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Fuentealba M, Ferreira A, Salgado A, Vergara C, Díez S, Santibáñez M. An Optimized Method for Evaluating the Potential Gd-Nanoparticle Dose Enhancement Produced by Electronic Brachytherapy. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:430. [PMID: 38470761 DOI: 10.3390/nano14050430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/08/2024] [Accepted: 01/11/2024] [Indexed: 03/14/2024]
Abstract
This work reports an optimized method to experimentally quantify the Gd-nanoparticle dose enhancement generated by electronic brachytherapy. The dose enhancement was evaluated considering energy beams of 50 kVp and 70 kVp, determining the Gd-nanoparticle concentration ranges that would optimize the process for each energy. The evaluation was performed using delaminated radiochromic films and a Poly(methyl methacrylate) (PMMA) phantom covered on one side by a thin 2.5 μm Mylar filter acting as an interface between the region with Gd suspension and the radiosensitive film substrate. The results for the 70 kVp beam quality showed dose increments of 6±6%, 22±7%, and 9±7% at different concentrations of 10, 20, and 30 mg/mL, respectively, verifying the competitive mechanisms of enhancement and attenuation. For the 50 kVp beam quality, no increase in dose was recorded for the concentrations studied, indicating that the major contribution to enhancement is from the K-edge interaction. In order to separate the contributions of attenuation and enhancement to the total dose, measurements were replicated with a 12 μm Mylar filter, obtaining a dose enhancement attributable to the K-edge of 29±7% and 34±7% at 20 and 30 mg/mL, respectively, evidencing a significant additional dose proportional to the Gd concentration.
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Affiliation(s)
- Melani Fuentealba
- Departamento de Cs. Físicas, Universidad de La Frontera, Temuco 4811230, Chile
- Laboratorio de Radiaciones Ionizantes, Universidad de La Frontera, Temuco 4811230, Chile
- Departamento de Fisiología, Universitat de Valencia, 46010 Valencia, Spain
| | - Alejandro Ferreira
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago 7510602, Chile
| | | | - Christopher Vergara
- Departamento de Cs. Físicas, Universidad de La Frontera, Temuco 4811230, Chile
- Laboratorio de Radiaciones Ionizantes, Universidad de La Frontera, Temuco 4811230, Chile
| | - Sergio Díez
- Departamento de Fisiología, Universitat de Valencia, 46010 Valencia, Spain
- Medical Physics Department, Hospital Clínico Universitario de Valencia, 46010 Valencia, Spain
| | - Mauricio Santibáñez
- Departamento de Cs. Físicas, Universidad de La Frontera, Temuco 4811230, Chile
- Laboratorio de Radiaciones Ionizantes, Universidad de La Frontera, Temuco 4811230, Chile
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Insley B, Bartkoski D, Balter P, Prajapati S, Tailor R, Salehpour M, Jaffray D. Proof-of-concept for a thin conical X-ray target optimized for intensity and directionality for use in a carbon nanotube-based compact X-ray tube. Med Phys 2024; 51:447-463. [PMID: 37947472 DOI: 10.1002/mp.16835] [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: 05/02/2023] [Revised: 10/20/2023] [Accepted: 10/29/2023] [Indexed: 11/12/2023] Open
Abstract
BACKGROUND Carbon nanotube-based cold cathode technology has revolutionized the miniaturization of X-ray tubes. However, current applications of these devices required optimization for large, uniform fields with low intensity. PURPOSE This work investigated the feasibility and radiological characteristics of a novel conical X-ray target optimized for high intensity and high directionality to be used in a compact X-ray tube. METHODS The proposed device uses an ultrathin, conical tungsten-diamond target that exhibits significant heat loading while maintaining a small focal spot size and promoting forward-directedness of the X-ray field through preferential attenuation of oblique-angled photons. The electrostatic and thermal properties of the theoretical tube were calculated and analyzed using COMSOL Multiphysics software. The production, transport, and calculation of radiological properties associated with the resultant X-ray field were performed using the Geant4 toolkit via its wrapper, TOPAS. RESULTS Heat transfer analysis of this X-ray tube demonstrated the feasibility of a 200-kV electron beam bombarding the proposed target at a maximum current of 100 mA using a 1-ms symmetric duty cycle. The cathode of the X-ray tube was designed to be segmented into nine switchable electrical segments for modulation of the focal spot size from 0.4- to 10.8-mm. After importing the COMSOL-derived electron beam into TOPAS for X-ray production simulations, radiological analysis of the resultant field demonstrated high levels of intrinsic beam collimation while maintaining high intensity. A maximum dose rate of 17,887 cGy/min was calculated for 1-mm depth in water at 7-cm distance. CONCLUSIONS The proposed X-ray tube design can create highly directional X-ray fields with superior fluence compared to that of current commercial X-ray tubes of comparable size.
