Intensity-modulated Radiotherapy For Cancer Research Articles

Analysis of Local Control in Patients Receiving IMRT for Resected Pancreatic Cancers

Intensity-modulated radiotherapy (IMRT) is increasingly incorporated into therapy for pancreatic cancer. A concern regarding this technique is the potential for geographic miss and decreased local control. We analyzed patterns of first failure among patients treated with IMRT for resected pancreatic cancer. Seventy-one patients who underwent resection and adjuvant chemoradiation for pancreas cancer are included in this report. IMRT was used for all to a median dose of 50.4 Gy. Concurrent chemotherapy was 5-FU-based in 72% of patients and gemcitabine-based in 28%. At median follow-up of 24 months, 49/71 patients (69%) had failed. The predominant failure pattern was distant metastases in 35/71 patients (49%). The most common site of metastases was the liver. Fourteen patients (19%) developed locoregional failure in the tumor bed alone in 5 patients, regional nodes in 4 patients, and concurrently with metastases in 5 patients. Median overall survival (OS) was 25 months. On univariate analysis, nodal status, margin status, postoperative CA 19-9 level, and weight loss during treatment were predictive for OS. On multivariate analysis, higher postoperative CA19-9 levels predicted for worse OS on a continuous basis (p < 0.01). A trend to worse OS was seen among patients with more weight loss during therapy (p = 0.06). Patients with positive nodes and positive margins also had significantly worse OS (HR for death 2.8, 95% CI 1.1-7.5; HR for death 2.6, 95% CI 1.1-6.2, respectively). Grade 3-4 nausea and vomiting was seen in 8% of patients. Late complication of small bowel obstruction occurred in 4 (6%) patients. This is the first comprehensive report of patterns of failure among patients treated with adjuvant IMRT for pancreas cancer. IMRT was not associated with an increase in local recurrences in our cohort. These data support the use of IMRT in the recently activated EORTC/US Intergroup/RTOG 0848 adjuvant pancreas trial.

Irradiation of the chest wall and regional nodes as an integrated volume with IMRT for breast cancer after mastectomy: from dosimetry to clinical side-effects

Objective To discuss dosimetric characteristics of an intensity-modulated radiotherapy (IMRT) technique for treating the chest wall and regional nodes as an integrated volume after modified radical mastectomy ( MRM ),and observe acute side-effects following irradiation.Methods From June 2009 to August 2010,75 patients were randomly enrolled.Of these,41 had left-sided breast cancer.Each eligible patient had a planning CT in treatment position,on which the chest wall,supraclavicular,and infraclavicular nodes,+/-internal mammary region,were contoured as an integrated volume.A muhi-beam IMRT plan was designed with the target either as a whole or two segments divided at below the clavicle head.A dose of 50 Gy in 25 fractions was prescribed to cover at least 90％ of the PTV.Internal mammary region was included in 31 cases.Dose volume histograms were used to evaluate the IMRT plans.The acute side effects were followed up regularly during and after irradiation.The independent two-sample t-test was used to compare the dosimetric parameters between integrated and segmented plans.Results Planning design was completed for all patients,including 55 integrated and 20 segmented plans,with median number of beams of 8.The conformity index and homogeneity index was 1.43 ± 0.15 and 0.14 ± 0.02,respectively.Patients with internal mammary region included in PTV had higher homogeneity index PT.The percent volume of PTV receiving ＞ 110％ prescription dose was ＜ 5％.None of the dose constraints to normal structures was violated.There were statistically significant differences in the means of dosimetric parameters of PTV,such as Dmax,Dmean V107％,and V110％,between integrated and segmented plans (t=2.19 -2.53,P=0.013-0.031 ).≥ grade 2 radiation dermatitis was identified in 3 2 patients ( grade 2 in 2 2 patients,grade 3 in 10 patients ),mostly occurred within 1 - 2 weeks after treatment.The sites of moist desquamation were anterior axillary fold (27/37) and chest wall (10/37).Only 2 patients developed grade 2 radiation pneumonitis.Conclusions The IMRT technique applied after MRM with integrated locoregional target volume is dosimetrically feasible,and the treatment was proved to be well-tolerated by most patients. Key words: Breast neoplasms/surgery; Breast neoplasms/radiotherapy; Dosimetry; Acute side-effects

