AND METHODS We delivered a 10 × 10 cm2 open field at 90° and head-and-neck clinical plan, generated with the volumetric modulated arc therapy (VMAT) technique, to an anthropomorphic phantom in three scenarios: with no bolus on the phantom's surface, with Superflab, and with eXaSkin. In each scenario, we measured dose to a central planning target volume (PTV) in the nasopharynx region with an ionization chamber, and we measured dose to the skin, at three different positions within the vicinity of a neck lymph node PTV, with MOSkin™, a semiconductor dosimeter. Measurements were compared against calculations with the treatment planning system (TPS). RESULTS For the static field, MOSkin results underneath the eXaSkin were in agreement with calculations to within 1.22%; for VMAT, to within 5.68%. Underneath Superflab, those values were 3.36% and 11.66%. The inferior agreement can be explained by suboptimal adherence of Superflab to the phantom's surface as well as difficulties in accurately reproducing its placement between imaging and treatment session. In all scenarios, dose measured at the central target agreed to within 1% with calculations. CONCLUSIONS eXaSkin was shown to have superior adaptation to the phantom's surface, producing minimal air gaps between the skin surface and bolus, allowing for accurate positioning and reproducibility of set-up conditions. eXaSkin with its high density material provides sufficient build-up to achieve full skin dose with less material thickness than Superflab.
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Verification using in vivo optically stimulated luminescent dosimetry of the predicted skin surface dose in patients receiving postmastectomy radiotherapy. Med Dosim 2020; 46:e1-e6. [PMID: 33941320 DOI: 10.1016/j.meddos.2020.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/14/2020] [Accepted: 10/01/2020] [Indexed: 11/21/2022]
Abstract
The purpose of this study was to evaluate whether dose to the skin surface underneath bolus, was accurately predicted by a 3D treatment planning system (TPS) in patients receiving 50 Gy/25# postmastectomy radiotherapy (PMRT) using optically stimulated luminescent dosimetry (OSLD) for verification. In vivo dosimetry using OSLDs was performed in 20 consecutive patients receiving PMRT. An array of 9 OSLDs were applied to the chest wall or neobreast in a grid arrangement. Dosimetry data were recorded on 3 separate treatment fractions, averaged, and extrapolated to 25 fractions. On the 3D TPS, the predicted dose was calculated using the departmental planning algorithm at points corresponding to the OSLDs. The mean within patient difference between the planned and measured dose at each of the 9 points was calculated and Bland-Altman limits of agreement used to quantify the extent of agreement. Paired t-tests were used to test for evidence of systematic bias at each point. The coefficient of variation of the 3 OSLD readings per patient at each of the 9 points was low for 8 points (≤4.4%) demonstrating comparable dose received per fraction at these points. The mean ratio between the in vivo measured extrapolated OSLD (IVME OSLD) dose and the planned TPS dose ranged between 0.97 and 0.99 across all points (standard deviation range 0.05 to 0.08). The mean within patient difference between the IVME OSLD and planned TPS was <1 Gy at 7 of the 9 points and the t-test for evidence of systematic bias was significant (p = 0.03) at only 1 of the 9 points. Our commercially available 3D TPS closely predicted PMRT skin surface dose underneath bolus as verified by OSLDs. At all sites, the average ratio of delivered to predicted dose was >0.97 but <1. This practical and feasible OSLD assessment of only 3 of 25 fractions facilitates quality assurance of a TPS in predicting skin surface dose under bolus.
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Jamalludin Z, Jong WL, Ho GF, Rosenfeld AB, Ung NM. In vivo dosimetry using MOSkin detector during Cobalt-60 high-dose-rate (HDR) brachytherapy of skin cancer. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2019; 42:1099-1107. [PMID: 31650362 DOI: 10.1007/s13246-019-00809-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 10/16/2019] [Indexed: 01/10/2023]
Abstract
The MOSkin, a metal-oxide semiconductor field-effect transistor based detector, is suitable for evaluating skin dose due to its water equivalent depth (WED) of 0.07 mm. This study evaluates doses received by target area and unavoidable normal skin during a the case of skin brachytherapy. The MOSkin was evaluated for its feasibility as detector of choice for in vivo dosimetry during skin brachytherapy. A high-dose rate Cobalt-60 brachytherapy source was administered to the tumour located at the medial aspect of the right arm, complicated with huge lymphedema thus limiting the arm motion. The source was positioned in the middle of patients' right arm with supine, hands down position. A 5 mm lead and 5 mm bolus were sandwiched between the medial aspect of the arm and lateral chest to reduce skin dose to the chest. Two calibrated MOSkin detectors were placed on the target and normal skin area for five treatment sessions for in vivo dose monitoring. The mean dose to the target area ranged between 19.9 and 21.1 Gy and was higher in comparison with the calculated dose due to contribution of backscattered dose from lead. The mean measured dose at normal skin chest area was 1.6 Gy (1.3-1.9 Gy), less than 2 Gy per fraction. Total dose in EQD2 received by chest skin was much lower than the recommended skin tolerance. The MOSkin detector presents a reliable real-time dose measurement. This study has confirmed the applicability of the MOSkin detector in monitoring skin dose during brachytherapy treatment due to its small sensitive volume and WED 0.07 mm.
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Affiliation(s)
- Z Jamalludin
- Medical Physics Unit, University of Malaya Medical Centre, 59100, Kuala Lumpur, Malaysia
- Department of Clinical Oncology, University of Malaya Medical Centre, 59100, Kuala Lumpur, Malaysia
- Clinical Oncology Unit, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - W L Jong
- Department of Clinical Oncology, University of Malaya Medical Centre, 59100, Kuala Lumpur, Malaysia
- Clinical Oncology Unit, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - G F Ho
- Department of Clinical Oncology, University of Malaya Medical Centre, 59100, Kuala Lumpur, Malaysia
- Clinical Oncology Unit, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - A B Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia
| | - N M Ung
- Department of Clinical Oncology, University of Malaya Medical Centre, 59100, Kuala Lumpur, Malaysia.
- Clinical Oncology Unit, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia.
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