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Radioisotope for occult lesion localisation (ROLL) of the breast does not require extra radiation protection procedures
The Breast (2003) 12, 150–152 0960-9776/03/$-see front matter r 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0960-9776(02)00265-5
SHORT REPORT
Radioisotope for occult lesion localisation (ROLL) of the breast does not require extra radiation protection procedures R. S. Rampaul,1 N. J. Dudley,2 J. Z. Thompson,3 H. Burrell,3 A. J. Evans,3 A. R. M. Wilson3 and R. D. Macmillan1 1
Professorial Unit of Surgery, Nottingham City Hospital, Nottingham, UK; 2 Department of Medical Physics, Nottingham City Hospital, Nottingham, UK and 3 Department of Radiology, Nottingham City Hospital, Nottingham, UK
S U M M A R Y . Aim of study: Dosimetry data from patients and hospital personnel involved in the use of radioisotope for occult lesion localisation (ROLL) of the breast were collected to determine the need for extra radiation protection procedures. Methods: Sixty-three patients have been enrolled to date into a randomised trial evaluating ROLL. Two megabecquerels of 99mTc- MAA in a syringe was mixed with X-ray contrast medium; this was injected directly into the lesion under image guidance. A gamma-detecting probe (Neo-Probe) was used to locate the area of radioactivity. Radiation doses to all staff groups were estimated using time and motion studies and dose rate measurements at a range of distances during each stage of ROLL. Results: The finger dose [FD](795% CI) was considered to be the critical variable for surgeons and radiologists. Surgeon FD=9.373.3mSv, Radiologist FD=0.570.13 mSv. Whole body doses [WBD](795% CI) were estimated for other staff groups. Nurse WBD=0.470.4 mSv, porter WBD: nil, contamination and waste: nil. Conclusions: In the case of a surgeon performing 100 procedures per annum, a FD dose of approximately 1 mSv is received, well within the annual dose limit of 150 mSv. Annual WBD to assisting staff may reach 0.04 mSv, compared to an annual limit of 6 mSv. These low doses and the lack of contamination of radioactive waste indicate that no additional radiation protection measures are required. r 2003 Elsevier Science Ltd. All rights reserved.
alternative for lesions of the breast–radioisotope for occult lesion localisation (ROLL).1 This is yet another application of radioisotopes adding to a growing number of diagnostic and therapeutic uses in the breast, such as sentinel node biopsy, radioimmunotherapy and scintimammography. Thus, it is imperative for us to quantify the possible exposure personnel may encounter in using any of these techniques. The benefits of increasing use of radioisotopes must not compromise safety to either patients or staff. We have used ROLL at our hospital as part of a prospective randomised ROLL vs wire trial.2 For this trial, Luini’s initial description of ROLL has been modified.3 Dosimetry data for the patients and hospital personnel involved have been collected and analysed with the aim of determining if specific radiation
INTRODUCTION The introduction of widespread breast screening programmes has led to an increased detection of impalpable lesions that require accurate biopsy or excision techniques. Standard practice is to utilise some sort of image-guided localisation such as wire or even carbon granules. These techniques are, however, not entirely ideal. Radioisotopeguided localisation has been advocated as an effective Address correspondence to: Dr R. S. Rampaul MB, BS, Research Fellow, The Breast Unit, City Hospital, Nottingham NG1 5PB, UK. Tel.: +44 0115 969 1169; Fax: +44 0115 840 2632; E-mail: [email protected] Received: 12 August 2002 Revised: 18 September 2002 Accepted: 23 October 2002
150
Radioisotope for occult lesion localisation protection issues should be considered by institutions wishing to undertake this technique.