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Affiliation(s)
- Ben Insley
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Dirk Bartkoski
- Empyrean Medical Systems, Inc., 950 Peninsula Corp Cir, Boca Raton, USA
| | - Peter Balter
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Surendra Prajapati
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Ramesh Tailor
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Mohammad Salehpour
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - David Jaffray
- Division of Office of the Sr. VP & Chief Technology and Digital Officer, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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Lozares-Cordero S, Bermejo-Barbanoj C, Badías-Herbera A, Ibáñez-Carreras R, Ligorred-Padilla L, Ponce-Ortega JM, González-Pérez V, Gandía-Martínez A, Font-Gómez JA, Blas-Borroy O, González-Ibáñez D. An open-source development based on photogrammetry for a real-time IORT treatment planning system. Phys Med 2023; 112:102622. [PMID: 37331081 DOI: 10.1016/j.ejmp.2023.102622] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 06/02/2023] [Accepted: 06/06/2023] [Indexed: 06/20/2023] Open
Abstract
PURPOSE This study presents a treatment planning system for intraoperative low-energy photon radiotherapy based on photogrammetry from real images of the surgical site taken in the operating room. MATERIAL AND METHODS The study population comprised 15 patients with soft-tissue sarcoma. The system obtains the images of the area to be irradiated with a smartphone or tablet, so that the absorbed doses in the tissue can be calculated from the reconstruction without the need for computed tomography. The system was commissioned using 3D printing of the reconstructions of the tumor beds. The absorbed doses at various points were verified using radiochromic films that were suitably calibrated for the corresponding energy and beam quality. RESULTS The average reconstruction time of the 3D model from the video sequence in the 15 patients was 229,6±7,0 s. The entire procedure, including video capture, reconstruction, planning, and dose calculation was 520,6±39,9 s. Absorbed doses were measured on the 3D printed model with radiochromic film, the differences between these measurements and those calculated by the treatment planning system were 1.4% at the applicator surface, 2.6% at 1 cm, 3.9% at 2 cm and 6.2% at 3 cm. CONCLUSIONS The study shows a photogrammetry-based low-energy photon IORT planning system, capable of obtaining real-time images inside the operating room, immediately after removal of the tumor and immediately before irradiation. The system was commissioned with radiochromic films measurements in 3D-printed model.
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Affiliation(s)
- Sergio Lozares-Cordero
- Physics and Radiation Protection Department, Miguel Servet University Hospital, Zaragoza, Spain.
