Three-Dimensional Dosimetry by Optical-CT and Radiochromic Gel Dosimeter of a Multiple Isocenter Craniospinal Radiation Therapy Procedure

Abstract

Craniospinal irradiation (CSI) is a complex radiation technique employed to treat patients with primitive neuroectodermal tumors such as medulloblastoma or germinative brain tumors with the risk of leptomeningeal spread. In adults, this technique poses a technically challenging planning process because of the complex shape and length of the target volume. Thus, it requires multiple fields and different isocenters to guarantee the primary-tumor dose delivery. Recently, some authors have proposed the use IMRT technique for this planning with the possibility of overlapping adjacent fields. The high-dose delivery complexity demands three-dimensional dosimetry (3DD) to verify this irradiation procedure and motivated this study. We used an optical CT and a radiochromic Fricke-xylenol-orange gel with the addition of formaldehyde (FXO-f) to evaluate the doses delivered at the field junction region of this treatment. We found 96.91% as the mean passing rate using the gamma analysis with 3%/2 mm criteria at the junction region. However, the concentration of fail points in a determined region called attention to this evaluation, indicating the advantages of employing a 3DD technique in complex dose-distribution verifications.

Dosimetric Double Network Hydrogel Based on Poly(vinyl-alcohol)/Phenylalanine-Derivatives with Enhanced Mechanical Properties

“…Moreover, the addition of the metallic-ion indicator like as Xylenol Orange (XO) 7,8 to the Fricke gel dosimeters makes these materials suitable for being analyzed by 3D-optical CT scanners. 9,10 Besides the great advantages, some limits, such as the spatial and temporal instability of the dosimetric information, make this kind of dosimeter still inadequate for routine applications in the clinical environment. Various FG dosimeters are discussed in the literature based on different polymeric matrices and readout approaches in order to overcome these limits.…”

“…A 3D spatial dose-information is achievable within the gel volume, and it can be captured and retrieved by Magnetic Resonance Imaging (MRI), , since the two iron ions influence differently the nuclear relaxation times of the protons in the molecules surrounding them. Moreover, the addition of the metallic-ion indicator like as Xylenol Orange (XO) , to the Fricke gel dosimeters makes these materials suitable for being analyzed by 3D-optical CT scanners. , …”

Gel Dosimetry

“…The manuscript entitled “Three-Dimensional Dosimetry by Optical-CT and Radiochromic Gel Dosimeter of a Multiple Isocenter Craniospinal Radiation Therapy Procedure” by de Silveira et al [ 9 ] proposed the use of a modified radiochromic FG dosimeters in craniospinal irradiation (CSI) scenario. The found results show that gel dosimetry using the radiochromic gel combined with optical computed tomography allows a three-dimensional dose determination of a CSI procedure with complex multiple-field planning.…”

Assessment of dosimetric sensitivity enhancement of xylenol orange Fricke gel by AuNPs: optical and MR imaging investigation

“…OT and x-ray computed tomography have analogous principles: they use a LED as light source, a high-resolution CCD camera as detector, and optical and electronic components. More details can be found in the paper by Silveria and collaborators (Silveira et al 2022). When OT is applied to Fricke gel dosimeters, changes in the gel matrix optical properties induced by ionizing radiation can be detected by changes in the Fricke dosimeter attenuation coefficient, which is directly related to the absorbed dose (Asena et al 2019).…”

“…When OT is applied to Fricke gel dosimeters, changes in the gel matrix optical properties induced by ionizing radiation can be detected by changes in the Fricke dosimeter attenuation coefficient, which is directly related to the absorbed dose (Asena et al 2019). The high spatial resolution and realtime monitoring capabilities of OT make it a powerful tool for three-dimensional dosimetry applications, particularly in radiation therapy, where precise and accurate dose measurements are critical (Jordan et al 2013, Silveira et al 2022.…”