METHODS Dose rates and handling times were measured for seven cases at each stage of the localisation and diagnostic process where the radioactive material was present and unshielded. Where dose rates were impractical to measure or very low, e.g, the tumour surface, dose rates were calculated from the specific gamma ray constant for 99mTc (0.017 mSv/MBq h at 1 m) and the injected activity. Skin (equivalent) doses and whole body (equivalent) doses were then calculated from summing dose–time products for each individual in each exposure event. In the first stage of the process, 2 MBq 99mTc- MAA was provided to the radiologist in a syringe and mixed with X-ray contrast medium in the same syringe. This was then injected directly into the breast tumour under ultrasound guidance. Dose rates were measured at the needle end (worst case) of the shielded syringe at 0 and 10 cm and total handling time was recorded. Finger dose was estimated as the product of dose rate (worst case at 0 cm) and handling time; this is somewhat unrealistic as the syringe is handled by the shield and plunger, we also calculated the unshielded dose for comparison. In the operating theatre, a gamma detecting probe (Neo-Probe) was used to locate the area of radioactivity, which was then excised. Dose rates at the skin surface, 10 and 50 cm were measured and the operating time and direct contact time with the tumour were recorded. Finger dose was estimated as the product of operating time and dose rate at the patient’s skin surface with the addition of the product of the dose rate at 1 cm from a point source (170 mSv/MBq h) of the injection activity and the direct tumour handling time. The whole body dose to staff in the theatre was estimated from the dose rate at 50 cm and the operation time. Specimen X-ray was used to verify completeness of excision. Specimens were carried from theatre to the Xray cabinet in a large plastic box. The radiation dose at the surface of the box was measured and the transport time recorded. Following injection and excision, the stages most likely to cause radioactive contamination and the area of work was monitored with a scintillation monitor. All potentially contaminated (non-sharp) items from the operation were placed in a plastic waste bag and monitored with a scintillation monitor.
Table 1
151
Critical doses for staff groups involved in the ROLL trial
Staff group
Critical dose
Radiologist Surgeon Nurse Porter
Finger Finger Whole body Lower limb
Mean dose per procedure (795% C I) (mSv) 0.5 7 0.13 mSv 9.3 7 3.3 mSv 0.4 7 0.4 mSv 0.5 7 0.05 mSv
RESULTS The skin (fingers) was considered to be the critical organ for radiologists and surgeons; whole body doses were at least an order of magnitude lower than finger doses for these staff. The finger dose to the radiologist if no syringe shield were used was calculated as 4.871.16 mSv. Whole body doses were estimated for the nurses. The radiation dose from the plastic box used to transport specimens was measured as zero; calculation based on the injected activity held at 10 cm for 10 min gave a mean dose of 0.5 mSv to the porter’s leg for each journey. Table 1 shows the critical doses to the staff involved. No contamination was detected and no radioactivity was demonstrated in the waste from the operation.
DISCUSSION In the worst case of the surgeon performing 100 procedures per annum, a skin dose of approximately 1 mSv would be received, mainly from handling the specimen for a short time. A radiologist performing 100 injections with an unshielded syringe would receive a skin dose of approximately 0.5 mSv. The UK annual dose limit to the skin for unclassified workers is 150 mSv. Annual whole body doses to assisting staff may reach 0.04 mSv, compared to the UK annual limit of 6 mSv. Luini et al.1 also investigated the extent of radiation exposure to staff that was encountered in the use of ROLL. They used a higher activity of 3.7 MBq and recorded a mean absorbed dose of 0.03 mGy/MBq. The surgeon’s hand dose was estimated as 7.5 mSv. Both our data and that of Luini et al. show that no additional radiation protection measures are required for the protection of staff or the general public. Despite the minimal radiation hazard associated with this procedure, legislation in many countries requires contamination monitoring following use of unsealed radioactive materials and controlled storage and disposal of radioactive waste. To this end, we recommend that users of this technique take advice on the local legal requirements.
152
The Breast
References 1. Luini A, Zurrida S, Paganelli G et al. Comparison of radioguided excision with localization of occult breast lesions. Br J Surg 1999; 86: 522–525. 2. Rampaul R S, Burrell H, Macmillan R D, Evans A J. Prospective randomized study comparing radio-guided surgery (ROLL) to
wire-guidance for occult breast lesion localization. Eur J Cancer 2001; 37 (5) (Suppl.): 2. 3. Bagnall M J C, Rampaul R S, Evans A J, Wilson A R M, Burrell H C, Geraghty J G. Radioguided occult lesion localization (ROLL) – a new method for locating impalpable breast lesions at surgery. Br J Radiol 2000; 73 (5) (Suppl.): 49.
