Analysis of volumetric and dosimetric changes in mid treatment CT scan in carcinoma nasopharynx: implications for adaptive radiotherapy.

OBJECTIVE: Carcinoma of nasopharynx is a radiosensitive tumor and therapeutic response during radiation treatment can result in dosimetric variations in the delivered dose to the tumor and critical organs. This study was done to evaluate the volumetric and dosimetric changes seen in tumor tissue and organs at risk in a mid treatment planning scan and its implications for adaptive replanning. Twenty patients of locally advanced carcinoma nasopharynx were evaluated. All patients were started on treatment with a baseline treatment plan on SIB-VMAT. To evaluate volumetric and dosimetric changes during treatment, a mid treatment CT scan (MTS) was taken at the 17th fraction of treatment and compared with the baseline planning CT scan (BS). Adaptive treatment plans were generated on the MTS and further treatment was continued on the adaptive plans. The mean weight loss observed at the 17th fraction of treatment was 3.4 ± 2.6 kg(Mean±S.D). The mean neck diameter at C2 level was 14.19±1.02 and 13.29 ± 1.14 cm in the BS and MTS respectively (p=0.001). The GTV 70 volume showed a 29.16% volume loss. The mean doses received by the right and left parotids were 25.45±0.98 and 24.64±3.8 Gy in the baseline treatment plan and 33.21±11.29 (p=0.054) and 31.76±8.44 Gy respectively in the MTS (p=0.016) The mean weight loss showed a statistically significant correlation with increase in the right parotid(p=0.043) and left parotid doses(p=0.024). Weight loss during treatment combined with volume changes in target tissues mandate routine adaptive replanning while treating carcinoma nasopharynx.

Simultaneous Integrated Boost (SIB) Versus Sequential Boost in Anal Cancer Patients: A Single-Center Experience.

PURPOSE: Concurrent chemoradiation is the standard of care for the treatment of anal cancer. Radiation can be delivered by sequential or simultaneous integrated boost (SIB) approach. The present study was conducted to compare the treatment outcomes and toxicity profile of patients with anal cancer treated with sequential boost and SIB approach. METHODS: A single-institution retrospective analysis of patients with squamous cell carcinoma of the anal canal treated between 2019 and 2022 with radical chemoradiation was performed. The sequential boost schedule consisted of 45 Gy in 25 fractions (1.8 Gy daily) to the gross tumor, nodes, and elective nodal volume, followed by a 9 Gy in five fractions boost to the gross disease. Patients receiving SIB were treated as per RTOG 0529 protocol. In both the groups, patients were treated with volumetric modulated arc therapy (VMAT). The two groups were compared in terms of overall survival (OS), colostomy-free survival (CFS), relapse-free survival (RFS), and acute toxicity profile. p-values < 0.05 were considered statistically significant. RESULTS: The patient and disease characteristics in both treatment arms were comparable. The only difference was a significantly longer overall treatment time of ≥ 50 days in the sequential arm (77.8% vs 43.8%, p = 0.04). The median follow-up was 18 months. The 2-year CFS was 80% in sequential vs 87.5% at 2 years for the SIB arm, 2-year OS 83.3% vs 58.6%, and 2-year RFS was 38.9% vs 41.7%, respectively. A total of 14 (77.8%) in sequential and 8 (50%) in the SIB arm had disease relapse. On univariate analysis, the involved pelvic lymph node significantly affected OS (HR 10.45, p = 0.03) while inguinal lymph node involvement adversely affected RFS (HR 6.16, p = 0.02). The most common acute toxicity was radiation-induced dermatitis, 15 (83.4%; 5 grade II, 10 grade III) in sequential vs 7 (43.8%; 3 each grade II and III) in the SIB group followed by hematological (61.1% vs 68.75%). However, the incidence of overall acute toxicities was significantly less in the SIB arm (p = 0.006). CONCLUSION: Our study showed that concurrent chemoradiation with the SIB-VMAT approach is well tolerated in patients of anal carcinoma and resulted in lesser treatment interruptions and comparable outcomes as compared to the sequential approach. Our results warrant further evaluation in a prospective study.

