Aust. Radiol. (1 975),19,303
Letters to the Editor Percutaneous Carotid Arteriography Resurrected. Reference to the scientific paper, “Carotid Angiography by Direct Needle Puncture: an Obsolete Technique,” in your issue of March, 1975. I wish to dissent with the opinions expressed by Palmer and Sorby. I find the title of the article provocative, particularly the words, “an obsolete technique.” In my opinion and those of many practising neuroradiologists, percutaneous carotid angiography is very much in vogue and by no means obsolete. I do not intend entering into a controversy with these authors, but may 1 state that the catheter technique is at best only an alternative method for the study of the carotid circulation. Complications do occur with both techniques, and these could only be minimised by scrupulous technique and good expertise. The illustrations in their paper d o not afford any scientific convincing evidence for the poor results with the percutaneous technique. Similar illustrations and complications could be listed with the catheter technique. In my opinion, there are specific indications for the use of the two methods. I would prefer the catheter approach in children and in patients requiring a simultaneous four-vessel study, while I would use the percutaneous approach in all other conditions, including cerebro-vascular disease. Cerebro-vascular disease in particular requires extensive study of the cerebral circulation. We use arch aortography followed by selective common carotid arteriography in these patients. The catheter method offers two sources for possible complications: 1 . Local complication at the site of femoral puncture. 2. Distal complication due to catheters and guide wires lodged in the cerebral circulation. We use both techniques. We have found the percutaneous method to be a safe and reliable method of investigating the carotid circulation, while we prefer the catheter technique for the vertebrobasilar circulation. With due respect to the authors, I wish to disagree with the opinions expressed in their
paper. Their arguments do not in any way augment the catheter technique, nor do they deride the percutaneous technique. Bertie Ameratunga, Consultant Neuroradiologist, Southland Hospital, Invercargill, N.Z. The Editor-Sir, The New Special Names of Si Units in the Field of Ionizing Radiations. At the meeting of the International Commission on Radiation Units and Measurements (ICRU) in July, 1974, the extensive worldwide response to the previous correspondence on SI units (refs. 1 and 2 ) was discussed in considerable detail. A statement on SI units was then prepared and sent to the International Committee of Weights and Measurements, CIPM, for consideration. In this statement the ICRU recommended the adoption of special names for the S1 unit the joule per kilogram, J/kg, when applied to absorbed dose and related quantities, and for the SI unit the reciprocal second, s - l , when applied to the quantity activity as a measure of the rate of spontaneous nuclear transformation of radioactive nuclides. The ICRU statement was also discussed at the IAEA symposium o n Advances in Biomedical Dosimetry, March 10-14, I975 (ref. 3). The CIPM treated the ICRU proposals with expedience and drafted two resolutions for consideration by the 15th General Conference of Weights and Measures, CCPM, at its meeting in May-June, 1975. At this meeting, which celebrated the 100-year anniversary of the Meter Convention, the CGPM adopted the following resolutions:
Resolution H I The Fifteenth Confirence GCnkrale des Poids et Mesures, --owing to the urgency, expressed by the International Commission on Radiation Units and Measurements (ICRU), to extend the use of the International System of Units to research work and applications in radiology; --owing to the necessity of making the use of units as simple as possible for non-specialists;
Australasian Radiology, Vol. XIX,N o . 3, September, 1975
303
LETTERSTO -taking into account the seriousness of the risk of errors in therapy: ADOPTS the following special name of SI unit for activity: the becquerel, symbol Bq, equal to the second to the power minus one. Resolution H 2 The Fifteenth Conference GCnCrale des Poids et Mesures, --owing to the urgency, expressed by the International Commission on Radiation Units and Measurements (ICRU), to extend the use of the International System of Units to research work and applications in radiology; --owing to the necessity of making the use of units as simple as possible for non-specialists; -taking into account the seriousness of the risk of errors in therapy; ADOPTS the following special name of SI unit for ionizing radiations: the gray, symbol Gy, equal to the joule per kilogram. Explanatory note.-The gray is the SI unit of absorbed dose. The gray can also be used with other physical quantities expressed in joules per kilogram provided these quantities belong to the field of ionizing radiations. Thus the SI unit the joule per kilogram when used for ionizing radiation (absorbed dose, kerma, specific energy imparted, etc.) is given the name gray with the symbol G y ; 1 Gy = 100 rad = 1 J/kg. And the SI unit the reciprocal second (one per second) for activity is given the name becquerel, symbol Bq. 1 Bq = 1 s-I -2.703 x Ci. Antoine Henri Becquerel (1852-1908) discovered radioactivity in 1896 (“rayons de Becquerel”) and was given the Nobel Prize in physics in 1903 together with Marie and Pierre Curie. Louis Harold Gray ( 1905-1965) made one of the most fundamental contributions to radiation dosimetry, the principle now known as the Bragg-Gray Principle.