Dosimetric Predictors of Radiation-induced Acute Nausea and Vomiting in IMRT for Nasopharyngeal Cancer

We wanted to investigate dosimetric parameters that would predict radiation-induced acute nausea and vomiting in intensity-modulated radiation therapy (IMRT) for undifferentiated carcinoma of the nasopharynx (NPC). Forty-nine consecutive patients with newly diagnosed NPC were treated with IMRT alone in this prospective study. Patients receiving any form of chemotherapy were excluded. The dorsal vagal complex (DVC) as well as the left and right vestibules (VB-L and VB-R, respectively) were contoured on planning computed tomography images. A structure combining both the VB-L and the VB-R, named VB-T, was also generated. All structures were labeled organs at risk (OAR). A 3-mm three-dimensional margin was added to these structures and labeled DVC+3 mm, VB-L+3 mm, VB-R+3 mm, and VB-T+3 mm to account for physiological body motion and setup error. No weightings were given to these structures during optimization in treatment planning. Dosimetric parameters were recorded from dose-volume histograms. Statistical analysis of parameters' association with nausea and vomiting was performed using univariate and multivariate logistic regression. Six patients (12.2%) reported Grade 1 nausea, and 8 patients (16.3%) reported Grade 2 nausea. Also, 4 patients (8.2%) complained of Grade 1 vomiting, and 4 patients (8.2%) experienced Grade 2 vomiting. No patients developed protracted nausea and vomiting after completion of IMRT. For radiation-induced acute nausea, V40 (percentage volume receiving at least 40Gy) to the VB-T and V40>=80% to the VB-T were predictors, using univariate analysis. On multivariate analysis, V40>=80% to the VB-T was the only predictor. There were no predictors of radiation-induced acute vomiting, as the number of events was too small for analysis. This is the first study demonstrating that a V40 to the VB-T is predictive of radiation-induced acute nausea. The vestibules should be labeled as sensitive OARs, and weightings should be considered for dose sparing during optimization in the treatment planning of IMRT.

Intra-fractional Set-up and Organ Motion Errors in Intensity-modulated Radiation Therapy for Prostate Cancer

The aim of this study is to investigate various intra-fractional errors and to determine the appropriate planning target volume (PTV) margins in intensity modulated radiation therapy (IMRT) for prostate cancer. Ten patients with prostate cancer treated with IMRT between July 2009 and March 2010 were analyzed. PTV was created by adding 4 mm posterior and 7 mm anterior and lateral margins to the clinical target volume (CTV) including prostate and proximal seminal vesicles. Intra-fractional set-up and organ motion errors were measured using cone beam computed tomography (CBCT) images before and after each irradiation. Systematic and random errors were calculated by van Herk and Stroom's models. Intra-fractional errors of set-up and organ motion were 0.70 ± 0.84 mm and 0.88 ± 0.95 mm in the left-right (L-R), 1.04 ± 0.98 mm and 1.69 ± 1.58 mm in the cranial-coudal (C-C), and 1.08 ± 1.01 mm and 1.91 ± 1.58 mm in the anterior-posterior (A-P) directions, respectively. The errors in the C-C and A-P were significantly larger than those in the L-R (p<0.01). The organ motion errors in the C-C and A-P were significantly larger than the set-up errors (p<0.01). The appropriate PTV margin estimated in this study was 4.73 mm. Intra-fractional errors in all directions were less than 2 mm and required PTV margin in the study was similar to actual posterior margin in our routine practice. It is important to determine intra-fractional errors as well as inter-fractional errors to deliver successful IMRT for prostate cancers.

Planning Margins to CTV for Image-Guided Whole Pelvis Prostate Cancer Intensity-Modulated Radiotherapy