Radiobiological modeling of radiation-induced acute mucosal toxicity (oral mucositis and pharyngeal mucositis): A single-institutional study of head-and-neck carcinoma.

Purpose/Objective(s): This study aimed to estimate the fitting parameters of sigmoidal dose-response (SDR) curve of radiation-induced acute oral and pharyngeal mucositis in head-and-neck (H and N) cancer patients treated with Intensity Modulated Radiation Therapy (IMRT) for the calculation of normal tissue complication probability (NTCP). Materials and Methods: Thirty H-and-N cancer patients were enrolled to model the SDR curve for oral and pharyngeal mucositis. The patients were evaluated weekly for acute radiation-induced (ARI) oral and pharyngeal mucositis toxicity, and their scoring was performed as per the common terminology criteria adverse events version 5.0. The radiobiological parameters, namely n, m, TD50, and γ50 were calculated from the fitted SDR curve obtained from the clinical data of H-and-N cancer patients. Results: ARI toxicity for oral and pharyngeal mucosa in carcinoma of H-and-N cancer patients was calculated for the endpoint oral mucositis and pharyngeal mucositis. The n, m, TD50, and γ50 parameters from the SDR curve of Grade 1 and Grade 2 oral mucositis were found to be [0.10, 0.32, 12.35 ± 3.90 (confidence interval [CI] 95%) and 1.26] and [0.06, 0.33, 20.70 ± 6.95 (CI 95%) and 1.19] respectively. Similarly for pharyngeal mucositis, n, m, TD50, and γ50 parameters for Grade 1 and Grade 2 were found to be [0.07, 0.34, 15.93 ± 5.48 (CI. 95%) and 1.16 ] and [0.04, 0.25, 39.02 ± 9.98(CI. 95%) and 1.56] respectively. Conclusion: This study presents the fitting parameters for NTCP calculation of Grade 1 and Grade 2 ARI toxicity for the endpoint of oral and pharyngeal mucositis. The provided nomograms of volume versus complication and dose versus complication for different grades of oral mucositis and pharyngeal mucositis help radiation oncologists to decide the limiting dose to reduce the acute toxicities.

Radiobiological modeling of radiation-induced acute rectal mucositis: A single-institutional study of cervical carcinoma.

Purpose: This study aimed to estimate the fitting parameters of sigmoidal dose-response (SDR) curve of radiation-induced acute rectal mucositis in pelvic cancer patients treated with Intensity Modulated Radiation Therapy (IMRT) for the calculation of normal tissue complication probability (NTCP). Materials and Methods: Thirty cervical cancer patients were enrolled to model the SDR curve for rectal mucositis. The patients were evaluated weekly for acute radiation-induced (ARI) rectal mucositis toxicity and their scoring was performed as per Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. The radiobiological parameters, namely n, m, TD50, and γ50 were calculated from the fitted SDR curve obtained from the clinical data of cervical cancer patients. Results: ARI toxicity for rectal mucosa in carcinoma of cervical cancer patients was calculated for the endpoint rectal mucositis. The n, m, TD50, and γ50 parameters from the SDR curve of Grade 1 and Grade 2 rectal mucositis were found to be 0.328, 0.047, 25.44 ± 1.21 (confidence interval [CI]: 95%), and 8.36 and 0.13, 0.07, 38.06 ± 2.94 (CI: 95%), and 5.15, respectively. Conclusion: This study presents the fitting parameters for NTCP calculation of Grade 1 and Grade 2 ARI rectal toxicity for the endpoint of rectal mucositis. The provided nomograms of volume versus complication and dose versus complication for different grades of rectal mucositis help radiation oncologists to decide the limiting dose to reduce the acute toxicities.

Radiobiological modeling of radiation-induced acute proctitis: A single-institutional study of prostate carcinoma.