304
THE
EDITOR
The ICRU did not recommend to the International Committee of Weights and Measures that a special name be given to the SI unit of exposure to replace the currently used rontgen. The ICRU now recommends that the special units the rad, the rontgen and the curie be gradually abandoned over a period not less than about 10 years and replaced by the SI units the gray (Gy ), the coulomb per kilogram (C/kg) and the becquerel (Bq), respectively. It is desirable that preparatory steps be taken as soon as possible by various national and international bodies in order to facilitate a smooth, safe and efficient transition. In its report “Supplement to ICRU Report 19, Dose Equivalent” (ref. 4 ) the ICRU published its decision that the physical dimension of the quantity dose equivalent should be the same as for absorbed dose. From the radiation protection point of view the availability of a proper set of quantities and units in this field is of paramount importance. The formulation (for selection) of a suitable unit for dose equivalent is therefore a special problem which will be thoroughly discussed by ICRU. On behalf of the International Commission on Radiation Units and Measurements: H. 0.Wyckoff, Chairman. A. Allisy, Vice-chairman. Prof. K. LidCn, Scientific Secretarv of ICRU. Radiation Physic; Department, University Hospital, S-221 85, LUND, Sweden. REFERENCES ‘Liden, K. ( 1973) : Australian Radiology, 17, 116. ‘Liden, K. (1974): Acta Radiol. Tlier. Pkys. Biol., 13, 95. 3Lidtn, K. ( 1975): SI Units in Biomedical Dosimetry. In “Advances in Biomedical Dosimetry,” IAEA. Vienna (in press). ‘International Commission on Radiation Units and Measurements: Dose Equivalent Suppl. to Report 19, ICRU, Washington, D.C. (1973).
Australasian Radiology, Vol. X I X , N o . 3, September, I975
Letters to the Editor Percutaneous Carotid Arteriography Resurrected. Reference to the scientific paper, “Carotid Angiography by Direct Needle Puncture: an Obsolete Technique,” in your issue of March, 1975. I wish to dissent with the opinions expressed by Palmer and Sorby. I find the title of the article provocative, particularly the words, “an obsolete technique.” In my opinion and those of many practising neuroradiologists, percutaneous carotid angiography is very much in vogue and by no means obsolete. I do not intend entering into a controversy with these authors, but may 1 state that the catheter technique is at best only an alternative method for the study of the carotid circulation. Complications do occur with both techniques, and these could only be minimised by scrupulous technique and good expertise. The illustrations in their paper d o not afford any scientific convincing evidence for the poor results with the percutaneous technique. Similar illustrations and complications could be listed with the catheter technique. In my opinion, there are specific indications for the use of the two methods. I would prefer the catheter approach in children and in patients requiring a simultaneous four-vessel study, while I would use the percutaneous approach in all other conditions, including cerebro-vascular disease. Cerebro-vascular disease in particular requires extensive study of the cerebral circulation. We use arch aortography followed by selective common carotid arteriography in these patients. The catheter method offers two sources for possible complications: 1 . Local complication at the site of femoral puncture. 2. Distal complication due to catheters and guide wires lodged in the cerebral circulation. We use both techniques. We have found the percutaneous method to be a safe and reliable method of investigating the carotid circulation, while we prefer the catheter technique for the vertebrobasilar circulation. With due respect to the authors, I wish to disagree with the opinions expressed in their
paper. Their arguments do not in any way augment the catheter technique, nor do they deride the percutaneous technique. Bertie Ameratunga, Consultant Neuroradiologist, Southland Hospital, Invercargill, N.Z. The Editor-Sir, The New Special Names of Si Units in the Field of Ionizing Radiations. At the meeting of the International Commission on Radiation Units and Measurements (ICRU) in July, 1974, the extensive worldwide response to the previous correspondence on SI units (refs. 1 and 2 ) was discussed in considerable detail. A statement on SI units was then prepared and sent to the International Committee of Weights and Measurements, CIPM, for consideration. In this statement the ICRU recommended the adoption of special names for the S1 unit the joule per