Impact of collimator leaf width and treatment technique on stereotactic radiosurgery and radiotherapy plans for intra- and extracranial lesions

Background:
This study evaluated the dosimetric impact of various treatment techniques as well as collimator leaf width (2.5 vs 5mm) for three groups of tumors – spine tumors, brain tumors abutting the brainstem, and liver tumors. These lesions often present challenges in maximizing dose to target volumes without exceeding critical organ tolerance. Specifically, this study evaluated the dosimetric benefits of various techniques and collimator leaf sizes as a function of lesion size and shape.
Methods:
Fifteen cases (5 for each site) were studied retrospectively. All lesions either abutted or were an integral part of critical structures (brainstem, liver or spinal cord). For brain and liver lesions, treatment plans using a 3D-conformal static technique (3D), dynamic conformal arcs (DARC) or intensity modulation (IMRT) were designed with a conventional linear accelerator with standard 5mm leaf width multi-leaf collimator, and a linear accelerator dedicated for radiosurgery and hypofractionated therapy with a 2.5mm leaf width collimator. For the concave spine lesions, intensity modulation was required to provide adequate conformality; hence, only IMRT plans were evaluated using either the standard or small leaf-width collimators.
A total of 70 treatment plans were generated and each plan was individually optimized according to the technique employed. The Generalized Estimating Equation (GEE) was used to separate the impact of treatment technique from the MLC system on plan outcome, and t-tests were performed to evaluate statistical differences in target coverage and organ sparing between plans.
Results:
The lesions ranged in size from 2.6 to 12.5cc, 17.5 to 153 cc, and 20.9 to 87.7 cc for the brain, liver, and spine groups, respectively. As a group, brain lesions were smaller than spine and liver lesions. While brain and liver lesions were primarily ellipsoidal, spine lesions were more complex in shape, as they were all concave. Therefore, the brain and the liver groups were compared for volume effect, and the liver and spine groups were compared for shape. For the brain and liver groups, both the radiosurgery MLC and the IMRT technique contributed to the dose sparing of organs-at-risk(OARs), as dose in the high-dose regions of these OARs was reduced up to 15%, compared to the non-IMRT techniques employing a 5mm leaf-width collimator. Also, the dose reduction contributed by the fine leaf-width MLC decreased, as dose savings at all levels diminished from 4 -11% for the brain group to 1 – 5% for the liver group, as the target structures decreased in volume. The fine leaf-width collimator significantly improved spinal cord sparing, with dose reductions of 14 -19% in high to middle dose regions, compared to the 5mm leaf width collimator.
Conclusions:
The fine leaf-width MLC in combination with the IMRT technique can yield dosimetric benefits in radiosurgery and hypofractionated radiotherapy. treatment of small lesions in cases involving complex target/OAR geometry will especially benefit from use of a fine leaf-width MLC and the use of IMRT.

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Kidney Disease Link To Cancer In Older Men

WESTMEAD, Australia — Australian researchers suggest moderate kidney disease raises an older man’s risk of cancer. The study, published in the Journal of the American Society of Nephrology, finds the risk for lung and urinary tract cancers — but not prostate cancer — was higher among men with kidney disease. The researchers discovered that men with moderate kidney dysfunction had a 39 percent increased risk of developing cancer over the risk seen in men with normal kidney function. Inflammation associated with chronic kidney disease may contribute to the development of cancer, or a lack of vitamin D — highly prevalent among people with moderately reduced kidney function — might increase cancer risk. Additional…

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Massage Therapist Saves a Life!

Massage Therapist Saves a Life! We all know massage offers great benefits to clients, everything from physical to emotional wellbeing, but I was as surprised as the doctor, when a massage turned out to be a lifesaver. While giving my athletic firefighter husband a relaxing massage, I found a melanoma on the bottom arch of his right foot, the last place you would expect to find it.

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Women Smokers Have A Greater Cancer Risk Than Men, Says New Report

Women smokers are more vulnerable to fatal cancers than men, according to new research. Scientists who studied lung cancer patients found females tended to be younger than males when they developed the disease, despite the fact that on average they smoked significantly less. The findings are particularly important in Scotland, which is one of the world’s most cancer-prone nations, with around 2000 women developing lung cancers each year. Approximately 90 percent of lung cancer cases are caused by smoking, and the majority of patients are male, but researchers now believe that women are more easily affected by the harmful carcinogens contained in tobacco smoke. Dr Martin Fueh, from St Gallen Canton Hospital in Swi…

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Peregrine Pharmaceuticals Reports Positive Preliminary Data From Phase II Bavituximab Lung Cancer Trial

Peregrine Pharmaceuticals, Inc., announced that updated preliminary data from the initial cohort of 21 patients in its Phase II trial evaluating bavituximab in combination with carboplatin and paclitaxel showed that 11 of 17 evaluable patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) achieved an objective tumor response according to RECIST criteria, after completing the maximum six treatment cycles. The company also reported that patient dosing is underway in the expansion stage of the trial, which will enroll an additional 28 patients for a total of 49 patients overall. “We are very pleased to see these additional objective tumor responses in this difficult-to-treat cancer following the full regimen of six…

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On the performances of Intensity Modulated Protons, RapidArc and Helical Tomotherapy for selected paediatric cases

