In vivo skin dose measurement using MOSkin detectors in tangential breast radiotherapy.

The purpose of this study is to measure patient skin dose in tangential breast radiotherapy. Treatment planning dose calculation algorithm such as Pencil Beam Convolution (PBC) and in vivo dosimetry techniques such as radiochromic film can be used to accurately monitor radiation doses at tissue depths, but they are inaccurate for skin dose measurement. A MOSFET-based (MOSkin) detector was used to measure skin dose in this study. Tangential breast radiotherapies ("bolus" and "no bolus") were simulated on an anthropomorphic phantom and the skin doses were measured. Skin doses were also measured in 13 patients undergoing each of the techniques. In the patient study, the EBT2 measurements and PBC calculation tended to over-estimate the skin dose compared with the MOSkin detector (p<0.05) in the "no bolus radiotherapy". No significant differences were observed in the "bolus radiotherapy" (p>0.05). The results from patients were similar to that of the phantom study. This shows that the EBT2 measurement and PBC calculation, while able to predict accurate doses at tissue depths, are inaccurate in predicting doses at build-up regions. The clinical application of the MOSkin detectors showed that the average total skin doses received by patients were 1662±129cGy (medial) and 1893±199cGy (lateral) during "no bolus radiotherapy". The average total skin doses were 4030±72cGy (medial) and 4004±91cGy (lateral) for "bolus radiotherapy". In some cases, patient skin doses were shown to exceed the dose toxicity level for skin erythema. Hence, a suitable device for in vivo dosimetry is necessary to accurately determine skin dose.

Chemotherapy extravasation at hospital pulau pinang, malaysia.

PURPOSE: Extravasation with intravenous chemotherapy is a common complication of chemotherapy which carries the risk of devastating complications. This study aims to determine the rate of extravasation with intravenous chemotherapy in a major hospital where chemotherapy is delivered in various departments other than the oncology department. PATIENTS AND METHODS: All patients who underwent intravenous chemotherapy in the oncology department and surgical wards in Penang General hospital from 1st February 2008 till 31st June 2008 were recruited retrospectively for this study to look at the rate of extravasation. RESULTS: A total of 602 patients underwent intravenous chemotherapy during this period. Fifty patients received chemotherapy in the general surgical ward while another 552 patients received chemotherapy in the oncology department. There were 5 cases of extravasation giving an overall extravasation rate of 0.8% (5/602). however, 4 of these cases occurred in the general surgical ward giving it a rate of 8% (4/50). CONCLUSION: The rate of extravasation in our hospital was 0.8%. however, this rate can be significantly increased if it is not done under a specialized unit delivering intravenous chemotherapy on a regular basis. Preventive steps including a standard chemotherapy delivery protocol, staff and patient education must be put in place in all units delivering intravenous chemotherapy.

Comparison of planned and measured rectal dose in-vivo during high dose rate Cobalt-60 brachytherapy of cervical cancer.

Cobalt-60 (Co-60) is a relatively new source for the application of high-dose rate (HDR) brachytherapy. Radiation dose to the rectum is often a limiting factor in achieving the full prescribed dose to the target during brachytherapy of cervical cancer. The aim of this study was to measure radiation doses to the rectum in-vivo during HDR Co-60 brachytherapy. A total of eleven HDR brachytherapy treatments of cervical cancer were recruited in this study. A series of diodes incorporated in a rectal probe was inserted into the patient's rectum during each brachytherapy procedure. Real-time measured rectal doses were compared to calculated doses by the treatment planning system (TPS). The differences between calculated and measured dose ranged from 8.5% to 41.2%. This corresponds to absolute dose differences ranging from 0.3 Gy to 1.5 Gy. A linear relationship was observed between calculated and measured doses with linear regression R(2) value of 0.88, indicating close association between the measured and calculated doses. In general, absorbed doses for the rectum as calculated by TPS were observed to be higher than the doses measured using the diode probe. In-vivo dosimetry is an important quality assurance method for HDR brachytherapy of cervical cancer. It provides information that can contribute to the reduction of errors and discrepancies in dose delivery. Our study has shown that in-vivo dosimetry is feasible and can be performed to estimate the dose to the rectum during HDR brachytherapy using Co-60.