51
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Grams MP, Wilson ZC, Sio TT, Beltran CJ, Tryggestad EJ, Gupta SK, Blackwell CR, McCollough KP, Sarkaria JN, Furutani KM. Design and characterization of an economical (192)Ir hemi-brain small animal irradiator. Int J Radiat Biol 2014; 90:936-942. [PMID: 24844370 PMCID: PMC4564891 DOI: 10.3109/09553002.2014.922719] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To describe the design and dosimetric characterization of a simple and economical small animal irradiator. MATERIALS AND METHODS A high dose rate (HDR) (192)Ir brachytherapy source from a commercially available afterloader was used with a 1.3 cm thick tungsten collimator to provide sharp beam penumbra suitable for hemi-brain irradiation of mice. The unit was equipped with continuous gas anesthesia to allow robust animal immobilization. Dosimetric characterization of the device was performed with Gafchromic film measurements. RESULTS The tungsten collimator provided a sharp penumbra suitable for hemi-brain irradiation, and dose rates on the order of 200 cGy/minute were achieved. The sharpness of the penumbra attainable with this device compares favorably to those measured experimentally for 6 MV photons, and 6 and 20 MeV electron beams from a linear accelerator, and was comparable to those measured for a 300 kVp orthovoltage beam and a Monte Carlo simulated 90 MeV proton beam. CONCLUSIONS Due to its simplicity and low cost, the apparatus described is an attractive alternative for small animal irradiation experiments requiring steep dose gradients.
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Affiliation(s)
- Michael P Grams
- Department of Radiation Oncology , Mayo Clinic , Rochester , Minnesota , USA
| | - Zachary C Wilson
- Department of Radiation Oncology , Mayo Clinic , Rochester , Minnesota , USA
| | - Terence T Sio
- Department of Radiation Oncology , Mayo Clinic , Rochester , Minnesota , USA
| | - Chris J Beltran
- Department of Radiation Oncology , Mayo Clinic , Rochester , Minnesota , USA
| | - Erik J Tryggestad
- Department of Radiation Oncology , Mayo Clinic , Rochester , Minnesota , USA
| | - Shiv K Gupta
- Department of Radiation Oncology , Mayo Clinic , Rochester , Minnesota , USA
| | - Charles R Blackwell
- Department of Radiation Oncology , Mayo Clinic , Rochester , Minnesota , USA
| | - Kevin P McCollough
- Department of Radiation Oncology , Mayo Clinic , Rochester , Minnesota , USA
| | - Jann N Sarkaria
- Department of Radiation Oncology , Mayo Clinic , Rochester , Minnesota , USA
| | - Keith M Furutani
- Department of Radiation Oncology , Mayo Clinic , Rochester , Minnesota , USA
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52
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A comparison of surface doses for very small field size x-ray beams: Monte Carlo calculations and radiochromic film measurements. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2014; 37:303-9. [DOI: 10.1007/s13246-014-0260-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 03/04/2014] [Indexed: 12/15/2022]
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53
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Hill R, Healy B, Holloway L, Kuncic Z, Thwaites D, Baldock C. Advances in kilovoltage x-ray beam dosimetry. Phys Med Biol 2014; 59:R183-231. [DOI: 10.1088/0031-9155/59/6/r183] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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54
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Noblet C, Chiavassa S, Paris F, Supiot S, Lisbona A, Delpon G. Underestimation of dose delivery in preclinical irradiation due to scattering conditions. Phys Med 2014; 30:63-8. [DOI: 10.1016/j.ejmp.2013.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 02/20/2013] [Accepted: 03/04/2013] [Indexed: 10/27/2022] Open
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55
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Iqbal K, Gifford KA, Ibbott G, Grant RL, Buzdar S. Comparison of an anthropomorphic PRESAGE® dosimeter and radiochromic film with a commercial radiation treatment planning system for breast IMRT: a feasibility study. J Appl Clin Med Phys 2014; 15:4531. [PMID: 24423854 PMCID: PMC5711233 DOI: 10.1120/jacmp.v15i1.4531] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 07/30/2013] [Accepted: 07/16/2013] [Indexed: 11/23/2022] Open
Abstract
This work presents a comparison of an anthropomorphic PRESAGE® dosimeter and radiochromic film measurements with a commercial treatment planning system to determine the feasibility of PRESAGE® for 3D dosimetry in breast IMRT. An anthropomorphic PRESAGE® phantom was created in the shape of a breast phantom. A five-field IMRT plan was generated with a commercially available treatment planning system and delivered to the PRESAGE® phantom. The anthropomorphic PRESAGE® was scanned with the Duke midsized optical CT scanner (DMOS-RPC) and the OD distribution was converted to dose. Comparisons were performed between the dose distribution calculated with the Pinnacle3 treatment planning system, PRESAGE®, and EBT2 film measurements. DVHs, gamma maps, and line profiles were used to evaluate the agreement. Gamma map comparisons showed that Pinnacle3 agreed with PRESAGE® as greater than 95% of comparison points for the PTV passed a ± 3%/± 3 mm criterion when the outer 8 mm of phantom data were discluded. Edge artifacts were observed in the optical CT reconstruction, from the surface to approximately 8 mm depth. These artifacts resulted in dose differences between Pinnacle3 and PRESAGE® of up to 5% between the surface and a depth of 8 mm and decreased with increasing depth in the phantom. Line profile comparisons between all three independent measurements yielded a maximum difference of 2% within the central 80% of the field width. For the breast IMRT plan studied, the Pinnacle3 calculations agreed with PRESAGE® measurements to within the ±3%/± 3 mm gamma criterion. This work demonstrates the feasibility of the PRESAGE® to be fashioned into anthropomorphic shape, and establishes the accuracy of Pinnacle3 for breast IMRT. Furthermore, these data have established the groundwork for future investigations into 3D dosimetry with more complex anthropomorphic phantoms.