Background:
To evaluate the performance of three different advanced treatment techniques on a group of complex paediatric cancer cases.
Methods:
CT images and volumes of interest of five patients were used to design plans for Helical Tomotherapy (HT), RapidArc (RA) and Intensity Modulated Proton therapy (IMP). The tumour types were: extraosseous, intrathoracic Ewing Sarcoma; mediastinal Rhabdomyosarcoma; metastatic Rhabdomyosarcoma of the anus; Wilm’s tumour of the left kidney with multiple liver metastases, and metastastis of base of skull with bone, para-nasal and left eye infiltration from Nephroblastoma of right kidney. Cases were selected for their complexity regardless the treatment intent and stage. Prescribed doses ranged from 18 to 53.2 Gy, with four cases treated using a Simultaneous Integrated Boost strategy. Results were analysed in terms of dose distributions and dose volume histograms.
Results:
For all patients, IMP plans lead to superior sparing of organs at risk and normal healthy tissue. In terms of conformity and of spillage of high doses outside targets (external index (EI)), all three techniques were comparable; CI90 ranged from 1.0 to 2.3 and EI from 0 to 5%. Concerning target homogeneity, IMP showed a variance (D5-D95) measured on the inner target volume (highest dose prescription) ranging from 5.9 to 13.3%, RA from 5.3 to 11.8%, and HT from 4.0 to 12.2%. The range of minimum significant dose to the same target was: (72.2%,89.9%) for IMP, (86.7%,94.1%) for RA, and (79.4%,94.8%) for HT. Similarly, for maximum significant doses: (103.8%,109.4%) for IMP, (103.2%,107.4%) for RA, and (102.4%,117.2%) for HT. treatment times (beam-on time) ranged from 123 to 129 s for RA and from 146 to 387 s for HT.
Conclusions:
Five complex pediatric cases were selected as representative examples to compare three advanced radiation delivery techniques. While differences were noted in the metrics examined, all three techniques provided satisfactory conformal avoidance and conformation.

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Urine Test May Determine If A Smoker Is At Risk For Lung Cancer

Researchers may have uncovered why lung cancer afflicts some smokers and not others, according to data presented at the American Association for Cancer Research 100th Annual Meeting 2009 (see also American Association for Cancer Research). “A history of smoking has always been thought of as a predictor of lung cancer, but it is actually not very accurate,” said Jian-Min Yuan, Ph.D., M.D., associate professor of public health at the University of Minnesota. “Smoking absolutely increases your risk, but why it does so in some people but not others is a big question.” Yuan and colleagues hypothesized that the presence of the metabolite NNAL in a patient’s urine might predict risk of lung cancer. This metabolite has been shown to induce lung…

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Don’t Ignore Skin Cancer Warning Signs

As we move toward beach season, we’ll all be spending more time outdoors and raising our chances of joining the ranks of the 1 million people the American cancer Society tells us are diagnosed with skin cancer each year, which is why it’s vital not to ignore skin cancer warning signs. Experts firmly believe many of these cancers are sun related, which means there are things you can do, even in the summer or at the beach, to protect yourself and those you love from this most common of cancers.

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Racial Disparities Persist In The Treatment Of Lung Cancer

Black patients suffering from lung cancer are less likely to receive recommended chemotherapy and surgery than white lung cancer patients, a disparity that shows no signs of lessening. That is the conclusion of a new study published in the May 15, 2009 issue of CANCER, a peer-reviewed journal of the American Cancer Society. The study’s findings indicate that efforts are needed to provide appropriate treatments for black patients and to educate them about the value of those treatments. Researchers led by Dale Hardy, Ph.D., of the University of Texas School of Public Health analyzed data from 83,101 patients 65 years old or older who were diagnosed with non-small cell lung cancer, the most common type of lung cancer, between 1991 and 2002….

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Recommendations for implementing stereotactic radiotherapy in peripheral stage IA non-small cell lung cancer: report from the Quality Assurance Working Party of the randomised phase III ROSEL study

Background:
A phase III multi-centre randomised trial (ROSEL) has been initiated to establish the role of stereotactic radiotherapy in patients with operable stage IA lung cancer. Due to rapid changes in radiotherapy technology and evolving techniques for image-guided delivery, guidelines had to be developed in order to ensure uniformity in implementation of stereotactic radiotherapy in this multi-centre study.
Methods:
A Quality Assurance Working Party was formed by radiation oncologists and clinical physicists from both academic as well as non-academic hospitals that had already implemented stereotactic radiotherapy for lung cancer. A literature survey was conducted and consensus meetings were held in which both the knowledge from the literature and clinical experience were pooled. In addition, a planning study was performed in 26 stage I patients, of which 22 were stage 1A, in order to develop and evaluate the planning guidelines. Plans were optimised according to parameters adopted from RTOG trials using both an algorithm with a simple homogeneity correction (Type A) and a more advanced algorithm (Type B) . Dose conformity requirements were then formulated based on these results.
Conclusions:
Based on current literature and expert experience, guidelines were formulated for this phase III study of stereotactic radiotherapy versus surgery. These guidelines can serve to facilitate the design of future multi-centre clinical trials of stereotactic radiotherapy in other patient groups and aid a more uniform implementation of this technique outside clinical trials.

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