Patient description: The patient is a 16-year-old girl recently diagnosed with myasthenia gravis, class IIa. She complains of diplopia and weakness affecting in her upper extremities. She had a positive anti-AChR antibody test, and her single fiber electromyography (SFEMG) was positive. She is on acetylcholinesterase inhibitor treatment combined with immunosuppressants. But she still has some symptoms. She does not smoke or use illicit drugs. She is not sexually active, and her menses are regular. Her physical exam and lab studies are not remarkable for any other abnormalities. BP: 110/75 Hgb: 11 g/dl WBC: 8000 /mm3 Plt: 300000 /ml Creatinine: 0.5 mg/dl BUN: 10 mg/dl Beta hcg: negative for pregnancy

Clinical trial eligibility criteria: eligible ages (years): 0.5-25.0,  Neuroblastoma Ganglioneuroblastoma Participants must have histologically confirmed neuroblastoma or ganglioneuroblastoma or elevated urinary catecholamine metabolites. If tumor tissue was obtained, pathological review of surgical specimen at the Massachusetts General Hospital or other DF/HCC institution is required, but preliminary report only required prior to enrollment. If no tumor tissue was obtained, urinary catecholamine metabolites are required Participants do not need to have measurable disease at the time of radiation. Age ≥ 3 and ≤ 25 years at the time of diagnosis because this study evaluates this disease entity in the pediatric population which may differ from the adult population Life expectancy of greater than 12 months ECOG performance status ≤2 (Karnofsky ≥60%, Lansky ≥60%, see Appendix A) Diagnostic Imaging MRI and/or CT of the area to be treated within 8 weeks of any treatment. Baseline bone marrow biopsy and bone scan (with 99mTc-diphosphonate or MIBG scan (131I-MIBG or 123I-MIBG) from time of original diagnosis is required Because radiation is known to be teratogenic, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately Ability of the patient or the patient's legal guardian to understand and the willingness to sign a written informed consent document Participants or their legal guardian must sign consent prior to the initiation of radiation therapy  Patients will be ineligible if any prior therapeutic radiation therapy > 500 cGy has been delivered Patients will be ineligible if chemotherapy was completed ≥ 1 year from the planned start date of radiation therapy or if the patient is referred for radiation therapy after a relapse following a regimen with chemotherapy alone Individuals with a history of a different malignancy are ineligible except for the following circumstances. Individuals with a history of other malignancies are eligible if they have been disease-free for at least 5 years and are deemed by the investigator to be at low risk for recurrence of that malignancy. Individuals with the following cancers are eligible if diagnosed and treated within the past 5 years: cervical cancer in situ, and basal cell or squamous cell carcinoma of the skin Pregnant females are excluded. Women of childbearing age/menstruating must have a negative pregnancy test prior to initiation of radiation therapy