To evaluate the use of tandem and cylinder as an intracavitary brachytherapy device for carcinoma of the cervix with regard to local control and toxicities.

Introduction: Brachytherapy always remains a keystone in the treatment of gynecological carcinoma for both definitive and adjuvant treatments. Due to the rapid fall-off nature of brachytherapy, the target gets a high dose with a low dose to the normal organs nearby and thereby increasing the tumor control probability. Aims and Objectives: This study aims at the evaluation of local control and toxicities in the carcinoma of the cervix using tandem and cylinder as brachytherapy applicator. Materials and Methods: The study was conducted between January 2014 and December 2018 in a tertiary care hospital. Thirty-one patients who fulfilled our set criterion of Clinical stage IB3-IVA, Performance status Eastern Cooperative Oncology Group 0-2 were selected. All patients were treated initially with external beam radiotherapy and later by high dose rate intracavitary brachytherapy after completion of external beam radiation therapy (EBRT). A dose of 18-21 Gy was delivered to the residual disease in three sessions with a 1-week interval between each session. The dose was optimized in such a way that the organs at risk (OAR), namely bladder and rectum received doses within their tolerance levels. The patients were continuously monitored using Common Terminology Criteria for Adverse Events version 5.0 for both acute and late toxicities and by imaging for local control. Statistical analysis using SPSS Version 20.0 (SPSS Inc., Chicago, Illinois, USA) was used to evaluate the results. Continuous variables were expressed as mean ± standard deviation, and categorical variables were summarized as frequencies and percentages. Results: Out of the 31 patients, 5 (16.1%) experienced radiation-induced Grade 1 skin changes which were due to EBRT, 1 (3.2%) had Grade 1 G. I. T toxicity, 1 (3.2%) had Grade 1 radiation-induced vaginal mucositis after brachytherapy. At 6-8-week follow-up, all the patients showed no evidence of disease on radiological imaging. At 3 months of follow-up, 1 (3.2%) patient had radiation-induced proctitis of Grades 2 and 3 (9.7%) had radiation-induced cystitis of Grades 1 and 1 (3.2%) had Grade 2 cystitis. At 6 months of follow-up, 1 (3.2%) had Grade 1, 1 (3.2%) had Grade 2, and 1 (3.2%) had Grade 3 radiation-induced proctitis. At 3 months of follow-up, 29 (93.5%) patients had no evidence of disease, while 2 (6.5%) were having residual disease on imaging. At 6 months of follow-up, all the patients were disease-free. At 12 months of follow-up, 26 (83.9%) patients were disease-free, 1 (3.2%) had local recurrence, 2 (6.5%) had distant metastasis, and 2 (6.5%) had expired. At 24 months of follow-up, 26 patients were disease-free. Acute and late toxicities were similar to those used in the treatment of carcinoma cervix by standard brachytherapy applicators. Local control was achieved in 83.87% of cases. Two-year survival was 93.5%. Conclusion: We observed that the tandem and cylinder applicator is an acceptable applicator to be used for intracavitary brachytherapy. It is safe and simple besides this; the toxicities and local control are similar to the other standard applicators used in brachytherapy in carcinoma cervix. However, the required dose prescription to point A was not possible in all the patients due to limitations of OARs. Furthermore, long-term follow-up is needed to see the patterns of failure, recurrence-free survival, overall survival, and long-term toxicities in the treated patients.

In vitro quality assurance of three-dimensional conformal radiotherapy mono-isocentric plan for simultaneous treatment of two targets.

OBJECTIVE: The purpose of this study was to check the in vitro efficacy of a radiotherapy plan generated for the treatment of two femoral targets simultaneously in the pelvis. METHODS: The target positions for conformal radiotherapy were simulated by joining two identical water phantoms (approximating the patient dimensions), and a treatment plan to treat the two targets simultaneously with a common isocenter was planned. Calculations were made with a dose prescription of 300cGy to each lesion. The plan was executed on a medical linear accelerator and verified for point doses for individual targets with two ion chambers. Two-dimensional dose verification for fluence was also performed using an array detector of ion chambers (I'mRTMatriXX) to further validate the technique. RESULTS: The minimum, mean and maximum dose in centiGray(cGy) covered by both Ionization Chamber-1 (IC-1) and Ionization Chamber-2 (IC-2) was 295, 303 and 307 as per dose statistics from the treatment plan. The global dose max obtained from the plan was 307 cGy. Measured point doses to both the targets were within ±2%. Dose Difference and Distance to agreement (3%, 3 mm criteria) criteria also passed for 2Dfluence verification. CONCLUSIONS: Radiotherapy of two or multiple targets using monoisocentric technique can appreciably reduce the scatter dose to the normal surrounding tissue around the target/s and also the required setup and treatment time is reduced significantly. Therefore, the technique can be efficiently used to save time without compromising the radio therapeutic ratio and quality treatment, for both palliative and curative intent.

