Objectives: The radio-guided detection of sentinel lymph node has recently been introduced by the European Association of Urology in the guidelines for staging of prostate cancer. Due to the multiple lymph nodes sites that directly drain the prostate, a higher dose of radiopharmaceutical is used compared to the one conventionally used for the other body districts thus potentially carrying a higher risk of personnel radiation exposure. Moreover tracer is directly injected in the tumour trough transrectal ultrasound in a dedicated clinical urology room. Purpose of this study was to measure radiation exposure levels for the staff involved in these procedures. Surface and personal contamination were also measured after tracer administration and surgical dissection. Methods: Data from 21 patients were evaluated. According to our internal protocol, dose administration of four doses of 60 MBq of Tc-99m-albumin nanocolloid each was scheduled at midday of the first day, followed by a SPECT 1/2 hours later and dissection at 8.00 am of the following day. Histological analysis of surgical specimens was made starting at least 36 hours from the administration. Radiation exposure levels were measured in contact to the patient and at 50 cm in front of him at the end and 1/2 hours after tracer administration. Exposure levels were recorded in the surgeons, scrub nurse and anesthetistis positions during surgical dissection. Measurements were used to evaluate radiation doses to the staff. Results: Immediately after radioactivity administration external exposure rates were 48.6±17.0 microGy/h (range 25-87) and 7.2±1.1 microGy/h (5-10) in contact to the abdomen of the patient and 50 cm in front of him respectively. These values reduce to 17.4±8.0 microGy/h (7-33) and 4.6±1.8 microGy/h (2-8) due to urinary excretion and radioactive decay 1/2 hours after the administration. Exposure levels in the surgical room were: 0.7±0.4 microGy/h for the first surgeon, 0.6±0.2 microGy/h for the second and third surgeons, 0.3±0.1 microGy/h for the scrub nurse and 0.2±0.1 microGy/h for the anesthetistis. The higher dose found was 22 microSv/precedure for nuclear medicine physician hands during administration, while global external exposure was lower than 2 microSv/procedure for all the operators. No surface contamination was recorded in any of the situations. Conclusion: external exposure levels in radio-guided detection of sentinel lymph node of prostate cancer are very low and don't represent an added risk for the staff involved.
Dosimetry in radio-guided sentinel lymph node dissection in patients with prostate carcinoma
Cristina Messa;
2012
Abstract
Objectives: The radio-guided detection of sentinel lymph node has recently been introduced by the European Association of Urology in the guidelines for staging of prostate cancer. Due to the multiple lymph nodes sites that directly drain the prostate, a higher dose of radiopharmaceutical is used compared to the one conventionally used for the other body districts thus potentially carrying a higher risk of personnel radiation exposure. Moreover tracer is directly injected in the tumour trough transrectal ultrasound in a dedicated clinical urology room. Purpose of this study was to measure radiation exposure levels for the staff involved in these procedures. Surface and personal contamination were also measured after tracer administration and surgical dissection. Methods: Data from 21 patients were evaluated. According to our internal protocol, dose administration of four doses of 60 MBq of Tc-99m-albumin nanocolloid each was scheduled at midday of the first day, followed by a SPECT 1/2 hours later and dissection at 8.00 am of the following day. Histological analysis of surgical specimens was made starting at least 36 hours from the administration. Radiation exposure levels were measured in contact to the patient and at 50 cm in front of him at the end and 1/2 hours after tracer administration. Exposure levels were recorded in the surgeons, scrub nurse and anesthetistis positions during surgical dissection. Measurements were used to evaluate radiation doses to the staff. Results: Immediately after radioactivity administration external exposure rates were 48.6±17.0 microGy/h (range 25-87) and 7.2±1.1 microGy/h (5-10) in contact to the abdomen of the patient and 50 cm in front of him respectively. These values reduce to 17.4±8.0 microGy/h (7-33) and 4.6±1.8 microGy/h (2-8) due to urinary excretion and radioactive decay 1/2 hours after the administration. Exposure levels in the surgical room were: 0.7±0.4 microGy/h for the first surgeon, 0.6±0.2 microGy/h for the second and third surgeons, 0.3±0.1 microGy/h for the scrub nurse and 0.2±0.1 microGy/h for the anesthetistis. The higher dose found was 22 microSv/precedure for nuclear medicine physician hands during administration, while global external exposure was lower than 2 microSv/procedure for all the operators. No surface contamination was recorded in any of the situations. Conclusion: external exposure levels in radio-guided detection of sentinel lymph node of prostate cancer are very low and don't represent an added risk for the staff involved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