Purpose: To estimate the fitting parameters of the sigmoidal dose response (SDR) curve of radiation-induced acute proctitis in prostate cancer patients treated with intensity modulated radiation therapy (IMRT) for the calculation of normal tissue complication probability (NTCP). Materials and Methods: Twenty-five prostate cancer patients were enrolled and evaluated weekly for acute radiation-induced (ARI) proctitis toxicity. Their scoring was performed as per common terminology criteria for adverse events version 5.0. The radiobiological parameters namely n, m, TD50, and γ50 were calculated from the fitted SDR curve obtained from the clinical data of prostate cancer patients. Results: ARI toxicity for rectum in carcinoma of prostate patients was calculated for the endpoint of acute proctitis. The n, m, TD50, and γ50 parameters from the SDR curve of Grade 1 and Grade 2 acute proctitis are found to be 0.13, 0.10, 30.48 ± 1.52 (confidence interval [CI] 95%), 3.18 and 0.08, 0.10, 44.37 ± 2.21 (CI 95%), 4.76 respectively. Conclusion: This study presents the fitting parameters for NTCP calculation of Grade-1 and Grade-2 ARI rectum toxicity for the endpoint of acute proctitis. The provided nomograms of volume versus complication and dose versus complication for different grades of acute proctitis in the rectum help radiation oncologists to decide the limiting dose to reduce the acute toxicities.

Radiobiological modelling of radiation-induced acute skin toxicity (dermatitis): A single institutional study of breast carcinoma.

Purpose: The purpose of the study was to estimate the fitting parameters of the sigmoidal dose response (SDR) curve of radiation-induced acute dermatitis in breast cancer patients treated with intensity-modulated radiation therapy for calculation of normal tissue complication probability (NTCP). Materials and Methods: Twenty-five breast cancer patients were enrolled to model the SDR curve for acute dermatitis. The acute radiation-induced (ARI) dermatitis toxicity was assessed weekly for all the patients, and their scores were determined using the common terminology criterion adverse events version 5.0. The radiobiological parameters n, m, TD50, and γ50 were derived using the fitted SDR curve obtained from breast cancer Patient's clinical data. Results: ARI dermatitis toxicity in carcinoma of breast patients was calculated for the end point of acute dermatitis. The n, m, TD50, and γ50 parameters from the SDR curve of Grade-1 dermatitis are found to be 0.03, 0.04, 28.65 ± 1.43 (confidence interval [CI] 95%) and 1.02 and for Grade-2 dermatitis are found to be 0.026, 0.028, 38.65 ± 1.93 (CI. 95%) and 1.01 respectively. Conclusion: This research presents the fitting parameters for NTCP calculation of Grade-1 and Grade-2 acute radiation-induced skin toxicity in breast cancer for the dermatitis end point. The presented nomograms of volume versus complication probability and dose versus complication probability assist radiation oncologists in establishing the limiting dose to reduce acute toxicities for different grades of acute dermatitis in breast cancer patients.

Accelerated hypofractionated breast radiotherapy with simultaneous integrated boost: a feasibility study.

PURPOSE: To assess the feasibility of accelerated hypofractionated radiotherapy with simultaneous integrated boost (SIB) in patients with breast cancer. MATERIALS AND METHODS: A total of 27 patients after breast-conserving surgery were included in this study. Patients were planned on a four-dimensional computerized tomogram, and contouring was done using RTOG guidelines. The dose was 34 Gy/10#/2 week to the breast and 40 Gy/10#/2 week to the tumor bed as SIB with volumetric modulated arc technique. The primary endpoint was grade 2 acute skin toxicity. Doses to the organs-at-risk were calculated. Toxicities and cosmesis were assessed using RTOG/LENT/SOMA and HARVARD/NSABP/RTOG grading scales, respectively. Disease-free survival (DFS) and overall survival (OS) were calculated with Kaplan-Meier curves. RESULTS: The mean age of the patients was 42 years. Left and right breast cancers were seen in 17 (63%) and 10 (37%) patients, respectively. The mean values of ipsilateral lung V16 and contralateral lung V5 were 16.01% and 3.74%, respectively. The mean heart doses from the left and right breast were 7.25 Gy and 4.37 Gy, respectively. The mean doses to the contralateral breast, oesophagus, and Dmax to brachial plexus were 2.64 Gy, 3.69 Gy, and 26.95 Gy, respectively. The mean value of thyroid V25 was 19.69%. Grade 1 and 2 acute skin toxicities were observed in 9 (33%) and 5 (18.5%) patients, respectively. Grade 2 hyperpigmentation, edema, and induration were observed in 1 (3.7%), 2 (7.4%), and 4 (14.8%) patients, respectively. Mild breast pain and arm/shoulder discomfort were reported by 1 (3.4%) patient. The median follow-up was 51 months (range, 12 to 61 months). At four years, breast induration, edema, and fibrosis were observed in 1 (3.7%) patient. Cosmesis was excellent and good in 21 (78%) and 6 (22%) patients, respectively. Local recurrence and distant metastases occurred in 1 (3.7%) and 2 (7.4%) patients, respectively. DFS and OS at four years were 88% and 92%, respectively. CONCLUSION: With this radiotherapy schedule, acute and late toxicity rates were acceptable with no adverse cosmesis. Local control, DFS, and OS were good.