In vivo Dosimetry for Dose Verification of Total Skin Electron Beam Therapy Using Gafchromic® EBT3 Film Dosimetry.

Background and Purpose: Total skin electron beam therapy (TSEBT) is an important skin-directed radiotherapeutic procedure done in the treatment of cutaneous T-cell lymphomas, namely, mycosis fungoides (MF). This procedure is usually done at larger source-to-surface distances with the patient standing on a rotatory platform. As the patient has to stand in different positions without any rigid immobilization devices, there are chances that the total skin may not get uniformly irradiated which could lead to nonuniform dose distributions. Therefore, all the necessary arrangements should be made to evaluate the dose for different regions of the skin using suitable in vivo dosimeters at the radiotherapy centers offering these treatments. This study aimed to evaluate the consistency between the delivered and planned doses in vivo during TSEBT using Gafchromic EBT3 film dosimetry. Materials and Methods: The surface dose for the six MF patients treated for TSEBT at our hospital from 2018 to 2022 was measured and evaluated. 2 cm × 2 cm Gafchromic® EBT3 films were used to measure skin dose at reference body positions of clinical interest. All the patients were treated with the modified Stanford technique. The irradiated film strips were analyzed for the dose using the IMRT OmniPro software. The doses at respective positions were expressed as mean dose ± standard deviation and the deviation was calculated as the percentage of the prescribed dose. Results: One hundred and fifty-four Gafchromic® EBT3 film strips irradiated on six TSEBT patients showed a maximum dose variation of 2.00 ± 0.14 Gy, in the central body regions. The dose variation in the peripheral areas such as hands and ears was larger. A variation of 2 ± 0.32 Gy was observed on the hands and ears. The uniformity of the dose delivered to maximum body parts was within -7% and +16% for the peripheral areas like hands. The American Association of Physicists in Medicine recommends a dose uniformity of 8% and 4% in the vertical and horizontal patient plane for direct incident beam; however, for oblique incidences like in the modified Stanford technique, the dose variation is about 15%. Conclusion: In vivo dosimetry using Gafchromic EBT3 film dosimetry for TSEBT yields objective data to find the under or overdose regions. That can be useful to provide quality treatment, especially when treatments tend to be as complex as TSEBT.

Skin Sparing in Intensity-Modulated Radiation Therapy of Nasopharyngeal Carcinoma.

Background and Purpose: Radiation therapy of nasopharyngeal carcinomas (NPCs) involves high doses to the target structures which are superficial to the skin surfaces. As a result, the skin toxicities involved are higher and sometimes worsens to such an extent that radiotherapy needs to be interrupted unplanned. This leads to a break in radiation therapy which overall affects the local control and cure rates. The aim of this study is to decrease the skin dose by contouring skin as an organ at risk (OAR) to include in inverse planning calculation. Materials and Methods: Seventy-three cases of nasopharyngeal cancers were planned for 60 Gy to intermediate-risk planning target volume (PTVIntermediate) and 70 Gy to high risk (PTVHigh), by three different modes of Intensity-modulated radiation therapy (IMRT)- namely conventional sequential intensity-modulated radiation therapy (S-IMRT PH-I and PH-II), Skin Spared sequential intensity-modulated radiation therapy (SS-IMRT PH-I and PH-II), and Skin Spared simultaneously instantaneous boost intensity-modulated radiation therapy (SS-SIB IMRT). The plans were compared by dose volume histograms and dose statistics to the PTV as well as to the OAR's. For PTV, mean dose (Dmean), maximum dose (Dmax), and minimum dose (Dmin) were compared to check the homogeneity index (HI) while sparing the skin. For other OAR's Dmean, Dmax and dose to to 1 cubic cm was used for comparison. The skin doses to various volumes from volume to receive 5 Gy (V5) to volume to receive 70 Gy (V70) were evaluated and compared between the three techniques. Statistical analysis was done using one away ANOVA on the data editor SPSS Version 26.0 (SPSS Inc., Chicago, Illinois, USA) to evaluate the results. Continuous variables were expressed as mean ± standard deviation, and categorical variables were summarized as frequencies and percentages. Survival analysis was done by Kaplan-Meier Estimator. Results: When the skin was considered as an OAR, the skin volume to receive 5, 10, 15, 20, 30, 40, 50, 60, 70 Gy was reduced by 6.5%, 6.5%, 6%, 11.5%, 7%, 6%, 6%, 5%, 2%, respectively, by SS-IMRT PH-I and II and 2%, 4.05%, 4%, 7%, 5%, 3%, 6%, 5%, 1%, respectively, by SS-SIB IMRT when both the SS techniques were compared with S-IMRT PH-I and II. Volume of skin to receive 20 Gy showed maximum reduction in SS-IMRT PH-I and II. A one-way ANOVA was carried out to find the differences in the skin doses between the three techniques. The skin dose in the two SS techniques, i.e., SS-IMRT PH-I and PH-II and SS-SIB IMRT was found significantly lower than that of IMRT plans without skin as an OAR, i.e., S-IMRT PH-I and PH-II (P = 0.000). The PTV doses were well within the 95%-107% of the prescribed dose (HI) and there were no significant differences in the means of the prescribed dose between the simple and skin spared IMRT techniques. The other OARs doses were also evaluated and there were no significant differences between the means of the doses among the techniques. Conclusions: SS IMRT for NPC has demonstrated reduction in skin dose while using skin as an OAR in the optimization. Moreover, decreased skin dose can decrease the skin related toxicities provided there is no compromise on Target dose coverage and OAR dose. We recommend that skin should be contoured as an OAR for NPC, provided PTV is minimally 3-5 mm beneath skin surface, in order to have a better disease control with lesser toxicities and less unplanned treatment interruptions.

