Radiological protection in medicine

Draft document: Radiological protection in medicine
Submitted by Toru Fujita, JSRT - Japanese Society of Radiological Technology
Commenting on behalf of the organisation

We would like to appreciate the remarkable efforts of the International Commission on Radiological Protection (ICRP) and also express special gratitude for the openness and sincerity in revising the drafts in response to public comments. We highly appraise this draft and hope our comments would contribute to make the excellent publication even better. These are the comments of the Japanese Society of Radiological Technology (JSRT) on the draft of Radiological Protection in Medicine in Jan. 2007 #1. Technical comments: 1-1. P8, 3.1 Deterministic Effects (Tissue Reactions) AmendmentF The explanation and the historical background of implementing the new term gtissue reactionh would be helpful to understand the text. Reason: The term "non-stochastic effects" and "deterministic effects" were too notional for medical practitioners. On the other hand the proposed term "tissue reactions" is more familiar to medical practitioners. Therefore we appreciate these new terms. However it is desirable that the reason and historical background of these news terms were added briefly to avoid confusion. 1-2. P8, 3.1 Deterministic Effects (Tissue Reactions), line 12-15 AmendmentF The magnitude of this threshold will depend on the dose rate (i.e., dose per unit time) and LET (linear energy transfer) of the radiation, the organ irradiated, the size of irradiated part of the organ, and the clinical effect of interest. Reason: Beam size also affects the threshold of tissue reactions. Moreover appropriate beam size control is important in medical radiation. 1-3. P9, 3.2 Stochastic Effects (Cancer and Hereditary Effects), line 28-30 AmendmentF It is expected to explain that whether there is a small threshold or not is a meaningless issue for radiation protection. Reason: The existence of such a small threshold hardly affects clinical judgment and risk perception. The risk perception of a patient depends on the risk communication rather than risk assessment in the psychological aspect. Therefore the improvement of risk communication is the key role to secure the reliability of radiological examinations. 1-4. P11, 4. Dosimetric Quantities, line 15-17 AmendmentF For example, defined tissue is irradiated skin for the risk assessment of tissue reaction. Reason: It would be helpful to add the example of gdefined tissueh. 1-5. P12, 4. Dosimetric Quantities, line 22-28 AmendmentF It should be distinguish the protection quantity and exposed dose index for the usage of the effective dose. Reason: Clinical physicians assess the risk not only by the effective dose but also with relating factors. Epidemiologists assess the risk not only by the effective dose but also with the distribution of sensitivity. Therefore it seems that this sentence is not adequate because medical practitioners use effective dose as the exposed dose index rather than protection quantity for radiation safety. 1-6. P15, 5.6 Demographics of the Patient Population, line 25-27 AmendmentF It should be noted on the treatment for multiple organs exposure. Reason: In medical radiation, multiple organs are exposed and comparison of doses to multiple organs is necessary to assess the radiological examination. Therefore the combination of the doses of organs seems to be important in planning a radiological examination. 1-7. P16, 5.7 Range of Detriments from Radiation Uses in Medicine, line 10-13 AmendmentF In the long period of exposure, it might be considered about reduction factor on radiation effect for past exposure as shown in 17.2. Although physicians have to explain their patient about the sufficient benefit of radiological examination, especially to discuss the accumulated dose, it is necessary to consider about the anxiety of a patient. One of the major issues in medical radiation is risk communication between a physician and a patient. In almost all case, it seems that the problem is not risk assessment but risk communication. Therefore it is expected that ICRP would provide basic knowledge and skills of risk communication in medical radiation based on the recent development of psychology such as the feeling of salient value similarity (SVS) model for social trust acquirement. Moreover it is recommended to prepare the consultation service for patients on medical radiation safety in a hospital. Reason: For the relief of patient, the informed consent is very important. However patients suffer anxiety any time in their process of diagnosis or medical treatment. In Japan some hospitals set up medical radiation safety counter and it works a lot. 1-8. P28, 11. Radiological protection in Emergency Medical Situations with Radioactive Materials. line 22-24 AmendmentF It is desirable to mention on misadministration that causes the extravasations of radiopharmaceuticals with high-energy beta or auger electrons leads the skin injury as Williams G, Palmer MR, Parker JA, Joyce R mentioned at their paper; extravazation of therapeutic yttrium-90-ibritumomab tiuxetan (zevalin): a case report in Cancer Biother. Radiopharm. 21(2),101-5, 2006. 1-9D Sub-ClauseF12.4 Exposure of Comforters and Cares of Patients, page 32, line 7 AmendmentsF 5mSv per episode for adults and 1mSv per episode for children. ReasonF To unify Sub-Clause17.7. 1-10. AmendmentF The description about cataract would be necessary to unify to the approved 2007 recommendations. #2 Editorial Comments 2-1. Sub-ClauseF17.4 Computed Tomography(Publication 87) AmendmentsF The meaning of the term goperatorh should be clarified. ReasonF The radiological technician should be distinguished from the operator. 2-2. AmendmentsF The glossary would be prepared at an appendix. ReasonF The glossary would help to grasp the outline of this document for medical practitioners.