Objective： This study aimed to evaluate of the accuracy and efficiency of the in-vivo dosimetry systems for routine cancer patient dose verification. Methods： In vivo dosimetry, using diodes and thermoluminescent do...Objective： This study aimed to evaluate of the accuracy and efficiency of the in-vivo dosimetry systems for routine cancer patient dose verification. Methods： In vivo dosimetry, using diodes and thermoluminescent dosimeters （TLD） is performed in many radiotherapy departments to verify the dose delivered during treatment. A total of 40 TLD divided into two batches （one of 20 and other of 20 TLD） were used. Different doses of Co6~ beam were delivered to the TLD chips at different depths. Diodes were irradiated at different depths in a （30 x 30 x 30） cm3 water slab phantom with various conditions of Field sizes, monitor units and SSDs. Results： The limitation of the in-vivo dosimetry technique is that dose can only be in system readout difficulty and type of readout （TLD system and diode） as the patient dose is directly measured. Several authors have investigated the measurements was 1.3%, with a standard deviation of 2.6%. Results were normally distributed around a mean as -0.39 and 0.34 respectively. After the evaluation of in vivo dosimetry brain case as an example, the mean doses for both eyes were 1.8%, with a standard deviation of 2.7%. These results are similar to studies conducted with diodes and TLD＇s. Conclusion： The diode is superior to TLD, since the diode measurements can be obtained on line and allows an immediate check. Other advantages of diodes include high sensitivity, good spatial resolution, and small size, simplicity of used.展开更多
基金Supported by grants from the Al-Hosain Hospital, Faculty of Medicine, Al Azhar University and Tanta University
文摘Objective： This study aimed to evaluate of the accuracy and efficiency of the in-vivo dosimetry systems for routine cancer patient dose verification. Methods： In vivo dosimetry, using diodes and thermoluminescent dosimeters （TLD） is performed in many radiotherapy departments to verify the dose delivered during treatment. A total of 40 TLD divided into two batches （one of 20 and other of 20 TLD） were used. Different doses of Co6~ beam were delivered to the TLD chips at different depths. Diodes were irradiated at different depths in a （30 x 30 x 30） cm3 water slab phantom with various conditions of Field sizes, monitor units and SSDs. Results： The limitation of the in-vivo dosimetry technique is that dose can only be in system readout difficulty and type of readout （TLD system and diode） as the patient dose is directly measured. Several authors have investigated the measurements was 1.3%, with a standard deviation of 2.6%. Results were normally distributed around a mean as -0.39 and 0.34 respectively. After the evaluation of in vivo dosimetry brain case as an example, the mean doses for both eyes were 1.8%, with a standard deviation of 2.7%. These results are similar to studies conducted with diodes and TLD＇s. Conclusion： The diode is superior to TLD, since the diode measurements can be obtained on line and allows an immediate check. Other advantages of diodes include high sensitivity, good spatial resolution, and small size, simplicity of used.