| | | | - Alberto Badías-Herbera
- Higher Technical School of Industrial Engineering, Polytechnic University of Madrid, Spain
| | | | - Luis Ligorred-Padilla
- Esophagogastric Surgery and Sarcoma Unit (Department of General and Gastrointestinal Surgery), Miguel Servet University Hospital, Zaragoza, Spain
| | | | | | | | - José Antonio Font-Gómez
- Physics and Radiation Protection Department, Miguel Servet University Hospital, Zaragoza, Spain
| | - Olga Blas-Borroy
- Engineering and Maintenance Service, Miguel Servet University Hospital, Zaragoza, Spain
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Feasibility of electronic brachytherapy in cervix cancer-A dosimetric comparison of different brachytherapy techniques. Brachytherapy 2022; 21:389-396. [PMID: 35246391 DOI: 10.1016/j.brachy.2022.01.006] [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: 10/20/2021] [Revised: 01/03/2022] [Accepted: 01/04/2022] [Indexed: 11/23/2022]
Abstract
INTRODUCTION This study analyzes cases in which electronic brachytherapy (eBT) led to acceptable treatment plans in cervical cancer. Findings were compared with dosimetry values obtained in 192Ir-based treatments according to the high-risk clinical target volume (HR-CTV) and the disease stage. MATERIAL AND METHODS We retrospectively analyzed 48 patients with cervical cancer from two centers. The patients were treated with 192Ir based on MRI. It was possible to use interstitial needles via an Utrecht-type applicator. Dosimetry was simulated using eBT and the parameters D90 and D98 (HR-CTV) and D2cc, D1cc, and D0.1cc (bladder, rectum, and sigmoid colon) were evaluated. The Mann-Whitney U test was used for comparison. The overall cohort of patients was analyzed, as were the sub-cohorts based on stage (FIGO stages I+IIA, IIB and III-IV). Finally, the dosimetry of the eBT plans was evaluated, and the plans obtained were classified as "good", "acceptable", or "poor". RESULTS Statistically significant differences were found between the eBT and 192Ir plans for D98 (HR-CTV), D1cc and D0.1cc (bladder), and D1cc and D0.1cc (sigmoid colon). A total of 31 cases (64.6%) were considered good, seven (14.6%) were considered acceptable, and 10 (20.8%) were considered poor. For volumes <30 cc, all the plans were good or acceptable; for volumes >30 cc, 54.3% were good, and 71.4% were good or acceptable. By stage, eBT plans for patients with stage IB-IIA disease were good in 100%, whereas those for patients with stage IIB were good in 70.6% and III-IV disease were good in 50%. CONCLUSIONS eBT provides appropriate dosimetry for treatment of cervical cancer in selected cases.
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Lozares S, Font JA, Gandía A, Campos A, Flamarique S, Ibáñez R, Villa D, Alba V, Jiménez S, Hernández M, Casamayor C, Vicente I, Hernando E, Rubio P. In vivo dosimetry in low-voltage IORT breast treatments with XR-RV3 radiochromic film. Phys Med 2021; 81:173-181. [PMID: 33465753 DOI: 10.1016/j.ejmp.2020.12.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 12/12/2020] [Accepted: 12/16/2020] [Indexed: 12/30/2022] Open
Abstract
PURPOSE The objectives of the study were to establish a procedure for in vivo film-based dosimetry for intraoperative radiotherapy (IORT), evaluate the typical doses delivered to organs at risk, and verify the dose prescription. MATERIALS AND METHODS In vivo dose measurements were studied using XR-RV3 radiochromic films in 30 patients with breast cancer undergoing IORT using the Axxent® device (Xoft Inc.). The stability of the radiochromic films in the energy ranges used was verified by taking measurements at different depths. The stability of the scanner response was tested, and 5 different calibration curves were constructed for different beam qualities. Six pieces of film were placed in each of the 30 patients. All the pieces were correctly sterilized and checked to ensure that the process did not affect the outcome. All calibration and dose measurements were analyzed using the Radiochromic.com software application. RESULTS The doses were measured for 30 patients. The doses in contact with the applicator (prescription zone) were 19.8 ± 0.9 Gy. In the skin areas, the doses were as follows: 1-2 cm from the applicator, 1.86 ± 0.77 Gy; 2-5 cm, 0.73 ± 0.14 Gy; and greater than 5 cm, 0.28 ± 0.17 Gy. The dose delivered to the pectoral muscle (tungsten shielding disc) was 0.51 ± 0.27 Gy. CONCLUSIONS The study demonstrated the viability of XR-RV3 films for in vivo dose measurement in the dose and energy ranges applied in a complex procedure, such as breast IORT. The doses in organs at risk were far below the tolerances for cases such as those studied.
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Affiliation(s)
- Sergio Lozares
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain.
