ABSTRACT
PURPOSE: This study assessed the appropriateness of full parameter addition (FPA) methods with respect to the 3-dimensional deformable dose composite method for evaluating combined external beam radiation therapy (EBRT) and intracavitary brachytherapy (ICBT). METHODS AND MATERIALS: A total of 22 patients who received EBRT and high-dose-rate ICBT were retrospectively evaluated. Split-ring and tandem applicators were used for all patients. Additional interstitial needles were used for 5 patients to supplement the implant. Deformable image registrations were performed to deform the secondary EBRT and ICBT planning computed tomography (CT) images onto the reference CT from the third fraction of ICBT. The Dice similarity coefficient was used to evaluate the quality of deformable registration. Doses were transferred to the reference CT, scaled to the equivalent dose in 2-Gy fractions and combined to create the dose composite. Eight dose-accumulation methods were evaluated and compared. D2cc and D0.1cc for organs at risk were investigated. RESULTS: The differences in D2cc for rectum, bladder, sigmoid, and bowel between the FPA method for whole-pelvis EBRT and ICBT, calculated using an old American Brachytherapy Society worksheet (FPA_Eh + I_old) and deformable composite for EBRT with boosts and ICBT (Def_E + B + I) were -2.19 ± 1.37 Gyα/ß = 3, -0.64 ± 1.13 Gyα/ß = 3, -2.06 ± 2.71 Gyα/ß = 3, and -1.59 ± 0.89 Gyα/ß = 3, respectively. The differences in D2cc for rectum, bladder, sigmoid, and bowel between the new ABS worksheet (FPA_Eh + B + I_abs) and the Def_E + B + I method were 1.21 ± 1.22 Gy α/ß = 3, 1.93 ± 1.38 Gyα/ß = 3, 0.72 ± 1.12 Gyα/ß = 3, and 1.19 ± 1.46 Gyα/ß = 3, respectively. Differences in dose-volume histogram parameter values among Def_E + B + I and other FPA methods were not statistically significant (P > .05). CONCLUSIONS: Compared with the FPA-based method, deformable registration-based dose composites demonstrated lower OAR D2cc and D0.1cc values; however, the differences were not statistically significant. The current ABS-recommended FPA-based sheet can serve as an acceptable plan evaluation tool for clinical purposes.
Subject(s)
Brachytherapy/methods , Uterine Cervical Neoplasms/radiotherapy , Female , Humans , Radiotherapy Dosage , Retrospective StudiesABSTRACT
PURPOSE: This study identified and evaluated the factors that are responsible for delay in the clinical workflow of radiation therapy, starting from the CT simulation (CT-Sim) to the first fraction of treatment delivery using the Failure Mode and Effects Analysis (FMEA) methodology. MATERIALS AND METHODS: A total of 1106 patient cases were retrospectively analyzed using FMEA methodology. For each failure mode (FM), the following factors were rated and discussed by the group: occurrence (O), severity (S), detectability (D), and methods of improvement or mitigation. In addition, two new factors, namely social effect (SE) and economic effect (EE), were introduced to evaluate the impact of FM on the department or hospital. Risk priority number (RPN) and the product of RPN, SE, and EE (i.e. RPNSE-EE) were calculated for each FM. RESULTS: Average delay caused by identified FM was 8â¯days while 76% of the FMs resulted in delay of less than 5â¯days. The RPN of all the FMs ranged from 4 to 60 with an average value of 18. "Tumor volume, prescription and objective" had the highest average RPN of 23. The majority of FMs with high RPN were identified in "CT-Sim" (RPN: 21.5⯱â¯11.1; RPNSE-EE: 97.0⯱â¯46.4) and "treatment planning" (RPN: 20.1⯱â¯8.1, RPNSE-EE: 152.9⯱â¯76.5) stages. CONCLUSION: The FMEA enabled identification of the factors that caused delay in the pre-treatment process of radiation therapy. "CT-Sim" and "treatment planning" stages had more FMs with high RPN values which have higher priority for future improvement. Two new factors, SE and EE, were introduced and appeared to be valuable in evaluating the impact of FMs on radiation oncology department or hospital in general.