Purpose: We investigated the margin recipes with different alignment techniques in the image-guided intensity-modulated radiotherapy (IMRT) of whole pelvis prostate cancer patients. Materials and Methods: Forty-eight computed tomography (CT) scans of eight prostate cancer patients were investigated. Each patient had an initial planning CT scan and 5 consecutive serial CT scans during the course of treatment, all of which were acquired using 3 mm slice separation and 0.94 mm resolution in the axial plane at 120 kVp, on a PQ 5000 CT scanner. Three different whole pelvis planning margin recipes, ranging from 3 to 13 mm, were investigated. A unique IMRT plan was created with each PTV on the initial CT scan, and was then registered to the 5 serial CT scans, by bony alignment or by prostate gland-based alignment. The dose computed on each serial CT scans was accumulated back to the initial CT scan using deformable image registration for final dosimetric evaluation of the interplay of the margin selection and alignment methods. Results: Bony alignment and prostate gland-based alignment gave very similar result to the pelvic lymphatic nodes (PLNs), regardless of its margin around. The prostate gland-based alignment greatly enhanced the coverage to the prostate and SV, especially with small margins. Meanwhile, the soft-tissue alignment also raised the incidental dose to the rectum and reduces the dose to the bladder. With small to intermediate margins, only soft-tissue alignment gave acceptable mean coverage to SV. Margin of 13mm or more was needed for PLNs to maintain good target coverage. Conclusion: We commend prostate-based alignment along with margins less than or equal to 5mm around prostate and SV, and margins greater than or equal to 13 mm around the vascular spaces.

Submandibular gland-sparing intensity modulated radiotherapy in the treatment of head and neck cancer: Sites of locoregional relapse and survival

Background and purpose. To evaluate the patterns of locoregional relapse and survival following submandibular gland (SMG)-sparing intensity modulated radiotherapy (IMRT). Patients and methods. Eighty patients with laryngeal (n = 15), oropharyngeal (n = 50), hypopharyngeal (n = 11) or nasopharyngeal cancer (n = 4) were treated by submandibular gland-sparing IMRT for head and neck squamous cell cancer between July 2000 and December 2008. All patients were treated by bilateral IMRT. Thirty-nine (49%) received definitive radiotherapy (RT) and 41 (51%) postoperative RT. The contralateral parotid gland (PG) and SMG were included in the dose optimization planning program with intent to keep the mean doses for PG and SMG below 23 Gy and 28–30 Gy, respectively. The ipsilateral glands were also spared when considered feasible. Results. During a median follow-up time of 51 months (range, 24–117 months) nine local recurrent tumors were observed. Four of these nine patients were salvaged by surgery with no further recurrence. All local recurrences were located within the high-dose CTVs. None of the locally recurrent cancers were located at the vicinity of the spared PGs or SMGs. No recurrent tumors were observed in the contralateral neck. The Kaplan-Meier estimate for local control at five years following IMRT was 88% for the whole cohort and the corresponding figure for local control following salvage surgery was 94%. The estimates for five-year overall survival and disease-specific survival were 85% and 90%, respectively. Conclusion. In selected head and neck cancer patients who are estimated to have a low risk of cancer recurrence at the nodal levels I–II and who are treated with SMG-sparing IMRT the risk of cancer recurrence at the vicinity of the spared salivary glands is low.

Intensity modulated radiotherapy treatment for prostate cancer, first experience in Chile

Intensity modulated radiotherapy (IMRT) is an important step forward in cancer treatment. To report the first experience in Chile with IMRT for prostate cancer and compare the results obtained with different doses. From January 1997 through June 2008, 156 patients with a mean age of 70 years, were treated with radiotherapy and 121 with IMRT. Patients were staged according to American Commission on Cancer Staging. Their biochemical relapse risk was classified according to the MD Anderson classification. Patients were routinely checked during and after therapy to evaluate side effects and relapse. Median follow up was 46 months (4-120). Overall five years survival was 85%. Biochemical relapse free five years survival for low, intermediate and high risk patients was 100, 82 and 70%, respectively. Biochemical relapse free survival for patients receiving radiotherapy doses over 76 Gy was 83%, compared to 30% for those receiving lower doses (p < 0.05). Urinary and gastrointestinal acute toxicity was low in 80% and 90% of patients respectively. Late toxicity developed in less than 3% of patients. IMRT for prostate cancer is readily available and safe in Chile. Biochemical disease free survival improved with higher doses with low toxicity rates.

