Intraoperative radiation therapy using mobile electron linear accelerators: Report of AAPM Radiation Therapy Committee Task Group No. 72

Beddar, Sam; Biggs, Peter J.; Chang, S; Ezzell, Gary A.; Faddegon, Bruce A.; Hensley, Frank W.; Mills, Michael D.

doi:10.1118/1.2194447

Cited by 118 publications

(100 citation statements)

References 65 publications

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“…Treatment can also be delivered intra-operatively as a single fraction soon after surgical excision of the tumour. Electron-only linear accelerators have been used for this approach, and recent mobile devices can be used in unmodified theatres if the workload is limited or thick mobile shielding panels are used [2][3][4]. The Intrabeam system (Carl Zeiss Surgical, Oberkochen, Germany) is a compact X-ray unit used for intra-operative partial breast irradiation [5][6][7][8], currently in an international randomised controlled trial (Targit) [9,10].…”

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confidence: 99%

Radiation protection for an intra-operative X-ray device

Eaton

Gonzalez²,

Duck³

et al. 2011

BJR

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Objectives: Therapeutic partial breast irradiation can be delivered intra-operatively using the Intrabeam 50 kVp compact X-ray device. Spherical applicators are added to the source to give an isotropic radiation dose. The low energy of this unit leads to rapid attenuation with distance, but dose rates are much greater than for diagnostic procedures. Methods: To investigate the shielding requirements for this unit, attenuation measurements were carried out with manufacturer-provided tungsten-rubber sheets, lead, plasterboard and bricks. A prospective environmental dose rate survey was also conducted in the designated theatre. Results: As a result of isotropic geometry, the scattered dose around shielding can be 1% of primary and thus often dominates measured dose rates compared with transmission. The absorbed dose rate of the unshielded source at 1 m was 11.6 mGy h 21 but this was reduced by 95% with the shielding sheets. Measured values for the common shielding materials were similar to reference data for the attenuation of a 50 kVp diagnostic X-ray beam. Two lead screens were constructed to shield operators remaining in the theatre and an air vent into a service corridor. A lead apron would also provide suitable attenuation, although a screen allows greater flexibility for treatment operators. With these measures, staff doses were reduced to negligible quantities. Survey measurements taken during patient treatments confirmed no additional measures were required, but the theatre should be a controlled area and access restricted.

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confidence: 99%

Radiation protection for an intra-operative X-ray device

Eaton

Gonzalez²,

Duck³

et al. 2011

BJR

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“…5) Consistent with these recommendations and in order to fulfill IEC standards, the accelerator head parameters for the new mobile unit described in this paper were optimized for IORT in any OR. 6) We studied the effects of different materials and geometry of accelerator head components on such critical beam properties as flatness, X-ray and neutron contamination, and the amount of dose delivered outside the treatment field.…”

Section: Introductionmentioning

confidence: 82%

Monte Carlo Study of a New Mobile Electron Accelerator Head for Intra Operative Radiation Therapy (IORT)

Wysocka-Rabin

Adrich

Wasilewski

2011

Progress in Nuclear Science and Technology

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All authors contributed equally A specially constructed highly-mobile electron accelerator is being developed for Intra Operative Radiation Therapy (IORT) in Poland. The aim of this work was to study the effects of different materials and geometry of accelerator head components on such critical beam properties as flatness, X-ray and neutron contamination, and the amount of dose delivered outside the treatment field. Based on these findings, a treatment head and applicators for the new mobile electron accelerator are being designed. The Monte Carlo code, BEAMnrc/EGSnrc, was used to build two models of a treatment head with plastic and metal applicators. FLUKA code was used for beam-stopper and shielding estimations. Both models fulfill basic requirements for quality of the therapeutic beam, as well as for radiation protection against stray and leakage radiation. The new aspects of our study were simulations for applicators with diameters of 15 and 22 cm for larger field intra operative treatment, which are not generally available on the market.

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“…Of the note, although the efficacy of EB‐IORT for breast cancer is limited by the irregular contour of deep cavity tumor beds as well as the close proximity of the critical structures, EB‐IORT with electron beam also has normal tissue sparing effect as seen in IB‐IORT, especially for low‐energy electron beams 26. This study only concerns the tumor bed less than 15‐mm depth, thus the normal tissue sparing effect and therapeutic advantage of EB‐IORT were not discussed as we know at this depth the electron beam EB‐IORT can be approximated as a uniform dose radiotherapy.…”

Section: Discussionmentioning

confidence: 99%

Therapeutic analysis of Intrabeam‐based intraoperative radiation therapy in the treatment of unicentric breast cancer lesions utilizing a spherical target volume model

Schwid

Donnelly

Zhang

2017

J Applied Clin Med Phys

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It is postulated that the outcomes in treating breast cancer with intraoperative radiotherapy (IORT) would be affected by the residual cancer cell distribution within the tumor bed. The three‐dimensional (3D) radiation doses of IntrabeamTM (IB) IORT with a 4‐cm spherical applicator at the energy of 50 and 40 kV were calculated. The modified linear quadratic model (MLQ) was used to estimate the radiobiological responses of the cancer cells and interspersed normal tissues with various radiosensitivities. By comparing the average survival fraction of normal tissues in IB‐IORT and uniform dose treatment for the same level of cancer cell killing, the therapeutic ratios (TRs) were derived. The equivalent uniform dose (EUD) was found to increase with the prescription dose and decrease with the cancer cell infiltrating distance. For 50 kV beam at the 20 Gy prescription dose, the EUDs are 18.03, 16.49 and 13.56, 11. 29, and 9.28 Gy respectively, for 1.5, 3.0, 6.0, 9, and 15.0 mm of the cancer cell infiltrating distance into surrounding tissue. The dose rate of 50 kV is at least 1.87× higher than that of 40 kV beam. The EUDs of 50 kV beam are up to 15% higher than that of the 40 kV beam. The TR increases with the prescription dose, but decreases with the distance of cancer cell infiltration distance. Average TRs of 50 kV beam are up to 30% larger than that of 40 kV beam. In conclusion, IB‐IORT can provide a possible therapeutic advantage on sparing more normal tissue compared with the External Beam IORT (EB‐IORT) for shallowly populated unicentric breast lesion. Our data suggest that IB‐IORT dose size should be adjusted based on the individual patient's cancer cell infiltrating distance for delivering an effective dose, one dose‐fits‐all regimen may have undertreated some patients with large cancer infiltrating distance.

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Intraoperative radiation therapy using mobile electron linear accelerators: Report of AAPM Radiation Therapy Committee Task Group No. 72

Cited by 118 publications

References 65 publications

Radiation protection for an intra-operative X-ray device

Radiation protection for an intra-operative X-ray device

Monte Carlo Study of a New Mobile Electron Accelerator Head for Intra Operative Radiation Therapy (IORT)

Therapeutic analysis of Intrabeam‐based intraoperative radiation therapy in the treatment of unicentric breast cancer lesions utilizing a spherical target volume model

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