Precision multi-lesion phantom sharpens stereotactic radiosurgery
Stereotactic radiosurgery (SRS) treats small tumours in the brain by delivering high doses of radiation to the target area with sub-millimeter precision, preserving the surrounding healthy tissue. Initially, the treatment was focused on patients with a small number of lesions. But interest in the approach has broadened as clinicians have discovered that survival times and benefits persist even for more complex cases.
Treating multiple brain metastases simultaneously means fewer patient trips to the clinic, and minimizes the amount of time that patients need to be immobilized while treatment takes place. It also allows more people to benefit from more productive use of hospital resources.
But the challenge comes in finding a more efficient way of assessing the treatment plan, which already posed a number of technical hurdles. “Many of those lesions are very small targets,” points out Jacqueline Maurer, a medical physicist based in the US.
The delivery dose can be difficult not just to model, but also to measure. Using the most common detector arrays, the spacing between individual sensing elements is too coarse. There are time constraints to consider too – for example, using a single device to evaluate 10 targets one by one requires the treatment plan to be delivered 10 times, which is impractical.
The solution is a precision brain phantom that features as many as 29 parallel imaging planes, each one loaded with radiation-sensitive film spaced at 5 mm increments. “You can deliver the plan a single time and get high-resolution absolute dose measurements by arranging the film so that it bisects each of the lesions,” Maurer explains.
Customer-led design
Unable to realize a set-up using existing materials, Maurer sketched out her idea to CIRS, a US manufacturer of tissue-equivalent phantoms and simulators for medical imaging, radiation therapy and procedural training. “I thought this geometry might work, but there wasn’t a product on the market and so I approached Vladimir, one of the engineers at CIRS,” Maurer remembers.
Back in the factory, the CIRS team worked up several prototypes and added a range of useful features. The phantom – dubbed model 037 – measures 150 mm (W) x 190 mm (H) x 170 mm (L) to cover variations in brain anatomy, and weighs 5 kg. Constructed from brain-equivalent epoxy resin, the unit is designed to exhibit a linear attenuation that’s within 1% of real tissue from 50 keV to 15 MeV.
“We wanted to make multi-lesion treatment available to our patients, but at the same time we didn’t want to risk inaccuracies in the procedure,” says Maurer. “The phantom let us do it confidently.” This includes running a sequence of patient quality assurance (QA) and characterization tests to ensure that the radiation is being delivered as expected.
End-to-end testing
In the clinic, Maurer and her colleagues were able to take the QA device through each part of the process that the patient goes through. “You can put the phantom on the CT scanner, take an image, and send the information to your treatment planning system,” she explains. “And from there you can carry out the QA steps, which include imaging the phantom on the linear accelerator (linac) and checking the film to see how well you did.”
SRS treatments can involve very steep dose gradients, which puts extra pressure on the team to make sure that everything is positioned correctly. “You could have a 40% dose error for just being 1 mm off target,” Maurer cautions.
The precision with which CIRS is able to construct the product is a key part of the SRS multi-lesion brain QA phantom’s success. When loaded with sheets of radiation-sensitive film – also available from the firm – each layer in the device is exactly 5 mm apart, according to the specification.The M037 phantom from CIRS
Holding the phantom together are four threaded bolts, positioned one in each corner, but that’s not their only feature. Because the bolts are made of materials with different Hounsfield units – a measure of linear attenuation – the combination provides X-ray visible reference structures that can be used for positioning by the linac’s onboard imaging software.
“Automatic image registration algorithms tell you exactly what your shifts in rotation need to be to get your phantom in precisely the right spot,” says Maurer. “And if you agree with the match then the alignment software will automatically send those shifts and rotations to your machine, which make those hairline adjustments for you.”
Just like during treatment, the phantom can be positioned complete with couch kicks (table rotations) so that the geometry is the same as the patient geometry. “What you see on the film is an actual representation of the dose to the patient,” Maurer concludes.