| | - Jose A Font
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Almudena Gandía
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Arantxa Campos
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Sonia Flamarique
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Reyes Ibáñez
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - David Villa
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Verónica Alba
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Sara Jiménez
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Mónica Hernández
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Carmen Casamayor
- Endocrine, Bariatric and Breast Surgery Unit. General and Digestive Surgery Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Isabel Vicente
- Breast Unit. Gynaecology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Ernesto Hernando
- Endocrine, Bariatric and Breast Surgery Unit. General and Digestive Surgery Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Patricia Rubio
- Breast Unit. Gynaecology Department. Miguel Servet University Hospital Zaragoza, Spain
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Lozares-Cordero S, Font-Gómez JA, Gandía‐Martínez A, Miranda‐Burgos A, Méndez‐Villamón A, Villa‐Gazulla D, Alba‐Escorihuela V, Jiménez‐Puertas S, González‐Pérez V. Treatment of cervical cancer with electronic brachytherapy. J Appl Clin Med Phys 2019; 20:78-86. [PMID: 31183970 PMCID: PMC6612687 DOI: 10.1002/acm2.12657] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 05/09/2019] [Accepted: 05/20/2019] [Indexed: 11/09/2022] Open
Abstract
PURPOSE We report the first cervical cancer cases treated with interstitial electronic brachytherapy (eBT) at our hospital and compare them with plans made with high-dose-rate interstitial brachytherapy based on Ir192 (HDR-BT). MATERIALS AND METHODS Eight patients with cervical cancer were treated with the Axxent eBT device (Xoft, Inc.). Planning was with magnetic resonance imaging and computed tomography following the recommendations of the EMBRACE protocol. The dosimetry parameters of organs at risk (OAR) were evaluated for the bladder, rectum, and sigmoid colon (D2cc, D1cc, and D0.1cc). In addition, the V150 and V200 of irradiated tissue were compared for both eBT and HDR-BT. All patients received intensity-modulated external beam radiation therapy with a regimen of 23 sessions of 2 Gy followed by four sessions of 7 Gy of eBT performed over 2 weeks (two sessions followed by another two sessions a week later) following the EMBRACE recommendations. Each of the eight patients was followed to assess acute toxicity associated with treatment. RESULTS The doses reaching OAR for eBT plans were lower than for HDR-BT plans. As for acute toxicity associated with eBT, very few cases of mucositis were detected. No cases of rectal toxicity and one case with grade 1 urinary toxicity were detected. The results at 1 month are equally good, and no relapses have occurred to date. CONCLUSIONS The first results of treatment with the Axxent eBT device are promising, as no recurrences have been observed and toxicity is very low. eBT is a good alternative for treating cervical cancer in centers without access to conventional HDR.
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Affiliation(s)
- Sergio Lozares-Cordero
- Department of Physics and Radiation ProtectionMiguel Servet University HospitalZaragozaSpain
| | - José Antonio Font-Gómez
- Department of Physics and Radiation ProtectionMiguel Servet University HospitalZaragozaSpain
| | | | | | | | - David Villa‐Gazulla
- Department of Physics and Radiation ProtectionMiguel Servet University HospitalZaragozaSpain
| | | | - Sara Jiménez‐Puertas
- Department of Physics and Radiation ProtectionMiguel Servet University HospitalZaragozaSpain