SHORT REPORT
Radioisotope for occult lesion localisation (ROLL) of the breast does not require extra radiation protection procedures R. S. Rampaul,1 N. J. Dudley,2 J. Z. Thompson,3 H. Burrell,3 A. J. Evans,3 A. R. M. Wilson3 and R. D. Macmillan1 1
Professorial Unit of Surgery, Nottingham City Hospital, Nottingham, UK; 2 Department of Medical Physics, Nottingham City Hospital, Nottingham, UK and 3 Department of Radiology, Nottingham City Hospital, Nottingham, UK
S U M M A R Y . Aim of study: Dosimetry data from patients and hospital personnel involved in the use of radioisotope for occult lesion localisation (ROLL) of the breast were collected to determine the need for extra radiation protection procedures. Methods: Sixty-three patients have been enrolled to date into a randomised trial evaluating ROLL. Two megabecquerels of 99mTc- MAA in a syringe was mixed with X-ray contrast medium; this was injected directly into the lesion under image guidance. A gamma-detecting probe (Neo-Probe) was used to locate the area of radioactivity. Radiation doses to all staff groups were estimated using time and motion studies and dose rate measurements at a range of distances during each stage of ROLL. Results: The finger dose [FD](795% CI) was considered to be the critical variable for surgeons and radiologists. Surgeon FD=9.373.3mSv, Radiologist FD=0.570.13 mSv. Whole body doses [WBD](795% CI) were estimated for other staff groups. Nurse WBD=0.470.4 mSv, porter WBD: nil, contamination and waste: nil. Conclusions: In the case of a surgeon performing 100 procedures per annum, a FD dose of approximately 1 mSv is received, well within the annual dose limit of 150 mSv. Annual WBD to assisting staff may reach 0.04 mSv, compared to an annual limit of 6 mSv. These low doses and the lack of contamination of radioactive waste indicate that no additional radiation protection measures are required. r 2003 Elsevier Science Ltd. All rights reserved.
alternative for lesions of the breast–radioisotope for occult lesion localisation (ROLL).1 This is yet another application of radioisotopes adding to a growing number of diagnostic and therapeutic uses in the breast, such as sentinel node biopsy, radioimmunotherapy and scintimammography. Thus, it is imperative for us to quantify the possible exposure personnel may encounter in using any of these techniques. The benefits of increasing use of radioisotopes must not compromise safety to either patients or staff. We have used ROLL at our hospital as part of a prospective randomised ROLL vs wire trial.2 For this trial, Luini’s initial description of ROLL has been modified.3 Dosimetry data for the patients and hospital personnel involved have been collected and analysed with the aim of determining if specific radiation
INTRODUCTION The introduction of widespread breast screening programmes has led to an increased detection of impalpable lesions that require accurate biopsy or excision techniques. Standard practice is to utilise some sort of image-guided localisation such as wire or even carbon granules. These techniques are, however, not entirely ideal. Radioisotopeguided localisation has been advocated as an effective Address correspondence to: Dr R. S. Rampaul MB, BS, Research Fellow, The Breast Unit, City Hospital, Nottingham NG1 5PB, UK. Tel.: +44 0115 969 1169; Fax: +44 0115 840 2632; E-mail: [email protected] Received: 12 August 2002 Revised: 18 September 2002 Accepted: 23 October 2002
150
Radioisotope for occult lesion localisation protection issues should be considered by institutions wishing to undertake this technique.
