Fetal dose assessment in a pregnant patient with brain tumor: A comparative study of proton PBS and 3DCRT/VMAT radiation therapy techniques.

PURPOSE: The treatment of brain tumors in pregnant patients poses challenges, as the out-of-field dose exposure to the fetus can potentially be harmful. A pregnant patient with prior radiation treatment was presented with a brain tumor at our clinic. This work reports on our pre-treatment study that compared fetal dose exposure between intensity-modulated proton therapy (IMPT) using pencil beam scanning (PBS) and conventional photon 3D conformal radiation therapy (3DCRT) and volumetric-modulated arc therapy (VMAT), and the subsequent pregnant patient's radiation treatment. MATERIALS AND METHODS: Pre-treatment measurements of clinical plans, 3DCRT, VMAT, and IMPT, were conducted on a phantom. Measurements were performed using a device capable of neutron detections, closely following AAPM guidelines, TG158. For photon measurements, fetus shielding was utilized. On patient treatment days, which was determined to be proton treatment, shielding was used only during daily imaging for patient setup. Additionally, an in vivo measurement was conducted on the patient. RESULTS: Measurements showed that IMPT delivered the lowest fetal dose, considering both photon and neutron out-of-field doses to the fetus, even when shielding was implemented for photon measurements. Additionally, the proton plans demonstrated superior treatment for the mother, a reirradiation case. CONCLUSION: The patient was treated with proton therapy, and the baby was subsequently delivered at full term with no complications. This case study supports previous clinical findings and advocates for the expanded use of proton therapy in this patient population.

The influence of patient positioning and immobilization equipment on MR image quality and image registration in radiation therapy.

INTRODUCTION: MRI is preferred for brain tumor assessment, while CT is used for radiotherapy simulation. This study evaluated immobilization equipment's impact on CT-MRI registration accuracy and MR image quality in RT setup. METHODS: We included CT and MR images from 11 patients with high-grade glioma, all of whom were immobilized with a thermoplastic mask and headrest. T1- and T2-weighted MR images were acquired using an MR head coil in a diagnostic setup (DS) and a body matrix coil in RT setup. To assess MR image quality, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were considered in some dedicated regions of interest. We also evaluated the impact of immobilization equipment on CT-MRI rigid registration using line profile and external contour methods. RESULTS: The CNR and SNR reduction was in the RT setup of imaging. This was more evident in T1-weighted images than in T2-weighted ones. The SNR decreased by 14.91% and 12.09%, while CNR decreased by 25.12% and 20.15% in T1- and T2-weighted images, respectively. The immobilization equipment in the RT setup decreased the mean error in rigid registration by 1.02 mm. The external contour method yielded Dice similarity coefficients (DSC) of 0.84 and 0.92 for CT-DS MRI and CT-RT MRI registration, respectively. CONCLUSION: The image quality reduction in the RT setup was due to the imaged region's anatomy and its position relative to the applied coil. Furthermore, optimizing the pulse sequence is crucial for MR imaging in RT applications. Although the use of immobilization equipment may decrease the image quality in the RT setup, it does not affect organ delineation, and the image quality is still satisfactory for this purpose. Also, the use of immobilization equipment in the RT setup has increased registration accuracy.

A radiobiological comparison of hypo-fractionation versus conventional fractionation for breast cancer 3D-conformal radiation therapy.

BACKGROUND: The present research was aimed to compare the toxicity and effectiveness of conventional fractionated radiotherapy versus hypo-fractionated radiotherapy in breast cancer utilizing a radiobiological model. MATERIALS AND METHODS: Thirty-five left-sided breast cancer patients without involvement of the supraclavicular and axillary lymph nodes (with the nodal stage of N0) that had been treated with conventional or hypo-fractionated were incorporated in this study. A radiobiological model was performed to foretell normal tissue complication probability (NTCP) and tumor control probability (TCP). RESULTS: The data represented that TCP values for conventional and hypo-fractionated regimens were 99.16 ± 0.09 and 95.96 ± 0.48, respectively (p = 0.00). Moreover, the NTCP values of the lung for conventional and hypo-fractionated treatment were 0.024 versus 0.13 (p = 0.035), respectively. Also, NTCP values of the heart were equal to zero for both regimens. CONCLUSION: In summary, hypo-fractionated regimens had comparable efficacy to conventional fraction radiation therapy in the case of dosimetry parameters for patients who had left breast cancer. But, utilizing the radiobiological model, conventional fractionated regimens presented better results compared to hypo-fractionated regimens.