Tratamiento del cáncer de próstata con radioterapia por modulación de intensidad, primera experiencia en Chile

Intensity modulated radiotherapy (IMRT) is an important step forward in cancer treatment.To report the first experience in Chile with IMRT for prostate cancer and compare the results obtained with different doses.From January 1997 through June 2008, 156 patients with a mean age of 70 years, were treated with radiotherapy and 121 with IMRT. Patients were staged according to American Commission on Cancer Staging. Their biochemical relapse risk was classified according to the MD Anderson classification. Patients were routinely checked during and after therapy to evaluate side effects and relapse.Median follow up was 46 months (4-120). Overall five years survival was 85%. Biochemical relapse free five years survival for low, intermediate and high risk patients was 100, 82 and 70%, respectively. Biochemical relapse free survival for patients receiving radiotherapy doses over 76 Gy was 83%, compared to 30% for those receiving lower doses (p < 0.05). Urinary and gastrointestinal acute toxicity was low in 80% and 90% of patients respectively. Late toxicity developed in less than 3% of patients.IMRT for prostate cancer is readily available and safe in Chile. Biochemical disease free survival improved with higher doses with low toxicity rates.

The effect of 6 and 15 MV on intensity-modulated radiation therapy prostate cancer treatment: plan evaluation, tumour control probability and normal tissue complication probability analysis, and the theoretical risk of secondary induced malignancies

The aim of this study was to investigate the effect of 6 and 15-MV photon energies on intensity-modulated radiation therapy (IMRT) prostate cancer treatment plan outcome and to compare the theoretical risks of secondary induced malignancies. Separate prostate cancer IMRT plans were prepared for 6 and 15-MV beams. Organ-equivalent doses were obtained through thermoluminescent dosemeter measurements in an anthropomorphic Aldersen radiation therapy human phantom. The neutron dose contribution at 15 MV was measured using polyallyl-diglycol-carbonate neutron track etch detectors. Risk coefficients from the International Commission on Radiological Protection Report 103 were used to compare the risk of fatal secondary induced malignancies in out-of-field organs and tissues for 6 and 15 MV. For the bladder and the rectum, a comparative evaluation of the risk using three separate models was carried out. Dose-volume parameters for the rectum, bladder and prostate planning target volume were evaluated, as well as normal tissue complication probability (NTCP) and tumour control probability calculations. There is a small increased theoretical risk of developing a fatal cancer from 6 MV compared with 15 MV, taking into account all the organs. Dose-volume parameters for the rectum and bladder show that 15 MV results in better volume sparing in the regions below 70 Gy, but the volume exposed increases slightly beyond this in comparison with 6 MV, resulting in a higher NTCP for the rectum of 3.6% vs 3.0% (p=0.166). The choice to treat using IMRT at 15 MV should not be excluded, but should be based on risk vs benefit while considering the age and life expectancy of the patient together with the relative risk of radiation-induced cancer and NTCPs.

VMAT Reduces Moderate to High Integral Dose When Compared to Conventional IMRT for Treatment of Prostate Cancer

VMAT Reduces Moderate to High Integral Dose When Compared to Conventional IMRT for Treatment of Prostate Cancer

Evaluation of Hippocampal Dose for Patients Undergoing Intensity Modulated Radiotherapy for Nasopharyngeal Cancer

Evaluation of Hippocampal Dose for Patients Undergoing Intensity Modulated Radiotherapy for Nasopharyngeal Cancer

Development of a Standardized Method for Contouring the Lumbosacral Plexus: A Preliminary Dosimetric Analysis of this Organ at Risk among 15 Patients Treated with IMRT for Lower Gastrointestinal Cancers and the Incidence of Radiation Induced Lumbosacral Plexopathy

