brass and Breast-Neoplasms

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.. 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.. 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.. 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.

Topics: Breast Neoplasms; Female; Humans; Mastectomy; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted; Radiotherapy, Intensity-Modulated; Thoracic Wall

The brass mesh bolus alloy has been shown to be a promising substitute for tissue-equivalent bolus to increase the surface dose during breast cancer radiotherapy treatment. This study is aimed to evaluate the brass alloy density in order to better understand the brass qualities as a bolus in radiotherapy. The mass density of brass alloy determined in this work are using solid approaches, i) traditional density method, ii) Computed Tomography (CT) number using electron density phantom and CT scan and iii) mean pixel value via ImageJ software. According to ANOVA F (2,6) 2.982, p0.126, there was no statistically significant difference between the groups. As a result, all methods for calculating the density of brass alloy are valid. The X

Topics: Alloys; Breast Neoplasms; Copper; Electrons; Female; Humans; Phantoms, Imaging; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted; Zinc

Radiotherapy treatments of post-mastectomy chest walls are complex, requiring treatment close to skin, necessitating bolus use. Commonly used 5- and 10-mm-thick boluses develop full skin dose, needing removal for the latter half of treatment and requiring two treatment plans to be generated. Can a thinner bolus be used for all treatment fractions, requiring only one plan?. Investigation of doses received using (A) a half-time 10-mm-thick Vaseline® bolus (current situation); (B) a brass mesh (Whiting & Davis, Attleboro Falls, MA) and (C) 3- and 5-mm Superflab™ (Mick Radio-Nuclear Instruments, Mount Vernon, NY) for 6 and 15 MV. Dosimetric measurements in Barts WT1 solid water and an anthropomorphic phantom, using ionization chambers and thermoluminescent dosemeters, were used to study the effect of different bolus regimes on the photon depth-dose curves (DDCs) and skin doses.. Measured skin doses for the current 10-mm-thick Vaseline bolus, brass mesh and 3-mm bolus were compared (5 mm bolus has been rejected). The brass mesh has the least effect on the DDC, with changes <0.7% for depths greater than dmax. Brass mesh conforms superiorly to skin surfaces. Measurements on an anthropomorphic phantom demonstrate an increased skin dose compared with our current treatment protocol.. Brass mesh has the smallest effect on the DDC, whilst sufficiently increasing surface dose. It can be removed at any fraction, based on a clinical decision, without the need for generating a new plan. Treating with one plan significantly reduces planning times.. Quantification of skin doses required and achieved from wax-on/wax-off treatment compared with alternative available breast boluses.

Topics: Breast Neoplasms; Calibration; Copper; Dose Fractionation, Radiation; Female; Humans; Mastectomy; Petrolatum; Phantoms, Imaging; Radiometry; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted; Skin; Surgical Mesh; Thoracic Wall; Zinc