Pediatric Myeloid Sarcoma of the Testes Treated With Surgery and Adjuvant Radiation Therapy.

Myeloid sarcoma (MS) is a rare extramedullary tumor of immature granulocytic cells and is most often associated with acute myeloid leukemia (AML). Myeloid sarcomas can occur anywhere in the body but are seldom present in the testicles, especially in the pediatric population. The treatment of MS, especially testicular myeloid sarcoma (TMS) is not well defined in the literature and the role of radiation therapy in the treatment of TMS is even less well defined. In this case report, we discuss the treatment for TMS in a pediatric patient, review the literature, and discuss the role of radiation therapy in the treatment.

Salvage Radiosurgery for Recurrent Cardiac Sarcoma: A Case Report.

Primary cardiac sarcoma is a rare malignant tumor that arises from the cardiac myocardium. Surgical resection is the standard of care, and median survival ranges from 6 to 12 months. The role of salvage chemotherapy and radiation is not well defined. A 53-year-old female presented with acute congestive heart failure and underwent complete surgical resection of an undifferentiated pleomorphic sarcoma of the left atrium, followed by six cycles of adjuvant doxorubicin/hydroxydaunorubicin and ifosfamide. An MRI scan demonstrated an asymptomatic, 24 mm, recurrent atrial mass. The patient was treated with frameless robotic radiation therapy over three weeks. The tumor was treated with a dose of 72 Gy in 15 fractions to the 84% isodose line. A repeat cardiac MRI at four weeks showed in-field local progression with greater protrusion into the left atrium and invasion of the left ventricle. The patient therefore elected to proceed with salvage single-fraction frameless robotic radiosurgery. 25 Gy in one fraction was prescribed to the 76% isodose line. She tolerated treatment well without any acute toxicity and was subsequently treated with a variety of chemotherapy regimens, including tyrosine kinase inhibitors (TKIs) and immunotherapy. Unfortunately, the patient relapsed with metastases in the spine and pelvis. She underwent palliative radiation therapy at multiple bony sites with a partial response. She resumed chemotherapy treatment with TKIs but passed away due to septic shock without evidence of local failure. Fractionated SBRT was ineffective at controlling our patient's cardiac sarcoma. Our patient demonstrated local control of disease at 12 months after salvage of 25 Gy in one fraction of radiosurgery without any evidence of cardiac toxicity. High-dose single-fraction radiosurgery is a reasonable palliative option for long-term local control of unresectable cardiac sarcomas.

Tapia Syndrome and Severe Pain Induced by Occipital Bone Metastasis of Prostate Cancer.

Tapia syndrome is characterized by unilateral tongue paralysis, hoarseness, and dysphagia. It is often associated with issues in the lower cranial nerves and is rarely caused by malignant tumors. A 71-year-old Japanese male with prostate cancer and bone metastases experienced severe headaches, oral discomfort, dysphagia, and hoarseness for a month. Neurological examination revealed left-sided tongue atrophy and left vocal cord paralysis, suggesting problems with cranial nerves IX and XII. CT scans showed bone metastasis in the left occipital bone. Brain MRI showed no brain or meningeal metastasis, but neck MRI revealed a mass near the left hypoglossal canal. His prostate-specific antigen (PSA) level was 53.2 ng/mL. Based on these findings, we diagnosed him with occipital bone metastasis of prostate cancer with Tapia syndrome. We treated him with palliative radiation therapy (RT), delivering 30 Gy in 10 fractions over two weeks. We did not use drug treatment or chemotherapy due to side effects and the patient's preferences. After just one day of RT, his severe headache and oral discomfort significantly improved. By the end of the two-week treatment, his hoarseness had also improved, and he was able to eat. However, tongue atrophy had not improved three months after RT. We presented a unique case of palliative RT for occipital bone metastasis of prostate cancer with Tapia syndrome. Within two weeks, the patient's headache and dysphagia had greatly improved, although tongue atrophy remained partially unresolved after palliative RT.

Concurrent Radiation and Targeted Therapy for Papillary Craniopharyngioma: A Case Report.