Radiation therapy is an essential component in the multidisciplinary treatment of lower gastrointestinal (GI) malignancies. With increased use of intensity modulated radiation therapy (IMRT), accurate identification of all potential organs-at-risk (OAR) is necessary for reduction in treatment related toxicity. The RTOG endorsed brachial plexus contouring atlas was devised at our institution in this effort. Currently there are no guidelines for delineating the lumbosacral plexus (LSP) and we propose a standardized method for contouring this OAR, with a preliminary dosimetric analysis on 15 patients treated for lower GI cancers with IMRT. Utilizing anatomic texts, radiographic imaging, and input from an expert diagnostic radiologist, a standardized method for contouring the LSP on axial CT treatment planning images was created. The LSP was referenced to identifiable anatomic structures from the L4 – 5 interspace inferiorly to the level of the sciatic nerve. This OAR was then contoured retrospectively on 15 patients having undergone IMRT treatment for rectal or anal cancer. There were no dose limitations placed on this OAR on initial treatment planning. LSP volumes and dosimetric parameters were then evaluated utilizing CERR software (St. Louis, MO). The incidence of radiation-induced lumbosacral plexopathy (RILSP), defined as neuropathy in the L4 – S4 distribution in the absence of other etiologies was calculated. Total prescribed dose to 95% of the planned target volume ranged from 50.4 – 59.4 Gy (median 54 Gy). The mean LSP volume for the 15 patients was: 100 +/- 22 cc (range, 71 – 138 cc). The mean maximal dose to the LSP was: 52.6 +/- 3.9 Gy (range, 44.5 – 58.6 Gy). The mean percentage irradiated volumes of the LSP were 73 +/- 19% (30 Gy), 58 +/- 19% (40 Gy), 22 +/- 23% (50 Gy), 0.5 +/- 0.9% (55 Gy), and 0 +/- 0% (60 Gy). 2 out of 15 patients (13%) were found to have developed RILSP at 13 and 28 months post-treatment. The true incidence of RILSP in the literature is likely underreported and is not a toxicity commonly assessed by radiation oncologists. We found a significant portion of our small sample having developed this potentially avoidable toxicity. In our analysis the LSP commonly received doses approaching the prescribed target dose. Identification of the LSP during IMRT planning is necessary to reduce dose dumping and potentially unnecessary RILSP. Therefore, we have provided a reproducible step-wise method for accurate delineation of the LSP on CT planning images and a preliminary dosimetric analysis for potential future dose constraints.

Survey of IMRT Practices in Centers Participating in the International Evaluation of Radiotherapy Technology Effectiveness in Cervical Cancer (IntERTECC) Trial

Multiple studies indicate that intensity-modulated radiation therapy (IMRT) decreases toxicity in cervical cancer patients, but prospective studies are limited. Little is known about IMRT techniques used internationally. We aimed to assess IMRT techniques used by institutions participating in the International Evaluation of Radiotherapy Technology Effectiveness in Cervical Cancer (IntERTECC) trial, a multi-institutional phase II/III trial of IMRT for cervical cancer.

Pharyngoesophageal stricture after treatment for head and neck cancer

The purpose of this study was to report the risk of pharyngoesophageal stricture after treatment for head and neck cancer. Human studies on radiation therapy with or without chemotherapy for head and neck cancer published in peer-reviewed journals with assessment of pharyngoesophageal stricture with barium swallow or endoscopy were included. A total of 4727 patients from 26 studies treated between 1989 and 2008 were eligible for analysis. The reported overall risk of stricture was 7.2%. The risks of pharyngoesophageal stricture in both conventional and intensity-modulated radiation therapy (IMRT) studies were 5.7% and 16.7%, respectively (p < .001). Use of concurrent (p < .001) and taxane (p = .01) chemotherapy was associated with the IMRT technique. Prospective studies reported a 3.3-fold increased risk of stricture compared with that of retrospective studies (odds ratio: 3.3; 95% confidence interval: 2.3-4.8; p < .001). Pharyngoesophageal stricture after IMRT and chemotherapy treatment for head and neck cancer is not uncommon. Videofluoroscopic swallow study should be performed prospectively to evaluate swallowing function.

Impact of tumor volume and systemic therapy on outcome in patients undergoing IMRT for large volume head neck cancer

BackgroundFormer prospective analyses revealed gross tumor volume (GTV) as the most reliable parameter to statistically significantly predict disease control in head neck cancer (HNC) patients treated with definitive intensity modulated radiation therapy (IMRT) +/-concomitant systemic therapy. The most 'unfavourable' subgroup was characterized by total GTV (tGTV) of > 70 cc, translating in ~50 and 65% 3-year disease free (DFS) and overall survival (OAS, vs 68% and 88% in tGTV < 70 cc, p = 0.001 and 0.0001), and ~25% distant spread (vs 6% for tGTV < 70 cc, p < 0.0001).The aim of this report was to analyze whether there is a subgroup out of patients with tGTV > 70 cc, which only marginally benefits from intensive curative treatment.ResultsBetween 03/2002-03/2011, 112 HNC patients with tGTV > 70 cc were definitively irradiated with curative intention. Mean tGTV was 104 cc (71-251). 98/112 (88%) patients underwent systemic therapy. Parameters with potential impact on disease outcome were retrospectively tested. The 3-year local-regional control (LRC), DFS and OAS rates were 61%, 50%, and 58%. The used cut-off value of 130 cc revealed an inverse association between tGTV and outcome. Patients able to undergo any systemic therapy (n = 98, mean tGTV0 103 cc, mean age 60 years) showed a satisfying and significantly superior outcome compared to the subgroup with radiation alone (n = 14, mean tGTV 99 cc, mean age 73 years), with 53% vs 17% 3-year DFS (p = 0.01). Radiation alone for tGTV > 130 cc failed to aim its curative goal in 3/3 patients.ConclusionPatients with tGTV > 70 cc unable to undergo any systemic therapy represented a subgroup in which disease control was achievable in < 20% following curatively intended IMRT. Prospective testing of a larger sample size is needed to evaluate, if radiation alone for tGTV >~130 cc fails to meet its curative aim.

