Abstract
The Monte Carlo method was employed to simulate realistic treatment situations for photon and proton radiation therapy for a set of Oak Ridge National Laboratory (ORNL) pediatric phantoms for 15, 10, 5 and 1-year olds as well as newborns. Complete radiotherapy situations were simulated using the previously developed NRUrad input code for Monte Carlo N-Particle (MCNP) code package. Each pediatric phantom was irradiated at five different positions, namely, the testes, colon, liver, left lung and brain, and the doses in targeted organs (Dt) were determined using the track length estimate of energy. The dispersed photon and proton doses in non-targeted organs (Dd), namely, the skeleton, skin, brain, spine, left and right lungs were computed. The conversion coefficients (F = Dd/Dt) of the dispersed doses were used to study the dose dispersion in different non-targeted organs for phantoms for 15, 10, 5 and 1-year olds as well as newborns. In general, the F values were larger for younger patients. The F values for non-targeted organs for phantoms for 1-year olds and newborns were significantly larger compared to those for other phantoms. The dispersed doses from proton radiation therapy were also found to be significantly lower than those from conventional photon radiation therapy. For example, the largest F values for the brain were 65.6% and 0.206% of the dose delivered to the left lung (P4) for newborns during photon and proton radiation therapy, respectively. The present results demonstrated that dispersion of photons and generated electrons significantly affected the absorbed doses in non-targeted organs during pediatric photon therapy, and illustrated that proton therapy could in general bring benefits for treatment of pediatric cancer patients.
Highlights
In the United States, 3,000 out of 12,000 pediatric cancer patients each year required radiation therapy as their main treatment scheme [1]
The absorbed doses in targeted organs, i.e., testes (P1), colon (P2), liver (P3), left lung (P4) and brain (P5), for five different pediatric Oak Ridge National Laboratory (ORNL) phantoms are shown in Tables 1 and 2 for photon and proton irradiation, respectively
The relative statistical uncertainties associated with the absorbed photon doses in targeted organs were found to range from 0.81 to 0.19% for Irradiation position Targeted tissue
Summary
In the United States, 3,000 out of 12,000 pediatric cancer patients each year required radiation therapy as their main treatment scheme [1]. Pediatric patients are more vulnerable to radiation-induced risks than adult patients mainly due to their swiftly growing tissues and increased cellular distribution of skeletal active marrow [2] In this connection, Vassileva et al [9] conducted studies on large pediatric population and noted that the increase in the cancer incidence could be due to ionizing radiations from computed tomography, the radiation doses were relatively small compared to those used during the radiation therapy. Vassileva et al [9] conducted studies on large pediatric population and noted that the increase in the cancer incidence could be due to ionizing radiations from computed tomography, the radiation doses were relatively small compared to those used during the radiation therapy This demonstrated the importance of dispersed photon doses to non-targeted organs in pediatric radiotherapy, where the doses were significantly higher and led to a higher cancer incidence. Precise determination of the absorbed dose during radiotherapy to targeted and non-targeted organs would be important, considering the potential induction of secondary cancers by unintended radiation doses [10,11,12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