Craniopharyngiomas are rare epithelial malformations in the sellar or suprasellar regions of the craniopharyngeal ducts. Complete surgical resection is difficult due to the location of the base of the skull and the risk of injury to vital neurological structures. Fractionated radiation is effective in controlling residual tumors, but craniopharyngiomas can progress during treatment. The papillary subtype is driven by BRAF V600E mutations. Treatment with BRAF and MEK inhibitors alone has a response rate of 90% but a median progression-free survival of only 12 months. A 57-year-old female presented in May 2017 with complaints of headaches and blurriness in her right eye. Brain MRI demonstrated a 2 cm suprasellar mass engulfing the right optic nerve and optic chiasm. The patient underwent a transsphenoidal hypophysectomy with pathology consistent with a benign pituitary adenoma. Follow-up imaging in August, however, showed recurrence, and a re-resection was performed which surprisingly demonstrated papillary craniopharyngioma. Due to subtotal resection, the patient elected to proceed with intensity-modulated radiation therapy (IMRT) to the tumor bed in April of 2018 with an intended dose of 5400 cGy. After treatment with 2160 cGy in 12 fractions, the patient experienced visual deterioration and progression of the cystic tumor. The patient underwent another debulking procedure but due to rapid recurrence, an endoscopic transsphenoidal fenestration was performed. On postoperative imaging, a cystic mass was still engulfing the right optic nerve and chiasm. Due to the extended break and limited radiation tolerance of the optic chiasm, we elected to re-treat the tumor with an additional 3780 cGy IMRT in conjunction with one cycle of Taflinar and Mekinist, which was completed in August 2018. The cumulative dose to the optic chiasm was 5940 cGy.The patient had an excellent clinical response to treatment with the improvement of vision in her right eye. A brain MRI on 3/29/2019 demonstrated no residual craniopharyngioma. Four-year follow-on CT scan showed no evidence of tumor recurrence. The patient had preservation of vision and did not suffer any late neurological toxicity or new endocrine deficiency. Surgical resection and radiation were ineffective at treating our patient's craniopharyngioma due to rapid cystic progression. This is the first case report in the literature detailing concurrent radiation therapy with BRAF and MEK inhibitors for papillary craniopharyngioma. Despite a suboptimal dose of radiation, our patient had no tumor recurrence and no late toxicity four years after treatment. This represents a potentially novel treatment strategy in this challenging entity.

Partial breast irradiation: An updated consensus statement from the American brachytherapy society.

PURPOSE: In recent years, results with mature follow-up have been reported for several Phase III trials randomizing women to receive whole breast irradiation (WBI) versus varying modalities of partial breast irradiation (PBI). It is important to recognize that these methods vary in terms of volume of breast tissue treated, dose per fraction, and duration of therapy. As such, clinical and technical guidelines may vary among the various PBI techniques. METHODS: Members of the American Brachytherapy Society with expertise in PBI performed an extensive literature review focusing on the highest quality data available for the numerous PBI options offered in the modern era. Data were evaluated for strength of evidence and published outcomes were assessed. RESULTS: The majority of women enrolled on randomized trials of WBI versus PBI have been age >45 years with tumor size <3 cm, negative margins, and negative lymph nodes. The panel also concluded that PBI can be offered to selected women with estrogen receptor negative and/or Her2 amplified breast cancer, as well as ductal carcinoma in situ, and should generally be avoided in women with extensive lymphovascular space invasion. CONCLUSIONS: This updated guideline summarizes published clinical trials of PBI methods. The panel also highlights the role of PBI for women facing special circumstances, such as history of cosmetic breast augmentation or prior breast irradiation, and discusses promising novel modalities that are currently under study, such as ultrashort and preoperative PBI. Updated consensus guidelines are also provided to inform patient selection for PBI and to characterize the strength of evidence to support varying PBI modalities.

Dosimetric and radiobiological comparison in head-and-neck radiotherapy using JO-IMRT and 3D-CRT.