The role of radiotherapy for T4 non-melanoma skin carcinoma

To review outcomes of patients treated with radiotherapy (RT) for T4 non-melanoma skin cancer (NMSC). A retrospective chart review was performed of 21 patients who received RT for T4 NMSC from 2004 to 2010. Outcomes of treatment efficacy, RT technique and patient morbidity were analysed. Twelve patients (57.1%) were treated definitively without prior treatment, five (23.8%) were recurrent lesions and four (19.1%) were treated postoperatively. Ten patients (47.6%) had evidence of bony erosion at presentation, and four (19.1%) had nodal disease. Intensity-modulated radiotherapy (IMRT), three-dimensional conformal RT and electron treatment were included RT techniques. Median follow-up was 12 months (range, 5-48 months). Twelve patients (57.1%) following RT required no further treatment and had no disease recurrence. Three patients (14.3%) required salvage treatment and are disease-free following all treatment. Tumours treated initially or postoperatively had improved control rates following RT compared with recurrent lesions (58.3% and 100% vs. 20%). Sixty percent of patients treated with IMRT achieved local control following RT, and 80% were disease-free following surgical salvage treatment. Squamous cell carcinoma (SCC) histology, presence of bony erosion and/or nodal disease was associated with a higher incidence of disease recurrence. Patients presenting with untreated lesions, smaller tumour volumes (<70 cm(3)) postoperatively, basal cell histology and absence of bone erosion or nodal disease have improved local control and outcomes. Basal cell carcinoma and SCC should be staged and treated as two separate disease entities. The use of IMRT for advanced skin cancer warrants further investigation.

Influence of Antiflatulent Dietary Advice on Intrafraction Motion for Prostate Cancer Radiotherapy

To evaluate the effect of an antiflatulent dietary advice on the intrafraction prostate motion in patients treated with intensity-modulated radiotherapy (IMRT) for prostate cancer. Between February 2002 and December 2009, 977 patients received five-beam IMRT for prostate cancer to a dose of 76 Gy in 35 fractions combined with fiducial markers for position verification. In July 2008, the diet, consisting of dietary guidelines to obtain regular bowel movements and to reduce intestinal gas by avoiding certain foods and air swallowing, was introduced to reduce the prostate motion. The intrafraction prostate movement was determined from the portal images of the first segment of all five beams. Clinically relevant intrafraction motion was defined as ≥50% of the fractions with an intrafraction motion outside a range of 3 mm. A total of 739 patients were treated without the diet and 105 patients were treated with radiotherapy after introduction of the diet. The median and interquartile range of the average intrafraction motion per patient was 2.53 mm (interquartile range, 2.2-3.0) without the diet and 3.00 mm (interquartile range, 2.4-3.5) with the diet (p < .0001). The percentage of patients with clinically relevant intrafraction motion increased statistically significant from 19.1% without diet to 42.9% with a diet (odds ratio, 3.18; 95% confidence interval, 2.07-4.88; p < .0001). The results of the present study suggest that antiflatulent dietary advice for patients undergoing IMRT for prostate cancer does not reduce the intrafraction movement of the prostate. Therefore, antiflatulent dietary advice is not recommended in clinical practice for this purpose.