Voxel based evaluation of sequential radiotherapy treatment plans with different dose fractionation schemes.

OBJECTIVE: This study presents a methodology for voxel-based evaluation of two phase sequential radiotherapy treatment plans having conventional dose scheme in the first phase and subsequent hypofractionation dose scheme in the second phase based upon different priority [planning target volume (PTV), clinical target volume (CTV) and organs at risk (OAR)] of display modes. METHODS: A case of carcinoma prostate was selected for demonstration. Varian Eclipse treatment planning system (TPS) was used for contouring and planning. In the first phase, a dose of 52 Gy in 26 fractions to the PTV and in the second phase, a dose of 19.5 Gy in 3 fractions to the PTV Boost was planned on the same CT data set. Both the plans (Phase 1 and Phase 2) were exported and processed using "Voxel-based radiobiology display (VRb) tool". Plan Sum for Biologically effective dose (BED)-Cube and equivalent dose of 2Gy (EQD2)-Cube was reconstructed using a combination of linear quadratic (LQ) and linear quadratic-linear (LQ-L) radiobiological models. Tumor control probability (TCP) and normal tissue complication probability (NTCP) for different target volumes and organs were also calculated using EQD2-volume histograms of the Plan Sum. RESULTS: An in-house graphical user interface (GUI) is developed to present the qualitative and quantitative evaluation of the multiphase treatment plans with different display modes and dose regimens. The voxel based TCP obtained for the combined target volume was 90.56%. NTCP for the bladder and rectum was calculated from the Plan Sum histograms and found to be 0.33% and ~0.0% respectively. CONCLUSION: The proposed methodology using the VRb tool offers superior plan evaluation for multiphase sequential radiotherapy treatment plans over the existing methods. ADVANCES IN KNOWLEDGE: PTV, CTV and OAR priority based display modes in VRb tool offers better understanding of radiobiological evaluation of sequential radiotherapy treatment plans.

A comparative study for surface dose evaluation in conventional treatment of carcinoma breast patients irradiated with Co-60 and 6 MV radiation beam.

AIM: In the present study, surface doses within the target area and contralateral breast (CLB) received during conventional treatment of carcinoma breast are evaluate and compared for treatment on two different beam energies, i.e., Co-60 γ-ray and 6 MV X-ray beams with thermoluminescent dosimeter, LiF:Mg, Ti (TLD-100). MATERIALS AND METHODS: The study includes a group of 23 patients comprising 11 patients treated with Co-60 γ-ray beam and 12 patients by 6 MV X-ray beam. RESULTS AND DISCUSSION: The treatment using Co-60 γ-ray and 6 MV X-ray beams contributes an average percentage dose of 8.15% ± 0.56% and 4.73% ± 0.94%, respectively, to CLB in mastectomy patients. The contribution of tangential fields (mastectomy) to the CLB doses ranges between 12.71 and 16.40 cGy (5.45%-7.03%) for treatment with Co-60 γ-ray beam and 6.33-10.95 cGy (1.86-4.69%) for treatment with 6 MV X-ray beam. The supraclavicular field (SCF) contributes 1.45%-1.93% and 1.02%-1.43% for treatment with Co-60 γ-ray and 6 MV X-ray beams, respectively. The average surface dose (normalized with breast dose) 89.1% ± 8.5% for Co-60 beam in the SCF region differs significantly from the 60.2% ± 13.0% value for 6 MV X-ray beam. CONCLUSION: The CLB doses for mastectomy patients are higher for Co-60 beam as compared to 6 MV X-ray beam, and better dose homogeneity is achieved within the irradiated breast from 6 MV X-ray beam. The CLB doses are slightly higher for patients treated with breast conservative radiotherapy or lumpectomy. The average surface dose to SCF decreases by ~30% of treated breast dose for treatment with 6 MV X-ray beam.