Introduction: Dosimetric and radiobiological evaluations for the Jaws-only Intensity-modulated radiotherapy (JO-IMRT) technique for head and neck jaws-only intensity-modulated radiation therapy (JO-IMRT) and 3D conformal radiation therapy (3D-CRT). To compare the head-and-neck therapeutic approaches utilizing JO-IMRT and 3D-CRT techniques, different radiation dose indices were calculated, including: conformity index (CI), homogeneity index (HI), and radiobiological variables like Niemierko's equivalent uniform dose based tumor control probability (TCP) of planning target volume (PTV), normal tissue complication probability (NTCP) of organs at risk (OAR) (brainstem, spinal cord, and parotid grand). Materials and methods: Twenty-five nasopharynx patients were studied using the Prowess Panther Treatment Planning System (Prowess Inc). The results were compared with the dose distribution obtained using 3D-CRT. Results: Regarding tumor coverage and CI, JO-IMRT showed better results than 3D-CRT. The average doses received by the PTVs were quite similar: 72.1 ± 0.8 Gy by 3D-CRT and 72.5 ± 0.6 Gy by JO-IMRT plans (p > 0.05). The mean doses received by the parotid gland were 56.7 ± 0.7 Gy by 3D-CRT and 26.8 ± 0.3 Gy by JO-IMRT (p > 0.05). The HI and CI were 0.13 ± 0.01 and 0.14 ± 0.05 and (p > 0.05) by 3D-CRT and 0.83 ± 0.05 and 0.73 ± 0.10 by JO-IMRT (p < 0.05). The average TCP of PTV was 0.82 ± 0.08 by 3D-CRT and 0.92 ± 0.02 by JO-IMRT. Moreover, the NTCP of the parotid glands, brain stem, and spinal cord were lower using the JO-IMRT than 3D-CRT plans. In comparison to the 3D-CRT approach, the JO-IMRT technique was able to boost dose coverage to the PTV, improve the target's CI and HI, and spare the parotid glands. This suggests the power of the JO-IMRT over 3D-CRT in head-and-neck radiotherapy.

A Dosimetric Study Comparing 3D-CRT vs. IMRT vs. VMAT in Left-Sided Breast Cancer Patients After Mastectomy at a Tertiary Care Centre in Eastern India.

Introduction Post-mastectomy radiation in left-sided breast cancer in women continues to pose a significant risk to the underlying lungs and heart. This study analyzed the difference in planning target volume (PTV) coverage and dose to the organs at risk (OAR) by using three different planning methods for the same patient - three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric-modulated arc therapy (VMAT). Material and methods Thirty-five left-sided breast cancer patients' post-mastectomy were included in this study, and three different plans for adjuvant radiation were created using 3D-CRT, IMRT, and VMAT. The prescribed dose was 50Gy in 25 fractions. Kruskal-Wallis analysis of variance (ANOVA) was done, followed by a pairwise t-test to establish a hierarchy of plan quality and dosimetric benefits. The plans were compared with PTV95, homogeneity index (HI), conformity index (CI), hotspot (V107%), left lung V20Gy, mean lung dose, heart V25Gy, mean heart dose, and integral dose (ID) to the body. Results Both VMAT and IMRT led to improved PTV95% coverage (95.63±1.82%, p=0.000 in VMAT; 93.70±2.16 %, p=0.000; 81.40±6.27% in 3D-CRT arm) and improved CI (0.91±0.06 in IMRT [p<0.05] and 0.96±0.02 for VMAT plans [p<0.05]) as compared to 3D-CRT (0.66±0.11), which was statistically significant on pairwise analysis. In contrast, the difference in HI and reduction in hotspots were not significantly different. Left lung V20 was statistically very different between the three arms with the highest values in IMRT (36.64±4.45) followed by 3D-CRT (34.80±2.24) and the most negligible value in VMAT (33.03±4.20). Mean lung dose was also statistically different between the three arms. There was a statistically significant difference in mean heart dose between the three arms on pairwise analysis. Both the inverse planning methods led to a statistically significant increase in low dose volume (V5 and V10) of the ipsilateral lung, opposite lung, and heart, and increased ID to the body excluding the PTV. Conclusion While both the inverse planning modalities led to increased coverage, better CI, and better HI and decreased high dose volumes in OARs, there was increased low volume irradiation of heart, lungs, and body with VMAT faring marginally better than IMRT in coverage and decreasing lung irradiation with comparable heart irradiation.

A Pilot Study of Cardiac MRI in Breast Cancer Survivors After Cardiotoxic Chemotherapy and Three-Dimensional Conformal Radiotherapy.