For full product specifications, visit www.cirsinc.com
7/9/2018 FROM PHYSICSWORLD.COM
Irrespective of receiving daily oral or future injectable depot therapies, these require health care visits for medication and monitoring of safety and response. If patients are treated early enough, before a lot of immune system damage has occurred, life expectancy is close to normal, as long as they remain on successful treatment. However, when patients stop therapy, virus rebounds to high levels in most patients, sometimes associated with severe illness because i have gone through this and even an increased risk of death. The aim of “cure”is ongoing but i still do believe my government made millions of ARV drugs instead of finding a cure. for ongoing therapy and monitoring. ARV alone cannot cure HIV as among the cells that are infected are very long-living CD4 memory cells and possibly other cells that act as long-term reservoirs. HIV can hide in these cells without being detected by the body’s immune system. Therefore even when ART completely blocks subsequent rounds of infection of cells, reservoirs that have been infected before therapy initiation persist and from these reservoirs HIV rebounds if therapy is stopped. “Cure” could either mean an eradication cure, which means to completely rid the body of reservoir virus or a functional HIV cure, where HIV may remain in reservoir cells but rebound to high levels is prevented after therapy interruption.Dr Itua Herbal Medicine makes me believes there is a hope for people suffering from,Parkinson's disease,Schizophrenia,Lung Cancer,Breast Cancer,Colo-Rectal Cancer,Blood Cancer,Prostate Cancer,Scoliosis,Fibromyalgia,Fluoroquinolone Toxicity
ΑπάντησηΔιαγραφήSyndrome Fibrodysplasia Ossificans Progressiva.Fatal Familial Insomnia Factor V Leiden Mutation ,Epilepsy Dupuytren's disease,Desmoplastic small-round-cell tumor Diabetes ,Coeliac disease,Creutzfeldt–Jakob disease,Cerebral Amyloid Angiopathy, Ataxia,Arthritis,Amyotrophic Lateral Sclerosis,Alzheimer's disease,Adrenocortical carcinoma.Asthma,Allergic diseases.Hiv_ Aids,Herpe ,Copd,Glaucoma., Cataracts,Macular degeneration,Cardiovascular disease,Lung disease.Enlarged prostate,Osteoporosis.Alzheimer's disease,
Dementia.
Hpv,All Cancer Types,Diabetes,Hepatitis,I read about him online how he cure Tasha and Tara so i contacted him on drituaherbalcenter@gmail.com / info@drituaherbalcenter.com. even talked on whatsapps +2348149277967 believe me it was easy i drank his herbal medicine for two weeks and i was cured just like that isn't Dr Itua a wonder man? Yes he is! I thank him so much so i will advise if you are suffering from one of those diseases Pls do contact him he's a nice man.
Most prostate cancers are adenocarcinomas, cancers that arise in glandular cells of the prostate’s epithelial tissue. Prostate cancers usually progress slowly and produce no symptoms in the initial stages. Eventually, the tumor may enlarge like mine use too, the prostate gland, pressing on the urethra and causing painful or frequent urination and blood in the urine. So I was so uncomfortable with this prostate cancer diseases then I decided to do online search on how to cure cancer because I well have read a lot about herbal medicine, I came across a lot of testimony how Dr Itua cure HIV/herpes then Cancer was listed below the comment.with courage I contacted Dr Itua and he sent me his herbal medicine through Courier service then I was asked to pick it up at my post office which i quickly did. I contacted Dr Itua that i have received my herbal medicine so he instructs me on how to drink it for three weeks and that is how Dr Itua Herbal Medicine cure my prostate Cancer, The treatment takes three weeks and I was cured completely. Dr Itua is a god sent and I thank him every day of my life. Contact him now On:Email:drituaherbalcenter@gmail.com/ Whatsapp:+2348149277967.
ΑπάντησηΔιαγραφήHe listed to that he can as well cure the following diseases below.... Cerebral Amides. Lung Cancer,Brain cancer,Esophageal cancer,Gallbladder cancer,Gestational trophoblastic disease,Head and neck cancer,Hodgkin lymphoma Intestinal cancer,Kidney cancer,Leukemia,Liver cancer,Melanoma,Mesothelioma,Multiple myeloma,Neuroendocrine tumors,Hodgkin lymphoma,Oral cancer,Ovarian cancer,Sinus cancer,Soft tissue sarcoma,Spinal cancer,Stomach cancer,Testicular cancer,Throat cancer,Thyroid Cancer,Uterine cancer,Vaginal cancer,Vulvar cancer. Alzheimer's disease,Autism,measles, tetanus, whooping cough, tuberculosis, polio and diphtheria Adrenocortical carcinoma. Alma, Uterine Cancer, Breast Cancer, Allergic diseases. Kidney cancer, Love Spell, Glaucoma., Cataracts,Macular degeneration,Cardiovascular disease,Lung disease.Enlarged prostate,Osteoporosis.Generalized dermatitis,Alzheimer's disease,Brain Tumor,Lupus,Endomertil Cancer, cerebrovascular diseases
Dementia.Colo rectal cancer, Lottery Spell, Bladder Cancer, Skin Cancer,Ovarian Cancer,Pancreatic Cancer, HIV /Aids,Brain Tumor, Herpes, Non-Hodgkin lymphoma, Inflammatory bowel disease, Copd, Diabetes, Hepatitis