PATIENTS DOSE ESTIMATION IN CT EXAMINATIONS USING SIZE SPECIFIC DOSE ESTIMATES.

The present work reports data of radiation exposure to the patients during head, chest, pelvis and abdomen CT examinations performed on a third-generation 16-slice CT machine. Radiation exposure was estimated using size specific dose estimates (SSDE) method, which takes into account patient's physical dimensions in phantom measured computed tomography dose index (CTDI) value. The reported median CT dose volume index CTDIvol values in head, chest, pelvis and abdomen examinations were 26.76, 16.27, 29.81 and 14.74 mGy, respectively. The median doses evaluated using SSDE methodology for the above mentioned procedure were 54.1, 23.1, 42.8 and 20.1 mGy, respectively. Our results showed variation in dose values estimated using CTDI and SSDE methods in all examinations. The evaluated SSDE values were also compared to the values derived from data reported by the American Association of Physicist in Medicine (AAPM). SSDE values in present measurements are 4-8% lower than AAPM values. The present results show that CTDI parameters recorded on CT console should not be used to specify patient dose during CT procedures.

Prospective Study to Quantify Expansion Volumes Around the Involved Pelvic Lymph Nodes to Plan Simultaneous Integrated Boost in Patients With Cervical Cancer Undergoing Pelvic Intensity Modulated Radiation Therapy.

PURPOSE: This study aimed to calculate the expansion margins around enlarged pelvic lymph nodes to encompass internal motion and setup errors during intensity modulated radiation therapy with simultaneous integrated boost for cervical cancer. METHODS AND MATERIALS: Four-dimensional computed tomography scans were obtained for 19 patients with cervical cancer, and 32 fluorodeoxyglucose-avid pelvic lymph nodes were delineated in different respiratory phases to calculate respiratory displacement. Setup variations during daily treatments were estimated from on-board imaging. Descriptive statistics were used to quantify the expansion margins using Mc Kenzie and Van Herk formulas separately. An analysis of variance was used to analyze the volumetric impact of the margins. RESULTS: Based on the McKenzie formula, an internal margin (internal target volume) of 3 mm and setup margin (planning target volume) of 5 mm was required to adequately encompass respiratory and setup uncertainties, respectively. Although the use of the Van Herk formula necessitated a single 6 mm expansion margin for all uncertainties, which resulted in a significant reduction in boost volume, inherent limitations in our methodology might pose a higher risk of target miss with such smaller margins. CONCLUSIONS: An isotropic expansion margin of 3 mm for the internal target volume and 5 mm for the planning target volume is necessary for enlarged pelvic lymph nodes while planning intensity modulated radiation therapy with simultaneous integrated boost for cervical cancer.

Evaluation of Multimodality Management of Adenoid Cystic Carcinoma of the Head and Neck.

Adenoid cystic carcinoma is a relatively rare tumour arising from salivary glands of head and neck region. Surgery and radiotherapy form standard treatment modalities in the management of this tumor. In this analysis we present results of multimodality treatment in our cohort of patient. This retrospective analysis evaluated results of treatment in forty patients diagnosed with adenoid cystic carcinoma of the head and neck. Evaluation was done to identify prognostic factors affecting the disease free survival. A median disease free survival of 34 ± 2.42 (Median ± SE) versus 10 ± 5.45 months was seen in patients undergoing surgery followed by post operative radiotherapy versus radiotherapy alone (P = 0.01). A radiotherapy dose more than 60 Gy was associated with a better disease free survival compared with patients receiving less than 60 Gy (P = 0.01). Positive surgical margins and perineural invasion were associated with a poor treatment outcome (P = 0.02) Patients with c-kit positive status showed a poor local control rate (P = 0.05).