PURPOSE/OBJECTIVES: Node-positive breast cancer patients often receive chemotherapy and regional nodal irradiation. The cardiotoxic effects of these treatments, however, may offset some of the survival benefit. Cardiac magnetic resonance (CMR) is an emerging modality to assess cardiac injury. This is a pilot trial assessing cardiac damage using CMR in patients who received anthracycline-based chemotherapy and three-dimensional conformal radiotherapy (3DCRT) regional nodal irradiation using heart constraints. MATERIALS AND METHODS: Node-positive breast cancer patients (2000-2008) treated with anthracycline-based chemotherapy and 3DCRT regional nodal irradiation (including the internal mammary chain nodes) with heart ventricular constraints (V25 < 10%) were invited to participate. Cardiac tissues were contoured and analyzed separately for whole heart (pericardium) and for combined ventricles and left atrium (myocardium). CMR obtained ventricular function/dimensions, late gadolinium enhancement (LGE), global longitudinal strain (GLS), and extracellular volume fraction (ECV) as measures of cardiac injury and/or early fibrosis. CMR parameters were correlated with dose-volume constraints using Spearman correlations. RESULTS: Fifteen left-sided and five right-sided patients underwent CMR. Median diagnosis age was 50 (32-77). No patients had baseline cardiac disease before regional nodal irradiation. Median time after 3DCRT was 8.3 years (5.2-14.4). Median left-sided mean heart dose (MHD) was 4.8 Gy (1.1-11.2) and V25 was 5.7% (0-12%). Median left ventricular ejection fraction (LVEF) was 63%. No abnormal LGE was observed. No correlations were seen between whole heart doses and LVEF, LV mass, GLS, or LV dimensions. Increasing ECV did not correlate with increased heart or ventricular doses. However, correlations between higher LV mass and ventricular mean dose, V10, and V25 were seen. CONCLUSION: At a median follow-up of 8.3 years, this cohort of node-positive breast cancer patients who received anthracycline-based chemotherapy and regional nodal irradiation had no clinically abnormal CMR findings. However, correlations between ventricular mean dose, V10, and V25 and LV mass were seen. Larger corroborating studies that include advanced techniques for measuring regional heart mechanics are warranted.

Feasibility of Treatment Planning System in Localizing the COVID-19 Pneumonia Lesions and Evaluation of Volume Indices of Lung Involvement.

BACKGROUND AND PURPOSE: To assess the feasibility of a treatment planning system in localizing, contouring, and targeting lung lesions along with an evaluation of volume indices of lung involvement in patients with COVID-19 pneumonia. METHODS: We evaluated 10 patients with PCR-confirmed COVID-19 pneumonia. The CT images were imported into the ISOgray® treatment planning system to anatomically define and contour the volumes of the pulmonary lesions, the lungs, and other nearby organs. RESULTS: The ratio of lung lesion volume to lung volume in this study was 0.11 ± 0.13 (11.13%). The highest mean biosynthesis ratio of lung lesions was 0.36. The ratio of lesion volume in the left lung of patients with the highest volume of involvement, was 0.44, and the ratio of lesion volume in the right lung of these patients was 0.27 (approximately 1.5 times more in the left lung than the right lung). On average, CTDIvol and DLP for all patients studied in our study were 11.22 ± 2.47 mGy and 354.20 ± 65.11 mGy.cm. CONCLUSION: We reported the feasibility of using a treatment planning system in localizing COVID-19 pulmonary lesions and its validity in the volumetric assessment of infected lung regions.

Early detection of subclinical left ventricular dysfunction after breast cancer radiation therapy using speckle-tracking echocardiography: association between cardiac exposure and longitudinal strain reduction (BACCARAT study).

BACKGROUND: Breast cancer (BC) radiotherapy (RT) can induce cardiotoxicity, with adverse events often observed many years after BC RT. Subclinical left ventricular (LV) dysfunction can be detected early after BC RT with global longitudinal strain (GLS) measurement based on 2D speckle-tracking echocardiography. This 6-month follow-up analysis from the BACCARAT prospective study aimed to investigate the association between cardiac radiation doses and subclinical LV dysfunction based on GLS reduction. METHODS: The patient study group consisted of 79 BC patients (64 left-sided BC, 15 right-sided BC) treated with RT without chemotherapy. Echocardiographic parameters, including GLS, were measured before RT and 6 months post-RT. The association between subclinical LV dysfunction, defined as GLS reduction > 10%, and radiation doses to whole heart and the LV were performed based on logistic regressions. Non-radiation factors associated with subclinical LV dysfunction including age, BMI, hypertension, hypercholesterolemia and endocrine therapy were considered for multivariate analyses. RESULTS: A mean decrease of 6% in GLS was observed (- 15.1% ± 3.2% at 6 months vs. - 16.1% ± 2.7% before RT, p = 0.01). For left-sided patients, mean heart and LV doses were 3.1 ± 1.3 Gy and 6.7 ± 3.4 Gy respectively. For right-sided patients, mean heart dose was 0.7 ± 0.5 Gy and median LV dose was 0.1 Gy. Associations between GLS reduction > 10% (37 patients) and mean doses to the heart and the LV as well as the V20 were observed in univariate analysis (Odds Ratio = 1.37[1.01-1.86], p = 0.04 for Dmean Heart; OR = 1.14 [1.01-1.28], p = 0.03 for Dmean LV; OR = 1.08 [1.01-1.14], p = 0.02 for LV V20). In multivariate analysis, these associations did not remain significant after adjustment for non-radiation factors. Further exploratory analysis allowed identifying a subgroup of patients (LV V20 > 15%) for whom a significant association with subclinical LV dysfunction was found (adjusted OR = 3.97 [1.01-15.70], p = 0.048). CONCLUSIONS: This analysis indicated that subclinical LV dysfunction defined as a GLS decrease > 10% is associated with cardiac doses, but adjustment for non-radiation factors such as endocrine therapy lead to no longer statistically significant relationships. However, LV dosimetry may be promising to identify high-risk subpopulations. Larger and longer follow-up studies are required to further investigate these associations. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02605512, Registered 6 November 2015 - Retrospectively registered.