Modality of Radiotherapy and Overall Survival in Pediatric Diffuse Brainstem Gliomas: Implications for Resource-Constrained Settings.

BACKGROUND: Childhood diffuse brainstem glioma (dBSG) is a rare tumor with a poor prognosis. Any tumor-directed surgical intervention is difficult. Magnetic resonance imaging forms the mainstay of diagnosis and radiation therapy has remained the backbone of therapy. In this study, we compare the outcomes of conformal radiotherapy with conventional therapy in the context of resource-constrained settings. METHODS: In this retrospective analysis, conducted between 2010 and 2019, all pediatric patients with a diagnosis of dBSG were analyzed. The survival data were calculated in months from the date of diagnosis. Survival differences between variables were compared using the Log-rank test and the risk of death was calculated using Cox regression analysis. RESULTS: A total of 20 patients (11 males, 55%) with a diagnosis of dBSG were included. Median age at diagnosis was 6.5 years. No surgical resection or biopsy was done in any patient. Fifteen (75%) patients received radiotherapy and only 4 (20%) patients received additional chemotherapy. Five (25%) patients did not receive any form of anti-cancer therapy. Median overall survival (OS) was 8 months (95% CI 5.2-10.8). Females were at a higher risk of death than males. Children treated with radiotherapy had a longer OS than untreated children; however, the modality of radiotherapy employed or the addition of chemotherapy did not affect the OS. CONCLUSION: Radiotherapy, irrespective of the modality, increases the survival of children with dBSG in resource-poor settings. Additionally, socioeconomic concerns need to be addressed in the management of these tumors, especially in the case of female children. Lay summaryChildhood diffuse brainstem glioma (dBSG) is a rare tumor with a poor prognosis. Any tumor-directed surgical intervention is difficult. Magnetic resonance imaging forms the mainstay of diagnosis and radiation therapy has remained the backbone of therapy. In this 10-year retrospective study, we compare the outcomes of conformal radiotherapy with conventional therapy in the context of resource-constrained settings. A total of 20 patients with a diagnosis of dBSG were included with a median age at diagnosis of 6.5 years (5.25-8.75). No surgical resection or biopsy was done in any patient. Fifteen (75%) patients received radiotherapy and only 4 (20%) patients received additional chemotherapy. Five (25%) patients did not receive any form of anti-cancer therapy. Median overall survival (OS) was 8 months (95% CI 5.2-10.8). Females were at a 3.4-fold (95% CI 1.0-12.1) higher risk of death than males. Children treated with radiotherapy had a longer OS than untreated children; however, the modality of radiotherapy employed or the addition of chemotherapy did not affect the OS. Radiotherapy, irrespective of the modality, increases the survival of children with dBSG in resource-poor settings. Additionally, socioeconomic concerns need to be addressed in the management of these tumors, especially in the case of female children.