Radiation Effective patient dose

Approximation of the dose delivered to the patient during a CT scan that takes into account the different organ sensitivities to radiation. Effective patient dose is measured in millisieverts. 

Coy P, Hodson BM, Payne D, et al. The effect of dose of thoracic irradiation on recurrence in patients with limited stage small-cell lung cancer. Initial results of a Canadian multicenter randomized trial. Int J Radiat Oncol Biol Phys 1987 14 219-226. 

Kato I, Mori T, Kumatori T. 1983. Estimated absorbed dose in tissues and radiation effects in Japanese Thorotrast patients. Health Phys 44(Suppl 1) 273-279. 

The medical and scientific communities soon realized that the power of radiation had to be carefully channelled to ensure that its effects were curative rather than harmful. They devised shielding, remote handling devices, and ventilation systems to protect workers from radiation. They also developed international standards to gauge workers exposure to radiation and calibrate doses given to patients. Working with radium came to involve protection as much as application. 

Radioactive iodine is given by tlie primary health care provider, orally as a single dose The effects of iodides are evident within 24 hours, with maximum effects attained after 10 to 15 days of continuous therapy. If the patient is hospitalized, radiation safety precautions identified by the hospital s department of nuclear medicine are followed. 

This royal-blue-colored drug is an anthracenedione that inhibits DNA topoisomerase II. The pharmacokinetics of mitoxantrone may best be described by a three-compartment model, with an a half-life of 3 to 10 minutes, a 3 half life of 0.3 to 3 hours, and a median terminal half-life of 12 days. Biliary elimination appears to be the primary route of elimination, with less than 10% of the drug eliminated by the kidney.23 Mitoxantrone has shown clinical activity in the treatment of acute leukemias, breast and prostate cancer, and non-Hodgkin s lymphomas. Myelosuppression, mucositis, nausea and vomiting, and cardiac toxicity are side effects of this drug. The total cumulative dose limit is 160 mg/m2 for patients who have not received prior anthracycline or mediastinal radiation. Patients who have received prior doxorubicin or daunorubicin therapy should not receive a cumulative dose greater than 120 mg/m2 of mitoxantrone. Patients should be counseled that their urine will turn a blue-green color. 

In HSCT, very high doses of chemotherapy with or without total-body radiation (TBI) are given in an attempt to potentiate leukemia cell kill. Hematopoiesis is restored by the infusion of stem cells harvested from an HLA-compatible donor, thereby rescuing the patient from the consequences of total aplasia.13 It is the most effective antileukemic therapy currently available. 

After phase I trials had determined the safety of paclitaxel doses of 45-50 mg/m2/ wk and carboplatin of AUC 2/wk concurrent with standard RT of 66 Gy/7 wk, phase II trials yielded encouraging survival results (69). Acute esophageal grade III or greater toxicity was high (30-50%) however, most patients fully recovered from these acute effects. Choy extended the experience with concurrent radiation and paclitaxel/ carboplatin using hyperfractionated radiation to 69.6 Gy and observed a 1-yr survival of 63% (70). 

The optimal dose of radiation therapy for patients with limited stage disease is unknown. Full dose radiation therapy is critical to achieve the therapeutic gain of local tumor control. Effective chemotherapy may allow a decrease in the radiation dose needed for local control (26). In the presence of chemotherapy, the radiation dose theoretically can be reduced 20% to control the tumor. Thus the dose for complete response, approx 70 Gy, can be decreased to 55 Gy (26). Local recurrence is still around 40-50% (27). Retrospective trials revealed that doses less than 40 Gy were not adequate for local control (28). 

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