METHODS Dose rates and handling times were measured for seven cases at each stage of the localisation and diagnostic process where the radioactive material was present and unshielded. Where dose rates were impractical to measure or very low, e.g, the tumour surface, dose rates were calculated from the specific gamma ray constant for 99mTc (0.017 mSv/MBq h at 1 m) and the injected activity. Skin (equivalent) doses and whole body (equivalent) doses were then calculated from summing dose–time products for each individual in each exposure event. In the first stage of the process, 2 MBq 99mTc- MAA was provided to the radiologist in a syringe and mixed with X-ray contrast medium in the same syringe. This was then injected directly into the breast tumour under ultrasound guidance. Dose rates were measured at the needle end (worst case) of the shielded syringe at 0 and 10 cm and total handling time was recorded. Finger dose was estimated as the product of dose rate (worst case at 0 cm) and handling time; this is somewhat unrealistic as the syringe is handled by the shield and plunger, we also calculated the unshielded dose for comparison. In the operating theatre, a gamma detecting probe (Neo-Probe) was used to locate the area of radioactivity, which was then excised. Dose rates at the skin surface, 10 and 50 cm were measured and the operating time and direct contact time with the tumour were recorded. Finger dose was estimated as the product of operating time and dose rate at the patient’s skin surface with the addition of the product of the dose rate at 1 cm from a point source (170 mSv/MBq h) of the injection activity and the direct tumour handling time. The whole body dose to staff in the theatre was estimated from the dose rate at 50 cm and the operation time. Specimen X-ray was used to verify completeness of excision. Specimens were carried from theatre to the Xray cabinet in a large plastic box. The radiation dose at the surface of the box was measured and the transport time recorded. Following injection and excision, the stages most likely to cause radioactive contamination and the area of work was monitored with a scintillation monitor. All potentially contaminated (non-sharp) items from the operation were placed in a plastic waste bag and monitored with a scintillation monitor.
Table 1
151
Critical doses for staff groups involved in the ROLL trial
Staff group
Critical dose
Radiologist Surgeon Nurse Porter
Finger Finger Whole body Lower limb
Mean dose per procedure (795% C I) (mSv) 0.5 7 0.13 mSv 9.3 7 3.3 mSv 0.4 7 0.4 mSv 0.5 7 0.05 mSv
RESULTS The skin (fingers) was considered to be the critical organ for radiologists and surgeons; whole body doses were at least an order of magnitude lower than finger doses for these staff. The finger dose to the radiologist if no syringe shield were used was calculated as 4.871.16 mSv. Whole body doses were estimated for the nurses. The radiation dose from the plastic box used to transport specimens was measured as zero; calculation based on the injected activity held at 10 cm for 10 min gave a mean dose of 0.5 mSv to the porter’s leg for each journey. Table 1 shows the critical doses to the staff involved. No contamination was detected and no radioactivity was demonstrated in the waste from the operation.
DISCUSSION In the worst case of the surgeon performing 100 procedures per annum, a skin dose of approximately 1 mSv would be received, mainly from handling the specimen for a short time. A radiologist performing 100 injections with an unshielded syringe would receive a skin dose of approximately 0.5 mSv. The UK annual dose limit to the skin for unclassified workers is 150 mSv. Annual whole body doses to assisting staff may reach 0.04 mSv, compared to the UK annual limit of 6 mSv. Luini et al.1 also investigated the extent of radiation exposure to staff that was encountered in the use of ROLL. They used a higher activity of 3.7 MBq and recorded a mean absorbed dose of 0.03 mGy/MBq. The surgeon’s hand dose was estimated as 7.5 mSv. Both our data and that of Luini et al. show that no additional radiation protection measures are required for the protection of staff or the general public. Despite the minimal radiation hazard associated with this procedure, legislation in many countries requires contamination monitoring following use of unsealed radioactive materials and controlled storage and disposal of radioactive waste. To this end, we recommend that users of this technique take advice on the local legal requirements.
152
The Breast
References 1. Luini A, Zurrida S, Paganelli G et al. Comparison of radioguided excision with localization of occult breast lesions. Br J Surg 1999; 86: 522–525. 2. Rampaul R S, Burrell H, Macmillan R D, Evans A J. Prospective randomized study comparing radio-guided surgery (ROLL) to
wire-guidance for occult breast lesion localization. Eur J Cancer 2001; 37 (5) (Suppl.): 2. 3. Bagnall M J C, Rampaul R S, Evans A J, Wilson A R M, Burrell H C, Geraghty J G. Radioguided occult lesion localization (ROLL) – a new method for locating impalpable breast lesions at surgery. Br J Radiol 2000; 73 (5) (Suppl.): 49.