Evaluation of Reirradiation in Locally Advanced Head and Neck Cancers: Toxicity and Early Clinical Outcomes.

OBJECTIVES: Locoregional recurrence is the predominant pattern of treatment failure in advanced head and neck cancers. Reirradiation is a useful modality to treat inoperable head and neck cancer patients with recurrent disease. The aim of the present study was to analyze the treatment toxicity and early clinical outcomes in patients undergoing reirradiation. METHODS: Twenty patients of head and neck cancers with recurrences or second cancers were evaluated. Reirradiation was done using simultaneous integrated boost volumetric modulated arc therapy (SIB VMAT), intensity modulated radiotherapy (IMRT), or conventional radiotherapy using 6MV photons. Dose prescription ranged from 30 to 60 Gy in conventional fractionation. RESULTS: Seventeen males and three females were evaluated in this analysis. The median age of patients under study was 56.5 years. At time of analysis 8 patients (40%) had a complete response, 7 patients (35%) had progressive disease, and 25% had partial response or stable disease. Grade III-IV mucositis, dermatitis, xerostomia, dysphagia, and trismus were seen in 20%, 20%, 50%, 35%, and 45% patients, respectively, during retreatment. Patients receiving a radiotherapy dose less than 45 Gy showed a higher incidence of progressive disease (p = 0.01). The median disease-free survival for patients receiving reirradiation dose of ≥46 Gy was 19 ± 3.3 months (median ± S Error) compared to 8 ± 2.61 months for those with a dose prescription less than 45 Gy (p = 0.03). At 18-month follow-up 26% of patients undergoing reirradiation were disease-free. CONCLUSIONS: Our results show improved tumor control using a prescription of doses ≥46 Gy in retreatment setting.

Pre-Treatment Nutritional Status and Radiotherapy Outcome in Patients with Locally Advanced Head and Neck Cancers.

AIM: Poor oral intake and associated nutritional depletion can affect treatment outcome in locally advanced head and neck cancers. The aim of this study was to evaluate the pre radiotherapy nutritional status as a predictor for response to radiotherapy treatment. PATIENTS AND METHODS: Fifty patients of locally advanced head and neck cancers undergoing radical chemoradiotherapy were evaluated in this prospective analysis. Patients were treated with definitive radiotherapy to a total dose of 60-70 Gy along with concurrent chemotherapy with injection Cisplatin 100mg/m2 delivered three weekly. The patients were evaluated for pre-treatment nutritional status using the Patient-Generated Subjective Global Assessment (PG-SGA) questionnaire. The PG-SGA evaluation was completed just before starting radiotherapy treatment and scores correlated to treatment outcome. RESULTS: Forty-seven male and three female patients were evaluated in this analysis. The median PG-SGA score was 8 with a range from 2-14.Grade 3-4 mucositis was seen in seven patients (21.8%) with PGSGA <9 compared to 55.5% in those with PG-SGA score = 9 (p=0.01). At the time of evaluation a complete response was seen in 16 patients (32%) with a PG-SGA score <9 compared to 4 patients (8%) with a PGSGA =9 (p=0.05). The median survival was 16±2.8months (Median ±S. Error) and 17±2.9 months in those with PG-SGA <9 and =9 respectively (p=0.49, log rank). CONCLUSION: PG-SGA nutritional score <9 is associated with a better local control and acute toxicity profile in radically treated head and neck cancer patients.

Vaginal dose, toxicity and sexual outcomes in patients of cervical cancer undergoing image based brachytherapy.