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Postoperative endometrial cancer treatments with electronic brachytherapy source. JOURNAL OF RADIOTHERAPY IN PRACTICE 2018. [DOI: 10.1017/s1460396918000353] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractPurposeThis study is a dosimetric and acute toxicity comparison of endometrial cancer patients treated with either Axxent (Xoft, Inc., San José, CA, USA) electronic and interstitial brachytherapy versus interstitial high dose rate brachytherapy (HDRBT).Materials and MethodsBetween 2015 and 2017, 94 patients with postoperative endometrial cancer were treated in our centre with the Axxent electronic brachytherapy (eBT) system. The V150 and V200 are evaluated prospectively for each plan. The mean age of patients was 65.9 years (age range 33–84 years), with different tumour staging. Of the 94 patients, 37 received exclusive adjuvant brachytherapy (25 Gy in five sessions); the remaining patients received external beam radiotherapy (EBRT) with a regimen of 23 sessions of 2 Gy each to the entire pelvis, followed by eBT (15 Gy in three sessions). Additionally, the absorbed doses received by the organs at risk (OAR), urinary bladder, rectum and sigmoid colon were compared with HDRBT plans, evaluating D2cc, V50% and V35%. Median follow-up was done for each of the 94 patients to assess the toxicity of the treatment: vaginal mucosa toxicity, rectal and urinary toxicity; and results are presented for acute toxicity, toxicity at 1 month after the end of treatment and follow-up after 12 months for a portion of patients according to the Radiation Therapy Oncology Group (RTOG) toxicity criteria.ResultsThe doses in OAR for eBT plans were lower than that for HDRBT plans, both Ir-192 and Co-60 plans, whose doses were similar. The dose in bladder with eBT was 63.8% of the prescribed dose for D2cc versus 70.1% for HDRBT Ir-192, for V50% was 7.2% versus 12.7% and for V35% was 15.2% versus 28.2%. In rectum the D2cc was 61.2% versus 68.4%, for V50% was 7.9% versus 14.3% and for V35% was 16.7% versus 32%. Results demonstrated lower doses to OAR in all eBT plans. Acute toxicity in eBT was very low in cases of mucositis, with only one case of toxicity greater than grade 1, rectal toxicity and urinary toxicity; results at 1 month are equally good, toxicity symptoms disappeared and no relapses have occurred to date.ConclusionsThe results of treatment with the Axxent eBT unit for 94 patients are very good, as no recurrence has been observed and the toxicity of the treatment is very low. The increase in V150 and V200 has not produced an increase in vaginal mucosa toxicity, and the doses in the OAR are lower than in the plans implemented for HDRBT with Ir-192 or Co-60. eBT is a good alternative to treat endometrial cancer in centres without conventional HDR availability. To date, there are limited published studies reporting on outcomes from patients treated with eBT.
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Feasibility of dose enhancement assessment: Preliminary results by means of Gd-infused polymer gel dosimeter and Monte Carlo study. Appl Radiat Isot 2018; 141:210-218. [PMID: 29678602 DOI: 10.1016/j.apradiso.2018.04.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 03/22/2018] [Accepted: 04/05/2018] [Indexed: 11/23/2022]
Abstract
This work reports the experimental development of an integral Gd-infused dosimeter suitable for Gd dose enhancement assessment along with Monte Carlo simulations applied to determine the dose enhancement by radioactive and X-ray sources of interest in conventional and electronic brachytherapy. In this context, capability to elaborate a stable and reliable Gd-infused dosimeter was the first goal aimed at direct and accurate measurements of dose enhancement due to Gd presence. Dose-response was characterized for standard and Gd-infused PAGAT polymer gel dosimeters by means of optical transmission/absorbance. The developed Gd-infused PAGAT dosimeters demonstrated to be stable presenting similar dose-response as standard PAGAT within a linear trend up to 13 Gy along with good post-irradiation readout stability verified at 24 and 48 h. Additionally, dose enhancement was evaluated for Gd-infused PAGAT dosimeters by means of Monte Carlo (PENELOPE) simulations considering scenarios for isotopic and X-ray generator sources. The obtained results demonstrated the feasibility of obtaining a maximum enhancement around of (14 ± 1)% for 192Ir source and an average enhancement of (70 ± 13)% for 241Am. However, dose enhancement up to (267 ± 18)% may be achieved if suitable filtering is added to the 241Am source. On the other hand, optimized X-ray spectra may attain dose enhancements up to (253 ± 22) %, which constitutes a promising future alternative for replacing radioactive sources by implementing electronic brachytherapy achieving high dose levels.