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Affiliation(s)
- Khalid Iqbal
- The University of Texas M D Anderson Cancer, The Islamia University, Shaukat Khanum Cancer Hospital & Research Center.
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56
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Schneider F, Clausen S, Thölking J, Wenz F, Abo-Madyan Y. A novel approach for superficial intraoperative radiotherapy (IORT) using a 50 kV X-ray source: a technical and case report. J Appl Clin Med Phys 2014; 15:4502. [PMID: 24423847 PMCID: PMC5711231 DOI: 10.1120/jacmp.v15i1.4502] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 08/01/2013] [Accepted: 07/30/2013] [Indexed: 12/28/2022] Open
Abstract
The use of IORT as a treatment modality for patients with close or positive margins has increased over the past decade. For situations where a flat area (up to 6 cm in diameter) has to be treated intraoperatively, new applicators for superficial treatment with a miniature X‐ray source (INTRABEAM system) were developed. Here we report our evaluation of the dosimetric characteristics of these new applicators and their first clinical use. Each of these flat and surface applicators consists of a radiation protective metal tube and a flattening filter, which converts the spherical dose distribution of the X‐ray source into a flat one. The homogeneity of each dose distribution and depth‐dose measurements were evaluated using film dosimetry in a solid water phantom and a soft X‐ray ionization chamber in a water tank. The first patient was treated with 5 Gy delivered in 5 mm using a 4 cm FLAT applicator over 21 minutes. The flat applicators show the maximum homogeneity, with a uniformity ratio of 1.02‐1.08 in certain depths. In 1 mm depth surface applicators show a uniformity ratio of 1.15‐1.28. They also show a higher dose rate and a steeper dose gradient compared to the flat applicators. The results of this investigation demonstrated that the flat and surface applicators have unique dosimetric characteristics that need to be considered during the treatment planning stages. This work also showed that it is possible to perform a superficial localized IORT which provides new application possibilities for use of the INTRABEAM system. PACS number: 87.55.ne
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A study on the use of Gafchromic™ EBT3 film for output factor measurements in kilovoltage X-ray beams. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2013; 36:465-71. [DOI: 10.1007/s13246-013-0226-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Accepted: 10/21/2013] [Indexed: 10/26/2022]
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58
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Gorjiara T, Hill R, Bosi S, Kuncic Z, Baldock C. Water equivalence of NIPAM based polymer gel dosimeters with enhanced sensitivity for x-ray CT. Radiat Phys Chem Oxf Engl 1993 2013. [DOI: 10.1016/j.radphyschem.2013.05.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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59
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Nwankwo O, Clausen S, Schneider F, Wenz F. A virtual source model of a kilo-voltage radiotherapy device. Phys Med Biol 2013; 58:2363-75. [DOI: 10.1088/0031-9155/58/7/2363] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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60
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Odgers D, Haque M. Near-catheter dosimetry of a HDR brachytherapy source using Gafchromic film. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2013; 36:159-66. [DOI: 10.1007/s13246-013-0186-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 02/18/2013] [Indexed: 10/27/2022]
Affiliation(s)
- David Odgers
- Institute of Medical Physics, School of Physics, University of Sydney, Australia.