Utilization of intensity modulated radiation therapy for anal cancer in the United States.

BACKGROUND: Chemoradiotherapy for anal cancer (AC) can incur substantial treatment-related toxicities. Whereas radiotherapy (RT) for AC has historically been delivered with two- or three-dimensional conformal RT (2D/3DCRT) techniques, intensity-modulated RT (IMRT) is associated with improved target conformality and lower doses to organs-at-risk (OARs). This is the first investigation to date evaluating trends of IMRT utilization in the United States. METHODS: The National Cancer Data Base (NCDB) was queried [2004-2015] for AC patients receiving definitive chemoradiotherapy with a defined RT technique (3DCRT versus IMRT). Following analysis based on temporal trends, multivariate logistic regression determined factors associated with receipt of IMRT. Secondarily, Kaplan-Meier analysis compared OS between the 3DCRT and IMRT groups, and Cox proportional hazards modeling determined variables associated with OS. RESULTS: Altogether, 11,396 patients met study criteria; 1,288 (11%) were treated with 3DCRT and 10,108 (89%) with IMRT. Temporally, utilization of IMRT rose significantly, from 28% in 2004 to 96% in 2015, corresponding with a progressive decrease in 3DCRT usage. IMRT was more likely delivered in node-positive disease, at academic centers, and in southern/western regions (P<0.05 for all). T3-4 disease was less likely to receive IMRT (P<0.05). As expected, there were no OS differences based on RT technique (P=0.402). Predictors of worse OS included advancing age, male gender, increasing comorbidities, advanced T-stage, and nodal positivity (P<0.05 for all). In addition to racial- and insurance-related factors, receipt of therapy at academic centers independently predicted for improved OS (P<0.05 for all). CONCLUSIONS: Based on findings from this large, contemporary dataset, IMRT is now the most widely utilized RT technique for AC, and 3DCRT is used in a very small minority of patients. IMRT utilization is impacted by multiple characteristics, such as disease- and regional-related factors. These observations have implications for payers and insurance coverage; improved survival at academic centers has ramifications for patient counseling.

Incidence of, and risk factors for, mandibular osteoradionecrosis in patients with oral cavity and oropharynx cancers.

OBJECTIVES: To evaluate the incidence of, and risk factors associated with, mandibular osteoradionecrosis (MORN) following radiation therapy (RT) for oral cavity and oropharyngeal cancers. MATERIALS AND METHODS: Patient and treatment records of 252 consecutive patients with oral cavity or oropharynx cancers treated with RT by a single radiation oncologist at a high volume academic institution from August 2009 to December 2015 were retrospectively reviewed. A Cox regression model was used to assess factors associated with the development of MORN. RT dosimetry was compared between patients with MORN and a matched cohort of patients without MORN. RESULTS: MORN developed in 14 patients (5.5%), occurring 3-40 (median 8) months post-RT. Factors associated with MORN on univariable analysis included primary diagnosis of oral cavity vs oropharynx cancer (hazard ratio [HR]: 3.0, p=0.04), smoking at the time of RT (HR: 3.1, p=0.04), mandibular invasion of the primary (HR: 3.7, p=0.04), pre-RT tooth extraction (HR: 4.52, p=0.01), and treatment with 3D-conformal RT vs intensity-modulated RT (HR: 5.1, p=0.003). On multivariable analysis, pre-RT tooth extractions and RT technique remained significant. A dosimetric comparison between patients with and without MORN showed no significant differences. CONCLUSIONS AND RELEVANCE: The incidence of MORN is low in the modern era at a high volume academic center. Modifiable risk factors including pre-RT tooth extractions, smoking, and RT technique are associated with MORN, and the risk should be minimized with appropriate dental evaluation and treatment, smoking cessation efforts, and the use of intensity-modulated RT.