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Dadkhah H, Kim Y, Wu X, Flynn RT. Multihelix rotating shield brachytherapy for cervical cancer. Med Phys 2016; 42:6579-88. [PMID: 26520749 DOI: 10.1118/1.4933244] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
PURPOSE To present a novel brachytherapy technique, called multihelix rotating shield brachytherapy (H-RSBT), for the precise angular and linear positioning of a partial shield in a curved applicator. H-RSBT mechanically enables the dose delivery using only linear translational motion of the radiation source/shield combination. The previously proposed approach of serial rotating shield brachytherapy (S-RSBT), in which the partial shield is rotated to several angular positions at each source dwell position [W. Yang et al., "Rotating-shield brachytherapy for cervical cancer," Phys. Med. Biol. 58, 3931-3941 (2013)], is mechanically challenging to implement in a curved applicator, and H-RSBT is proposed as a feasible solution. METHODS A Henschke-type applicator, designed for an electronic brachytherapy source (Xoft Axxent™) and a 0.5 mm thick tungsten partial shield with 180° or 45° azimuthal emission angles and 116° asymmetric zenith angle, is proposed. The interior wall of the applicator contains six evenly spaced helical keyways that rigidly define the emission direction of the partial radiation shield as a function of depth in the applicator. The shield contains three uniformly distributed protruding keys on its exterior wall and is attached to the source such that it rotates freely, thus longitudinal translational motion of the source is transferred to rotational motion of the shield. S-RSBT and H-RSBT treatment plans with 180° and 45° azimuthal emission angles were generated for five cervical cancer patients with a diverse range of high-risk target volume (HR-CTV) shapes and applicator positions. For each patient, the total number of emission angles was held nearly constant for S-RSBT and H-RSBT by using dwell positions separated by 5 and 1.7 mm, respectively, and emission directions separated by 22.5° and 60°, respectively. Treatment delivery time and tumor coverage (D90 of HR-CTV) were the two metrics used as the basis for evaluation and comparison. For all the generated treatment plans, the D90 of the HR-CTV in units of equivalent dose in 2 Gy fractions (EQD2) was escalated until the D2cc (minimum dose to hottest 2 cm3) tolerance of either the bladder (90 Gy3), rectum (75 Gy3), or sigmoid colon (75 Gy3) was reached. RESULTS Treatment time changed for H-RSBT versus S-RSBT by -7.62% to 1.17% with an average change of -2.8%, thus H-RSBT treatments times tended to be shorter than for S-RSBT. The HR-CTV D90 also changed by -2.7% to 2.38% with an average of -0.65%. CONCLUSIONS H-RSBT is a mechanically feasible delivery technique for use in the curved applicators needed for cervical cancer brachytherapy. S-RSBT and H-RSBT were clinically equivalent for all patients considered, with the H-RSBT technique tending to require less time for delivery.
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Affiliation(s)
- Hossein Dadkhah
- Department of Biomedical Engineering, University of Iowa, 1402 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242
| | - Yusung Kim
- Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242
| | - Xiaodong Wu
- Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 and Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242
| | - Ryan T Flynn
- Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242
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Stoll A, van Oepen A, Friebe M. Intraoperative delivery of cell-killing boost radiation – a review of current and future methods. MINIM INVASIV THER 2016; 25:176-87. [DOI: 10.3109/13645706.2016.1173563] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Buge F, Chiavassa S, Hervé C, Rigaud J, Delpon G, Supiot S. Preclinical Evaluation of Intraoperative Low-Energy Photon Radiotherapy Using Spherical Applicators in Locally Advanced Prostate Cancer. Front Oncol 2015; 5:204. [PMID: 26442216 PMCID: PMC4569969 DOI: 10.3389/fonc.2015.00204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 09/01/2015] [Indexed: 11/13/2022] Open
Abstract
Background Surgery plus adjuvant radiotherapy is standard care for locally advanced prostate cancer (stage pT3R1). Intraoperative low-energy photon radiotherapy offers several advantages over external beam radiotherapy, and several systems are now available for its delivery, using spherical applicators, which require only limited shielding. The aim of this study was to evaluate the feasibility of this technique for the prostate bed. Materials and methods Applicators were assessed using MRI image data and cadaveric dissection. In cadavers, targeted tissues, defined as a urethral section, both neurovascular bundle sections, the bladder neck and the beds of the seminal vesicles, were marked with metallic surgical clips. Distances between clips and applicator were measured using CT. A dosimetric study of the application of 12 Gy at 5 mm depth was performed using CT images of prostatectomized cadavers. Results Using MRI images from 34 prostate cancer patients, we showed that the ideal applicator diameter ranges from 45 to 70 mm. Using applicators of different sizes to encompass the prostate bed in nine cadavers, we showed that the distance between target tissues and applicator was <2 mm for all target tissues except the upper extremity of the seminal vesicles (19 mm). Dosimetric study showed a good dose distribution in all target tissues in contact with the applicator, with a low probability of rectum and bladder complication. Conclusion Intraoperative radiotherapy of the prostate bed is feasible, with good coverage of targeted tissues. Clinical study of safety and efficacy is now required.
