Evolution of clinical radiotherapy physics practice under COVID-19 constraints

As the COVID-19 spread continues to challenge the societal and professional norms, radiotherapy around the globe is pushed into an unprecedented transformation. We will discuss how clinical physics has transformed to ascertain safety and quality standards across four facilities around the world through diversity of action, innovation, and scientific flexibility.This article is freely available via Open Access. Click on the Publisher URL to access it via the publisher's site.published version, accepted version (12 month embargo), submitted versio

Clinical and Dosimetric Implications of Air Gaps between Bolus and Skin Surface during Radiation Therapy

Purpose: The main objective of the study was to evaluate the effect of air gaps of 0 - 5.0 cm between bolus and skin for 1.0 cm Superflab bolus on surface dose (DSurf) and depth of maximum dose (dmax) in solid water and Rando® phantoms. Methods: In this work, the effects of bolus to surface distance on DSurf and variation in dmax were analyzed in a solid water phantom and in an anthropomorphic Rando® phantom for different field sizes, using Gafchromic® EBT films and farmer chamber. Results: For field sizes of 5 × 5 cm2 the DSurf is significantly affected by increasing air gaps greater than 5 mm. For field sizes larger than 10 × 10 cm2, DSurf is nearly the same for air gaps of 0 - 5.0 cm. For small fields and 6 MV photon beam, dmax increases with increasing air gap, while for 10 MV beam and smaller field sizes (i.e. 5 × 5 and 10 × 10 cm2) the dmax first decreases and then increases with the air gaps. For both 3DCRT and IMRT plans on Rando®, DSurf reduction is more prominent with increasing air gaps. Conclusion: For field sizes larger than 10 × 10 cm2 DSurf is largely unaffected by air gaps. However, smaller air gap results in shallower dmax for both 6 MV and 10 MV photon beams at all fields sizes. Special consideration should be taken to reduce air gaps between bolus and skin for field sizes smaller than 10 × 10 cm2 or when surface contour variations are greater or when the bolus covers small area and at the border of the field

Investigation of EBT3 radiochromic film’s response to humidity

Purpose: The aim of this work is to investigate the effects of immersing EBT3 radiochromic film in water and to evaluate its contribution to the total uncertainty in dose determination. Materials and methods: We used 3 cm 9 3 cm EBT3 radiochromic films irradiated in the range of 0–70 Gy to study the impact of water immersion on the change in net optical density. These films were placed in a water container for a period of 24 h. The net optical density was measured before (0 h) and after of the immersion in water (1, 3, 6, 12, 18, and 24 h). The absorbance spectrum of the EBT3 radiochromic film was measured at 0 h and 24 h after immersion in water. The uncertainty in dose determination due to the effects of keeping the EBT3 radiochromic film submerged in water at 0, 1, and 24 h were recorded in the red, green, and blue channels. Results: We observed an increase in the net optical density as an effect on the film due to its immersion in water. The penetration of the water at the edges of the radiochromic film was observed to be a function of time during which the film remained in the water. On the other hand, the penetration of water at the edges of the film was found to be independent of irradiation dose. Conclusions: EBT3 radiochromic film is found more resistant to water penetration through the edges than its predecessors. However, there is evidence that suggest that liquid water damage the Nylon cover layer of the film by changing its optical properties. Therefore, it is recommended to build a new calibration curve for radiochromic films for a specific situation involving dose measurements in liquid water.UAEMex INN

Diferencias de la presentación y tratamiento en las neoplasias primarias de hígado en un centro de hepatología y un centro oncológico

Introducción y objetivos: El cáncer primario de hígado es un problema de salud pública en México y en el mundo. El trasplante hepático (TH) es el tratamiento ideal para el carcinoma hepatocelular (CHC) temprano. El objetivo fue evaluar las características de los pacientes con CHC y colangiocarcinoma (CC) en dos centros e identificar a los candidatos a trasplante. Material y métodos: Estudio retrospectivo, observacional del 2012 al 2018 en el Centro de Hepatología (CH) y el Centro Universitario contra el Cáncer (CUCC). Se confirmó CHC o colangiocarcinoma intrahepático (CCi) en 109 pacientes, a los CHC se les aplicaron clasificaciones de estadiaje, modelos de selección para trasplante y modelo pronóstico de recidiva post-TH. Resultados: De la población total, 93% (n = 102) eran cirróticos. El 86% (n = 94) tuvo CHC (58% CH y 42% CUCC) y 14% (n = 15) CCi (40% CH y 60% CUCC). En los pacientes con CHC del CH predominó Okuda I-II, clasificación de Barcelona Clinic Liver Cancer (BCLC) A-B y niveles 1,000 ng/mL de AFP. La mitad de la población del CH con CHC cumplía con los criterios para TH, en cambio, en el CUCC solo lo hizo el 23%. Se valoraron 15 pacientes para TH y, a la fecha, se trasplantaron seis

Experimental investigation of GafChromic® EBT3 intrinsic energy dependence with kilovoltage x rays, 137Cs, and 60Co

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141567/1/mp12682_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141567/2/mp12682.pd