Hypofractionated breast cancer radiotherapy. Helical tomotherapy in supine position or classic 3D-conformal radiotherapy in prone position: which is better?

We propose a comparative dosimetric study of whole-breast hypofractionated radiation therapy using helical tomotherapy (HT) in supine position and 3-D conformal radiotherapy (3D-CRT) in prone position. Twelve patients undergoing breast-conserving therapy were retrospectively selected from October to December 2012. Specific dose-volume parameters were selected for the study. The target coverage was adequate in all patients for both techniques. Significant differences in lung dose distribution were observed: maximum dose (mean value over the 12 plans) was 23.41 Gy in HT plans and 6.65 Gy in 3D-CRT; V20 (i.e. the lung volume receiving 20 Gy) was 0.31% in HT plans and 0.0% in 3D-CRT plans. The mean dose to the heart was 5.57 Gy and 0.93 Gy, respectively. The differences between the two techniques were significant (p<0.05) only for some parameters. We noted better results in the prone position, but with HT, dose constraints were mentioned for the whole set of considered organs.

Comparison study of the partial-breast irradiation techniques: dosimetric analysis of three-dimensional conformal radiation therapy, electron beam therapy, and helical tomotherapy depending on various tumor locations.

The partial-breast irradiation (PBI) technique, an alternative to whole-breast irradiation, is a beam delivery method that uses a limited range of treatment volume. The present study was designed to determine the optimal PBI treatment modalities for 8 different tumor locations. Treatment planning was performed on computed tomography (CT) data sets of 6 patients who had received lumpectomy treatments. Tumor locations were classified into 8 subsections according to breast quadrant and depth. Three-dimensional conformal radiation therapy (3D-CRT), electron beam therapy (ET), and helical tomotherapy (H-TOMO) were utilized to evaluate the dosimetric effect for each tumor location. Conformation number (CN), radical dose homogeneity index (rDHI), and dose delivered to healthy tissue were estimated. The Kruskal-Wallis, Mann-Whitney U, and Bonferroni tests were used for statistical analysis. The ET approach showed good sparing effects and acceptable target coverage for the lower inner quadrant-superficial (LIQ-S) and lower inner quadrant-deep (LIQ-D) locations. The H-TOMO method was the least effective technique as no evaluation index achieved superiority for all tumor locations except CN. The ET method is advisable for treating LIQ-S and LIQ-D tumors, as opposed to 3D-CRT or H-TOMO, because of acceptable target coverage and much lower dose applied to surrounding tissue.

Dosimetric evaluation of 3Dconformal acceleratedpartial-breast irradiation vs. whole-breast irradiation: A comparative study.

BACKGROUND: Conventional early breast cancer treatment consists of lumpectomy followed by whole-breast irradiation (WBI) therapy. Accelerated partial-breast irradiation (APBI) is also an approach to post-lumpectomy radiation for early breast cancer. AIM: The purpose of this study is to compare two different external-beam APBI techniques using three-dimensional (3D) conformal radiation therapy (3DCRT), with conventional whole-breast irradiation based on the radiation conformity index, dose homogeneity index, and dose to organs at risk. MATERIALS AND METHODS: WBI treatment plans were compared with two different 3DCRT APBI plans for each of 15 patients (8 with right sided lesions, 7 with left sided lesions). The first APBI plan (APBI 1) used two small coplanar fields conformed to the planning target volume (PTV) using multileaf collimators (MLCs) and wedges, while the other APBI plan (APBI 2) used three non-coplanar fields conformed to the PTV using MLCs and wedges. RESULTS: Both the APBI techniques improved the conformity index significantly over whole-breast tangents while maintaining dose homogeneity and not causing significant increase in dose to organs at risk. CONCLUSION: Both the 3DCRT APBI techniques are technically feasible and dosimetrically appealing,with better target coverage and relative sparing of normal critical organs.