Clinical Dosimetry, Calibration and Quality Assurance in Qatar
September 27, 2026
10 min read
DITEC Experts, Radiation Protection Team, ALDuha Institute for Training and Environmental Consulting
Where the medical section stops asking and starts measuring
The first three articles of this medical block asked questions: who carries the duty, is this exposure justified, what extra rules apply once the source is inside the patient. Articles 45, 46 and 47 stop asking. They require numbers - determined, documented, traceable and checked on a schedule.
The three fit together in one line. Article 45 says which quantities have to be known. Article 46 says the instrument that produced them must itself be trusted, and says what makes it trustworthy. Article 47 says all of that has to live inside a written programme rather than in one physicist's head. Miss any one of the three and the other two lose their value.
One warning before the detail. None of these three articles contains a dose figure, a tolerance or a time interval in numbers. Anyone who quotes a number and attributes it to Articles 45 to 47 has taken it from somewhere else. Where the Regulation wants an interval it says so in words: on the periods decided by the Council.
Article 45: five quantities, and the patient they are measured on
Article 45 is headed Clinical dosimetry, and it opens by requiring the licensees to measure clinical doses and to satisfy themselves that the items that follow are determined and documented. Two verbs, not one. Measure, and then make sure the result is determined and documented. A number that exists only on a screen during the procedure has not satisfied this article.
Item 1 covers diagnostic radiology: the typical values of entrance surface dose, dose position, dose rates and exposure times for adult patients of typical size - or organ doses in the case of radiological examinations. Note the reference population: adult patients of typical size. The article asks for a representative figure per examination type, not a reading filed for every patient who walks in.
Items 2, 3 and 5 move to therapy, and there the article does want it per patient. For external beam: the maximum and minimum absorbed dose delivered to the planned treatment volume, together with the absorbed dose delivered to a relevant point such as the centre of that volume, and to the other relevant points the prescribing medical practitioner chooses - and that is required for every patient treated with external beam equipment. Maximum, minimum, and a named reference point - for every patient.
Item 4 is the one clinics overlook: the typical absorbed doses patients receive in diagnosis or treatment with unsealed sources. Unsealed sources - nuclear medicine - are inside item 4 whether the department calls what it does diagnosis or therapy. And item 5 sweeps the organs: the absorbed doses delivered to the relevant organs in all types of radiotherapy.
What Article 45 asks for, by modality
| Modality | What must be determined and documented | Per patient? |
|---|---|---|
| Diagnostic radiology | Entrance surface dose, dose position, dose rates, exposure times - or organ doses | Typical values for adults of typical size |
| External beam therapy | Maximum and minimum absorbed dose to the planned target volume, dose at a relevant point such as its centre, and at other points the prescribing practitioner chooses | Yes - expressly |
| Brachytherapy with sealed sources | Absorbed doses at relevant points selected in each patient | Yes |
| Unsealed sources - nuclear medicine | Typical absorbed doses patients receive, in diagnosis or in therapy | Typical values |
| All radiotherapy | Absorbed doses delivered to the relevant organs | Relevant organs |
Article 46: the chain that ends in a standards laboratory
Article 46 is headed Calibration requirements, and it opens by requiring the licensees to observe those requirements and, in particular, to verify what follows. The first item is the one that decides whether the other four mean anything: that the calibration of the sources used in medical exposures can be traced to a standards dosimetry laboratory.
The word the article uses is traceability. A calibration certificate that cannot be traced back to a standards dosimetry laboratory is paper. This is the item that most often fails in practice, and it fails quietly: the certificate exists, it carries a date and a signature, and nobody asked which standard it hangs from.
Item 2 tells a therapy department what its beams are calibrated for: the quality or energy of the radiation, and the absorbed dose or absorbed dose rate at a pre-set distance under stated conditions, following the recommendations issued by international institutions or bodies such as the International Atomic Energy Agency. Quality or energy, absorbed dose or dose rate, at a pre-set distance, under stated conditions - four variables, and the international recommendations named as the method.
Items 3 and 4 split the sources. Sealed sources for brachytherapy are calibrated in terms of activity, or the reference air kerma rate, or the absorbed dose rate in a specified medium at a specified distance and for a specified reference date. For nuclear medicine the item requires the activity of the radiopharmaceutical to be administered, with the value of that activity determined and recorded at the time of use - not at the time of delivery.