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61
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The dosimetry of eye shields for kilovoltage X-ray beams. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2012. [DOI: 10.1007/s13246-012-0166-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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62
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Lessard F, Archambault L, Plamondon M, Despres P, Therriault-Proulx F, Beddar S, Beaulieu L. Validating plastic scintillation detectors for photon dosimetry in the radiologic energy range. Med Phys 2012; 39:5308-16. [PMID: 22957599 DOI: 10.1118/1.4738964] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Photon dosimetry in the kilovolt (kV) energy range represents a major challenge for diagnostic and interventional radiology and superficial therapy. Plastic scintillation detectors (PSDs) are potentially good candidates for this task. This study proposes a simple way to obtain accurate correction factors to compensate for the response of PSDs to photon energies between 80 and 150 kVp. The performance of PSDs is also investigated to determine their potential usefulness in the diagnostic energy range. METHODS A 1-mm-diameter, 10-mm-long PSD was irradiated by a Therapax SXT 150 unit using five different beam qualities made of tube potentials ranging from 80 to 150 kVp and filtration thickness ranging from 0.8 to 0.2 mmAl + 1.0 mmCu. The light emitted by the detector was collected using an 8-m-long optical fiber and a polychromatic photodiode, which converted the scintillation photons to an electrical current. The PSD response was compared with the reference free air dose rate measured with a calibrated Farmer NE2571 ionization chamber. PSD measurements were corrected using spectra-weighted corrections, accounting for mass energy-absorption coefficient differences between the sensitive volumes of the ionization chamber and the PSD, as suggested by large cavity theory (LCT). Beam spectra were obtained from x-ray simulation software and validated experimentally using a CdTe spectrometer. Correction factors were also obtained using Monte Carlo (MC) simulations. Percent depth dose (PDD) measurements were compensated for beam hardening using the LCT correction method. These PDD measurements were compared with uncorrected PSD data, PDD measurements obtained using Gafchromic films, Monte Carlo simulations, and previous data. RESULTS For each beam quality used, the authors observed an increase of the energy response with effective energy when no correction was applied to the PSD response. Using the LCT correction, the PSD response was almost energy independent, with a residual 2.1% coefficient of variation (COV) over the 80-150-kVp energy range. Monte Carlo corrections reduced the COV to 1.4% over this energy range. All PDD measurements were in good agreement with one another except for the uncorrected PSD data, in which an over-response was observed with depth (13% at 10 cm with a 100 kVp beam), showing that beam hardening had a non-negligible effect on the PSD response. A correction based on LCT compensated very well for this effect, reducing the over-response to 3%. CONCLUSION In the diagnostic energy range, PSDs show high-energy dependence, which can be corrected using spectra-weighted mass energy-absorption coefficients, showing no considerable sign of quenching between these energies. Correction factors obtained by Monte Carlo simulations confirm that the approximations made by LCT corrections are valid. Thus, PSDs could be useful for real-time dosimetry in radiology applications.
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Affiliation(s)
- Francois Lessard
- Département de physique, de génie physique et d'optique, Université Laval, Québec, Québec, Canada
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63
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Eaton DJ. Quality assurance and independent dosimetry for an intraoperative x-ray device. Med Phys 2012; 39:6908-20. [DOI: 10.1118/1.4761865] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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64
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Kim JH, Hill R, Kuncic Z. An evaluation of calculation parameters in the EGSnrc/BEAMnrc Monte Carlo codes and their effect on surface dose calculation. Phys Med Biol 2012; 57:N267-78. [DOI: 10.1088/0031-9155/57/14/n267] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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65
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Avanzo M, Rink A, Dassie A, Massarut S, Roncadin M, Borsatti E, Capra E. In vivodosimetry with radiochromic films in low-voltage intraoperative radiotherapy of the breast. Med Phys 2012; 39:2359-68. [DOI: 10.1118/1.3700175] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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66
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Eaton DJ, Best B, Brew-Graves C, Duck S, Ghaus T, Gonzalez R, Pigott K, Reynolds C, Williams NR, Keshtgar MRS. In vivo dosimetry for single-fraction targeted intraoperative radiotherapy (TARGIT) for breast cancer. Int J Radiat Oncol Biol Phys 2012; 82:e819-24. [PMID: 22300571 DOI: 10.1016/j.ijrobp.2011.11.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 10/31/2011] [Accepted: 11/01/2011] [Indexed: 10/14/2022]
Abstract
PURPOSE In vivo dosimetry provides an independent check of delivered dose and gives confidence in the introduction or consistency of radiotherapy techniques. Single-fraction intraoperative radiotherapy of the breast can be performed with the Intrabeam compact, mobile 50 kV x-ray source (Carl Zeiss Surgical, Oberkochen, Germany). Thermoluminescent dosimeters (TLDs) can be used to estimate skin doses during these treatments. METHODS AND MATERIALS Measurements of skin doses were taken using TLDs for 72 patients over 3 years of clinical treatments. Phantom studies were also undertaken to assess the uncertainties resulting from changes in beam quality and backscatter conditions in vivo. RESULTS The mean measured skin dose was 2.9 ± 1.6 Gy, with 11% of readings higher than the prescription dose of 6 Gy, but none of these patients showed increased complications. Uncertainties due to beam hardening and backscatter reduction were small compared with overall accuracy. CONCLUSIONS TLDs are a useful and effective method to measure in vivo skin doses in intraoperative radiotherapy and are recommended for the initial validation or any modification to the delivery of this technique. They are also an effective tool to show consistent and safe delivery on a more frequent basis or to determine doses to other critical structures as required.
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Affiliation(s)
- David J Eaton
- Department of Radiotherapy Physics, Royal Free Hospital, University College London, London, United Kingdom.
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67
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Smith L, Hill R, Nakano M, Kim J, Kuncic Z. The measurement of backscatter factors of kilovoltage X-ray beams using Gafchromic™ EBT2 film. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2011; 34:261-6. [DOI: 10.1007/s13246-011-0073-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Accepted: 04/05/2011] [Indexed: 10/18/2022]
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68
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Gorjiara T, Hill R, Kuncic Z, Adamovics J, Bosi S, Kim JH, Baldock C. Investigation of radiological properties and water equivalency of PRESAGE®dosimeters. Med Phys 2011; 38:2265-74. [DOI: 10.1118/1.3561509] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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