Assessment of The Effect of Beam Modifiers on Skin Dose For External Beam Radiotherapy Using Gafchromic EBT2 Films

ABSTRACT 

In radiotherapy, a patient may present irregular surface contour at the point of beam entry and this coupled with tissue heterogeneities within the irradiated region would pose problems for dose optimization if beam modifiers are not used. Skin dose is of great concern in external beam radiotherapy with megavoltage beam as the skin is very radiosensitive, and there is the need to minimize the radiation dose received by the skin. The use of beam modifiers affects the skin dose and the level of their influence on skin dose needs to be investigated. The purpose of this study was to assess the effect of different beam modifiers on the skin dose for 60Co and 15 MV photon beams. Skin doses were measured for solid water (PMMA) phantoms with Gafchromic films. It was observed that, skin dose for all the beam modifiers as well as that for the open beams increases as field size increases. At SSD of 80 cm, skin doses for 10 x 10 cm2 and 25 x 25 cm2 were, 36.9%, and 61.8% respectively for the 60Co unit. It was observed that, for a particular field size, skin dose for the 15 MV photon beam was much lower than that for 60Co beam, which gives an advantage of using the 15 MV photon beam over 60Co beam. As SSD increases skin dose reduces for both 60Co and 15 MV photon beams. For wedged fields (with 60º motorized wedge), it was found that there were very little effects on skin dose for smaller fields but significant effects for the larger fields (≥15 x 15 cm2 ) as compared with open beams for the 15 MV photon beam. Skin dose for bolus was higher compared with that of open beam and were 57.4% and 73.8% for 10 x 10 cm2 and 20 x 20 cm2 at 100 cm SSD respectively. For 60Co beam, the physical wedges and the 1.5 cm thickness compensator greatly reduced skin doses as compared to all the other beam modifiers. The skin doses for 10 × 10 cm2 field were 21.3%, 19.4%, 18.7%, 19.1% and 23.6% for 15º, 30º, 45º, 60º and the 1.5 cm thickness compensators respectively, 2 at SSD of 80 cm). These compared with 35.4% and 33.7% for the tray and open fields at the same SSD and field size as those for the wedges and compensator above. Skin doses reduced as the compensator thickness was increased. 

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APA

Ignatius, K (2021). Assessment of The Effect of Beam Modifiers on Skin Dose For External Beam Radiotherapy Using Gafchromic EBT2 Films. Afribary. Retrieved from https://afribary.com/works/assessment-of-the-effect-of-beam-modifiers-on-skin-dose-for-external-beam-radiotherapy-using-gafchromic-ebt2-films

MLA 8th

Ignatius, Komakech "Assessment of The Effect of Beam Modifiers on Skin Dose For External Beam Radiotherapy Using Gafchromic EBT2 Films" Afribary. Afribary, 17 Apr. 2021, https://afribary.com/works/assessment-of-the-effect-of-beam-modifiers-on-skin-dose-for-external-beam-radiotherapy-using-gafchromic-ebt2-films. Accessed 23 Jun. 2024.

MLA7

Ignatius, Komakech . "Assessment of The Effect of Beam Modifiers on Skin Dose For External Beam Radiotherapy Using Gafchromic EBT2 Films". Afribary, Afribary, 17 Apr. 2021. Web. 23 Jun. 2024. < https://afribary.com/works/assessment-of-the-effect-of-beam-modifiers-on-skin-dose-for-external-beam-radiotherapy-using-gafchromic-ebt2-films >.

Chicago

Ignatius, Komakech . "Assessment of The Effect of Beam Modifiers on Skin Dose For External Beam Radiotherapy Using Gafchromic EBT2 Films" Afribary (2021). Accessed June 23, 2024. https://afribary.com/works/assessment-of-the-effect-of-beam-modifiers-on-skin-dose-for-external-beam-radiotherapy-using-gafchromic-ebt2-films