SU-E-J-13: Dosimetric Discrepancy Investigation with Cone-Beam CT for Adaptive RT of Head-and-Neck Cancer

Purpose: To investigate the discrepancy between planned and delivereddoses due to tumor regression and anatomic changes using weekly Cone‐ Beam CT(CBCT) for patients with head and neck cancertreated with intensity modulated radiation therapy(IMRT). Methods: Nine patients each with eight weekly CBCTimages who received IMRT for head and neck cancer were analyzed. For each patient, weekly CBCTimage was converted into “CT of the week” using deformable image registration and fused with the planning CT. The weekly dose was calculated on the fused CBCTimages, and the calculated weekly doses were registered back into planning CT space using deformable image registration. The accumulated dose was then calculated in planning CT space. For the gross tumor volume (GTV) and lymph nodes, the minimum dose and dose range were compared with the treatment plan; for the parotids, the mean dose was evaluated. Results: The minimum dosedelivered to the GTV and nodes was reduced from the treatment plan with a mean discrepancy of 1.0Gy (1.6%) and 2.5Gy (5.3%), respectively. The range of dosesdelivered increased by 2.1Gy (39.3%) for the GTV and 4.0Gy (16.2%) for the lymph nodes compared to the planned dose. For the parotid, the mean dosedelivered increased by 2.0Gy (4.5%) from the treatment plan. Conclusions: Dosimetric discrepancy from treatment plans of patients with head and neck cancer resulted from tumor regression and anatomic changes during IMRT. Such discrepancy can be monitored and investigated with on‐board CBCTimaging. Further studies are needed to determine how best to intervene to provide more accurate radiation therapy.

Cervical Lymph Node Metastases From Unknown Primary Cancer: A Single-Institution Experience With Intensity-Modulated Radiotherapy

To determine the effectiveness and rate of complications of intensity-modulated radiotherapy (IMRT) in the treatment of cervical lymph node metastases from unknown primary cancer. Between February 2005 and November 2008, 25 patients with an unknown primary cancer underwent IMRT, with a median radiation dose of 70 Gy. The bilateral neck and ipsilateral putative pharyngeal mucosa were included in the target volume. All patients had squamous cell carcinoma, except for 1 patient who had adenosquamous differentiation. They were all treated with curative intent. Of the 25 included patients, 20 were men and 5 were women, with a median age of 54 years. Of these patients, 3 had Stage III, 18 had Stage IVa, and 4 had Stage IVb. Of the 25 patients, 18 (72%) received platinum-based chemotherapy in a combined-modality setting. Neck dissection was reserved for residual disease after definitive IMRT. Overall survival, disease-free survival, and locoregional control were calculated using the Kaplan-Meier method. With a median follow-up of 38 months, the overall survival, disease-free survival, and locoregional control rates were all 100% at 3 years. No occurrence of primary cancer was observed during the follow-up period. The reported rates of xerostomia reduced with the interval from the completion of treatment. Nine patients (36%) reported Grade 2 or greater xerostomia at 6 months, and only 2 (8%) of them reported the same grade of salivary function toxicity after 24 months of follow-up. In our institution, IMRT for unknown primary cancer has provided good overall and disease-free survival in all the patients with an acceptable rate of complications. IMRT allowed us to address the bilateral neck and ipsilateral putative pharyngeal mucosa with minimal late salivary function toxicity. The use of concurrent chemotherapy and IMRT for more advanced disease led to good clinical results with reasonable toxicities.

Feasibility of Tomotherapy to spare the cochlea from excessive radiation in head and neck cancer

We would like to evaluate the effectiveness of Tomotherapy for decreasing radiation dose to the cochlea in head and neck cancer patients. A retrospective review of 72 patients undergoing radiation for head and neck cancer was performed. Cochlea dose was compared between 20 patients treated with conventional intensity modulated radiotherapy (IMRT) and 52 treated with Tomotherapy. A review of literature was performed to assess cochlea dose reported with the IMRT technique for head and neck cancer. Mean total cochlea dose was 36 Gy for IMRT compared to 12.1 Gy for Tomotherapy (p=0.002). Mean right cochlea dose was respectively, 16.6 and 6.2 Gy for IMRT and Tomotherapy (p=0.007), and 19.3 and 5.9 Gy for the left. Cochlea (p=0.002). Mean cochlea dose reported in the literature ranged from 16 to 55 Gy with IMRT for head and neck cancer. Helical Tomotherapy for head and neck cancer may significantly decrease radiation dose to the cochlea without sacrificing target volume coverage.