Item 5 is the schedule, and it has three triggers, not one: calibration at the time the unit is prepared for operation, after any maintenance capable of affecting the calibration, and at the intervals the Council decides. Commissioning. After any maintenance capable of affecting calibration. And at the Council's intervals. The middle trigger is a judgement the department has to make and write down every time an engineer touches the machine.
Article 47: a programme, and the experts it names by discipline
Article 47 requires a comprehensive quality assurance programme for medical exposures, drawn up with the participation of qualified experts in the relevant fields, such as radiation physics, radiopharmacy or medical physics. Three disciplines named. And the word is participation - they take part in building it, rather than reviewing it afterwards.
The article then points outward for the principles: the programme is to have regard to the principles laid down by the relevant organisations, such as the World Health Organization and the Pan American Health Organization. Two organisations named in the text itself. A programme written with no reference to recognised principles is not what this article describes.
The five components are where the programme becomes checkable. Measurements on the physical parameters of radiation generators, imaging devices and irradiation installations at the time of preparation for operation and periodically thereafter. Verification of the appropriate physical and clinical factors used in diagnosing or treating patients. Written records of the relevant procedures and results. Verification of the proper calibration and operating conditions of dosimetry and monitoring equipment. And, wherever possible, regular independent review of the quality assurance programme for radiotherapy procedures.
That last one is the only item in the three articles softened by a condition: independent review is required wherever possible. It is still written in, and a department that has never once had an outside audit of its radiotherapy quality assurance should be able to say why it was not possible.
What a department can check about itself this week
None of this needs a project. Four questions, answered honestly in an afternoon, tell a department where it stands against Articles 45 to 47.
Four questions
Article 45
- Can you produce, today, a typical entrance surface dose for your five commonest examinations - on paper, with a date?
- For therapy patients, is the maximum and minimum absorbed dose to the planned target volume recorded per patient, or only the prescribed dose?
Article 46
- Take your dosimeter's calibration certificate. Which standards laboratory does it trace to, and is that written on the certificate?
- Was the unit recalibrated after the last maintenance visit that could have affected calibration - and who decided it could not?
Article 47
- Is there a written quality assurance programme, and does it name the qualified expert who took part in writing it?
- Are the periodic measurements on generators and imaging devices being done, and are the results written down rather than passed on verbally?
Questions people actually ask
Does Article 45 mean we must record a dose for every single patient?
Not for diagnostic radiology. Item 1 asks for typical values for adult patients of typical size - a representative figure per examination type. Items 2 and 3, which cover external beam therapy and brachytherapy, are expressly per patient. So: typical values in diagnosis, per patient in therapy.
How often must equipment be calibrated under Article 46?
The article gives no interval in numbers. It gives three triggers: at commissioning, after any maintenance capable of affecting calibration, and on the periods decided by the Council. Anyone quoting a fixed number of months as the requirement of Article 46 has taken it from a standard or a manufacturer, not from this text.
Must a clinic employ a medical physicist to satisfy Article 47?
The article requires the programme to be built with the participation of qualified experts in the named disciplines. It does not say the expert must be an employee. What it does not allow is a programme with no qualified expert taking part in it at all. How that participation is arranged is the licensee's decision and should be documented.
Our supplier calibrates our equipment. Is that enough?
It depends on one thing the Regulation names and the supplier's invoice usually does not: traceability. Item 1 requires that the calibration be capable of being traced to a standards dosimetry laboratory. Ask for that on the certificate. If it is not there, the calibration has been done but Article 46 item 1 has not been met.
How the Institute can help
Articles 45 to 47 are where a hospital discovers that radiation protection has become a measurement discipline. The Institute's part in that is training and advice: preparing the people who will run the programme, and reviewing what a department already has against what the Regulation requires.
Advanced radiation protection training for the RPO / RSO in the medical sector, awareness sessions for radiology and nuclear medicine staff, and a documentation review that maps what you hold against Articles 45, 46 and 47 item by item.
Scope of what the Institute does: training and consulting. Field radiation surveys are carried out through specialist partners working in the field. The Institute does not carry out laboratory analysis, instrument calibration or equipment testing.
This explanation is published for awareness by the radiation protection team at ALDuha Institute for Training and Environmental Consulting. The English text is an explanation, not a certified translation: the Arabic text published in the Official Gazette governs in case of any difference, and the official Arabic wording of every article discussed here is quoted in full on the Arabic version of this article. This article does not replace the official text or advice from the competent authority. Last updated 27 September 2026. Reviewed by Dr. Said Kaddouch, PhD in Medical Physics, radiation protection expert.