kilogram, J/kg, when applied to absorbed dose and related quantities, and for the SI unit the reciprocal second, s - l , when applied to the quantity activity as a measure of the rate of spontaneous nuclear transformation of radioactive nuclides. The ICRU statement was also discussed at the IAEA symposium o n Advances in Biomedical Dosimetry, March 10-14, I975 (ref. 3). The CIPM treated the ICRU proposals with expedience and drafted two resolutions for consideration by the 15th General Conference of Weights and Measures, CCPM, at its meeting in May-June, 1975. At this meeting, which celebrated the 100-year anniversary of the Meter Convention, the CGPM adopted the following resolutions:
Resolution H I The Fifteenth Confirence GCnkrale des Poids et Mesures, --owing to the urgency, expressed by the International Commission on Radiation Units and Measurements (ICRU), to extend the use of the International System of Units to research work and applications in radiology; --owing to the necessity of making the use of units as simple as possible for non-specialists;
Australasian Radiology, Vol. XIX,N o . 3, September, 1975
303
LETTERSTO -taking into account the seriousness of the risk of errors in therapy: ADOPTS the following special name of SI unit for activity: the becquerel, symbol Bq, equal to the second to the power minus one. Resolution H 2 The Fifteenth Conference GCnCrale des Poids et Mesures, --owing to the urgency, expressed by the International Commission on Radiation Units and Measurements (ICRU), to extend the use of the International System of Units to research work and applications in radiology; --owing to the necessity of making the use of units as simple as possible for non-specialists; -taking into account the seriousness of the risk of errors in therapy; ADOPTS the following special name of SI unit for ionizing radiations: the gray, symbol Gy, equal to the joule per kilogram. Explanatory note.-The gray is the SI unit of absorbed dose. The gray can also be used with other physical quantities expressed in joules per kilogram provided these quantities belong to the field of ionizing radiations. Thus the SI unit the joule per kilogram when used for ionizing radiation (absorbed dose, kerma, specific energy imparted, etc.) is given the name gray with the symbol G y ; 1 Gy = 100 rad = 1 J/kg. And the SI unit the reciprocal second (one per second) for activity is given the name becquerel, symbol Bq. 1 Bq = 1 s-I -2.703 x Ci. Antoine Henri Becquerel (1852-1908) discovered radioactivity in 1896 (“rayons de Becquerel”) and was given the Nobel Prize in physics in 1903 together with Marie and Pierre Curie. Louis Harold Gray ( 1905-1965) made one of the most fundamental contributions to radiation dosimetry, the principle now known as the Bragg-Gray Principle.
304
THE
EDITOR
The ICRU did not recommend to the International Committee of Weights and Measures that a special name be given to the SI unit of exposure to replace the currently used rontgen. The ICRU now recommends that the special units the rad, the rontgen and the curie be gradually abandoned over a period not less than about 10 years and replaced by the SI units the gray (Gy ), the coulomb per kilogram (C/kg) and the becquerel (Bq), respectively. It is desirable that preparatory steps be taken as soon as possible by various national and international bodies in order to facilitate a smooth, safe and efficient transition. In its report “Supplement to ICRU Report 19, Dose Equivalent” (ref. 4 ) the ICRU published its decision that the physical dimension of the quantity dose equivalent should be the same as for absorbed dose. From the radiation protection point of view the availability of a proper set of quantities and units in this field is of paramount importance. The formulation (for selection) of a suitable unit for dose equivalent is therefore a special problem which will be thoroughly discussed by ICRU. On behalf of the International Commission on Radiation Units and Measurements: H. 0.Wyckoff, Chairman. A. Allisy, Vice-chairman. Prof. K. LidCn, Scientific Secretarv of ICRU. Radiation Physic; Department, University Hospital, S-221 85, LUND, Sweden. REFERENCES ‘Liden, K. ( 1973) : Australian Radiology, 17, 116. ‘Liden, K. (1974): Acta Radiol. Tlier. Pkys. Biol., 13, 95. 3Lidtn, K. ( 1975): SI Units in Biomedical Dosimetry. In “Advances in Biomedical Dosimetry,” IAEA. Vienna (in press). ‘International Commission on Radiation Units and Measurements: Dose Equivalent Suppl. to Report 19, ICRU, Washington, D.C. (1973).
Australasian Radiology, Vol. X I X , N o . 3, September, I975