BACKGROUND: The aim of the study was to evaluate the vaginal dose and toxicity in patients of cervical cancer treated with image guided brachytherapy at our institute. MATERIALS AND METHODS: Thirty-five patients treated with image based brachytherapy for cervical cancer were included. Vaginal contouring was done on MRI at brachytherapy and with CT scans of subsequent brachytherapy fractions. Dose volume parameters (DVH) were reported in accordance with the GEC-ESTRO guidelines. These were correlated with vaginal toxicity (assessed by CTCAE version 3) and quality of sexual life assessed at one year of completion of treatment. RESULTS: Vaginal shortness was observed in 22 out of 30 (62.8%) patients, Nine (25.7%) had vaginal dryness and in 10 (28.5%) patients, there was contact bleeding. No association could be demonstrated between the dose volume parameters and vaginal toxicity in the present study. CONCLUSIONS: The lack of association between dose volume parameters of vagina with vaginal morbidity may be due to uncertainties involved in the delineation of vaginal wall and dosimetry. Future research is required to accurately define vaginal dose distribution to study its correlation with vaginal morbidity. Vaginal morbidity needs to be documented in order to improve the sexual outcome in these patients.

Evaluation of intrafraction motion of the organs at risk in image-based brachytherapy of cervical cancer.

PURPOSE/INTRODUCTION: To assess the variation in the doses received by the organs at risk (OARs) that can occur during treatment planning of cervical cancer by image-based brachytherapy. METHODS AND MATERIALS: After intracavitary application, two sets of images-CT and MRI-were obtained. The two sets of images were fused together with respect to the applicator. Contouring was done separately on CT and MR images. Dose received by the OARs on CT images with respect to the plans made on the MR images was estimated and compared with those on the MR images. RESULTS: Although there was always a difference between the dose received by the OARs based on the CT and MRI contours, it was not significant for the bladder and rectum; 2 cc doses differed by 0.49 Gy (±0.44) p = 0.28 for the bladder and 0.30 Gy (±0.29) p = 0.16 for the rectum. The 1 cc and 0.1 cc differences were also not significant. However for the sigmoid colon, there was significant intrafraction variation in the 2 cc doses 0.61 (±0.6) p = 0.001, 1 cc doses 0.73 (±0.67) Gy p = 0.00, and 0.1 cc dose 0.97 (±0.93) Gy p = 0.009. CONCLUSIONS: The variation in the doses to the OARs must be considered while weighing target coverage against overdose to the OARs. Although not significant for the bladder and rectum, it was significant for the sigmoid colon. Estimated doses to OARs on the planning system may not be the same dose delivered at the time of treatment.

Conformal radiotherapy in the treatment of advanced juvenile nasopharyngeal angiofibroma with intracranial extension: an institutional experience.

PURPOSE: To describe the results of conformal radiotherapy in advanced juvenile nasopharyngeal angiofibroma in a tertiary care institution. METHODS AND MATERIALS: Retrospective chart review was conducted for 8 patients treated with conformal radiotherapy between 2006 and 2009. The median follow-up was 17 months. All patients had Stage IIIB disease with intracranial extension. Radiotherapy was considered as treatment because patients were deemed inoperable owing to extensive intracranial/intraorbital extension or proximity to optic nerve. All but 1 patient were treated with intensity-modulated radiotherapy using seven coplanar fields. Median (range) dose prescribed was 39.6 (30-46) Gy. Actuarial analysis of local control and descriptive analysis of toxicity profile was conducted. RESULTS: Despite the large and complex target volume (median planning target volume, 292 cm(3)), intensity-modulated radiotherapy achieved conformal dose distributions (median van't Reit index, 0.66). Significant sparing of the surrounding organs at risk was obtained. No significant Grade 3/4 toxicities were experienced during or after treatment. Actual local control at 2 years was 87.5%. One patient died 1 month after radiotherapy secondary to massive epistaxis. The remaining 7 patients had progressive resolution of disease and were symptom-free at last follow-up. Persistent rhinitis was the only significant toxicity, seen in 1 patient. CONCLUSIONS: Conformal radiotherapy results in good local control with minimal acute and late side effects in juvenile nasopharyngeal angiofibromas, even in the presence of advanced disease.