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Affiliation(s)
- François Buge
- Department of Urology, Centre Hospitalier Universitaire de Nantes , Nantes , France
| | - Sophie Chiavassa
- Centre de Recherche en Cancérologie Nantes-Angers, INSERM U892, Université de Nantes , Nantes , France ; Department of Medical Physics, Institut de Cancérologie de l'Ouest , St-Herblain , France
| | - Chloé Hervé
- Centre de Recherche en Cancérologie Nantes-Angers, INSERM U892, Université de Nantes , Nantes , France
| | - Jérôme Rigaud
- Department of Urology, Centre Hospitalier Universitaire de Nantes , Nantes , France
| | - Grégory Delpon
- Centre de Recherche en Cancérologie Nantes-Angers, INSERM U892, Université de Nantes , Nantes , France ; Department of Medical Physics, Institut de Cancérologie de l'Ouest , St-Herblain , France
| | - Stéphane Supiot
- Centre de Recherche en Cancérologie Nantes-Angers, INSERM U892, Université de Nantes , Nantes , France ; Department of Radiation Oncology, Institut de Cancérologie de l'Ouest , St-Herblain , France
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Abbas H, Mahato DN, Satti J, MacDonald CA. Measurements and simulations of focused beam for orthovoltage therapy. Med Phys 2014; 41:041702. [PMID: 24694122 DOI: 10.1118/1.4866224] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Megavoltage photon beams are typically used for therapy because of their skin-sparing effect. However, a focused low-energy x-ray beam would also be skin sparing, and would have a higher dose concentration at the focal spot. Such a beam can be produced with polycapillary optics. MCNP5 was used to model dose profiles for a scanned focused beam, using measured beam parameters. The potential of low energy focused x-ray beams for radiation therapy was assessed. METHODS A polycapillary optic was used to focus the x-ray beam from a tungsten source. The optic was characterized and measurements were performed at 50 kV. PMMA blocks of varying thicknesses were placed between optic and the focal spot to observe any variation in the focusing of the beam after passing through the tissue-equivalent material. The measured energy spectrum was used to model the focused beam in MCNP5. A source card (SDEF) in MCNP5 was used to simulate the converging x-ray beam. Dose calculations were performed inside a breast tissue phantom. RESULTS The measured focal spot size for the polycapillary optic was 0.2 mm with a depth of field of 5 mm. The measured focal spot remained unchanged through 40 mm of phantom thickness. The calculated depth dose curve inside the breast tissue showed a dose peak several centimeters below the skin with a sharp dose fall off around the focus. The percent dose falls below 10% within 5 mm of the focus. It was shown that rotating the optic during scanning would preserve the skin-sparing effect of the focused beam. CONCLUSIONS Low energy focused x-ray beams could be used to irradiate tumors inside soft tissue within 5 cm of the surface.
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Affiliation(s)
- Hassan Abbas
- Department of Therapeutic Radiology, Yale University School of Medicine, Yale-New Haven Hospital, New Haven, 344 Lane Street Hamden, Connecticut 06514
| | - Dip N Mahato
- Intel Corporation, Mail-Stop RA3-410, 2501 NW 229th Avenue, Hillsboro, Oregon 97124
| | - Jahangir Satti
- Department of Radiation Oncology, Albany Medical Center, 43 New Scotland Avenue, Albany, New York 12208
| | - C A MacDonald
- Department of Physics, University at Albany, SUNY, 1400 Washington Avenue, Albany, New York 12222
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Radiobiological rationale and clinical implications of hypofractionated radiation therapy. Cancer Radiother 2011; 15:221-9. [PMID: 21514198 DOI: 10.1016/j.canrad.2010.12.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2010] [Revised: 11/18/2010] [Accepted: 12/21/2010] [Indexed: 11/23/2022]
Abstract
Recent clinical trials of hypofractionated radiation treatment have provided critical insights into the safety and efficacy of hypofractionation. However, there remains much controversy in the field, both at the level of clinical practice and in our understanding of the underlying radiobiological mechanisms. In this article, we review the clinical literature on hypofractionated radiation treatment for breast, prostate, and other malignancies. We highlight several ongoing clinical trials that compare outcomes of a hypofractionated approach versus those obtained with a conventional approach. Lastly, we outline some of the preclinical and clinical evidence that argue in favor of differential radiobiological mechanisms underlying hypofractionated radiation treatment. Emerging data from the ongoing studies will help to better define and guide the rational use of hypofractionation in future years.
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